a few tuning questions for 50cc

[Coyoteman]

We just bought this 50cc new several weeks ago. The setup I just installed is a Hetrick pipe, 4 gram rollers, Koso black 1000rpm compression spring, Koso 2000rpm clutch springs, 90 main jet. (all included in Hetrick power up kit) Seems to be way lean to me. It falls on it's face just after engagement. Seems to be slightly better (but not much) with the choke on. Is anybody running a similar set-up? The stock jet was an 87.5 and when we put the pipe on my daughter fired it up and took off and it semmed to run great. Then after I installed the clutch parts I started to experience the bogging issue. I installed the 90 main and got the same results. I then tried the 80 main (also came with kit) just because I was starting to doubt myself and got way worse. I'm heading to town now in search of a few larger main jets hoping this is my issue. Any input greatly appreciated.

[3400ben]

Is it the clutch set up? Have you ran it with setting in the air?

[rmuscle]

sounds to me like clutching . 4 gr rollers with a 1000 spring , rollers are to heavy for that spring you are probaly shifting way to fast. if u want to keep 4gr rollers try maybe a 2000 spring or a 1500 with like 3.5. also if u are using red 2000 shoe springs (i think those are the stiffest ones ) u may be engagen to hi and dumping ur belt and starting in 2nd gear , even more so with that heavy of rollers and light os torque spring . jimo

[3400ben]

I your post you said it started after you installed the clutch mod.

[Coyoteman]

This quad is used alot in tight and hilly trailriding and was looking for a setup that give it more usable power. Not being experienced with cvt's, I used what Hetrick recommended. Anyway, you guys think a 90 main is plenty for the pipe?
I'm open to suggestion on any clutch setup to suite the riding style. I also have 1000 and 1500 shoe springs but only have 4g rollers and a 1000 compression spring, but I want it to right, so if I need to get other springs or rollers I will. Although, my hillbilly methods probably make it harder than it really is to change springs, and I ain't looking forward to applying my redneck skills on that clutch again.:ermm:

[Coyoteman]

3400ben, I never ran it on the lift. Would this tell if my jetting is correct.
I would think it is the clutch also since it ran fine when when we changed the pipe only with stock 87.5 main. After I changed the springs and rollers, it all went downhill.

rmuscle, It would be easier for me to change the rollers than springs but I'll do whatever it takes.

[3400ben]

Last week I had a buddys drr would cut out in mid range he thought it was the carb. Well it ran fine on a stand but when it had a rider it would cut out in midrange. We changed the rollers and it worked fine. The problem was the clutch was engaging to early and bogging the motor down. If you read some of the old posts the first thing they tell people to do is run it on a stand to see if the clutch is right. It is a starting point . To check to see if the jetting is right no it won't tell you if it is right but it will eliminate other problems. imo

[Coyoteman]

Thanks for the advice. I ran it on a stand, no bog.

[rmuscle]

yea i would at least start with the rollers then see what happens

[bulldogfallon]

I take it that you have the small Mikuni carb


Yes the main jet is too lean then Should be around 105 to 110 size.

Needle is probably too lean too...

Your set up is not really what I would recommend for your use.


We are good with 50s.....give me a call and we will get you straightened out.


No BS or fancy words to make you buy something.....I'll shoot it straight and then you can buy what u need from me or another dealer here.

[bulldogfallon]

Originally posted by 3400ben
If you read some of the old posts the first thing they tell people to do is run it on a stand to see if the clutch is right. It is a starting point


Running on a stand doesn't simulate a load...which effects jetting and electrical load needs.

[bulldogfallon]

Originally posted by rmuscle
sounds to me like clutching . 4 gr rollers with a 1000 spring , rollers are to heavy for that spring you are probaly shifting way to fast. if u want to keep 4gr rollers try maybe a 2000 spring or a 1500 with like 3.5. also if u are using red 2000 shoe springs (i think those are the stiffest ones ) u may be engagen to hi and dumping ur belt and starting in 2nd gear , even more so with that heavy of rollers and light os torque spring . jimo


Dang....Where did you learn that fancy cvt stuff? ;)

[Coyoteman]

Originally posted by bulldogfallon
I take it that you have the small Mikuni carb


Yes the main jet is too lean then Should be around 105 to 110 size.

Needle is probably too lean too...

Your set up is not really what I would recommend for your use.


We are good with 50s.....give me a call and we will get you straightened out.


No BS or fancy words to make you buy something.....I'll shoot it straight and then you can buy what u need from me or another dealer here.

It has a Sunworld carb on it. This morning I put all the stock clutch springs and rollers back in it because my daughter wants to ride it. That zip tie trick on the belt I seen going thru some old post really helps. It was actually pretty easy the second time around, but does anybody have a better method for changing out them darn shoe springs. (I'm sure most of you guys can do this blindfolded).
I will call you tomorrow (Monday).
Happy Fathers day, fellas. And thanks for all of your help.

[bulldogfallon]

Small sunworld or large sunworld carb?

If it had a remote tube

Small carb=metal tube
Big carb = black tube

[Coyoteman]

Small Sunworld carb I think....It has the chrome looking tube. It is an 08' air cooled dual a arm 50, we bought new less than a month ago.

[Coyoteman]

Hey Gary your a busy man, I talked to your NW guy Les and got the skinny on the cvt and ordered the parts I need, thanks again. I would still like to hear your input on the jetting though, I'm not much of a tuner.

[bulldogfallon]

Sent you a pm....think jétting was listed there

Let me know

[rmuscle]

Originally posted by bulldogfallon
Dang....Where did you learn that fancy cvt stuff? ;) oh just about a year of bugging some guy i know lol