Topic: CB550 RACE BIKE CLUTCH ISSUE ON LAUNCH

[cb550fcafe]

Racing my 550 for the last 3 years and I can never get a good start. Stock trans ratios. I modified clutch basket for an additional friction plate. AMSOIL. Honda friction plates. The clutch works prefect all the time, in pits, on track while racing, upshift, downshift, perfect. Except on the launch. I hold throttle to about 6,000 on the 1 board and then let it rip. The clutch chatters so bad it tries to stall the bike, I have to pull clutch back in and slide it out a second time to keep momentum. I have no idea what I'm doing wrong. 

[Don R]

 The late 750's and gl1000's used a double steel plate in the middle of the pack. The drag racers seem to like them, the thought is it makes it work like two separate clutches. I wonder if two plates could be rosette welded through a few holes or riveted like the 750 clutch is?
 Just to see what it looks like, look up a 22322-371-020

[turboguzzi]

i remember having a grabby clutch at starts when i first buiilt the bike with barnett plates, but switching to OEM plates cured the problem

are you using the stock release mechanism? might be slow in release and lets the plates skim instead of clamping down.

could be also oil related...

rattly basket, loose rivets,

[bwaller]

For sure you have to "feather" the clutch to launch smoother. Not all the way to T1, but to get it off the line then release after couple seconds.

Make certain your steels are in good shape too. Launches wi heat them and show blue areas. I replace when necessary but have dressed them on a surface plate. Don't bead blast them, the clutch will grab worse during the launch. I eventually switched to Barnett springs, but OEM plates & discs.

Another trick is to speed up the clutch rotation by using 650 primary gears. You need to relieve the cases and cover for the larger gear (end of primary shaft) and attach the smaller drive gear to the basket. It's not a dramatic change but a slight improvement. Make sure oil is cool for a wet clutch.

[Ramrod_Racing]

Is it something that's always been a character of this bike, or did it change somewhere along the way? My technique isn't so much a let 'er rip as much as slip the clutch from the engagement point to released while rolling the throttle from mid to full. Going all Barnett components fixed my on track issues but changed my launch feel a bit.

Sorry it's hard to diagnose over the boards. If you want to swap bikes for a session at one of the upcoming rounds I could probably offer a better opinion after a launch from hot pit.

[MRieck]

 For what it worth I've always gone with OEM fibers and steels with Barnett springs.

[scottly]

I modified clutch basket for an additional friction plate.

Perhaps this is causing the problem?

[bear]

I agree, honda plates give the best and most consistent launch.
I used to load the clutch up as much as possible aswell. It helped reduce that initial stumble of the line.

[cb550fcafe]

thanks everyone. It sounds like I need a better technique and practice the launch more.

[Ramrod_Racing]

I think racing motocross for a decade or so gave me a big leg up on the starts when starting road racing. The drag racers here are probably the ones who really have it dialed, but you can't beat a dirtbike for repeatably practicing technique and reaction time.

[MRieck]

thanks everyone. It sounds like I need a better technique and practice the launch more.

I had a fella that roadxraced in the mid 90's for my shop. He was good except for smoking to much pot and drinking beers. He had his clutch set to engage way out....it was a water cooled GSXR BUT I think the principle was good. He did get really good drag type good starts. You might want to reduce the stack height which will give you more feel and control and rev that thing.