FMF 4.1c and megabomb

I bought a 2010 250 sxf after getting the deal of a life time. I had and left a 06 stock and it was a great bike. All mt friends got bigger bikes the 350 or 450s. I wanted to run a little stronger so I got a FMF 4.1C with a megabomb. The 1st weekend it brought the bike to life! It started better and ran harder. It then sat for 2 weeks before I rode it again. I went to go ride and she started right up 1st kick. I made it 300 or 400 yards before pulling the clutch in to slow down. The bike died on me like I was out of gas. I released the clutch and it bumb started ran for 20 yeads and died again. Now she wont will not even start. The biks has maybe 15 hours on it. She will start with starter fluid and run for about 5 or six seconds...

The gas was on.

I had half a tank of gas.

Is my jetting worng?

I dont see how it ran fine for 300 or 400 yards to then die. I checked and I do have spark not sure how strong.

Also does anyone use the scary fast power now valve and the scary fast power plus valve... do they help? How much jetting will I have to do?

What are other good mods for your buck?

1) Put a new plug in the bike

2) Check for pinched or cloggged gas cap vent tube

How old was the gas you put in the bike?

Check for spark.

Do not waste the money on the power now junk, if your bike has jetting issues, resolve them instead of masking with the gimmick.

Other mods, your best bet is to ask in the KTM forum

I put a new plug in the bike still no luck.

We tried to kick it over with the gas cap off to make sure that wasnt the issue.

The gas was maybe 2 or 3 weeks old.

Drain the carb, confirm fuel is in there and there is no water in it from when you washed the bike.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now