spark plug gap

nmason · #1 07-22-2008, 08:20 PM

Recently I put a 80cc chinese engine on my bike, does anyone know what the proper plug gap is? It ran great the first day I tried it but now it runs but doesn't have any power. I was going to put a new plug in it thinking I might have fouled the one that came with it out trying to get it to run.

**Bikeguy Joe** · #2 07-22-2008, 08:21 PM

.020"

Check your intake for an air leak.

**Dave31** · #3 07-22-2008, 08:23 PM

Welcome to the forum

nmason · #4 07-22-2008, 08:31 PM

Thanks, I'll get a new plug and check the intake.

**Ilikeabikea** · #5 07-22-2008, 08:34 PM

Welcome to the forum. Glad you joined us..................

Quick1 · #6 08-26-2008, 05:18 PM

I just installed my 80cc and my spark plug gap was set to .045 and I adjusted it to where this forum recommended (some said .018-.023 & some said .020-.028). I set it to .025 & it wouldn't start. I tried everything and finally re-set the original gap & it started right up!

Quick1 · #7 08-26-2008, 10:37 PM

I'm sure it has something to do with the fuel/oil ratio used for break-in. It would probably have to be a bigger spark to fire through all that oil (16:1). It could also be due to the quality of components used. I'm using the stock plug/plug wire and will be changing that pretty soon. I'm learning a lot on the forum, but I haven't been able to find anything about upgrading my plug wire. Just recommendations to upgrade to a 7mm or 8mm wire. Not to change the direction of the thread, but can you point my in the right direction?

eDJ · #8 08-27-2008, 03:00 AM

Ya know alot of automobile engines are running gaps in the .040 neighborhood too. I think it's more to do with the CDI ignition they are set up for. As far as the plug wire I don't know just what the ohms resistance (per foot) of the wire
should be, but if you take the wire off and check it with someone who knows and understands this stuff then you could make that calculation.

I've seen guys put solid metal spark wires on High Energy Ignitions and burn the
system out. They generally rely on some resistance. The resistance helps to prevent the premature burn off of the electrodes (both center and ground) of the plug and maintain the longevety of the ignition system. Generally the wider gap gave better bottom end and starting characteristics where as the narrower gap gave the best top speed running. Bear in mind motor's aren't designed to run at 100% for long and 75% is a more sane cruising speed.

al1971 · #9 08-30-2008, 07:49 AM

hello everyone new to site have read some great stuff on this site on a spark plug gap which is better if it calls for a range between .028 to .034 a smaller gap seems to make more sense????

**Bikeguy Joe** · #10 08-30-2008, 07:57 AM

With the weak mag the china in-frame kits have, the general consensus is to gap @ .018-.024

If you can get a consistant spark at .034, go for it.