M8 lag at bottom end

[thepwood]

My wife has a 2008 M8, its not the snow pro, This year it started to run pretty crappy off bottom end. once you get some RPM's it straitens out, I think it might be running fat off bottom end. A guy told me I might have an exhaust leak.Just wanted your guys opinion.

 

[Shredder]

Check your belt deflection first.

 

[thepwood]

huh!

 

[Longhorn]

I have a similar issue on an M7...

 

[Shredder]

Make sure your belt deflection is set properly. Could be the easiest cheapest thing there is. I set mine up so the track just creeps when it's up on the jackstand. A belt sitting too low in the secondary will give you a bog.

 

[Longhorn]

As a total admitted noob here, can you easily explain how to do this...I didnt get a manual with the sled, have experience with skidoo but this is first Cat and I have looked and fiddled but havent figured it out. What you are explaining seems correct and when I look at the belt it seems to be riding too low in the pully. The ribs are below the top of pully.

thanks

 

[foothills m8]

i think u have to add shimm`s to get the belt up.If belt sits up on the secondary about 3/16 it is right. just my thoughts.Are u able to add shimms to secondary?

 

[foothills m8]

OPPPPPPPs u might have to take shimmmmms out to get the belt to riase up on the secondary. I had to take one out on mine to get belt right with proper belt deflection.

 

[foothills m8]

On mine the shimms are on the secodary bolt thin ones and thick ones.

 

[Shredder]

I run an RKT and never ran the stock set-up. But I think this thread should help you out. Step by step deflection instructions towards the bottom of the page.

07 M8 loading up at idle? - SnoWest Forum

 

[Longhorn]

So now im completey confused...sorry for my lack of knowledge here...

I 'thought' there was a deflection adjustment without adding or removing shims. Again, I will repeat that I know NOTHING about a/c but please tell me what purpose the white colored plastic ring has. The ring with 3 holes in it...

It seemed to make an adjustment yet when I took it right off to try and determine what it does, it doesnt seem to do anything...

 

[Bighairybeast]

My wife has a 2008 M8, its not the snow pro, This year it started to run pretty crappy off bottom end. once you get some RPM's it straitens out, I think it might be running fat off bottom end. A guy told me I might have an exhaust leak.Just wanted your guys opinion.

My 07 M8 has had these symptoms twice and my problem ended up being chipped reeds both times. Mine started with low end bog and got progressively worse (as reeds broke more)until I figured out the problem.

This problem occurred with stock reeds.

 

[swabby]

had same problem on m6 2005 , removed shiming and back running like new ., belt deflection can big a big problen the lower the cc seams to hurt more from improper belt deflection, also eliminates excess belt heat and pre mature belt failure.

 

[0neoldfart]

So now im completey confused...sorry for my lack of knowledge here...

I 'thought' there was a deflection adjustment without adding or removing shims. Again, I will repeat that I know NOTHING about a/c but please tell me what purpose the white colored plastic ring has. The ring with 3 holes in it...

It seemed to make an adjustment yet when I took it right off to try and determine what it does, it doesnt seem to do anything...

I am presuming you have a threaded adjuster with an allan head bolt holding your secondary on? If so, you have an earlier style secondary. Loosening the center allan bolt and rotating the threaded adjuster willallow the sheaves to open or close depending on which way you turn it. If it won't close any more so the beltwill ride higher in the secondary, I suspect your belt is worn out. You do have to loosen the adjuster so that it is just free of the sheaves, and then work the belt around the pulley to let the spring close the sheaves.

 

[Longhorn]

I am presuming you have a threaded adjuster with an allan head bolt holding your secondary on? If so, you have an earlier style secondary. Loosening the center allan bolt and rotating the threaded adjuster willallow the sheaves to open or close depending on which way you turn it. If it won't close any more so the beltwill ride higher in the secondary, I suspect your belt is worn out. You do have to loosen the adjuster so that it is just free of the sheaves, and then work the belt around the pulley to let the spring close the sheaves.

Threaded adjuster (or what appears to be an adjuster) yes...no allen bolt though. I do have a tool with 3 pegs that fits the plastic ring, and it is threaded. On the ring are some thin metal shims...I have loosened the ring, tightened the ring, taken shims out, and cant seem to see any change. Only thing I havent tried is more shims as I dont have any, and dont know if this is even how to adjust. I have taken a pic to show what I have.

Thanks

 

[0neoldfart]

Threaded adjuster (or what appears to be an adjuster) yes...no allen bolt though. I do have a tool with 3 pegs that fits the plastic ring, and it is threaded. On the ring are some thin metal shims...I have loosened the ring, tightened the ring, taken shims out, and cant seem to see any change. Only thing I havent tried is more shims as I dont have any, and dont know if this is even how to adjust. I have taken a pic to show what I have.

Thanks

Inside that plastic adjuster ring is an allen headed bolt - you need to loosen it before adjusting the ring. BDX makes an aluminum adjuster that will last a bunch longer then the plastic one. Loosen the allen bolt, and loosen the adjuster ring one or two turns, and seat the belt by rotating it. If the belt is 1/16" above the driven pulley, tighten the allen bolt and you are good to go. If you cannot get the belt above the sheaves, time for a new belt.

 

[TurboRoss]

I have a 07' M8 with a turbo and it was doing the same thing on the last ride. Really doggy on bottom end, had to feather it until a high throttle and then it was fine. Turns out temperature probe was toast. If you take the temp probe off and check for continuity on the pins with a multimeter it should read .22 or so , if it is 0 then buy a new probe for a $150 rip. This may be the case if it worked fine when you put it away or on the previous ride?
Hope it works!

 

[Longhorn]

Inside that plastic adjuster ring is an allen headed bolt - you need to loosen it before adjusting the ring. BDX makes an aluminum adjuster that will last a bunch longer then the plastic one. Loosen the allen bolt, and loosen the adjuster ring one or two turns, and seat the belt by rotating it. If the belt is 1/16" above the driven pulley, tighten the allen bolt and you are good to go. If you cannot get the belt above the sheaves, time for a new belt.

You have helped me greatly. Thanks for the advice and help, seems to run entirely different now. Belt is finally where it should be...

thanks again!

 

[0neoldfart]

No problem Brad. Glad I could help - that's what this forum is about. I'm no expert on sleds, but am a licenced mechanic by trade and have repaired a lot of toboggans over the years. If anyone has REV, S-chassis, or cat M-chassis with problems, they are welcome to PM me - my memory isn't as good as it used to be, but I'll do my best...

 

[Longhorn]

Memory seemed pretty good to me, and again thanks!!