Rate my plug

Zak

Active Member
Joined
Mar 21, 2019
Messages
251
So I snapped my chain the other day and now I have a new one and I'm replacing it and part of replacing it is pulling my spark plug so I can turn the engine. I don't really check my spark plug is often as I should so this is really the first time I've seen it in a month or two. Is this running lean do you think. it seems to run perfect and if I go wide open it'll four stroke. I'm running a dellorto clone with a 65 jet at 3850 feet on a stock engine.

IMG_20191008_222533850~2.jpg
 


BIG BOBBY

Active Member
Joined
Mar 22, 2019
Messages
123
the four-stroking IS because youre running rich,..95% of the time. so without even looking at your plug,...you're running rich.

drop your needle lower,...and/or lower your float height,....and/or unrestrict your exhaust/intake.

I did all those things and im still 4 stroking all over the throttle range till wide open,....and then it screams (powerfully) up to 6-6500,....and then starts sputtering like she has more to give but cant breathe. 4-stroking. I now have to resort to re-jetting. (down-jetting) and she is still running like a fat b*tch with a 66 jet!! (down from the stock 70)

---im prepared to,..and am going to,...go as low as a 60 if necessary.
 

LewieBike

Active Member
Joined
May 21, 2014
Messages
659
Note that Bobby's engine is the newer, unified head and barrel and they're ported a bit differently.

I'll assume it breathes a little better than the older two piece topend and consequently needs a leaner overall mixture. So don't go too far in changing jetting because of Bobby's experience. Just one step at a time and double check your float height each time.
 

darwin

Well-Known Member
Joined
May 26, 2008
Messages
3,279
Zak what gap is your plug set at? In the above pic it looks huge, can't even see the bottom electrode at all. You might need a new plug or it's an illusion just from the pic. Gap should be .028 +/- .002.
 
Top