need setup and clutch help

[vislaguy]

my 6 yr old has started to improve on his bike and now wants to race but I have issues with the bike that really didnt matter befor when he putted around. I have a handling issue and some clutch issues. lets start with handling, its a eton viper 90 that has exstended single arms with 12" coil over fox shocks it has a 43" front width but!! it only has a 41" wheel base although it has a 3" ex swingarm ,so its shorter then it is wider!! the bike seems twitchie the rear end seems like it wants to come around to easy.I was told the wheelbase should be longer then the width. it also has i believe too big of a rear tire there 18x9.5x8 would the big tire hurt handling as well???



next is the clutch!! I bought it as is, it has a hetric pipe, 95 cc kit (I believe) and a hi comp head with a 21mm keihin carb. the clutch has white molossi clutch springs with a yellow main spring and the rollers are not marked. I have no idea how old those springs are!! its slow to get it up to rpms it does not leave the line well although my son is a slow rider i would like to see it snappy when you hit the gas at lower speeds . I need some input on a stage 6 ajustable cluttch it sems like that would be easyer to dial in or should i just stick with stock and play with springs ? so what springs should I start and what rollers.

and for rear tires what size should I try ? we run in west ga in red clay soil

thanks for the help

[mmsoup]

Move to a 24mm carb and a good intake.

PE Keihin is the most stable, PWK is tougher to tune but hits harder if you so desire, on a stock set-up we run the PE

Good starting point

1500 Torgue spring
1500 shoe springs
start at 4.5 gram rollers
start with a 787 16 30 belt

Run the rollers down in weight to quicken rev time and help on low end, but you sacrifice the ability to pull the belt down all the way into the rear pulley if you go too far
Heavier weights will shift quicker but could slow down hole shot
Buy a 3.5 through 5.5 and do 100 yard sprints with the spring combination stable adjusting only the rollers and see where he gets the best performance
You can mix rollers to gain specific weights if necessary
Have fun and good luck

[vislaguy]

I will try that to start thanks.

so you play with roller wieghts more then the springs??
what about ajustable cluches??
now I need some handling help and tire selection.

[oldyeller]

I went through this last year with our viper 90..I could not get it to come out of the hole well until I got some light wieght clutch shoes from Hetricks..The stock eton shoes are very heavy and even with the stiffest red spring would not let the engagement speed get high enough..

Believe it or not the stock carb works very well..I tried a 24mm Kiehin with koso intake and didn't really see any improvement on ours..

[vislaguy]

can you lighten the clutch shoes by drilling a hole in the thick area of the shoe??