pwk 39 on stock tri z

[pcs]

im currently running a mikuni tm34 carb but it leaks a little from the float bowl area and dont want to bother with a rebuild, so im think of getting a keihin pwk 39 (free) from my friends lt500r. my tri z is completely stock, i dont plan on getting it ported until late spring or if i sell my 200x. can any of you guys who have ran a big carb on a stock tri z or close to stock comment on how it will run? im sure low rpm throttle response will be bad but i dont really lug the engine nor putt around. im usually riding in the upper half of the rpm range.

[christph]

I've got an 86 Z and recently put a 38 pwk on it. I've also did some of the Tri-Z Wrench Report mods to the cylinder, e.g., additional boost port, cleaning the casting, etc. Up to now, I haven't gotten it to perform as well as I had hoped. It is weaker on the bottom than I expected. I may still be dealing with a jetting issue but it could be due--in part--to the larger carb. The smaller carb I had on it before made better power on the bottom end. My guess is a 39mm carb on a stock cylinder would bog severely on the bottom and wouldn't be that much better on top. It is just too much carb. For comparison, I have a 39mm on my Duncan 340 R, which is what Duncan recommends.

[Bryan Raffa]

try a CEL needle, 55 p... and a 180 main... you should be in the ball park to jet it..

[3 Wheel Drive]

If you are using the stock tri z thumb throttle and cable, they will need to be replaced. The stock stuff will not open the PWK 39 carb all the way. Banshee thumb throttle & cable will work, there are other substitutes which will work also.

You may want to go with an aftermarket silencer, and upgrade your stock reeds to some carbon fiber reeds, for more airflow you can remove the lid from the air box.

Prolly need to heat up the intake boot to recieve the larger carb, if your planning on using the stock one. Time to invest in some aftermarket upgrades! Cool heads, exhaust, porting, etc... Time to open up the wallet!

[Bryan Raffa]

83 84 R Cable and only the 85 throttle will not work... you can thred it so it will accept the cable. 86 throttle will work, a warror is smaller than a banshee throttle,,, it will give you more room for your master cyl.


It will fit in the stock intake with heat

[pcs]

thx for all the inputs
chrisph: im sure your right on the low end of the power band. not a fan of duncan or their engine combinations. i ran a 39pwk on a 250r with a ftz port and it actually ran better with a ported mikuni that was 40.5mm that i borrowed just to try it. depends on your engine combo i guess.
raffa: ill give it a go with those jets just to start and i have a few extra thumb throttles, 200x, 400ex, trx 250.
3 wheeldrive: you are right, it cost $$ to go fast haha. i got some boyesen reeds, and looking into a pipe. just dont want to drop $ on a pipe i will get rid of to better match a ported cylinder. might just go with a dg silencer for now. looking at the dyno port pipe, but i might contact LED to see if he can make remake the LRD pipe. looking to make my tri z a hi rpm screamer.