remove the spring and see if u can push the belt down low into the secondary ...it cannot go bettween the 2 sheave ...it will hit the bottom of secondary can't go further
mopar1rules
Active member
couple things, if your getting nylon coming out of the belts, your alignment is off. check clutch alignment.
your helix in the pic is fine.....it has not been altered.
if your engagement rpm dropped 300rpm, the primary spring is most likely shot. also, check primary clutch bushings, rollers, etc.
check secondary bushings.
check power valves again and re-adjust if necessary.
your helix in the pic is fine.....it has not been altered.
if your engagement rpm dropped 300rpm, the primary spring is most likely shot. also, check primary clutch bushings, rollers, etc.
check secondary bushings.
check power valves again and re-adjust if necessary.
I have belt marks below the sheaves (don't know how they got there). Anyway, the belt should be about 1/2 inch above where the grooves end on the sheaves. I have wear below that indicating the belt is dropping too much causing the strain on the motor at WOT. Going to replace the ramp shoes, and both spring and go from there. My engagement RPM dropped from 3,900 to 3,500 which tells me something's up with the primary. It never ends.
mopar1rules
Active member
yeah, if your belt is dropping down into secondary alot, the sides of the belt could be getting beat up from the burrs on the casting, where the belt shouldn't be riding.......if you know what i mean??
mopar1rules said:
I am thinking this more than alignment. It's gotta be the spring(s). Have 2 new on order.
weird that u can hit 8500 if its a bad spring ......... but wno knows..to me its sounds more like the belt is not wide enough for some reason ....
Belt is 34.05 mm wide. Min spec. is 32.5 mm. But who knows. These yamahas are fussy.
bluemonster1
LIFE MEMBER ONLY ONCE!!!
mod loves to cut things down..even belts..lmao
bluemonster1 said:
i didnt play with the belt its the only things stock on the sled lollllllllllll
maybe the secondary spring is good for garbage and can't hold pressure at top speed 
stupid things
bluemonster1
LIFE MEMBER ONLY ONCE!!!
mod..I see you have rain..tough Duck..it is -15 out here..going for a ridew after I eat something...lots of snow here yet and more coming tonight...
mopar1rules
Active member
modsrx said:
well it will be able to hit it right away, but then as the clutches start shifting too fast and getting ahead of the engine's powerband, then the rpm's drop and you overshifted.
mopar1rules said:
yeah sorry my bad i guess a bad secondary could do weird stuff
The belt marks you have on the secondary could be from your shot belt?
Most likely. Putting a new belt on the see if that makes a difference.
I replaced belt, 3 ramp shoes, and 3 worn out adjustment screws (for belt deflection) and cleaned the secondary thoroughly (bushings, helix, and sheaves). Will get a chance to try it out tomorrow and see if any of this makes a difference.
Well that didn't do it. Still runs up to 8,200 rpms and then back down to 6,800 after a couple of seconds. I cleaned and adjusted all the powervalves again and same thing, This is what I am now thinking the problem might be.
- Servo motor closing PV's at WOT after opening them (servo malfunctioning?)
- Floats in carbs need adjusting and/or carbs need cleaning
- Primary is shot (weights, bushings, rollers, spring, etc).
Any thoughts to this madness?
- Servo motor closing PV's at WOT after opening them (servo malfunctioning?)
- Floats in carbs need adjusting and/or carbs need cleaning
- Primary is shot (weights, bushings, rollers, spring, etc).
Any thoughts to this madness?
I had the same problem, swapped carbs and it went away! I believed it to be a faulty tps bit have not gotten a chance to test it 100%, I suppose it could be something else in the carbs ie float level but I believe it was the tps..
Are you totally sure you are not dropping one cylinder? The rpm would be the right range it would drop too if you lost one
Are you referring to the coil dropping at WOT RPM? It might be but how would I be able to test for that? Would't the motor vibrate more only running on 2 cylinders? When it happens, the engine bogs down like the brakes have been depressed. Sounds like a "load" bog. Dropping 1,400 RPM's is significant.
If you have an infared heat detector you can run the sled in its failed state for a mile then quickly measure temps on exhaust pipe near the cylinder. two even and one much cooler means one cylinder quit firing.
Harbor Freight has infared guns for around 29 bucks if memory serves me right.
Harbor Freight has infared guns for around 29 bucks if memory serves me right.