Primary Clutch inspection

[Grunt]

Hi all , 2016 MTX 153 bone stock.
Carrying on with inspection and now onto the clutches. Waiting for a BOP soft start spring and secondary adjuster.
Sled is new to me and i did take it for a little spin when I bought and noticed the jerky start with a 3800 rpm engagement. This is why i ordered the BOP spring.
Last evening I pulled primary spring out, green green green.
I also noticed , with the clutch completely open, the rollers are not touching the weights. There seems to be a gap of maybe 1/16". I would think that they should be touching or only a few thou clearance. The rollers dont look worn. Are there different size rollers available?
So i pulled the weights and also noticed them to be a bit bumpy at the base, just befor the hump
Could these bumps be contributing to the jerks starts??
Also I have read that one can file these off if you are very careful to do the same to all 3?

Thanks

 

[maim]

yes those bumps will contribute to a jerky start. lots of guys added notches there for drag racing. i have read that you can file them out as well but have never done it.

 

[jonlafon1]

Your belt could be worn and your belt to sheave clearance is out to far. Try running a new belt? The spring is probably not what's causing the jerky engagement. Not saying a soft start spring is a bad idea at all. The notched clutch weights can be sanded down as long as you get them into a holder and squared off.. So they get sanded evenly across all the weights surface at the same time. I like to do this with the linked product below. The weights on the Yamaha clutches do not touch the rollers when full open so this is normal. Start with cleaning the clutches and making sure the rollers are not flat spotted and spin freely.. Try new belt if belt is old? and then either buy new weights or sand the notches out of them.

Ramp Grinding Block – Wahl Bros Racing

wahlracing.com

 

[Grunt]

Your belt could be worn and your belt to sheave clearance is out to far. Try running a new belt? The spring is probably not what's causing the jerky engagement. Not saying a soft start spring is a bad idea at all. The notched clutch weights can be sanded down as long as you get them into a holder and squared off.. So they get sanded evenly across all the weights surface at the same time. I like to do this with the linked product below. The rollers on the Yamaha clutches do not touch the rollers when full open so this is normal. Start with cleaning the clutches and making sure the rollers are not flat spotted and spin freely.. Try new belt if belt is old? and then either buy new weights or sand the notches out of them.

Ramp Grinding Block – Wahl Bros Racing

wahlracing.com

Thanks for the info. The rollers seem to be in really good shape as the clutches as a whole. Sled only has 1400 miles and has never seen any hard riding in the mountains.
I do have a new belt im putting on. Im also waiting for a BOP secondary adjuster so Ill be able to keep the belt just perfect..
I will pin all three weights together and sand the bumps out..
Im looking forward to getting the BOP soft spring as I dont need 3800 rmp's to get this thing going. Looking to get some engagement at 2700-2800 as I do alot of slow riding around trees in deep powder.
Will try to get it back together tomorrow and take her out for a spin on Sunday. Should be enough ice on our local little bush lakes...lol
Thanks again

 

[74Nitro]

Those weights look normal to me, I don't see any abnormal wear.

 

[jonlafon1]

Thanks for the info. The rollers seem to be in really good shape as the clutches as a whole. Sled only has 1400 miles and has never seen any hard riding in the mountains.
I do have a new belt im putting on. Im also waiting for a BOP secondary adjuster so Ill be able to keep the belt just perfect..
I will pin all three weights together and sand the bumps out..
Im looking forward to getting the BOP soft spring as I dont need 3800 rmp's to get this thing going. Looking to get some engagement at 2700-2800 as I do alot of slow riding around trees in deep powder.
Will try to get it back together tomorrow and take her out for a spin on Sunday. Should be enough ice on our local little bush lakes...lol
Thanks again

No problem.. 911 clutch cover has a sheave adjuster on it also.. Try the things you mention and see if it helps. Good cleaning also

 

[74Nitro]

Whats the part number of the belt on it?

 

[Grunt]

I did a light and careful sanding on the belt sander, cleaned the clutch as good as I could, wasnt very dirty at all.

got it back together and went for a short rip last evening. Much smoother engagement. I did put a new belt on too, will get the # and post.... Still engaging at 3600-3700, but seems to be smoother. Cant wait for the soft start spring.Going for a longer run today. Thanks for the tips all...

 

[Srxspec]

Just dropping the engagement rpm will help it out. With a soft engagement spring those weights will come in very smoothly as well. A gap between the weights and rollers is fairly common. Larger rollers will actually provide less grab on the belt, you don't want that.

 

[Grunt]

Just dropping the engagement rpm will help it out. With a soft engagement spring those weights will come in very smoothly as well. A gap between the weights and rollers is fairly common. Larger rollers will actually provide less grab on the belt, you don't want that.

Looking forward to the soft spring. Seems stuck in shipping at the moment
Took the sled for a decent stretch yesterday, first ride since i bought it. very impressed with that 4 stroke. Quite a bit heavier then my summit, but ill get used to it. Broke some bush trails that access some lakes yesterday.... A good ride...