Help! What's this noise?

xfiredude · Nov 25, 2015

I have a knock in the crankcase when rocking the clutch back and forth by hand. And a pretty good rattle at idle on the clutch side. Are the two coming from the same place? The knock by hand won't do it with the plugs out. Only with compression. Which btw is 125 on each side. Will get vids up later.

mtncat1 · Nov 25, 2015

I would say a rod bearing or a wrist pin bearing , sorry but its time for a tear down

xfiredude · Nov 26, 2015

https://www.youtube.com/watch?v=MOhwwjVpMU0

https://www.youtube.com/watch?v=8ueQIfaTuLE

Bacon · Nov 26, 2015

How many miles on sled. Sound like something loose in the primary. Maybe broken spider or bad roller or loose clutch weight. I would look there before the motor. It's not unheard to have a bad rod bearing, just not that common.

xfiredude · Nov 26, 2015

Just under 1200. I will look closer into clutch. I did have a belt let go at full throttle once last year. And it did over rev. I've owned it since new that's the only thing that could have hurt the motor.

kidrman · Nov 26, 2015

My 2010 sounded similar before the clutch exploded on a deep powder day at 1200 miles.

kiliki · Nov 26, 2015

pull the hood off and pull out the power valves and look at the top of the piston for fine debris if you have bearing failing it will leave some residue. also as said above take the clutch cover off and look rollers and weight over. the motors do make some clunk when the pistons are at TDC and BDC as this is the point the piston rocks as the rod passed center.

0neoldfart · Nov 26, 2015

Check your primary

As already mentioned, inspect your primary. I had the same noise on my 2013 M800, clutch was shot. Replaced with a new P85, no noise since.

xfiredude · Nov 26, 2015

kiliki said:
pull the hood off and pull out the power valves and look at the top of the piston for fine debris if you have bearing failing it will leave some residue. also as said above take the clutch cover off and look rollers and weight over. the motors do make some clunk when the pistons are at TDC and BDC as this is the point the piston rocks as the rod passed center.

This would explain the knock noise with plugs in and not out. I'll dig into the clutch and check the exhaust valves after the Tday dinner wears off.

kiliki · Nov 26, 2015

xfiredude said:
This would explain the knock noise with plugs in and not out. I'll dig into the clutch and check the exhaust valves after the Tday dinner wears off.

your not checking the exhaust valve your using the hole to look at the pistons as this gives you a good view of the front and top.

leadfoot33 · Nov 26, 2015

sounds normal to me, noisy clutch that is probably going to let go soon

xfiredude · Nov 26, 2015

kiliki said:
your not checking the exhaust valve your using the hole to look at the pistons as this gives you a good view of the front and top.

Right. I got that. The second part of your post is what I meant makes sense. Because the piston would need compression to rock. I would think.

xfiredude · Nov 26, 2015

My buddy's '14 makes the same noise when rocking the clutch back and forth. His only has 250 miles on it. My exhaust valves are clean so I'm going to leave the motor alone for now and replace the primary clutch.
Thanks for the help!

Snowmow · Nov 26, 2015

xfiredude said:
My buddy's '14 makes the same noise when rocking the clutch back and forth. His only has 250 miles on it. My exhaust valves are clean so I'm going to leave the motor alone for now and replace the primary clutch.
Thanks for the help!

Every 2 stroke cat I've owned has made that noise doing the same thing you were doing. Scared me at first. But never had a failure. And after 3 making the same noise. I figured it must be normal.

xfiredude · Nov 26, 2015

Snowmow said:
Every 2 stroke cat I've owned has made that noise doing the same thing you were doing. Scared me at first. But never had a failure. And after 3 making the same noise. I figured it must be normal.

Thanks for the info. The rattle at idle is what I was chasing when i heard that clunk. Thought I had a much bigger problem then. Primary is not cheap but at least I don't have to rebuild the motor too.

fast8seccamaro · Nov 26, 2015

xfiredude said:
Thanks for the info. The rattle at idle is what I was chasing when i heard that clunk. Thought I had a much bigger problem then. Primary is not cheap but at least I don't have to rebuild the motor too.

I would simply pull yours apart and have a look. I believe all the rebuild parts are avaiable from Thunder Products if you find anything. If by chance its a broken spider, I have a brand new stock take off for sale.

Chris6060 · Dec 1, 2015

Interesting. My sled was idling (haven't ridden it in 2 years) today and I noticed a similar sound coming from the primary, but the primary is less than 250km's old, brand new from AC. Sled has 1951KM on it.

Very confused and slightly concerned considering I'm going riding tomorrow.

Snowmow · Dec 1, 2015

Chris6060 said:
Interesting. My sled was idling (haven't ridden it in 2 years) today and I noticed a similar sound coming from the primary, but the primary is less than 250km's old, brand new from AC. Sled has 1951KM on it.

Very confused and slightly concerned considering I'm going riding tomorrow.

I've said it once and I'll stay it again.

It's normal.

xfiredude · Dec 1, 2015

I pulled the primary cover. Didn't find anything obviously wrong other than the moveable sheave is loose on the fixed. Maybe just needs buttons and bushings.

diggerdown · Dec 1, 2015

Rock it back and forth using the inner sheave, that will tell you if it is the clutch or engine.

Help! What's this noise?

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads