WHY does hpd use the 39 kehin carb on there race set up for the 400? Why don't they use the 42 mm mikuni?
THe reason I ask is because I Hate the 39mm kehin.IT is always Flooding because the floats are always changing because of hard riding on rough ground.Also HPD has told me what Jetting I should use and it is so wrong! SO, i got the Dial A jet but, now I can even run the bike because te Floats are to high Again. I have Had it with this carb!!!
Can ANYONE TELL ME ABOUT 42mm TMX FLATSIDE CARB ON THIS 400 HPD RACE KIT.

 

Sorry that you have that problem. I prefer Keihin because they are simpler and are easier to jet. Flooding is not an issue with the carbs and I personally dont like Mikuni.

 

I am also having problems with the floats on my 39pwk after a while my bike starts a steady drip of gas out the overflow tube so i pull it apart and adjust the floats it helps for a little while then starts all over again i'm really getting sick of it.

 

Never had a problem with my 39 pwk either on my sport or my quadracer.

 

I have been running the 39 for 2 1/2 years without a single float problem.

 

Are you sure you aren't wearing out the needle and seat...hence fuel starts bypassing and then over-flows? If you want to run the 42, you'll need to get the leaner cut slide, and the richer needle from Hot Seat. It does work, but the 39 is crisper, and produces more hp....I have them both, and the 39 is on the machine.

 

Stay away from the TMX man! They've burned more pistons to the ground than you can count! I, unfortuately got some first hand experience with that problem. Always burned up in the midrange. Look at the Polaris owners profiles in this forum, almost everyone is running a Keihn. There is a reason.

 

Modquad how can i tell if i am wearing out the needle or seat

 

i think you should re-consider your carb the way it is trimmed out right now,you mean rough stuff,so maybe there something cracked inside,those carb vribate so bad at idle that it can cause that type of overflow,it is normal,the pwk is just fine for that engine,better carb,if you consider a mikuni don't go over 38mm (tmx 38),the 42mm is like putting 50+mm carb on a XCR 800,too much intake airflow,i had the tmx 38 in the past and it runned really fine,faster throttle response but less crisper and power output than kehin...

 

If you're bypassing fuel, it's a component in your bowl metering (float, needle/seat) A good visual inspection...and when i doubt, the parts are inexpensive, change them.
Actually with the leaner cut slide, and richer needle, that Hot Seat sells, the 42 can perform decent. I think Rick Ritter, or someone actually flowbench tested the carbs at one time, and the 39 actually flowed more CFM than the 42.