1997 MM600 only will get to 60Km/h

D

dolanmcduk

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Jul 7, 2020
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Hi all, question about a 1997 MM600.

Trying it out for the first time this season and noticed its not accelerating past ~60km/h.
Engine is holding rpm at 7500+ and sounds good, but the sled just doesn't go any faster.

Tested side by side with a 1996 600MM and they are equal to ~ 60 kph then the 96 just leaves it behind. In past years running these two side by side they were pretty equal on the top end.

Thinking it is a clutching / secondary problem...Checked the primary - all 3 rollers are worn bad - one actually has a pronounced flatspot on it. I have the Yamaha clutch rebuild kit to replace them as well as the bearings etc.

But before I tear it apart, what else should I be looking at with primary, secondary etc? With the flat spot I am guessing there is a bearing/tolerance problem somewhere?
I have the Service Manual for these years so I have that to reference to specs, tolerances etc.
Will be cleaning Primary when disassembled: other details

Secondary has been disassembled and cleaned.
New belt with adjustments made to the secondary adjustment bolts ( I threw the old belt on for fun and its the same problem)
Engine starts, idles, runs, takes off great, plugs look good
No weird noises, vibrations that are noticeable/different from when I remember it running properly
It will get up to 60 km/h with very little throttle- just doesn't go anywhere past that with mid or full throttle etc

Can provide more details after I travel to the storage location this weekend.

Thanks!
 
Would also replace the primary spring while you are at it.
Shoot for no more than 8500 rpm when at full throttle.
 
MURDER YAMAHA said:
Would also replace the primary spring while you are at it.
Shoot for no more than 8500 rpm when at full throttle.
Click to expand...

Ok thanks will do - I have a bad memory because I was sure I could remember what color was in there.

And great tip on the RPM I recall reading about that as well. Will report back with what I find.
Thanks
 
This is the twin engine , right? Should be targeting 8000 rpm. If the rollers are shot, the weights probably are too. If you're not sure how to inspect the primary thoroughly, find someone that can.
 


make sure you check the weights as well as they might be worn weird where the roller rides. x2 on the new primary spring. will not hurt.
 
74Nitro said:
This is the twin engine , right? Should be targeting 8000 rpm. If the rollers are shot, the weights probably are too. If you're not sure how to inspect the primary thoroughly, find someone that can.
Click to expand...
Correct info, thought it was a 700, look in the tech section on this site called TY Tech, you will find all the info you need in there for what your sled came with.
 
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