backfire

[bklyn400ex]

when i start my bike it is very difficult to start for the first time, and it backfires for the first couple of minutes, it stops when its warmed up could this be the jetting?

[Syrus]

set ur valves and jets i think :o

[bklyn400ex]

i put a pipe on, K+N filter, drilled holes in airbox, ground out welds in head pipe, and i never rejetted, it seemed ok, until it got cold, now it pops alot, can i do damage??

[joeroadking]

yes it is to lean richen it up !

[Wheelie]

You need to rejet.

A lean running motor can burn valves, cause the motor to run too hot, and, worse case scenario, cause piston siezure.

Here's a suggestion for a good starting point for jetting: #40 pilot jet (stock is #38), lower the clip on the needle one notch from stock, and try a #152 or #155 main jet (stock is #148).

As a bonus, when jetted properly, your machine will have more power and better throttle response.:macho

Good Luck!

[bklyn400ex]

i ordered a 40 and a 150, should that be ok??

[JabberJaw]

Backfire

I have the same problem when I stand too close to the fireplace!

[Wheelie]

That will be an improvement. Also, try setting the mixture screw at 2 1/2 turns out.......do this while changing the pilot jet, it's much easier than doing it while the carb is still mounted in the quad.

Later,
Jeremiah

[bklyn400ex]

i pulled my main jet out and found out that the last owner put in a 155, and the plugs are coming out black what should i do?

[bklyn400ex]

and the main said 155rd, there was no k for keihin, is this the wrong brand or sumtin?

:blah :blah :blah

No flame bklyn400 but you dont seem to want to accept that there is more jetting circuits than the main jet, and by what you keep saying over and again it looks like your motor is lean on one and rich on another like I had told you b4.

You need to check out the jetting guides on these sites (or others) and see how to figure which circuit is lean and rich etc.

Honda ex.com and denton web sites have some very good tuning info.

[mcmike]

I'd bet that you have leak on the exhaust. Around the clamp?:)