I got ahoold of a 400 carb for my trailblazer.Do you know what jets and stuff I need to make it work?I dont know my alltitude all I can say is I live 30 miles north of kansascity mo.Thanks for all your help and I was wanting to know how I acn make a 35mm keihn carb from hpd work on my bike.It is a 1998 non concentric drive model.It is brand new and it hits on my tranny if I use the hot seat manifold and adapter. thankyou

 

Any porting or a pipe? You can also do a search for info on Shotwell's page. TalonHawk also has done some 250 work.....not sure if Bubba has.


Ken

 

Like Modquad said, I've done alot of work on my 99TB. So how bad is the carb
hitting on the tranny? I had to take a belt sander to my intake manifold and
sand off about an 1/8 inch. Then file the corner down on the tranny case. Does
the 400 carb fit better? If it does then I would go with thatand check back into
the old archive files for the jetting it needs.

 

The 400 carb would work OK if it fits better. They are 34mm. Jetting should be around a 240 main and 25 pilot for starters. Depending on the motor combo would change the jetting. I would grind or sand like Talonhawk says to use the 35,though. It is a flatslide and would help the low end better. Altitude should be about the same as mine. Bubba

 

So a carb from a 400 will fit on my Trailblazer. I couldnt see why not. What gains will i notice? And does anything else have to be done to do it?

 

I would think that you will see an improvement with throttle responce and
an overall hp gain threwout the power band! Just get the Hotseat manifold
and re-jet.

 

The gains you will see are going to be mostly in the mid and top end. If anything, your bottom end may get a little "spongy".
I have a 34mmTM mikuni on my 300. It made my bottom end just about useless. The motor actually pulls too much air if you give it a little throttle at idle. Besides, with our piston port motors, it will be a little tricky to jet. The reason for that is that our piston port motors actually allow the air to pulse back and forth at low throttle settings. As the piston comes up to compression, the crankcase pulls in its next air charge. Then, as the piston starts coming down, some air under the piston actually gets pushed back down the intake and into the carb. Then the motor pulls it back throu the carb again. When this happens, you actually just doubled your pilot jet. The more efficient the carb works, the worse this scenerio gets.
The flat side carbs are usually more efficient at mixing the fuel and air than the round slides. It is my opinion that the round slides aren't as efficient so they don't over flood the air during this back pulse. Atleast not as much as the flat slides do.
For all out HP - use a flat slide
For more HP and still easy to use and jet - use a bigger round slide.
Just trust me when I say, the piston port motors and flat slide carbs are hard to set up for all riding conditions. Be carefull.
My opinion, use the SC carb.