Clutch slipping on dyno - 277 project

[AllanCaveNZ]

Finally got to putting my 277 project on the dyno today but clutch was slipping from 5000 to 6000 rpm range onwards. Is it just heavier springs needed or the actual plates or both likely need upgrading? It has fairly new plates in it but just the normal ones from Mikesxs.

I’m guessing horsepower might be low to mid 50s without the clutch slipping. It has a Heiden 750 kit and cam had a ‘mild grind’ but don’t know the exact cam profile used, stock headers and baffles removed from the muffler, vm34 carbs and we went up on the main jets one size, was 180 before that. New Trispark 277 Waste spark ignition ran flawlessly too.

 

[AUTOMAN]

Before you glaze the clutch add spring pressure.
cliff

Make sure rear tyre is not slipping

 

[Signal]

Assuming the clutch is adjusted properly. Then I would go to an 8 plate clutch and maybe heavier springs. Next step bead blast the steel plates, never had to do this though the 8 plate works really well.
Here is one supplier who is a forum member.
https://www.xs650.com/threads/clutch-slipping-on-dyno-277-project.64356/

I think you are about right with your estimate of power had a motor in a similar state of tune read about the same given that all dynos read differently.
Did BRM say anything about the carberation?

 

[AllanCaveNZ]

Hey Signal,
Thanks for advice. Presume I could just try heavier springs and a bit of roughening the plates up for first go then 8 plates if still happening?
Brett adjusted the carbs to where they are now on that last blue line on the dyno, seemed pretty happy with that as far as he could tell with the clutch slipping a bit. We added a bit of timing and that seemed to all look okay after that.

Ironically went to start it today and wouldn’t start cold after starting easily when warm yesterday so might have to look at where we ended up on the timing. I didn’t have long to mess around so just gave it a four or five kicks and got a couple chuffs and no start and called it quits.

 

[Signal]

If you are not trying to save a dollar fit the 8 plate and job done. Washers under the spring screw it a good way to test if heaver springs will help. My road bike that has a nice clutch pull weight and runs a mix of heavy duty and standard springs.
I have only recently heard of BRM and it was all good things. Its just a shame he is so far away best part of a days travel to get there from here.

 

[AllanCaveNZ]

Yeah budget is a little tight as should really be spent on family things but have an old dingo skid steer sitting there unused so it can go on trademe and bike parts budget will be good to go again.

BRM was a few hours drive so not ideal but he’s good chap and fairly patient. I’ve only dyno tuned fuel injected engines before and does feel a little like going back to the stone age working with carbs but the 277 phased engine noise is a ripper so all worth it, had to restrain a grin hearing that noise for the first time on Friday.