80cc motor knocking pretty badly

PJVolk

New Member
Sep 12, 2016
12
0
1
Portland,Or
So I was riding my 80cc motor bike into work this morning and about halfway it started vibrating worse and worse with a slight knocking. Also a kind of scraping noise. eventually I had to shut the engine off and pedal the rest of the way. When it was still running it really started to knock hard and loud and seemd to not have any power when giving it throttle almost like something was engaging correctly. I haven't been able to look at the anything yet since I am at work but thought I would ask you people to see if there is a particular place I should start. Any IDeas? Please help///

If anymore details are needed just let me know.
 

malatious

Member
Sep 23, 2014
61
14
8
Riverside, CA
Does it have oil in it. Quickest way to ruin an engine is to let it run out of oil. Knocking and scraping sounds like you ran low on oil and piston starts to seize and rod bearings start to go. It usually happens within minutes of oil level getting to low.
 

PJVolk

New Member
Sep 12, 2016
12
0
1
Portland,Or
Yeah it's a 2 stroke. I did the break in with a mixture of 20:1 and then went to 32:1. I've read so many different opinions on what mixture to run. But if I thought about it I would say when I went to that mixture it did seem to get a little louder. Hmmm. Well I'm gonna crack it open tonight and hope that. Itching horribly bad happened.
 

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
It might be the drive gear came loose. Nothing serious. Should be greasing that ting up every tank of gas anyway.
 

sboricic123

Member
Apr 15, 2013
172
3
18
Bailieboro, Ontario
I had a Flying Horse 66 cc that had some knocking. Eventually the piston snapped off and jammed in the cylinder. I'm not exactly sure what caused it. Maybe it was hitting bottom due to a loose clip that hold the piston on the crank. That's what I would check out by removing the spark plug and cylinder head, then turn it manually to see if it might be doing the same.
 
Jan 21, 2015
610
20
18
Portland, Oregon
Check and see if the woodruff key has come loose. Back when I had a 2 stroke this happened once and it made horrible knocking and scraping noises the whole way I pedaled home even with the engine off.
 

Parker

New Member
Feb 1, 2019
17
0
1
27
Check and see if the woodruff key has come loose. Back when I had a 2 stroke this happened once and it made horrible knocking and scraping noises the whole way I pedaled home even with the engine of.
This happened to me today on my way to work. I road it home from work for the first time yesterday (30 min ride) and it was perfectly fine. Today I got maybe ten mins from my house and my bike lost power and this weird loud cranking noise happened. It wouldn't start again and it was rolling easily even with the clutch out... any ideas?