KymcoForum.com
Scooters - 50cc => Agility 50 => Topic started by: 09agility50 on November 21, 2012, 09:00:10 PM
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I have recently installed a 72cc BBK and wanted to share my experiences. So far i am happy with the kit. It was and easy install everything went together well. You do lose the Exhaust gas recalculation stuff, but who needs that on a scooter! The low end torque is the biggest gain. from a stop to 30mph it pulls hard(for a scooter!). On the top end i gained about 4-5MPH over the stock 50cc. on the 50 and 72 i had a ncy cvt kit. i did put in an 87.5 main jet and it did help out a bit too. overall with 72cc, ncy cvt kit, and 87.5 jet i can do 50mph on flat ground with no wind. I also cut the cdi but that didnt cost anything.
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thats good to hear. keep us updated. want to put a 72 kit on mine soon so feedback is good
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Yeah i fancy a kit too eventually. So its pretty easy to fit then? No problems? Which kit is it, got a link for it?
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When you get used to the extra power and you're looking for something extra, I can recommend the NCY T2 camshaft, which is a perfect companion for a 72cc BBK...
It will not only increase power above 6000rpm or so, but it will also extend the powerband of the engine well beyond 8500rpm - which is especially noticeable in acceleration above 50km/h - it will make you smile, I guarantee ;D
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I second that on the cam, its such a difference. I thought wow ok so the 50mm kit made it faster but still no guts up top, finally installed the cam...BAM! day and night. Im running the NCY kit I love it. I have the 52.4mm naraku kit also but I would rather wait till I get a better crank.
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BANG......................another one bits the dust.....................
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Yes it was a fairly easy install. I would recommend having some mechanical ability for the install. A second set of hands is nice too. No problems so far only has less than 15 miles on it though. was going to run the stock head since valves are the same size, but on the new head the valve springs are stiffer so went ahead and used the new head. I am planning on a different cam down the road. Another thing i noticed, not a big deal, the new piston is dished compared to the 50cc piston which is domed. therefore the compression is actually a lot lower on the 72cc kit.
Link: http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html (http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html)
Can't beat the performance for 100 bucks!
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http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html (http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html)
on the picture listing it has everything. even an oil pump....is that nessery? i meen when you change to a bbk, do you need to change the oil pump as well?
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There's a reason that BBK kits from decent brands and suppliers don't include an oil pump :
You don't need to change the oil pump, the OEM one is just fine - and a cheapo chinese copy is only more likely to fail...
When you see a BBK kit with an oil pump included, it's very likely that the supplier just tossed in a cheap piece of sh** to make an already cheap piece of other sh** look more attractive ;D
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The oil pump isnt really necessary. I didn't change it on mine i left the stock one in it. I dint want to split the case to install it so i just left that part alone. BTW it isnt any more chinese than kymco is! I am not talking bad about kymco either i prefer my kymco over beamers and zumas and other scooters. My agility 50 will beat theirs all day even before a BBK.
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just as i thought. what makes of bbk do people recomend? so many on the market. whats the best? i keep looking at the narkau 72 kit. in the uk seems a good price at £50. but last thing i want is to put as cheep polish made bbk on that will brake and wreck the engine.
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BTW it isnt any more chinese than kymco is!
Lots of Kymco parts are made in China, but Kymco does a lot of quality control, and they use only a few selected well known manufacturers, whose brands are imprinted on those parts, together with the Kymco brand.
This is completely different from the generic no-brand GY6 and 139QMB parts out there, like those cheap BBKs, which can come from any source and without any sane quality check - and if you let those manufacturers decide for themselves how to manufacture cheap sh**, it will not only be cheap, but sh** indeed ;D
just as i thought. what makes of bbk do people recomend?
I'm very happy with my NCY 85cc BBK (including a cylinder head with larger valves) so far : quality and finish looks good to me, all fits well, runs well, sounds well, no excessive oil use... My engine runs like it was designed and manufactured this way ;D
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What size is the 85? 50mm comes out to 82cc 51 is 86, 52 - 90, 52.4-92cc.
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It was a lot larger than the 72cc that it replaced, and since a few cc more or less is completely irrelevant, I didn't check the exact size...
The design of the cylinder head makes a lot more difference than the exact number of ccs - but for those interested in meaningless numbers : the NCY catalogue says 50mm... which means 82cc (if LoveMyKymco is correct) - which is nice, considered that even well known motorcycle manufacturers often exaggerate the displacement of their engines by a larger margin... (it's standard industry practice to name round numbers instead of the exact sizes)
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Stroke times pi times radius squared divided by 1000. Stroke x (pi 3.14 ( radius squared)/ 1000
41.4(3.14( 25 x 25)/1000= 81.2475 cc so its actually closer to 81cc but they like to round up rather than down in engineering. A few irreverent CCs makes a generous 4-5% increase in bore size. Its funny how the Chinese don't know the same math the rest of the world does. I know mine quite well.
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Its funny how the Chinese don't know the same math the rest of the world does. I know mine quite well.
The math is obvious and simple, even for the Chinese, but the reason nobody cares about exact numbers in lots of cases is because they don't matter that much most of the time. There's no use, for example, bothering with a 4..5% difference in displacement if other variables in the same system make much larger differences in both actual and perceived performance...
Manufacturers just choose the actual sizes of their products for convenient design and production instead of aiming for round numbers. They round up the marketed numbers to the nearest common sounding number, because using numbers like 81.248cc in the name of a vehicle or aftermarket part would sound rather ridiculous to most people...
This is not something that's limited to Chinese manufacturers or motorcycle business, it's standard industry practice - and I'm happy with it, because it increases the signal to noise ratio of this already far too chaotic world ;D
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What ever happened to the old truth in advertising law? My 200 is only
a 175, I could use the extra 25cc's. Some 163's are called 200! When
your talking 80 cc's 8 is 10 percent! That's a lot in my book....
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I agree, there's a difference between rounding up for convenience and shameless inflation, and while 10% is not really dramatic in my book, selling a 163 for a 200 is over the edge indeed...
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Same reason a chevy 350 was only 346 CI, it just sounds better and if you dont know any better you go for it.
A 4-5% increase in cylinder bore can increase CR by .2-.4 ratio so it does in fact make a huge difference. If the piston were to be say dished instead of domed it wouldnt matter as much but if its the design for same design it will in fact make a difference.
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A 4-5% increase in cylinder bore can increase CR by .2-.4 ratio
This could only be important for kits that come without a matching cylinder head - and even then, the shape of the piston crown is the most determining factor, not the bore size....
Heck, I own a 72cc kit with a hollow shaped piston, which, when measured, proved to have almost the standard compression ratio with the standard head, although the displacement was increased by a factor of 1.4 ...
Apart from that, more compression doesn't always mean a significant increase of power. The compression vs. power curve is almost flat near the knock limit, which means that if the compression for your setup is already quite high, the only thing you'll gain is an increased chance of detonation...
(Interesting read for example : http://rescomp.stanford.edu/~efroeh/papers/RDH_Engine_Performance.pdf (http://rescomp.stanford.edu/~efroeh/papers/RDH_Engine_Performance.pdf) )
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The size of the bore directly effects the degree of slope towards the crown. Like I said it matters more on domed pistons more than dished.
Most 72cc kits have dished pistons and usually have same if not lower compression than stock.
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Still, when it comes to choosing a kit to buy, the only sensible prediction you can make from the size of the bore is the exact displacement in cc, which still says very little about the performance it will achieve compared to other kits with only a few cc more or less, especially when the kit comes with its own cylinder head...
From my experience, I prefer better build quality, a head with larger valves and a slightly lower compression ratio over a few cc more... Especially since a few percents of difference in performance isn't noticeable by any sane person without a dyno, but reliability sure as hell is.... 8)
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What ever happened to the old truth in advertising law? My 200 is only
a 175, I could use the extra 25cc's. Some 163's are called 200! When
your talking 80 cc's 8 is 10 percent! That's a lot in my book....
Manufacturers will claim that the badge on your vehicle is the model of your vehicle and does not really reflect the actual engine displacement or even a part of advertisement. The spec sheet says the actual engine displacement, right? However, when it comes to specific engine parts...it's a different story...
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Well if you call it 280Z that's ok but if you call it Yager 200i it should be close to 200.
It's like computer monitor's, used to be a 17" was 17" now it's 15.8" viewable. Their
always trying to pull one over on you. I'm surprised the Chinese 50's don't all have
big numbers on the side. "Squiggly 1000, Super Power 350, Mega Max 900!"
Kymco missed it with Super 8 and Super 9. I think those numbers are lucky in the Chinese
culture. Here it sounds weak. "Mine goes to 11!"
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"Mine goes to 11!"
;D ;D ;D ;D ;D ;D
http://youtu.be/EbVKWCpNFhY (http://youtu.be/EbVKWCpNFhY)
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Id ride the squiggly 1000 ;D
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Well if you call it 280Z that's ok but if you call it Yager 200i it should be close to 200.
It's like computer monitor's, used to be a 17" was 17" now it's 15.8" viewable.
Yeah....just like seedless water melons that contain seeds......
(http://www.vidfu.net/sites/default/files/images/Seedless%20Watermelon%20May%20Contain%20Seeds.preview.jpg)
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The oil pump isnt really necessary. I didn't change it on mine i left the stock one in it. I dint want to split the case to install it so i just left that part alone. BTW it isnt any more chinese than kymco is! I am not talking bad about kymco either i prefer my kymco over beamers and zumas and other scooters. My agility 50 will beat theirs all day even before a BBK.
While I love my a50 as well, there is no way in hell the agility would touch a Zuma on any day of the week for many reasons even with it derestricted. The Zuma is a 2 stroke and if both are stock the 4 stroke doesn't have the torque to hold a candle to the Zuma.
On the bbk, I've found that many sites have kits for short money. I'm researching one that is Taiwanese instead of Chinese because of quality. So far I've looked on monsterscooterparts.com, scootertronics.com, enviromoto.com, and racingplanetusa.com. Anyone that wants to comment on experiences or thoughts on quality, please let me know
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Well I was reading a 2 stroke tuning book and it turns out the displacement doesn't really tell the story.
It's really displacement above where the exhaust ports close that counts. I don't think you can get
enough info to tell how good a cylinder is before you buy it. The pipe makes a huge difference too.
I'd buy a kit that had pipe, cylinder and head all matched for best performance.
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...big difference in 2 stroke cylinders....ports are in the cylinder wall....4 t ports are in the head ..
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..any 50cc 4t that i've seen with a 70+cc upgrade craved a pipe and free flow air....
..the oem exhaust is too restrictive...
..gotta have more air to make it work...
..after that, plan on changing every component of your oem cvt, because it wont work either...
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Little update, I've talked to 4 suppliers and researched them too. Scootertronics is a scam artist so I won't be ordering from him again. Bad comments/reviews (google). Monsterscooterparts uses a Chinese kit which may be ok but I'm going Taiwanese. I looked for a 72cc kit from Taida with no luck. Enviromoto sells the same kit as monster (with head) for the same price. He also carries the NCY cylinder kits in 72,80,85 and I talked with him for 15 min today about testing with and without a head. He said the head isn't necessary with the 72 kit because there is no change in the valves. He dyno tested it and came up with a compression of 9:1. NCY is made in Taiwan and I've seen better quality parts but I trust it MUCH more than any Chinese kit. So I'll be going with the NCY 72cc kit with no head for now. I'll run that by itself then probably add a cam if it runs well.
On a side note I also researched the malossi vs polini variator and I got the polini over malossi both times. I also ran a polini in my Ruckus when it was stock and it was better than the malossi for the Ruckus too.
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NCY is OK.
With a 72cc I can recommend the NCY T2 camshaft.... You'll love it, but first try the 72cc on its own, the difference is interesting..
By the way, in my experience, it's better to go for the 85cc. Without the camshaft, it doesn't cost much more than the 72cc plus camshaft, and performs about the same or even a bit better... The difference is that you can go another step faster by adding the camshaft later on, while with the 72cc, you're stuck at a lower level...
And, if cash is a limiting factor, it's better spent on a good BBK and torquedrive than on a smaller/cheaper BBK and variator...
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Scootertronics is a scam artist so I won't be ordering from him again
...that is so true, and something i learned a cpl years ago for myself...
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Mono, I thought about it and have chosen to stay with the smaller bore for a few reasons. First my a50 is my daily driver. I need this thing to have more punch but not be a complete monster and beat the bag out of my engine. I understand I'm taking a risk by modifying it at all but I believe this will be a little easier on the engine. 2nd, while $ isn'tthe end all be all, I'm trying to keep it reasonable and I'm also rebuilding my ruckus witha 180cc engine if I want to go beastly fast. If I did an 80 or 85 bbk I would have to buy the matching head to really get the bigger bore to perform like it should. That being said if I was to get a bigger bore it would be even better quality than the Taiwanese NCY, I would buy Taida, the best. BIG $$$$$. Last, if I buy a bigger bore kit I'd want to go full tilt with performance options, exhaust, pod filter, sticky tires, carb, clutch, crank, upgears, etc. I'm just looking to fill a small void my bike has now. I want the stock airbox, I want to keep the carb and exhaust stock for now.
Which setup do you have now? Btw, I have an aftermarket torque diver already and a naraku variator. BBK aside, the variator and clutch are the most important mods to do even before a bbk, carb, cam, exhaust, etc. Just my opinion. All comments and pointers welcome.
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Well, if you already own a 180cc Ruckus, and just need a bit of an upgrade for the Agility as a reliable daily driver, I think it's fine to go with the 72cc indeed... With a decent kit, this will still be a very reliable setup, but it will be a lot easier to keep up with traffic, especially when you add a T2 camshaft for a bit of extra punch towards the top end...
I'm very pleased with my 85cc+T2 setup on the 12" A50 nowadays, but it's a bit early to tell whether it's as reliable as the 72cc setup on my 10" A50, which lasts for quite a while already and still shows no signs of wear...
My scoots both run the stock variator and belt + NCY and Malossi torquedrives + slightly modified stock airbox + stock exhaust + Bridgestone ML50 sticky tyres... Roller weights on the 10"/72cc are chosen for maximum power, but for the 12"/85cc I went for a lower revving setup, since it has power to spare and I like the deep sound 8)
I've been disappointed by some variators other than stock, and I also don't like the idea of noisy dry-weather-only open air filters and flaky/noisy/way-too-shiny performance exhausts...
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..try a malossi multivar...
...guarantee you will love it!!
;D
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Well, if you already own a 180cc Ruckus, and just need a bit of an upgrade for the Agility as a reliable daily driver, I think it's fine to go with the 72cc indeed... With a decent kit, this will still be a very reliable setup, but it will be a lot easier to keep up with traffic, especially when you add a T2 camshaft for a bit of extra punch towards the top end...
I'm very pleased with my 85cc+T2 setup on the 12" A50 nowadays, but it's a bit early to tell whether it's as reliable as the 72cc setup on my 10" A50, which lasts for quite a while already and still shows no signs of wear...
My scoots both run the stock variator and belt + NCY and Malossi torquedrives + slightly modified stock airbox + stock exhaust + Bridgestone ML50 sticky tyres... Roller weights on the 10"/72cc are chosen for maximum power, but for the 12"/85cc I went for a lower revving setup, since it has power to spare and I like the deep sound 8)
I've been disappointed by some variators other than stock, and I also don't like the idea of noisy dry-weather-only open air filters and flaky/noisy/way-too-shiny performance exhausts...
Can you see a noticeable difference in the malossi vs ncy torque driver? I know there is a BIG price difference $170 vs$33.
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..try a malossi multivar...
...guarantee you will love it!!
;D
I was about to order the malossi but I've gotten 2 responses from dealers saying the polini is better for my application. And I know they're not bullsh**ting me because the malossi is more expensive LOL
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Can you see a noticeable difference in the malossi vs ncy torque driver? I know there is a BIG price difference $170 vs$33.
There are some differences when you study them close enough, the NCY has a tiny bit more play than the Malossi, but on the other hand it gives a choice between two distinct settings for the guide track angle, while the two settings on the Malossi only have a very subtle difference...
In practice they're both good, and with both of them setup at the smallest angle of the two available (for the most constant rpm), I really can't tell the difference...
By the way, I've paid about €30,- for each of them... Sometimes they do get their pricing wrong, maybe I was lucky 8)
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I figured there had to be a glitch. On the malossi vs polini, I've searched on this subject and it seems everyone on here has the malossi and no polini reviews so I'm gonna take one for the team. If I don't see results than its an $80 backup variator :D
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Ive ran the Polini and the Malossi, the polini is better for top end speed and the Malossi is great over all. I run the Malossi on my full Malossi build for fun and polini on the other 2 zx50s I own.
The ramp plate for the malossi is much better than the polini ramp plate also, so I would use Malossi ramps for polini variators if I could, instead I use SEF ramps on my polinis and its comparable to the Malossi ramp I only run them because theyre a little cheaper than the Malossi ramps.
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..i never ran a polini variator..but they have gotten good reviews...
..and i totally agree about the malossi ramp...often over-looked, is that obscure component...
..i run malossi ramp plates even in my oem variators...
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..i never ran a polini variator..but they have gotten good reviews...
..and i totally agree about the malossi ramp...often over-looked, is that obscure component...
..i run malossi ramp plates even in my oem variators...
I see a pattern with you changing my mind ;) I guess for my application the malossi would be better. I'm looking for best thru the gears with more top end than the naraku.
LoveMyKymco, is there a REALLY noticeable difference in the way it works thru the gears?
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...lol..i saw that...
..jc, we all had good and bad experiences with even the same makers of bits...
..malossi, polini, dr pulley, gates, oem...
..ive NOT had good (over-all) experiences with some names tho...NCY, Naraku, Kenda, emco, scootertronics...
:o
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...lol..i saw that...
..jc, we all had good and bad experiences with even the same makers of bits...
..malossi, polini, dr pulley, gates, oem...
..ive NOT had good (over-all) experiences with some names tho...NCY, Naraku, Kenda, emco, scootertronics...
:D
:o
Yeah, seen some BAD reviews about scootertronics. I'm still up in the air about the 72cc NCY cylindar kit and even with all the good malossi variator reviews on here I'm still contemplating the polini from my past experiences. It's gonna be one of those shoot from the hip ordering experiences. Point, click, try what the mailman brings me.
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Hello all,
The day has come when I decide to upgrade my agility. So everything is stock for now. I planed to change the cylinder to BBK 72 (NCY) without to change the head. At the same time I will change the camshaft to NCY t2. At this point is it worth to change the camshaft (keeping in mind that everything else is stock), or I need also to change the CVT to NCY Overdrive2 ?
With changed BBK, Camshaft and CVT do I need to change exhaust as well ? The carb will stay the same, and I don know if i can run this setup with the stock nozzle.. What about consumption ? I run my scoot on 2-2.5l/100km (sorry for the measurement).. will it grow and how much to expect ?
Thanks
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Only changing the cylinder, camshaft and main jet is fine.
Main jet should be 2..4 sizes up from 50cc, mine was running fine with 86..88 (before I modded the filter box)...
Consumption will increase according to how much of the extra power you really use. Mine went from 1L/43km to 1L/35km..
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I am confused now. I was willing to order 72cc kit, but the guy at revolution70 is changing my mind... he says that with 72cc kit I will not get the good torque, and after a while I will want 85cc kit (85cc is marketing name, the true volume is 81.3cc because the diameter is 50mm). But he said I also need to buy a sport head for 80cc kit with bigger valves. The NCY kit consists of 85cc kit and sport head for it.
Please I need an advice: is it better to go with 85cc+head or 72cc with original head + t2 camshaft. (later i will buy overdrive2 vario)
Do I need to change the carburetor for bigger head (85cc), air filters and exhaust, or it can work good with stock parts?
Which setup will you choose, and why?
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Trust the guy at R70, he's always right.
My 72cc +T2 setup was nice, but I'm running the NCY 85cc + head together with the T2 now - and that is sooo much better that I wish I bought this immediately...
Instead of the Overdrive 2, I would go for the torquedrive (with straight guide tracks) from the same shop, and some 8,5 gram rollers for your stock variator, this gives a very smooth setup, with almost constant rpm and performance...
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Yes but with 85cc and head I also need to buy Rocker Arm Assembly, because after 2007 kymco has change something on it, and in 95% the sport head doesn't fit with stock rocker arm. Did you get this problem too? And with 85cc do I need to change filters, exhaust, carb, etc... ? Do i need to machine the block or something else, or it has a perfect fit ?
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With my 2010 Agility, the rocker arm assembly was just fine as it was... Even if you need an alternative one, the cost is almost nothing, especially compared to what you will spend over the next few years, now you've started modding...
Just like with the 72cc, the only "mandatory" changes are a larger main jet and heavier roller weights in the variator.
The best way to go about this, in my experience, is to only read the information on the Revolution70 website, and the manual they ship with the cylinder kits. These guys really know their stuff....
The world wide interweb, on the other hand, is full of stories about completely different parts and engines - and also full of morons who don't know or understand anything :-)
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Yep.. thanks a lot for your advices mono. The site is in dutch, so with Google translate is very hard to understand what they want to tell you :). They also tell me to buy their cheaper R70 80cc + replica camshaft, saying that the reliability is the same as NCY, with much lower price... but i think it is better to stick to NCY as its proven quality.
Why should I put the heavier roller weights, is it because I will run the engine on lower rpms.. so saving fuel...
What about increasing the top speed? Is it the best way (and cheaper) to change the variator only?
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Although I tend to trust what the R70 guys say, I wouldn't go cheap on things like this myself... It's about my daily transport, so I prefer to spend some extra cash, for that warm and fuzzy feel (or is it an illusion ?) of buying quality stuff...
You'll need heavier weights because the increased torque will pull the variator into a lower ratio, increasing rpm beyond the powerband or into the revlimiter. So it's not meant to lower rpm compared to a 50cc, instead, it's needed to keep rpm in its useful range...
If you want to increase the top speed, you'll need to do the usual variator derestriction (or install the Overdrive 2), and after that, you can also derestrict the CDI if you prefer speed over reliability - you can search this forum for plenty of advice on this...
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Hey mono, do you have a cold start problem with 85cc kit ?
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... and what about the crank shaft? is it stock? I am beginning to doubt that 85cc is a way to much for the agility... and I am afraid that if I put 85cc, the crank shaft will be gone for 1 year or less.. I watch the video of 85cc agility rs, and the guy in the comments has written that the crankshaft least for a half of year...
I can not decide yet.. in one side I will want the power of 85cc, but on the other i am afraid of overall durability of the scooter...
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The NCY 85cc starts easier than the 72cc did, the static compression ratio of cylinder and head appears to be lower for the 85cc..
Of course your crankshaft will wear quicker than with a 50cc, but it won't fail in a few miles, if all else is right...
I've been told by mechanics at different shops that a lot of the crankshaft failures they see in these Kymco engines occur with just the stock cylinder, and most failures can be traced back to oil pump failures or low oil levels in the past anyway...
And, if you really worry about durability, you shouldn't own a motorized vehicle I guess - they all tend to break expensive parts at the time your bank account is empty :-)
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Haha - motorized vehicle - good one...
Anyway R70 guys warn me that electric start is a way difficult with 85cc than 72cc especially in cold days, that's why I asked you, if you have that problem.. but obviously it is another way around in your case... :)
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Its all about compression ratios, if your 47mm kit has 9:1 ratio and your 50mm kit has 8:1 youll be fine, if its the other way you need a high torque starter and or a better higher CCA battery. Do not use your kick starter as an alternative. It is meant for back up only, unless you like replacing kicker covers.
Connecting rod failure on the A50s isnt very common at all.
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Well I don't know what compression 50mm kit has, when I look the piston it is some kind of flat top. But it really depends of the head design as well. The stock 50cc has a compression ratio 11:1, I have read that 47mm has indeed 9:1 compression and yet it is harder to start than the stock. If what you say is true: lower compression - the e-start will be easy vs higher compression - hard start... then I am confused :).
Anyway is there a high torque starter in the market for AG?
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Compression ratio only determines the maximum gas pressure that results when the piston reaches top dead center. (disclaimer : for a certain volumetric efficiency that is, which is rpm and engine dependent, probably close to 100% at low rpms for our engines, and also excluding the effect of rising gas temperature by compression itself, which will be less at extremely low rpms, and comparable in effect between a 50 and an 85cc)...
The area of the top of the piston, together with this pressure, determines the force needed to turn over the crankshaft towards and over that point...
Since an 85cc's piston has an area that is larger by a factor 1.7 than that of a 50cc (if it's really an 85cc), it's easy to see why an 85cc with a compression ratio of 9:1 will be harder to crank than a 50cc with a compression ratio of 11:1...
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I run the 50mm ncy kit and I get 8:1 compression just as you should if you have it as well, I dont know why anyone calls it a 85cc its simple math.
Theres quite a few other things that come into play but I decided not to delve into them such as the dcr, compression pressure, cam duration, the list goes on and on, but in the end the answer to the question is if you get the 50mm kit your stock starter will do just fine.
Ive got quite a few, probably near 30, 50mm kits installed and everyone of them starts with the stock starter fine. The 72cc kits actually do have an issue with starting due to higher compression ratio due to small combustion chamber heads used, and I found that using a higher cca battery will help alleviate the problem.
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Hey guys, its been a while since I've posted on here, but scooter season is almost here and its time to fire it up. I installed a 72cc kit last fall, and only got to ride it a couple of times. I was wondering what main jets are you guys using, and with what other mods? I've got a 90 jet in it now with a polini variator/6.5gr sliders, 2000k springs, open foam filter and stock head, cam, and exhaust (muffler has extra holes drilled in the end from the previous owner).