|
|
Post by blackedoutjog on Feb 1, 2011 19:29:12 GMT -5
So just put a new 72cc BBK in my jog. She ran great for a bit, then after a test ride yesterday, I went to start her up for work. KNOCK! KNOCK! A horrible knocking, very inconsistant, coming from the engine. Pulled it apart this morning. Wrist pin and bearing are good, crank shaft bearing is good. Noticed a strange burn mark on the cylinder wall and piston, positions directly in between the exhaust ports. I can upload pics if need be. Any guesses on the noise? Could running too rich cause this. I pulled the plug and its pitch black and oily. Much thanks.
|
|
|
|
Post by 90GTVert on Feb 1, 2011 20:49:45 GMT -5
:welcome:
Pics are always preferred. The more info, the better.
So it sounds like you have a kit with a bridged exhaust port, and there is a burn marking at the bridge? That's known to be a hot spot, but I wouldn't think you should be seeing burn marks. Is there scuffing or just black there or what?
It definitely does sound like you are running rich with a black, oily, spark plug. That doesn't usually cause a knock though.
|
|
|
|
Post by stepthrutuner on Feb 1, 2011 22:16:25 GMT -5
In Two Stroke Performance Tuning A. Graham Bell advises to file the piston a bit at the spot where the piston is bearing on the ex. port bridge. Are you certain of sufficient oil mixture? It's hard to get a handle on the inconsistent knock. Letting us know all the recent mods/repairs to the scoot would be helpful also.
|
|
|
|
Post by blackedoutjog on Feb 1, 2011 22:46:59 GMT -5
The is enough oil. If anything, I'm probably running it too rich based on the plug. I'll upload some pics in the AM. Thanks for all the input.
|
|
