Intermittent Engine Knock By jofos (Read 4,797 times)

[jofos]

Hey peoples...

I have developed a very loud knocking noise that seems to be in the engine. I have had trouble keeping enough oil in it, and have been low before, but I put some in and it was fine. It was running ok and suddenly started running slower and started making the knocking noise. Strange thing is that it doesn't happen all the time. It will sometimes seem to work itself out and upon returning to idle it comes back with a vengence. It is pretty loud and my stepdad said I shouldn't ride it...

The tempo is the same as the engine.

Is my engine fried?

[sprocket]

Engine knocks are usually terminal, certainly will need a rebuild...sounds to me like it may be an oil pump problem. They will sometimes work OK at high revs and then fail to pump enough oil at idle and things start to go bad with not enough oil flow...

Really need to take it apart and make an assessment.

[Alleyoop]

Yea, does not sound good, usually if the knocking keeps on going above Idle it is usually a bad crank if it is more of a metalic when at idle it is usually the Wrist Pin that holds the Piston.
But actual knocking Is probably a sloppy Crank which they sometimes smooth out as the velocity increases.
Alleyoop

[jofos]

Thanks guys for the quick responses... although the news is not good. Was thinking of getting the complete engine/ drive-train assembly listed here (at the very bottom of the page):

www.scrappydogscooters.com/Replacement_Parts.html

Noticed the back tire developed some serious wear. As in chunks gone. Had a slow leak and determined that that was causing a lot of my acceleration issues... So if someone asks, make sure they check their tire pressure! ( I really had no idea low tire pressure could cause so many problems...)

As for my engine I think the issues developed from a vacuum system flaw in these scoots that will suck out oil if you ride for extended periods at full throttle. I discovered this while looking at parts where in an item description it described the problem, with that part being the solution. Since I like to ride my scooter for long distances I will have to get that part! (Crankcase vent/oil catch can)

[jofos]

Hey guys!

Well, I decided to just ride the thing til it quit... And due to it being winter and all I haven't been riding it much. But guess what?

I disassembled the clutch area and found nothing wrong. Then reassembled it. The noise was still there... BUT after a day of short rides, the noise went away! I realize this could be either very good or very bad. But i am hoping it is good, of course.

Still have no idea what the cause was. Buut for now my scoot is running pretty well and not sounding like it has a glass-pak.

Fingers crossed!

Thanks

[mflorek]

Noise like you described could fall under two groups, first worn-out moving parts in the engine or detonation under a very lean condition. When the fuel to air ratio is too lean, the combustion is very violent. Extreme heat and a situation where the piston is burnt or broken can result. The quickest check is the spark plug.