very strainge clutch problem

[tomeriker]

I have an 80 xs11 with 20,000 mi. with the exception of needing some new needles in the carbs ( leaky ) the bike runs great.

The problem is: I was riding the other day and decided to blow the cobs out of it.

As the tach climed to 7000 rpm all was normal. Then at 7500 rpm it was like the clutch lever was pulled in and the engine revved to almost redline. I immediately slowed and tested the lever for play and the clutch for slip by doing several hard launches.

The clutch works perfect with no slip. The only time it slips is at 7500 rpm.

I don't run the bike at those rpm's normally so its not a problem for me unless its an indication of a real problem. So I guess thats the question. Is there a real problem???

[egsols]

Hey tomeriker,

It felt like mine was slipping so I went to forth at about 20 miles an hour and gave her, sure enough it was slipping. Went back to garage and adjusted it, went back out, no slippage.

How fast and what gear were you in at 7500 when it felt like it was slipping?

You said you did some hard launches but did you try rolling it off in a high gear at low speed?

Ernie

[webbcraft2150]

How long did the bike sit before you got it? With 20k on the clock I doubt the plates/fibers are worn out. Your plates may be glazed and need cleaning. Could have sacked out clutch springs. They are really easy and cheap to replace. I had over 60k on mine when I replaced the clutch. Every disc and plate was still in spec, springs were totally shot though. Easy/cheap fix would be to pull the clutch, measure discs and plates and if in spec, clean em up and reinstall. Springs may be in spec but could be weak. Lotsa tech tips on clutch replacement available here. I went with OEM Yamaha fibers and springs (ebay sucks my cash again) and it is working great.

[tomeriker]

clutches

The clutches looked new when I got the bike. ( I had the clutches out to inspect) I did think the springs looked small, as in not enough spring rate. They were small diameter wire and not very stiff for a clutch spring. The problem exhists in all gears.

The bike pulls hard in all gears up to 7500.
I can dump the clutch from stand still or from a roll or 30mph. No slip. could possibly pull wheelie but don't want the rear on the groung..lol

[mason79]

i think they get weak, mine slipped around there, measure them

[TADracer]

Clutch springs do weaken with age and use. Heavy duty spring sets are readily available from Dennis Kirk, Bike Bandit, etc. And, they are cheap (less then $20.00 for the set)....I would replace them first. Best part is you dont even have to drain the oil. Just put it on the side stand. Be patient and careful reinstalling the star plate otherwise you might crack an ear off.

Also, some say synthetic oil will slip the clutch.

[jeffe]

At my last oil change I followed the label instruction on a can of Seafoam for using it in the crankcase. The oil does not usually come out very dirty on my bike but it was almost black with all the junk it freeded up. An extra benifit was the clutch was much easier to use. My guess is that the Seafoam cleaned it up also. Just my two cents.

[mro]

I did the "extra steel plate" mod to my 80G when it had but 13/14,000 miles on it. Then about 5,000 miles later R&R'ed the springs. Another 10,000 and replaced fibers. Seems that clutch wear is directly related to how you ride it


mro

[tomeriker]

the way I ride

I don't ride aggressively so the clutches slipping at 7500rpm isn't a big deal as I won't let the rpm's get that high. I just wanted to make sure it wasn't something else. If its just weak springs I can live with that.

thanks for the imput..

[webbcraft2150]

Re: the way I ride

[QUOTE]Originally posted by tomeriker
[B]I don't ride aggressively so the clutches slipping at 7500rpm isn't a big deal as I won't let the rpm's get that high.

My clutch started slipping at high rpm/load but soon the slipping began creeping down the RPM range and simple things like a high speed pass or a energertic departure from a stoplight became a problem. I still suspect your springs are sacked out. That job can be done without removing the clutch assembly. the only parts you would need would be a case gasket and the springs. If ya don't pay attention to the tech tips, you will need a "star" also.

[tomeriker]

springs

I am just getting ready to do a bobber conversion, so I will put in a set of springs. I also have to replace the needles in the carbs. anyone have an idea where to get the best deal?

[79XS11F]

Clutch springs are cheap enough that if you have the clutch cover off for any reason just replace the springs unless they are pretty new already. If the clutch throw adjustment is correct then it is likely clutch slip you experienced. If clutch throw is correct then it's time to inspect the clutch for wear.
Rob