Not really a question more of what happened.

Got a 79 shov/chop and I recently changed out the plugs. Dual plug heads, 2 long reach champion and 2 short reach nkg, it was all the shop had.
Anyways I ride for weeks with no issues. The other day I went for a 2 hour ride and 1 in it started back firing and stalling out. Eventually dying on a bridge. I fired it back up and it ran like poop constantly back firing but I had no choice but to keep going forward. I eventually made it home and thought the bike needed some major repairs. Cleaned the carb, and then checked the plugs for spark. One of them bastards was not sparking! The nkg was nfg!!! Luckily I had dual plug heads otherwise I would have a tow bill.

Anyways I'm happy it was just a plug!!!!!!!

 

both plugs were fouling - it should run on one plug just fine - i think your compression is down in that cylinder or you have an intake leak

 

really? So I assume it will do it again? I want to rebuild it but not till winter. Do you think it will keep doing this then?
Thanks

 

Out of The two plugs on the cylinder one was fouled and the other was clean but no spark. I do have oil leaking out of the header or where the pipe mounts to the motor. I know it needs work but I'm hoping to run it till the winter.

 

go up 2 heat ranges in the plugs in that cylinder - low compression motors need a hotter plug BUT only use them in the one that has issues - 2 heat ranges will Help burn off the extra fuel that looks like oil

Try and drive it like a human being for the summer

 

Good call, I do ride it pretty hard. What plugs would you recommend? I didn't know there were different heat ranges. Last plugs I had were two nkg long reach and 2 champion short reach.

What would you recommend? Part number too so I can order em today.

Thanks you're very helpful John.

 

I've been reading a lot about the plugs now. One question I now have is, I saw on a car forum of a guy swapping out short reach for long reach plugs. Can I do that too?

I need to check all my plugs to see what the store gave me now that I know about heat ranges.
I know he gave me Champion Rn12YC for the short reach and nkg (not sure on number) for the long reach. So I'll get rn14yc for that cylinder.

If I could change all to long reach it would make it easier to find em. My parts store sucks here.

Thanks

 

Sorry for all the posts John,

Here's what I'm thinking of ordering. It's a 79 shov dual plug heads. One long and one short on each.
All nkg

2 bpr7hs (short)
2 bpr7es (long)
2 bpr5hs
2 bpr5es

That way I got extras.

Any advise

 

try that BUT DONT use a long plug in a short sparkplug hole - you wont be riding it this summer

the NGK are good plugs and the 7 is about right for low compression

 

So I used the hotter plugs and it ran great for a goal for 3 hours of riding over several days. Took it to my mechanic guy and he did a comp check and it had 85 in rear and 90 something in front, I thought that was bad but said it could be fine depending on what's been done to the motor. From what I've seen in the manual 90 and up with no more than 30 psi difference between cylinders. Anyways he thinks it's a jetting issue and its fouling plugs and leaving gas in the cylinder. The bike had straight pipes 2 years ago and last year I swapped a 2-1 With a shaker upsweep so that could be my problem.
What I don't understand is how I was able to ride all last summer without this problem. If it was the jetting wouldn't it have happened sooner?

Thanks for your input guys!!!!