OK...........I have been fine tuning my jetting and I just purchased a couple of new spark plugs. The one it looked pretty decent, it had been in the machine a while. Anyway, I looked at my new plug and it was ivory white!! At that time I was running 187.5 right (3 turns) / 185 left (2-1/2 turns) / clip in the 4th position on the needle. With stock pilots 22.5's / no airbox lid.

I just recieved some new jets so I bumped them up to 195 right (3 turns) / 190 left (2-1/2 turns) / clips in the 4th. position and I went back to the 25's for the pilots, no air box lid. STILL WHITE!!

I turned the screws out to 4 on the right & 3 on the left. Still lean!!
Comparison between my old plug and the new one. The new one is on the left.

New plug

The only thing that I have done is I went from having my clips in the 5th. position to having them in the 4th. position. My throttle response is a lot better now. Before I couldn't level out in 2nd. or 3rd. gear without it wanting to stumble a little. It was fine wide open, but bad at slower level speeds. It seems a lot stronger now with the bigger jets.

My question is this: I have heard (from a very reputable source) that you can be jetted too high and be running too much gas through the carbs and get a false reading. I have also heard (either King Raptor & Raptor727......One of the big boys) say that a person may need 200/205's if your around sea level. I am at 870'.

So, what now? I am going to call Harry tomorrow and probably order 200 & 205 main jets. I am heading off to Silver Lake tomorrow for a 2 day ride, and some drag racing. I DON"T WANT TO HAVE TO PUT MY AIR BOX LID BACK ON, but I will if I have to. The last time I was there I was running the 187.5/182.5.........

What do you Trinity boys think??

 

The largest Mikuni jet is a 200. I would not think you need that much jet. With 25 pilots you could be too far out on your screws. With the added size of the 25"s you should try turning your screws in 1/2 turn at a time. I have been down to 2 and 1/5 turns and that worked. 185/190 jets worked good too.

 

So, if I'm too far out on the screws I can have a lean looking plug too?? I would have expected a black wet looking plug tip. This thing is pearly white and dry as a bone.

What is your elevation?

 

It's Extremely Difficult to read plugs using Pump gas.
It has detergents that wash the plug clean.

Trinity Tech tips Has a good explination on reading plugs.
You need a 10X lighted magnifying glass to properly read a plug.

 

300 feet +/-.

 

It's running AWESOME now..........but, it's just so WHITE!!

I am running 93 octane (Station name = BP).

Thanks Guys.

 

<< It's running AWESOME now..........but, it's just so WHITE!! >>


I know the feeling!!
When I put my pipe on &amp; rejetted it &amp; I did some runs for a plug check. I have a place that's about 1/2 mile long, I can run wide open in 5th for about 30 seconds. I'd shut the throttle as I pulled the clutch &amp; hit the kill switch &amp; coast to a stop.
I checked the plug with the dynojet recomended jetting (DJ 146~148) &amp; it was white!!!
I bumped it up (DJ148~150) &amp; got the same results.
I didn't want to burn down my new Raptor so I took it to a dyno that has a 02 sensor. It showed rich with the bumped up jetting. I put the recomended Dynojets back in &amp; it was very close (slightly rich).
But the plug was still white!!
The detergents in pump gas just wash the plugs completely clean. This makes plug readings very difficult.

 

So what happens if you need more than a 200?

I am running a 175/170 right now, pipe and clamp-ons, at sea level. If I cammed and ported I would think I would be around the 200 mark. Lets just speculate I was going to do this where should I start, what size?

 

Here are the Mukini jet size and type specs use a different one if you can or a bigger carb!

http://www.justatv.com/pages/mikuni%...uni%20jets.htm

 

Ward, bigger than 200 means new carbs. That is where i am at now.