I started my Pro Sunday and noted a slight knocking sound around the heads when the panels are off, is this normal, never noticed it before, I have nearly 1000 miles on it, dont here it when I rev it up. I have a Honda TRX 250 that makes a simular noise but only a little louder, its a 4 stroke. Any one else hear this noise ? What causes this condition.
engine knocking ?
- Thread starter spencer
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don;t rev it..get as much old gas out...put in fresh and see if you still have the knock after running it abit...you just might have abit of old gas deto which can be dangerous..
Ya I have heard this noise before when u idle the pro with the side panels off. Goes away as soon as u touch the gas right? The only thing I could think of was the primary clutch weights slapping a little bit or something like that...I was confident it wasn't detonation.
Can almost guarantee you have a leaking oil check valve on the case. When the sled sits for a lengthy bit of time (over summer) the case fills up with oil and when fired up it makes a distinctive knocking noise. This is a pretty common failure.
To test the check valves you will need a small pump to pressure up the valves (they will hold 5psi then blow off pressure) If they dont hold back you found your leaking check valve.
To test the check valves you will need a small pump to pressure up the valves (they will hold 5psi then blow off pressure) If they dont hold back you found your leaking check valve.
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Oregonsledder
Well-known member
If it's the check valve it will also smoke like crazy for a few minutes. I had one go bad. I decided to just replace it. They can be kind of a pain to remove, so I figured if I was going to remove it to test it, I might as well replace it.
Problem solved.
They can be tested while still on the motor. Just a fyi.
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Oregonsledder
Well-known member
Good point.
I read over this one more time and didnt notice the sound stayed even after running it for a while. It could very well be the buttons in your clutch are worn making the sound.
Is this an 800?
Is this an 800?
Thanks to all, good points for sure, guess I will learn about the check valves.
I maybe overreacting to this noise. I started up my 08 700 and it has 1800 miles, it made a knocking noise twice as loud as my Pro, but sounds normal. One distinct thing I noted tonight was how smooth the 700 is compared to my pro, I also noted the power difference between the too when you rev them.
That said I love them both, but the 700 handles more like a tank compared to the Pro.
I hope to mod it with a pipe this year, when I do it will be informative when I pull the wye pipe and inspect the pistons for scuffing.
I maybe overreacting to this noise. I started up my 08 700 and it has 1800 miles, it made a knocking noise twice as loud as my Pro, but sounds normal. One distinct thing I noted tonight was how smooth the 700 is compared to my pro, I also noted the power difference between the too when you rev them.
That said I love them both, but the 700 handles more like a tank compared to the Pro.
I hope to mod it with a pipe this year, when I do it will be informative when I pull the wye pipe and inspect the pistons for scuffing.
The sound stays constant at idle, while I suffer hearing loss I can define rattles from engine noise, the plastic even has its own rattle, the clutch has its sound, I think its something I never noticed before and has been there all along.
Since the sound doesnt go away after a while I doubt its a check valve problem now.
To test you will need a pressure pump thats accurate at 5 psi. Pull the oil hose off each check valve ONLY, do not touch the main line or you will have to re-bleed the pump.
Run a piece of hose between check valve and pump to pressure it up. It should hold 4.5-5psi before blowing the pressure off. If it doesnt hold pressure its no good.
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