KymcoForum.com
General => Technical | How To => Topic started by: Geehun on August 18, 2012, 12:21:45 AM
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I'll be picking up my 70cc big bore kit tomorrow. And will be installing it. I have some questions. What weight rollers should i get and how big jets should i get? Currently mods on the bike are removing tube from airbox and welding the 2 ports on the exhaust to eliminate the recirc. Also have removable screw on exhaust pipe.
It would be great to get some answers by today. I dont want to make back and forth trips to the store.
Much appreciated.
Anthony
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Hard to say. I'd go ahead and buy a roller tuning kit. It comes with lots of different weights so you can find what works best for you. Once you do, you can order better quality ones in the weight you need. They will last longer. Weight of the rollers depend on the roads you ride on, riding style, and how much you weigh. Go ahead and get a yellow/1500 contra spring. Change the spring and if you're lucky you may find the rollers you already have are perfect. I also recommend some yellow clutch springs too.
Best thing to do is go ahead and get a bigger carb. Stock exhaust sucks no matter what you do. You'll want an expansion chamber type exhaust eventually and you'll definitely need a new carb with that. I'd just go ahead and bite the bullet on the carb. Dell orto 19mm carb is a great choice. You'll find it in a Malossi kit. Comes with everything you need.
As far as jetting same thing goes as with the rollers. There are a lot of variables when it comes to jetting and it's hard to say exactly what you need. Best thing to do is start way big and work your way down one jet at a time. Do a google search on "how to do a plug chop".
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Thank you sir.
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No problem :)
Sorry I went back and edited my post a little. Added a few things. Didn't think you would read it so quick :D
Good luck :)
Let us know if you have more questions
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alright thanks. Was going to just start with big bore kit first. Works slow so can really spend too much. It's pretty straight forward for the bore kit right?
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I understand. Just wanted to prepare you for what's about to happen ;D. We call this the performance bug on here. Once you start, you can't stop :D. Happened to me... In all seriousness, you will want a nice exhaust eventually. Especially with the BBK. Exhaust will increase HP, torque, and depending on the pipe you chose will bring the power band up around 8500 to 9500 rpms. It's really almost a must with the BBK. But, you don't have to right now. I understand. I know that Polini kit wasn't cheap.
straight forward?
Yes and no. I'm not familiar with the Polini kit but I know it's one of the best. You can spend a lot of time polishing all the ports, chamfering all edges especially the exhaust port, and making sure the squish band is right. It will last mush longer as well as perform better. I wish I had done all that. I just threw mine on. I haven't had any issues but still.
After you do get the cylinder installed, it's extremely important you get your jetting right. Rich is ok but lean will ruin that quality costly cylinder and piston. Ideally you want to be just a little rich. Altitude, climate, time of year, and many other things affect jetting. Just keep that in mind.
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Lol thanks Peter.
I know I will spend lots on the scoot but it's just if the wife finds out, I'm in sh** for spending too much money. I also have a 89 Toyota mr2 sc swapped with a v6 Camry engine. You should see how much I spent. Until work picks up in the fall, I won't hesitate to purchase the parts I need.
Thinking of getting a Leo Vince chamber exhaust. What is bbk? Can you elaborate on that?
Question. Thinking a installing 2nd battery in storage comparent and wiring it in parallel to the existing one. Reason is to add hid. Is it a good idea?
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bbk is big bore kit :)
Sure you could add a second battery. Hell, I never even use my glove box. Sounds like you've got big plans ;D
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Go figure :)
Sounds good. Can the gears be changed? Whats the max rpm i can get with mods? And whats the max top speed i can get?
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This may help you shop for exhausts. Won't hurt to go ahead and shop around now, find the pipe you want and then find the best price. If you're like me when you're ready to order you're ready to order.
http://www.tuningmatters.com/2012/05/17/review-the-ultimate-scooter-tuning-exhaust-comparison-test/ (http://www.tuningmatters.com/2012/05/17/review-the-ultimate-scooter-tuning-exhaust-comparison-test/)
Keep in mind these tests are on a stock scoot. A bbk could change the results. Tecnigas RS2 is one pipe actually designed to go with 70cc kits. I have the Next R. Bought it before I put my bbk on. Kinda wish I had got the RS2 :-\
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The gears can be changed and there are a few guys on here that have. The super 8 2t is a pretty new model. Not sure if there is anyone on here that has built one up. You'll be our guinea pig ;D ;).
With the bbk and some cvt tuning you should easily get 50mph on flat ground with huge improvements in acceleration. With an exhaust and new carb and again more cvt tuning, you should get up to 55+ and again more acceleration.
Tuning the cvt will allow you to balance acceleration with top speed. You can easily get 10,000 rpm out of a 2t. But unless you really go to town on it(like zombie), the power and torque curve will begin to fall off at about 10,000 or earlier. And that's with a good exhaust and open element air filter. With high rpms like that the engine needs to breathe. With stock exhaust not only will it produce less power/torque, it will begin to fall off around 7,500.
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Installed polini bbk and it was a breeze. Tuning was the sh**s.
I bought the bbk and Leo Vince exhaust. Exhaust was returned because I lost back pressure. Don't use the rollers that come with the exhaust which is 5.7 grams. The bike likes between 8-9grams. With the exhaust my top speed was 40km/h. I stuck with my 82 main jet. Tried 88 and 92 didn't work out so well.
Right now going to keep with stock exhaust and upgrade to the stiffest contra spring and clutch spring for faster acceleration. I really dont need top speed.
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Yeah I don't think Leo Vince is very good
Yeah, 40km/h is pathetic. Something's not right.
Don't worry, it never works out the first time. For me anyway. Especially when you're trying to change so many thing at once. Keep at it. You'll get it.
82 main jet has got to be too lean. I'll warn you be careful. Do some WOT plug chops.
Don't know what contra spring you have in right now but the stiffer the spring the heavier the roller weights will need to be. Clutch springs just control take off. I like the yellow ones but it's all a matter of opinion.
Just keep tuning you'll be happy when you get it right. Sounds like you've done your homework so that's good. Let us know if you have any questions :)
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I just want to catch up with my brother's vino.
I don't have contra springs nor clutch springs yet. Going to search on ebay for some. I'm more interested in the RED contra springs. Thinking of running 9g rollers.
I can feel a difference now in driving. Start is pretty good, middle range is so so. My top speed on flat is 69km/h. I weight 185lbs so maybe that's why i'm slow. Max speed up hill is 53-55km/h. Down hill speed at 83km/h.
SO you say i'm running too lean, i have a 85 main jet, should i put that in? The spark plug looks brown not white nor black.
Tell me what you think.
Thanks
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Contra spring will change everything. I run a red contra myself. I'm around 7 or 8g rollers right now. But, I have a people 50 2t. Not sure if they have the same engine or not. Probably doesn't make much difference anyway.
Your mid range issue may be of because of the needle setting in the carb. Unfortunately the needle is not adjustable in the stock carb. You can find a way to shim it. Wordslinger has. He does it by using aluminum from beer cans to shim the needle up :D. I never found a way to get the needle out of the plastic retainer myself. I was afraid I was going to break it.
I weigh about 275 lbs, so I don't think that's the issue
Yeah I think you're lean. I think. I'm not sure. Like I said lots of variables. What was the factory size? Where do you live? altitude? climate? Mine was really small. Like 75 or something like that.
You can not go by what the spark plug looks like. You have to do plug chops. This involves warming the engine up, installing a new plug, and starting it, then immediately running it wide open for a mile or two. When you're done, kill the ignition while keeping the throttle wide open. Let the engine come to a complete stop before letting go of the throttle. Pull the plug and look at the white insulator inside. You want a coffee(cream coffee) color on that insulator. There will be a ring of coloration. The distance from the tip also indicates fuel air mix. You can cut the threads off to get a better look(hence the name "plug chop") Here is a good link
http://www.kawtriple.com/mraxl/carb/plugchop.htm (http://www.kawtriple.com/mraxl/carb/plugchop.htm)
There is three ranges you need to check. Idle, mid range and full throttle. Idle is controlled by an idle/slow speed jet as well as the mix screw on the carb. The mid range(1/4 to 3/4 throttle) is controlled by the height of the needle as I mentioned earlier. Last, full throttle(3/4 to WOT) is controlled by the main jet. Much more to it than my brief break down so do some research. You can read for days on tuning a carb properly.
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alright i'll be patient and do a little bit more research.
btw i live in vancouver, british columbia.
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Gotcha. So cooler climate. Cooler generally means bigger jets. Cool air is dense air. Dense air means more oxygen. More oxygen means more fuel.
Higher altitude will offset this. Higher altitude means less oxygen, ect...
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Humidity has a lot to do with jetting too
I pretty sure higher humidity means smaller jetting
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alright just bought a set of 9 clutch springs, set of 3 contra springs, some 9 gram rollers and some 9.5 gram rollers. Once they arrive and installed, i will update you what happens.
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Hey Peters, i have some more questions.
Going to run red clutch springs with red contra springs and some 9 or 9.5 gram rollers. Exhaust will be changed soon maybe to technagis or stage 6. What carb should i purchase? Can you send or share a link?
Once i get the bigger carb, would jets have to be changed? or it's adjustable? It's a bitch changing the jets on the super 8's.
I'm looking for faster acceleration to reach my top speed quickly. With the bigger carb and exhaust, what would i gain?
Thanks
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Here is a 19mm carb kit. It's a Dell Orto. One of the best carbs you can get. Has adjustable needle. Comes with everything you need. Uses 5mm main jets.
http://www.racingplanetusa.com/carburetor-malossi-phbg-19mm-kymco-sf10-p-314-1.html?cPath=2_21356_21358&sessID=0b7a6bfa6ae6650a1fc6b723da4d6e62 (http://www.racingplanetusa.com/carburetor-malossi-phbg-19mm-kymco-sf10-p-314-1.html?cPath=2_21356_21358&sessID=0b7a6bfa6ae6650a1fc6b723da4d6e62)
The jets have to be changed. You don't have to completely remove the carb though. I just take the bolts out and turn it sideways just enough to remove the bowl. Once you get it dialed in, you really don't have to mess with it too much.
Here are the rest of the carbs on Racing Planet, as well as main jet sets and individual jets. I'm not going to promise you this is the cheapest place to buy the carb/jets. You'll have to shop around. Just remember that link is to the kit, not just the carb. Finding all the adapters and cables would be a pain in the ass. Better to just get the kit. If you do decide to order from Racing Planet, call and mention the forum. You should get a discount.
http://www.racingplanetusa.com/index.php?shop_ID=1&sessID=0b7a6bfa6ae6650a1fc6b723da4d6e62&olevel0=2&olevel1=21356&olevel2=21362&level0=2&level1=21356&level2=21358 (http://www.racingplanetusa.com/index.php?shop_ID=1&sessID=0b7a6bfa6ae6650a1fc6b723da4d6e62&olevel0=2&olevel1=21356&olevel2=21362&level0=2&level1=21356&level2=21358)
Bigger carb and exhaust will really open up that bbk. Just remember you're changing the hp and torque curve so you'll need higher rpms to take full advantage. This may involve changing the rollers again.
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Just ordered myself a techigas rs 2 exhaust. Going to pass on the carb. Just realized I keep gassing up a lot. A bigger carb means more hp and more gas guzzling
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Also means better cooling of the cylinder/piston and better atomization of the fuel meaning more efficient burn of the fuel and overall a longer lasting engine. I know it sucks you have to pour so much money into it but, you really should get a larger carb.
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I see now that Racing Planet is out of stock
It's the same kit as the people 50 2t
I'm doing a little searching right now
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Read this thread:
http://www.kymcoforum.com/index.php?topic=7083.msg76710#msg76710 (http://www.kymcoforum.com/index.php?topic=7083.msg76710#msg76710)
Josh(Areomyst) hooked stljimmy up with a kit. Likely cheaper too. I'm sure he'd help you out. Reply to that that post and/or send him a PM. He is very knowledgeable when it comes to scooters. He will tell you if you really need a bigger carb.
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ok my set of contra and clutch springs should arrive tomorrow. I already bought an electric impact wrench which was on sale. Peter would you know what size socket i should get to remove the clutch?
Thanks.
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14mm for the clutch/rear pulley
17mm for the variator
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Oh, and you may have to have somebody hold the rear brake while you loosen the nut. I usually just hold the tire with my feet. Works pretty well. Same thing when you go to loosen the variator. Except you have to put your feet on the variator itself.
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Thanks for the info.
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Ok exhaust came. Removed the restrictors inside. Installed malossi 8.5 rollers followed with red contra and clutch springs. Top speed on flat is 80km/h. Very steep hill from bottom to top, accelerates without hesitation and max speed is 70km/h. Downhill top speed is around 95km/h as per my gps. Exhaust is super loud.
Not running into any issues. No lag nor bogging issues.
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Great!
Sounds like you're right on track
Be careful though. Make sure you're not running lean. I shattered my piston rings from running just a tiny bit lean for a while.
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Alright. I'll up jet from 82-85
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Alright so i didn't like the feeling of the red contra and clutch springs. Was kind of dangerous driving on hills and in local city traffic. Replace from red to yellow. Still running malossi 8.5g rollers. Checked the spark plugs and the color was milky coffee brown. Still running on 82 jet.
After ripping around the block for 30min. While i was sitting at a light, my engine stalled/stopped. Has to restart engine. Went home, changed with my brand new NGK spark plugs. Ripped it around again and around 30min on a red light, engine stopped again. Had to restart and open throttle slightly.
Peter, what can the issues be for this type of scenario?
Thanks
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Well, I'd start by checking the simple things first. Air filter, vac lines, plug wire.
Have you done any plug chops?
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can you define the term plug chops?
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You can not go by what the spark plug looks like. You have to do plug chops. This involves warming the engine up, installing a new plug, and starting it, then immediately running it wide open for a mile or two. When you're done, kill the ignition while keeping the throttle wide open. Let the engine come to a complete stop before letting go of the throttle. Pull the plug and look at the white insulator inside. You want a coffee(cream coffee) color on that insulator. There will be a ring of coloration. The distance from the tip also indicates fuel air mix. You can cut the threads off to get a better look(hence the name "plug chop") Here is a good link
http://www.kawtriple.com/mraxl/carb/plugchop.htm (http://www.kawtriple.com/mraxl/carb/plugchop.htm)
This is from page one of this thread
At this point you may need to do a compression test. Running lean will ruin things quick. You want at least 120 psi. That's the bare minimum though. You should have around 140 or more.
Plug chop step by step:
1. Buy several new spark plugs
2. Warm the engine up with the old plug
3. Find a stretch of road you can run the scooter wide open on maybe 2 or 3 miles. You need a good starting place and a good stopping place(you'll find out why in a minute). I'll pull into somebody's driveway if I have to.
4. Install a new plug at the starting place(careful the old plug you take out will be hot). Be close to the road because you want to go full throttle within a few seconds of starting the engine
5. Be ready to go(no traffic coming). Start the engine and take off right away. Full throttle. It's very important you maintain full throttle through the whole run.
6. This next step is equally as important. As you approach your stopping place(last 100 ft or so), Keep the throttle wide open and kill the engine will the red kill switch on the handle bar. I repeat, hit the kill switch while still holding the throttle wide open. Slow down and let the engine come to a complete stop before you let go of the throttle.
7. Remove the test plug and reinstall the old one(caution hot)
8. Drive home and take a look at the results. I suggest cutting the threads off the plug to get a good look at the smoke ring. Take a look at this link again. It will give you a good idea of what the ring should look like.
http://www.kawtriple.com/mraxl/carb/plugchop.htm (http://www.kawtriple.com/mraxl/carb/plugchop.htm)
This is for checking if the main jet is lean or rich. You can use this same method to check mid range(needle setting) as well as idle. Mid range, you would just hold the throttle halfway during the test. Idle is easy.
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ok i did the plug chop last night and thankfully no one complained about the loud exhaust. Followed every step on my iphone and my spark plug is still creamy brown coffee color. The scoot didnt stall anymore, maybe it's colder at night time?
Should i still up jet from 82-85? would it hurt. You guys implied it's better to run more rich than lean.
Does idler jet need to be touched or changed to higher setting?
i don't plan on going bigger carb anytime soon. For air filter, if i replace the foam inside to a universal hi flow/ k&n filter, what are the pros and cons?
For my exhaust, i heard there were 2 restrictions. One near the flange and one inside the chamber. Is it worth it to grind the welder off the chamber, remove the restriction and re-weld chamber back in place? Has anyone done it and what are the gains?
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And also, i realized that when i go down hill really fast, my max speed always stays at 80km/h. It doesn't roll of the odometer and keep going. My cdi doesn't have the 2 pink wires, it was de-restricted from dealer. To my knowledge, there are no restrictions to my scoot. Anyway i can go past 80 downhill?
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my max speed always stays at 80km/h. It doesn't roll of the odometer and keep going.
That may be in the cvt....Need a bit finER tuning?..
The belt size affects this as well.. Of course Word is a CVT master..(bowing)
Should i still up jet from 82-85? would it hurt. You guys implied it's better to run more rich than lean.
Does idler jet need to be touched or changed to higher setting?
It wouldn't hurt to try and see what she feels like with a slightly bigger mj..
Do an idle plug chop and see what that chop says about the pj. IMO, it probably wouldn't hurt to slap at least one size bigger in. In your post earlier about the stalling, the mix being off or a tad lean at idle when hot.
For my exhaust, i heard there were 2 restrictions. One near the flange and one inside the chamber.
Yeah there is a cone that is the size of one side of the chamber. IMO it's not worth the trouble to go through to remove.(but of course my pipe is chrome...lol)
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Thanks batman.
I'm changing my yellow contra to red again today. Don't like the acceleration. Up jetting from 82-85. Going to find an universal k&n mesh filter cut out for my box.
I'm still running the same stock cvt belt. Which one do you prefer me run? kevlar? one size smaller?
What size is my factory idler jet?
I will update pictures after all my mods are in place.
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And also, i realized that when i go down hill really fast, my max speed always stays at 80km/h. It doesn't roll of the odometer and keep going. My cdi doesn't have the 2 pink wires, it was de-restricted from dealer. To my knowledge, there are no restrictions to my scoot. Anyway i can go past 80 downhill?
Two things, longer belt and the rear pulley is probably restricted
Wouldn't worry about the restricted pulley for now. Mine's still restricted too.
Mine did the same thing for the longest time. I bought a new Gates kevlar belt that was supposed to be the same size but it was actually a little longer. I get up to 55mph+ downhill now. I've heard that kevlar belts are rough on the CVT components though. I didn't find that out til after I bought it. So... Buying a little longer belt will probably give you that little extra top speed. If I were to do it all over again I'd get a Bando belt. Bando is OEM I believe and they last the longest but, it won't have any extra length like my Gates. Just go one step up in length. Parts for scooters is having a sale on Belts this month and they carry Bando too. Check em' out
Use The Coupon Code SUMMERBELT (All Caps Please) At Checkout To Get 10% Off Of Your Next Belt Order at PartsForScooters.
Good for one sale during the month of September 2012.
http://www.partsforscooters.com/ (http://www.partsforscooters.com/)
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Turn your idle mix screw all the way in, and count the turns. It should be between 1-3 turns out from seated. That alone will tell if you need a larger pilot jet.
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Ok. How does it look like? So just turn it in all the way and see how it goes? If it stalls, change the pj to a higher setting?
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The mix screw is the smaller screw on the side of the carb. Turn the screw all the way in. Then back it out say 2 full rotations to start with. Then go either out or in until you get the highest rpms. Keep track of how many total turns out it is. Zombie is saying between 1-3 turns is where you want it. If it takes more than 3 turns, you need a bigger PJ. Once you do find the highest idle, then you adjust the idle speed screw(big screw) to bring the rpms back down to where you prefer the idle speed to be.
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Thanks a lot guys. You actually helped me solve my issue. It's not dying anymore. And it sounds a bit meaner at idle now.
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I turned it in all the way and backed out 2 full turns. And then I just adjusted the speed big screw and happy with what I got.
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Fine tune it a bit more. Try 1/4 turn increments. That will get it Purrfect.
Wish we could fix politics...
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(http://i1258.photobucket.com/albums/ii539/boomchino/559328_10151124847204452_907407584_n.jpg)
(http://i1258.photobucket.com/albums/ii539/boomchino/551813_10151153249044452_461256895_n.jpg)
just thought you guys might want to take a look. =)
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Love that MR2 8) 8) 8)
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Awesome!
Very nice S8
Love that MR2 8) 8) 8)
Geehun plate ;D
Are you in NC?
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Nice toys. for sure.
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it's an 1989 mr2 fully restored with original engine. Not rebuilt.
Original red paint job.
4agze engine with cusco pulley kit ( was boosting 8psi, now 14psi ) belt has to changed every year due to oversized pulley.
d2 sport 26 point tension adjustment coil overs
hks sport exhaust
hks cams
Yes! it's a geehun custom plate. I'm from Vancouver, British Columbia, Canada.
Since you guys like the mr2 i'll upload more pics.
(http://i1258.photobucket.com/albums/ii539/boomchino/425002_10150638007904452_505729451_8611290_1907963567_n.jpg)
(http://i1258.photobucket.com/albums/ii539/boomchino/427477_10150638009514452_505729451_8611295_1774908722_n.jpg)
(http://i1258.photobucket.com/albums/ii539/boomchino/427497_10150638005589452_505729451_8611282_2147313918_n.jpg)
(http://i1258.photobucket.com/albums/ii539/boomchino/403352_10150637999689452_505729451_8611260_1389579420_n.jpg)
(http://i1258.photobucket.com/albums/ii539/boomchino/420952_10150708403762345_513332344_11061499_1507463311_n.jpg)
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clean solid lines indeed..... ;)
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I like the look of lowered cars but it sucks being so low you have to drive around beer cans so they don't get stuck under the car.
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I like the look of lowered cars but it sucks being so low you have to drive around beer cans so they don't get stuck under the car.
Pimps don't like lowered cars of course.... ;D
(http://www.cargods.com/wp-content/uploads/2011/03/OaktownCG.jpg)
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No, I role more like this.
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alright so i did a couple runs on my scoot last night. Had my carb idle mix and idle rpm adjusted again.
When i bought the scoot, after the upgrade to red clutch springs, there used to be a lag before the scoot would take off when throttle was fully opened. With now my idle rpm set a bit higher, i now have no lag from starting from the line. When i completely open the throttle it just goes.
My question is, is there anything wrong with this picture, should i need a bit more adjustment? Idle rpm is not high enough yet causing the back wheel to spin. Should i tune the speed down a bit or leave it the way it is?
Thanks
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As long as the back wheel doesn't spin(significantly) while on the main stand you should be fine. Just remember it will idle a little higher when it's cold. You don't want it to push itself off the kick stand while it's warming up :D ;). Really, you should warm it up on the main stand. I don't though ;D
I imagine with the red clutch springs the idle would have to be pretty high for that to happen
You never know... Somethin crazy could happen... Like a clutch spring breaking
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ok thanks for the advice.
2nd question, what do i have to tune/install/modify to run open air filter on my stock carb. Thinking of getting a k&n with a water repellent shroud.
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Larger MJ and tune the idle mix again
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my mj is 85 now. what number or size would you recommend?
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Does anyone here own a kymco s8 2 stroke and has an open air filter setup? If so can you share your build with what jet size i should get? I just need the range of jets i would require to run properly.
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I just need the range of jets i would require to run properly.
If you have a 85 in right now, then I would say that you should get 90-125
I'm thinking that a 100-105 should have you right there...(i was using a 90 w/arreche 19mm carb)
(had a 97 in my oem zx carb)
(running a 88 in my oem ag now)
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thanks
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Hey guys my stuff just arrived.
Just picked up my polini open air filter followed by some jets. The sad thing is, i think the jets dont fit?
The thread is the right size but the one i bought only has 3 thread counts, the stock one has four, Does this matter?
I tried from 92-100 with the 3 thread count jets and everytime i tried to start the scoot, it just doesnt turn over. Am i doing something wrong here?
I'm going to pick up the right main jet size locally to try it out. They're $5 each and the guy only has #92 and #102. If these jets still dont't work what could be the issue and would SPI carry a jet kit?
batman, zombie, peters? ??? >:(
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And just a note to add to above. I tried running opening air filter on my 85 jet. When I open throttle scoot will accelerate and then quickly dip in Hp. Can I also get an elaborate definition of this?
Thanks
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Not sure if you ever figured it out but youre running lean if theres a dip in HP lol. If it sounds like its gurggling out the exhaust its rich, if its quieter than normal its lean if that makes any sense.