Interesting spark plug problem.


Active Member
Local time
7:14 AM
Nov 6, 2007
Southeast Pa
Hello all.
My Whizzer has been a little hard starting lately. I had a coil problem that has been corrected. (the plug wire came out of the coil) The coil has been replaced however the bike still remained hard to start. I decided to check the plug. I have an NGK iridium plug installed. Well I was surprised to find the plug gap had closed to under .006. I did have the plug out recently but I thought I was careful with it but I guess I was not. The bad thing about this is all the testing that I have been doing with different hi speed jets has to be done all over again. I can't trust the results I got with the plug gaped that way. I'm surprised it even ran at all with that small of a spark plug gap. Correcting the plug gap solved the hard starting issue. I guess that moral of the story is when you are trying to trouble shoot a problem or trying to fine tune the engine, make very sure you have all other potential variables in line first. It will save you a lot of time and aggravation later.

We grow old so soon and smart so late.



Yep, Jim,
And sometimes it's dang near impossible to be smart enough. For example, when folks are learning to fly you always get told to be prepared for the unexpected... Now exactly how can you do that? If it's unexpected, how in heck can you be prepared??

Or, as a friend and fellow software writer once said, "Everything is strangely inter-twingled."


Quenton Guenther

Well-Known Member
Local time
6:14 AM
Aug 2, 2007
Outer Banks North Carolina
Hi RdKryton,
I have seen a few plugs slightly longer, make sure the exhaust valve isn't tapping the end of the plug. If possible mark the side of plug with a marker in line with the gap, use plug washers or copper washers to cause mark to head towards the center of the piston. This is called "indexing" and helps. I usually mark a whole box of plugs and use the one that needs the least amount of washers [too many washers may effect the heat transfer between the head and the base of the spark plug]. Just another tip from an ex motorcycle racer.

Have fun,
Whizzer OuterBanks LTD
A North Carolina Corporation


Local time
5:14 AM
Aug 10, 2008
Salt Lake, Utah

Another consideration. Iridium might be a better conductor than platinum but does it conduct as well as copper? The "ium" plugs are all about service interval. Most likely if you are jetted right and not sucking dirt you'll never have a problem with a copper plug. Your engine will probably wear out before the plug.

Back in the racing days I finally arrived at the ain't broke don't fix it and it worked well for me, I never dnf'd on mechanical. Sure pull it, look at it, check the gap, if it was running good don't replace it cause the new one might have a flaw.