I see how people are talking about running these huge main jets and was wondering if there is something I am missing...

When I rebuilt the motor on my 96 I did what I consider to be a few mods. When I put on the 38 mm carb I put in a 250 main. As soon as I had the motor back in the bike I started with the plug checks. After a few plugs I set the needle in the middle and left the 250. I used two new plugs for the checks and then put in a third one in June 00. I have not had to change the plug since. I check it almost everytime I run and it is nice and chocolate. Then I read on here that people are running 270 and 300 jets in their bikes. Are these bikes 4 strokes or am I missing something here? I run at sea level, so if anyone should be runnin' a fat jet I figure it should be me.

Is it possible to not run the bike lean and at the same time not be getting the full potential outta my bike (fuel wise of course)? Or is it that some people just run way too fat of a jet and consequently change plugs every other ride?

 

I live in NJ and I am around the same altitude as you. However it is a bit colder here so I run a 260 main and 3 1/2 clip on my needle (small plastic washer that is a half position) and the plug read is right on the money. The people you hear about are probably either at a higher altitude or in colder weather and that is why they run a larger jet, or they just like to waste gas and foul plugs. If your bike is running good and your plug is reading good why waste fuel and who wants to carry a gas can around with them all the time.

Ride with big ***** and land carefully!!

2000 sc400 4x4
hpd nickel pipe and clutch
air box mod (should be here today)
fox struts
dg bumber

 

I believe it can vary from one bike to another. You could probably set another one up identical to yours and might need a 270 jet.... it's not an exact science.

 

I believe that they are running a stock carb or bored carb,.I run a 170 in my scrambler with 39 PWK if it is running good and the plug check is good go with it.A piped scrambler with a bored carb would be running around a 260 or 270.

 

CDM

I have been trying to figure this out for ages, and get conflicting advice every time.

When I added the HPD pipe and clutch kit, I went up to a 260 MJ, and a 6CEY6 needle at 3 1/2 (middle with washer) as the instructions said. Since then i have done a few more bits, like K&N, Wiseco, Cool Head, muffler, reeds, reed spacer, and finally a RCR air box mod, but still have the stock carb. I have upped to a 270 MJ, but as we only have unleaded petrol here (91, 96 and now 98 Octane), plug checks are out. I am always afraid of running to lean, and like to see a bit of smoke out the back.

It would be really interesting to get get the comments of a pro on what they think (eg Rick Ritter)