Jump to content
Sign in to follow this  

Knocking noise accelerating from 4500 RPM

Recommended Posts

Hey everyone,

 

Allright I have read through a few posts regarding knocking noises. I have one that just started 2 days ago it sounds like something loose rattling around but I only hear it in 4th or 5th gear and around 4500 rpm when attempting to accelerate fast, no sound if smoothly accelerating and nothing on decel or standing revs. I checked the valves and they perfectly in spec, the cam chain is looking good too. The sound seems to be top end but its hard to tell when you moving 75 kmh, but I just finished reading the post about a bent balancer shaft and his symptoms were similar. There is no sound about 5k rpm and 1-3 gear is quiet. there is no power loss, no weird idle, no smoke, its not burning oil, no wierd harmonic sounds, regular oil changes 2500 kms ams full synthetic 10w40 91 octaine fuel. The motor has 21000 kms its a 2001 MCCt installed, full exhaust system Mikuni tm40 carb, 16/38 sprockets stock everything else. I looked at the posts regarding loctite fixes on countershaft nut, so I did that, but have not cracked the case to look at stator, would that make a constant sound or a sound like mine? Read about water pump too but my temps are good would the water pump make a specific sound liek this? Is there anything else I should consider before I end up having to gut the engine to inspect?  

Edited by Rukix

Share this post


Link to post
Share on other sites

Any metal debris on the oil drain bolt magnet ?

No Metal Debris, just did an Oil change 50 Km ago.

 

Could be Too Low an Octane rating in the fuel.....maybe filled up with a bad batch  or misrepresented fuel type....?

I could try fresh fuel, just used 91 octane, I will try that today with octane booster and see if it goes away.

 

Define knocking, tapping, ticking, worse under load, worse when warm.

The sound only happens when the coolant temp is 60C or higher, there is no sound when its below this. I removed valve cover and measured the valves intake are 0.15 and exhaust are 0.25.  the sound it almost like a tapping, its definitely not the normal DRZ engine noise. At 4500 rpm it will only happen if I crack the throttle fast and I get 3-4 taps or light knocks (not a ticking) then it goes away. At first I thought it was a slack cam chain the sound was almost like a chain with to much free play moving on a gear, but drive chain and cam chain are good. If I roll through the range there is no noise, no sound at idle or cruise speed, also in lower gears 1-3 there is no sound only 4th and 5th. I am wondering could it be the fact that I am running a 16/38 sprocket and its just piston slap because 4500 would be lugging? I Have am Mikuni tm40-6z flat slide pumper carb that I recently installed, could the sound be the result of more power at lower RPM range because I don't get the lugging sound I used to get with the 36 mm stock CV carb?

 

I am starting to wonder if it is the balancing shaft tapping the rod. The timing is bang on the cam marks are perfectly lined and the cam chain is at the right tension (MCCT) If it was the balancer shaft hitting the rod would the sound be evident at all engine speeds? 

 

I just ordered the clutch side gasket and a new cam chain once the parts are in I will open her up and take a peek at the crank nut and balancer nut is there anything else I should order like the Stator side plug and o-ring? .  I contacted the previous owner and he said he did the loctite fix about 10000 KM ago. 

Edited by Rukix

Share this post


Link to post
Share on other sites

No Metal Debris, just did an Oil change 50 Km ago.

I could try fresh fuel, just used 91 octane, I will try that today with octane booster and see if it goes away.

The sound only happens when the coolant temp is 60C or higher, there is no sound when its below this. I removed valve cover and measured the valves intake are 0.15 and exhaust are 0.25. the sound it almost like a tapping, its definitely not the normal DRZ engine noise. At 4500 rpm it will only happen if I crack the throttle fast and I get 3-4 taps or light knocks (not a ticking) then it goes away. At first I thought it was a slack cam chain the sound was almost like a chain with to much free play moving on a gear, but drive chain and cam chain are good. If I roll through the range there is no noise, no sound at idle or cruise speed, also in lower gears 1-3 there is no sound only 4th and 5th. I am wondering could it be the fact that I am running a 16/38 sprocket and its just piston slap because 4500 would be lugging? I Have am Mikuni tm40-6z flat slide pumper carb that I recently installed, could the sound be the result of more power at lower RPM range because I don't get the lugging sound I used to get with the 36 mm stock CV carb?

I am starting to wonder if it is the balancing shaft tapping the rod. The timing is bang on the cam marks are perfectly lined and the cam chain is at the right tension (MCCT) If it was the balancer shaft hitting the rod would the sound be evident at all engine speeds?

I just ordered the clutch side gasket and a new cam chain once the parts are in I will open her up and take a peek at the crank nut and balancer nut is there anything else I should order like the Stator side plug and o-ring? . I contacted the previous owner and he said he did the loctite fix about 10000 KM ago.

yeah I'm almost for sure it's your piston getting loose. Because the chamber expands with heat, etc. the piston can hit the sides making a tapping noise. It's not a SUPER big deal but it's not very good either.

Share this post


Link to post
Share on other sites

By piston getting loose do you mean, worn rings or scored cyclender wall. Or something like the wrist pin is starting to excessive play?

Share this post


Link to post
Share on other sites

I would be inclined to think you need a heavier oil, 15/50 instead of 10/40.

Not sure what your weather is like in Kentucky but I'm guessing it's summer.

Older high mileage engines need a thicker oil as tolerances increase even when there still running fine, plus the other reasons mentioned about your gearing and lugging can exacerbate the problem.

Share this post


Link to post
Share on other sites

Get in there and have a look, remedy before it explodes and costs you three times as much to fix

Share this post


Link to post
Share on other sites

Get in there and have a look, remedy before it explodes and costs you three times as much to fix

 

my thinking exactly, might be time for the BB kit... 

Share this post


Link to post
Share on other sites

my thinking exactly, might be time for the BB kit... 

Every problem presents an opportunity, in this case for more wheelies :)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...