Stella engine racing after spark plug change

RoaringTodd · Post by **RoaringTodd** » Wed Dec 23, 2015 1:16 pm

Last week my 2t Stella wouldn't start. She ran perfectly before that. I tested for spark, found none, so changed the spark plug. Gapped to .7 as per the manual. Same kind of spark plug as the previous one.

Now the engine races after riding around the block. I thought the spark plug wasn't in snug enough causing an air leak. Checked that with choke cleaner and removed and reinserted the plug. Engine still raced.

What gives? What in a spark plug change would cause the engine to race?

avescoots1134 · Post by **avescoots1134** » Wed Dec 23, 2015 3:00 pm

Pull the airbox lid and filter and make sure everything is closing correctly. Then you can check your jets if that isn't the case. Then go chasing air-leaks

RoaringTodd · Post by **RoaringTodd** » Mon Mar 14, 2016 6:44 pm

Update - it was the carburetor. Had my dealer take a look and he cleaned up the carburetor and worked his secret magic. I've never had her run this well before. What I thought was normal "Stella ya know" was not it. It's like a whole new scoot.

RoaringTodd · Post by **RoaringTodd** » Tue Mar 15, 2016 10:44 am

Forgot to add - the head was leaking a little bit. He machined the head smooth and put on a new gasket and torqued down everything tight.

fisher1 · Post by **fisher1** » Wed Mar 16, 2016 12:58 am

Wondering ..... what plug did they install / were you using? The Phila shop put a NGK B6ES in mine many years ago when I had it in for the 500 mi. warranty checkup. That's good for center city, but I'm in the 'burbs where I do a lot more sustained running and it showed up as increased temps on the CHT. So I swapped it out for a cooler B7ES which settled it back down to normal temps. Just FYI.

RoaringTodd · Post by **RoaringTodd** » Tue Mar 22, 2016 11:40 am

Yeah it's the B7ES.

However have been having problems with plugs fouling after only a few hours on the plug. We're talking wet black oil covered plugs. :facepalm:

Stellas. Gotta love them.

az_slynch · Post by **az_slynch** » Tue Mar 22, 2016 9:38 pm

RoaringTodd wrote:Yeah it's the B7ES.

However have been having problems with plugs fouling after only a few hours on the plug. We're talking wet black oil covered plugs. :facepalm:

Stellas. Gotta love them.

Still running the autolube? Does she seem to smoke a lot at idle? If so, you might have the pump disassembled and replace the O-rings that go on the pump's valve body. Besides that, your mixture might need to be leaned out a touch with your air leak fixed.

If you're premixing, what's your ratio, what's your jetting and what your mix screw set at?