Hi all,
This is regarding a 2001 Yamaha WR426F 4 stroke dirtbike.
I've recently noticed a slight mechanical whirring sound coming from my engine. It is not a high pitched metallic shriek. Just a continual squeak that comes around every revolution of the engine.
I'm not sure if it was like that when I bought the bike but I only took notice to it over the last 4 days.
It makes the noise when idling. When I rev the engine, the sound increases frequency. I let go of the throttle, the sound decreases back to the idle level.
The bike is kick start only. I noticed a "rough patch" in the kick starter movement path.
Say it starts at 12 o'clock position. At 6 o'clock, it is a full motion of the kicker. I hold the compression lever in and slowly push the kicker down. Around 9 o'clock, there is about 1-2 cm of "roughness". I can feel a slight scrape, maybe due to rough contact somewhere.
I did an oil change and the rough patch was slightly better afterwards.
I checked the filter and it did not have excessive metal frags in it. Just a small amount on the outside of the filter.
The exhaust is fine, no blue smoke during start-up and operation.
Power is still there, responsive throttle, plenty of acceleration when I need it.
The exhaust makes a gurgling sound accompanied by 2-3 "pops" in close succession when I let go of the throttle after a good hard blast. I don't believe this is backfiring (is it?).
I'm not sure if this is from the timing cams/chain or whether the piston itself is worn.
Any advice from the pros?
Is the bike about to blow up?
Is the timing chain slack or are piston seals worn down?
Or is this just the normal operation sound from this type of bike?
I found a youtube vid about cams/valves for a YZ250F. If I need to do a top end rebuild, can I follow the same instructions for my WR?
Hot Cams Installation Yamaha YZ250F - YouTube
Any advice is much appreciated.
Cheers
This is regarding a 2001 Yamaha WR426F 4 stroke dirtbike.
I've recently noticed a slight mechanical whirring sound coming from my engine. It is not a high pitched metallic shriek. Just a continual squeak that comes around every revolution of the engine.
I'm not sure if it was like that when I bought the bike but I only took notice to it over the last 4 days.
It makes the noise when idling. When I rev the engine, the sound increases frequency. I let go of the throttle, the sound decreases back to the idle level.
The bike is kick start only. I noticed a "rough patch" in the kick starter movement path.
Say it starts at 12 o'clock position. At 6 o'clock, it is a full motion of the kicker. I hold the compression lever in and slowly push the kicker down. Around 9 o'clock, there is about 1-2 cm of "roughness". I can feel a slight scrape, maybe due to rough contact somewhere.
I did an oil change and the rough patch was slightly better afterwards.
I checked the filter and it did not have excessive metal frags in it. Just a small amount on the outside of the filter.
The exhaust is fine, no blue smoke during start-up and operation.
Power is still there, responsive throttle, plenty of acceleration when I need it.
The exhaust makes a gurgling sound accompanied by 2-3 "pops" in close succession when I let go of the throttle after a good hard blast. I don't believe this is backfiring (is it?).
I'm not sure if this is from the timing cams/chain or whether the piston itself is worn.
Any advice from the pros?
Is the bike about to blow up?
Is the timing chain slack or are piston seals worn down?
Or is this just the normal operation sound from this type of bike?
I found a youtube vid about cams/valves for a YZ250F. If I need to do a top end rebuild, can I follow the same instructions for my WR?
Hot Cams Installation Yamaha YZ250F - YouTube
Any advice is much appreciated.
Cheers
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