Oil coming out from spark plug

[ballinchestr]

Oil slowly leaks out from the plug. I know it isn't the gasket because it drips down the fins of the head above the gasket.

I would immediately question the integrity of the spark plug threads. I removed and replaced the spark plug many times during the bike's construction.

I know new cylinder heads are cheap, but I can't find a 49cc one. do the 66cc heads work on the 49cc engine?

Thanks

 

[TakeiT]

This website is canada but... http://www.motorizedbicycle.ca/cylinder-parts/48cc-cylinder-head-cover.html

Are you sure that the spark plug is fully tight? Like, torqued down with the wrench. Inspect the threads of the head and the spark plug visually.

 

[2door]

If you are one of those who have the kit instructions that tell you to "finger tighten the spark plug", that's your problem. The plug needs to be a lot tighter than 'finger tight'.
If you have access to a torque wrench then tighten the plug to 60 to 80 inch pounds. If you don't have a torque wrench, or can't borrow one, buy one. It will pay for itself soon.

If the plug has been torqued numerous times then the plug gasket might be deformed and not sealing correctly. New spark plug gaskets can be purchased from a good auto parts store.

There is also a possibilty that you have a defective cylinder head and there is a crack in the head in the plug threads. In that case you'll need a new head. Nothing else will repair it. Don't even think of using JB Weld or any epoxy based repair. It won't work.

Tom

 

[rogergendron1]

I seen this twice before on bolth my dax motors.

Bolth dax motors i bought the head had verry loos plug threads one was soo bad i couldnt even use it!
The other was good after i wrapped the plug with a thin layer of plumbers tape and indexed the plug tlwith a thin copper washer

my advice is to toss that shiat in the scrap aluminum pile and order yourself a puch 70hi hi you will be blown away by the differance

 

[rangefinder]

Yeah, My Dax has the same issue.
I will post a photo of my plug later in my build thread.

 

[rangefinder]

Photo up on my build thread now.
http://motorbicycling.com/showthread.php?t=53036

 

[Redbiker]

This just happened to me and it was a crack in the head cover all the way to sparkplug. Kind of hard to see also

 

[wheelbender6]

I solved that "oil seeping around the plug" problem by installing a name brand spark plug, like NGK, Denso, etc. The mainland China made spark plug isn't machined as precisely as the name brand plugs. Some thread lock may help until you get a name brand plug.