Lurching While Decelerating and a Howl

[Freddy Snottgrass]

So last night I pulled off my derailleur and it let me slide my axle back to where I do t needu chain tensioner. I don't know if it is me looking for things but... When I let go of the throttle to slow down, clutch engaged, it seems to lurch forward at times randomly. Also, I've always hear a little howl, maybe it is louder now? What causes that howl. My gut says it comes from the clutch and the howl is caused by friction from slippage...

Any thoughts?

 

[FurryOnTheInside]

Engine braking is not good for the engine. All the lubrication is in the fuel.
You should really avoid engine braking as much as possible. Pull the clutch lever in and use the brakes instead.
I don't know what the lurching and howling is. I would take it as a bad omen.

 

[Freddy Snottgrass]

I'm gonna loosen my chain up a bit more and see. I was fine before I messed with the chain tension.

I'm sure I'm fine slowing down to take a turn or because a car is at a cross street waiting to pull out, without disengaging the clutch is fine.

 

[Mcdonns]

Speaking chain tension.., I’m gonna guess the lurching during deceleration is “wrap-up”, and the “howl” is either counter-rotational force on the gears or even the clutch maybe slipping against the lurch?

 

[Freddy Snottgrass]

That's what I was thinking too just not as smart. I thought maybe the chain may be hitting a tight spot and the lurch was when it slacked, and the howl was the clutch slipping when it happens. The best way I can explain the howl is by comparing it to a high powered electric RC car.

I did loosen the chain and it got better. I'm gonna loosen it a tad more and it seems like it should be right on spot. I also think now, with the derailuer gone, it might be slipping backwards on the drop outs and tightening. Causing the issue. I'll probably slide it all the way back, add a link, and throw the tensioner back on if it keeps giving me crap.

 

[Mcdonns]

That's what I was thinking too just not as smart. I thought maybe the chain may be hitting a tight spot and the lurch was when it slacked, and the howl was the clutch slipping when it happens. The best way I can explain the howl is by comparing it to a high powered electric RC car.

I did loosen the chain and it got better. I'm gonna loosen it a tad more and it seems like it should be right on spot. I also think now, with the derailuer gone, it might be slipping backwards on the drop outs and tightening. Causing the issue. I'll probably slide it all the way back, add a link, and throw the tensioner back on if it keeps giving me crap.

Not sure what your engine or drive system exactly looks like, but these do sound like suspects. The cycle between wrap-ups is VERY quick, and could actually cause the chain to jump off (given enough slack), or even ride high enough in the drive (small) sprocket teeth to maybe cause a lockup inside that housing. Trying to correlate that RC nitro sound to anything else, but I’m only coming up with chain to hollow metal...

A slack running chain at neutral (no +/- torque, as would be the case in the middle of each of those “chug” or lurch cycles) tries its best to be round. That means, the slack that wraps up on the bottom of the chain during positive load (acceleration), would inversely become wrap-up on the top during negative load (deceleration, or “engine-braking” like FOTI points out). That RC engine sound you’re talking about would really have me wanting to pull that left sprocket cover, check the gear, and look for aluminum.

Spitballin’ the description, but any significant deflection on the chain is eventually going to create a much more serious problem/failure than what you have now. Real curious, what you may see under that cover...

 

[Freddy Snottgrass]

I'll do that as soon as the shade starts working again.

 

[Mcdonns]

Yeah.., stupid shade! Never around when ye want it t’ be.

Again, be careful about adding slack... Too little, the chain sometimes tries to climb the sprocket teeth when the links bite in. Too much, she’ll lurch around, jump and start eatin’ stuff up (if it doesn’t flat break). Without something to control slack (tensioner/idler), that “sweet spot” where it just runs smooth like a moto should is short-lived. Look very closely, and move things around with that cover off, so you can see what’s going on.

When the shade returns, yes, very curious what you may see.

 

[Freddy Snottgrass]

Yeah I ran a magnet in there and didn't pick anything up so I don't think there are any shavings.

Is this normal or bad? Motor has about 175 miles.

 

[Mcdonns]

“Yeah I ran a magnet in there and didn't pick anything up so I don't think there are any shavings. “. Now.., THAT’s hilarious!

Yes, it’s bad, but nothing you can’t clean up and fix by keeping safe tension on the chain. That gear looks fine. There’s another fresh thread, on chain tension, where you could see where yours was headed... Good catch, Zak!

Check post “49cc no chain tensioner”. Awesome pics, that one...