I took my 350 on the road and the clutch was slipping under hard acceleration. Everything set according to specs, EBC heavy duty discs and springs, OE six disc basket. The basket has slight notching though. I feel too much power is lost there. What could be the cause? Anyone with a 350 having the same issue?
It may just be that the 6 plate clutch is not enough, unfortunately. Let's face it - the 350 is significantly more torquey than the 250 the clutch was designed for, and Yamaha themselves changed to a 7 plate for the Blue 250s.
I have only fitted 350 kits to later motors with 7 plate clutches. What gearing are you using?
Anyone else with a 4GY 350 care to chime-in?
-- Edited by mossproof on Sunday 19th of June 2022 04:54:33 PM
I use stock gearing 14-44 Simon. That is a logical explanation, unfortunately though. The power loss from the rear wheel is significant. The issue is more noticeable when the engine gets hot.
I know my girlfriends bandit was a little sensitive to fully synthetic oil, changed back to semi and it was okay - probably not the issue but worth considering
Hi Steve, Dan, thanks for the input. Dan, I hope you've tried the sequence: upshift-WOT, upshift-WOT, on your six plate 350 without any slipping, gradual throttle twisting is flawless. I use Silkolene super 4 10w40 semi. I noticed that my clutch lever had marginal free play, readjusted it but without testing it yet. I cannot think of anything else. The issue was noticed only on hard acceleration on tarmac (I can't go WOT on the gravel roads anyway). Could be the clutch cable needed a bit of loosening...I'll let you know.
Stock gearing will cause more "leverage" than the more off-tar set ups I suspect Dan Steve and I are running (14/47 in my case)
I think you may have found the design limits of the OE clutch. You could try filing the ridges in the clutch basket, but I don't think it will help in this case.
I bought a dr250 that had bar risers fitted, but standard cables, on the road every time I accelerated hard the clutch would slip as the forks extended and the cable got shorter 🤦♂️
Not sure how fork extension affects the clutch because the handle bars, frame, and engine are fixed distances...with the exception being when you turn the handlebars to the right. That's what caused my clutch to start slipping with bar risers.
