KymcoForum.com
General => General Discussion => Topic started by: macocoy on April 20, 2011, 04:05:33 AM
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How long does our two stroke last?(engine,pistons etc.)Is it true that 4 strokes last longer.?
I wonder what's the highest mileage/km a 2stroke has ever reach without changing pistons ,engine etc.
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I know there are a lot of variables that would determine the longevity of either engine configuration. I wonder if anyone has ever done a controlled test where the most important variables were the same to determine the results. Surely someone has somewhere along the line. I would like to hear my scooter mechanic Josh (a.k.a. "areomyst" on here) chime-in on this topic.
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How long does our two stroke last?(engine,pistons etc.)Is it true that 4 strokes last longer.?
I wonder what's the highest mileage/km a 2stroke has ever reach without changing pistons ,engine etc.
There is a large difference between "piston" (not "pistonS") and "engine".
Piston, rings and cylinder for air cooled 50 cc usually costs around 60-70 EUR. For water cooled, 110-120 EUR.
So, this cost is pretty much low, compared to everything else that may go wrong on the scoot, from suspension to crankshaft and many other things. Change of front disc and pads might easily cost roughly the same.
I consider piston+cylinder to be in a "mature" state after 20-25.000 kms, but they usually run well until the very last day when something goes very wrong and the little piston gets "bricked". :) :) :)
There are three things that every user can do to prolong their trouble free life:
- avoid overloading them and overheating during summer
- avoid going flat out for the first few minutes until little engine warms up (it is impossible to drive small 2 strokers below 5-6.000 rpms, but you do not have to rev it to 10.000 immediately...)
- use good quality semi synthetic oil and make sure that little oil pump is not clogged or that the belt is not snapped, if it is belt powered
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Thanks for replies,and being very specific(Axy),
So which 2stroke last longer(piston,crankshaft,cylinder etc.)?Modified or stock?I know what most people are thinking(stock r boring).I'm in the beginning of modifying my Sting/yup50.Just a curious question....
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Thanks for replies,and being very specific(Axy),
So which 2stroke last longer(piston,crankshaft,cylinder etc.)?Modified or stock?I know what most people are thinking(stock r boring).I'm in the beginning of modifying my Sting/yup50.Just a curious question....
All info I provided refers to STOCK engines.
If by "modified" you mean aftermarket cyl/piston kits, I have experience with Italian scooters and 72 cc kits.
The longest it worked properly was 10.000 kms, the shortest around 6.000 kms.
If you have stock kit for 20.000 kms, then install aftermarket 72 cc kit and it lasts 10.000 kms, the crankshaft is usually the next to go after 5.000 kms or so. OTOH, 2 stroke scoots rarely overall last for 30.000+ kms, they are either scrapped, used for parts, discarded or something like that...
Aftermarket 72 cc kits are usually of very poor quality and it is a guesswork trying to find a reputable source and long-lasting kit.
The real deal would be new kit + new performance crankshaft... however, performance crankshaft alone costs 250-300 EUR!
Performance exhaust that is a must is 250-300 EUR.
So it is really a game of numbers. If you take original value of new 50 cc 2 stroke scoot and add cost of new filter, carb, crankshaft, piston, rings, 72 cc cylinder and maybe pay for the work to be done, you have already exceeded the price of a good Taiwanese or Italian 125-150 cc 4stroke scoot.
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I didn't mean to say modify my engine ,I don't think I'll go that far,but basically thinking of expansion exhaust,aftermarket variators/clutch,maybe open airbox and bigger cylinder.most of the scooter here in the Philippines are 2stroke and they seem to last forever.
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they re very reliable
my one been fitted 72 cc kit runs so well , just make sure everytime before fill up gas tank. put like two caps of 2 stroke oil
in side tank , it will be sweet. my last 14000 km before stolen today >:(
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If you care for your scoot and dont do to many up grades to theam they well last a long time.If your the typ of person that has to do a lot of up grades and need the speed then you well shorten the life of the scoot. I have seen more scoots right out of the box last longer staying with all stock parts then the ones we all like to up grade.
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It seems to be generally accepted that ANY part that is not a stock replacement part is an upgrade on any powersport equipment . I like to think that the engineers and designers might have gotten it right occasonally . I suspect that a lot of money is wasted on "upgrades" that might actually be inferior to stock . JMO .
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Granturismo, that sucks man. Sorry to hear your scoot was stolen. You gonna get another one?
I absolutely agree. A lot of research and development goes into automobiles, scooters/motorcycles, atvs, and watercraft.
We tend to ruin these things with all the aftermarket parts. Sure they may perform better in certain situations but not all around.
I love the people trying to sell a car or truck and think it's worth more $ because of all the aftermarket parts. It's stupid >:(. If anything I think it's worth less money. I know the type of person that adds a lot of aftermarket parts. And I know not everybody that does tears them up but most do. Don't wanna piss anybody off on here ;). It's your ride you can do whatever you want with it.
I chose to put a few aftermarket parts on my scooter because I am a big dude and I like to keep up with traffic. Im not into racing or doing wheelies.
I think I pissed some people off when I bought my 4 wheeler and joined the Yamaha Blaster forum. I told them I wanted to keep it mostly stock and it was like I said something so horrible :D.
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Thanks for all replies,I just received the tecnigas next r for my kymco sting50,this question may not be related to topic but I'm just wondering do I have to upjet ?I'm leaving my stock airbox as is.my main jet right now is #75 .Would it be lean?
So Gran,was your bike oil injected?and adding capful of 2stroke oil in gas tank would be more protection?
I add 1oz of seafoam every tank hoping it will help more in lubrication and cleaning.I learned it here.
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Yes you will have to upjet. You never never want to run it lean. Running lean will do a lot of damage. As I understand the fuel/oil mix actually cools and lubricates the cylinder and piston. Especially in a 2 stroke air cooled small engine. You can burn holes in the piston running it lean.
A 75 main jet is very small. You should be at least at an 85 main or higher. You'll probably need a 90 main or higher with the Tecnigas pipe. Do a search on this forum on doing a "plug chop" it will help you to find the right main jet size. Good luck
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Thanks Peters,as I remember you're running with stock air box right?I read one if your post liking stock airbox than aftermarket ,.
Some people here told me I should be fine with stock main jet if I don't change my stock airbox,and you're saying go atleast #85(confusing)But I guess plugchop will answer that for me?
Is it hard to upjet?can a regular guy do this?
When I upjet ,do I have to adjust idle mix?where is the screw for adjustment.
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First off what scooter do you have? Is it 2 stroke?
Anytime you change to a less restrictive exhaust then you have to rejet. Doesn't have anything to do with the intake. Believe me or not.
Yes I run the stock air box. The aftermarket filter I bought was very cheap so I don't know if a name brand one would work better. Also it was very loud.
Changing out the jet is very simple. I didn't take the carb all the way out of my scooter. All I had to do is disconnect the air box duct, take off the throttle cable(screws off the top of the carb), pull off two small fuel lines, and remove the nuts holding the carb to the intake manifold. All you need is to be able to twist the carb sideways to remove the bowl from the bottom and there it is. Main jet is in the very center.
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Another helpful info peters,thanks.As I'm trying to build up courage to work on my own carb.I know a few people making mistakes on their carbs and didn't run the same again.when I change my main jet ,do I have to adjust any screws(idle,pilot/slow)?I see two screws on the side of my carb but not quite sure which is which,and how..my bike is sting50 2009 2stroke.Still didn't install my tecnigas next r(don't wanna run lean like u said.......
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The larger of the two would be the idle speed. The smaller would be the idle mix.
Try installing the pipe and new jet and just see how it runs. You may have to turn the mix screw out a little. The idle speed screw is exactly what it says. Won't hurt to play with it until you get the idle speed where you want it. Always remember where you started so you can always go back.
Good luck
Idle mix instuctions for reference
They say the mix screw should be 1 and 1/2 to 2 turns out. So you turn it clockwise and count the turns until it seats. Remember the number of turns so you can always return to that position. Then turn counterclockwise 1 and 1/2 to 2 turns and do a idle plug chop.
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So pretty much the two screws on the side of the carb are for idle,nothing to do with high/medium speed?
On my carb the 2 screws sit almost next to each other(one faces horizontal and the other in incline position)Is yours the same as mine?
So Peters when you upjet ,that's the time to turn the mix screw?What about the Pilot slow jet do I have to mess with that too,?
I'm starting to hate watching that brand new tecnigas in the living room
And not on my scoot,I'll be doing it soon.
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So pretty much the two screws on the side of the carb are for idle,nothing to do with high/medium speed?
Exactly Right
You should not have to change the pilot jet. The air/mix screw is just for fine tuning but you should get the right mix just by adjusting that a little to compensate for less restrictive exhaust.
From what I remember the pilot jet is used from idle to 1/4 throttle. The slide needle controls 1/4 to 3/4 throttle. And last the main jet kicks in at 3/4 to full wide open throttle.
Slide needle is not adjustable but I have read on here about people using a beer can to make a shim. To shim the needle up slightly. I couldn't ever figure out how to remove the needle from the retainer. I was afraid of breaking it. I tend to do that ;D. Anyway, you shouldn't need to do that. Is required with more modifications or aftermarket parts.
Let me search for an old post on here explaining it. It can get very complicated when adding lots of aftemarket parts. I only had to change the main jet though. Ohh, let me see if I can find a pic of my carb too.
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http://www.kymcoforum.com/index.php?topic=2150.0 (http://www.kymcoforum.com/index.php?topic=2150.0)
This was about a year ago when I started work on mine. Read the whole thing I got a lot of good advice. I was pretty apprehensive about messing with the carb then too. A couple of things I did wrong: I striped one of the stud bolts that holds my carb to the intake manifold because the carb has nuts in a little pocket on the side that I guess were slightly cockeyed when I put it back together. Also watch that you dont pinch any wires or hoses when you put it back on too.
Sooooo I remember now I tried to take a pic of my carb to show them but couldn't get a good one.
Let me search some more.
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http://www.kymcoforum.com/index.php?topic=1165.0 (http://www.kymcoforum.com/index.php?topic=1165.0)
Look at wordslinger's link and read the threads. I learned a a few things myself.
Also do some searching and reading on here. You'll have to dig through a lot of BS but you will learn a lot.
As far as which screw is which. Hard to say without a pic or being there to look....
I just looked at mine and my mix screw is slightly inclined too. The speed screw is completely horizontal.
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Peter lots of good info again,you're life saver.if you didn't advise me I would have put on my exhaust without upsetting as some folks here told me no need to upjet as long as I keep my stock air box.I would have been running lean (broken engine).
We both have the 2009 2stroke model so I'll follow whatever u did,I'm not thinking of buying open air filter,I'll stick with stock air box and maybe drill holes later on.It rains here in Hawaii(my part)about 30% of time.Don't like the idea of water getting in carb.
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I'm not thinking of buying open air filter,I'll stick with stock air box and maybe drill holes later on.It rains here in Hawaii(my part)about 30% of time.Don't like the idea of water getting in carb.
Good idea. I have trouble in the rain sometimes with the holes in my box
Well I thought mine was a 2009 but when I finally got my title from the dealer a few weeks ago(almost a year after I bought it RIDICULOUS >:() I found out it's a 2010. I'm pretty sure they are the same engine though.
Good luck and let us know what happens. Feedback is great for the next guy/girl that comes along.
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Sure thing Peters.By the way what is the size of your main jet right now?And when you drilled hole on the air box,did you drill on the cover (outer part) or behind (tire side)?
I just came back from the dealer looking for main jets but they couldn't find any(out stock).So I'm kinda thinking of drilling,hopefully it works..
Will be installing new pipe my next dayoff.I let you know the progress...
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Sure thing Peters.By the way what is the size of your main jet right now?And when you drilled hole on the air box,did you drill on the cover (outer part) or behind (tire side)?
I just came back from the dealer looking for main jets but they couldn't find any(out stock).So I'm kinda thinking of drilling,hopefully it works..
Will be installing new pipe my next dayoff.I let you know the progress...
My jet size? uhhh..... I am at like a #95 or .95mm. I am not positive on the exact size because the bits I bought went from .90mm to 1.00mm. I had to take a 1.00mm and very slightly grind it on a taper. Then I compared how far the bit went in on the #95 jet I bought(wrong threads). After I measured the depth it went in I drilled my stock jet to the same depth. So the wrong jet did actually come in handy to compare to the jet I was drilling.
I think I have it a little rich with the .95. Better a little rich than lean.
Important! Only drill holes in the air box cover. If you have holes in the box itself(beside the tire) you would be pulling in unfiltered air(bad).
You have to drill the holes on the dirty side of the filter(the cover) so the incoming air can be filtered.
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Okay thanks,I guess my target will be #95,seems large compare to my stock #75.How many holes 1/2 inch should I drill on the cover?
I ordered the torch welding tip cleaner,hopefully it will tell me size in (mm) so I can just copy what you did.I wonder how heavy the roller weights that came with the tecnigas next r?r u using it?Oh when u put the solder in the jet did u put it on the head or tip?thanks
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Start with like .90. The best thing to have is some welding tip cleaners and work your way up one at a time. When you get to like a .90 try it out and see what happens. Climate and elevation have a lot to do with it so you may not run the same jet as me.
Do a WOT plug chop. Warm the engine up on the plug you have now. Pull the old one out and install a fresh plug. Take off at Wide Open Throttle. I like to do a few miles to get a good sure color on the plug and kill the engine while still holding the thottle open. Pull the plug out and look at the white insulator. You want like a dark tan coffee color. The reason it's called a plug chop is some people cut the thread base off on the plug exposing the white insulator for a better veiw. You dont have to do that though.
Start with like 1 or 2 holes in the air box cover. Not sure on the weights that came with the pipe. I run 6.5g or 7g rollers now. Can't remember now ???. You should heat the the head where the hole is(thats what she said :D Sorry. I like to take the tip out of a soldering iron, put the iron in a vise, and fill just a little solder in the hole. Not to much. Make sure when you drill the hole you drill it straight not on an angle. Again a vice is helpful.
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Change the exhaust to the tecnigas,took a test run for 3 minutes ,then decided to drill main jet to #90,put everything back together.and Now my scoot woudnt start......Help........
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Allow a minute or two after the first few turns of the engine for the fuel to fill the carb. I think I had to turn my idle speed up a little. You may need to twist the throttle a little as you try to start it if you havent already. Try taking the air box cover off leaving the filter in. Try starting it that way. I find the best way to start mine when it's being difficult is to use the kick start. Trying too long(20-30mins) can flood the engine. Helps to let it sit an hour or two if you think you flooded it.
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Yehey,I did exactly what u said and after about 15 kicks,it finally started.I was about to bring it to the dealer(who knows how much they'll charge).you just save me big bucks.
I was already starting to panic.
Past days was depressing thinking I just broke my bike...Until I read your reply.
Maybe I should post something about that experience,I bet someone is going through all that.Thanks Bro.
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Great. Glad you are relieved :).
So you got it running the way you want again?
Hows that 90 jet?
Have you done a WOT plug chop?
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G'day ,no didn't do plugchop yet since I think I have exhaust leak with the tecnigas by the gasket side,I have to grind a little on the header part to fit nicely,also thinking of using thicker or 2 gaskets bonded with high temp epoxy.I'll see if the leak will be gone .I did what u said about setting the air fuel mix to 1 1/2 turn and it seems to be idling right.I'm waiting till tomorrow for dealership to open so I can buy the nut that holds pipe to cylinder.did u have any trouble installing your tecnigas next r?
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did u have any trouble installing your tecnigas next r?
No, I didn't have any trouble at all. Of course I have a people.
Where is the ehaust leak coming from? Where the pipe connects to the cylinder or at the silencer? Mine has a metal compression type ring at the cylinder end.
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I fixed the leak that was between the header and cylinder ,my oem gasket was the same as yours (round crushable metal)but the tecnigas pipe came with like oblong shape,I doubled up the gasket(aftermarket) and used high temperature epoxy to bond the two,and seems to be working fine.
I just did a plug chop today (2 miles WOT) and came out lean,You were right,even I'm still using my stock airbox I'm still getting a lot of air in with the tecnigas upgrade.I just upjetted again to about #97 from #90,and do another plug chop tomorrow....
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Ok I just went for a test run to get ready for plug chop,everytime I WOT it seems to be hesitating or losing power,so I pretty sure I'm too rich.I'm going to add maybe 2 more holes in the stock airbox and see what happens.....=3 half inch holes......
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If it hesitates, roll back a little on the throttle and if it picks up it usually is lean. It will sputter some when it is rich.
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Did another plug chop today,I noticed that it takes longer ride at WOT to give some color on the white part of the spark plug.it takes more than 5 miles , has anyone experience this?I don't think the 60 seconds or half mile plugchop will give accurate reading..
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I do not understand why these thereads aren't in the right board anymore.... ??? ??? ???
This is general discussion NOT the tech section or the right scoot board but dude, if it takes you 5 miles to get any color then you are way lean my friend. I was going for 1-1/2 miles on my chops but 1/2 mile IS long enough.. You may want to upjet......jus sayin ;)
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Hey Bat,only if I can,but one more step upjet makes my bike bog down or lose power,means too rich,.I read your posts when Shake ,zombie and Art were helping u out with tuning your oem carb,didn't take days for your plug to even get color?
The base of the white insulator on my plug came out in tan color though,but the tip close to the gap is whiter.
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It seems that i was taught to pay attention to the mix ring, more so than anything else..
Is your needle adjustable? try lowering it to lean a touch....
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I'm just beginning to pick up on mechanical things on these bikes,to be honest I'm not even sure where that famous "Needle "is.Is this needle the one that comes out with the throttle cable when pulled out?how do I adjust it?I am right now running a #97/98 main jet and the stock pilot jet(I think #35),with the tecnigas next r upgrade and an open Uni filter(loud)..
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You are correct.... ;)
It is held in by a clip... Remove the cable from the slide..(hemostats help hold the spring).
If the needle is in the 1st slot, it's all the way down... Raising the needle will richen the circuit, lowering will lean the circuit... If the 97 is big and a 95 is to small, try to dial it in with the needle... Hope this helps.... ;)
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Thanks Bat,will try that soon.... :)