replace stock carburator?

[emerson]

i own a 87 lt500r. boutght new fmf fatty,reeds,, new piston, clutch, soon to get k&n filter. no plans on porting cylinder for now. It runs good. I was wondering if anyone has expertise on what carburator I should get to replace the stock (mikuni). It does works though. I heard the keihin pwk39 is better and it can be bored up to 40mm. others say theres a 44mm carb out there and ive even heard a 50. It seems overkill. but im pondering between the 39 and the 44. They say the 87 has a bigger intake than later models so I don´t know. Ide appreciate some input. ill try to post pics some time. thanks

[ProTTZilla]

What do plan to do with your quad????Trail ride,drg race ect...A PWK 39 will fit in the stock location without removeing the stock air box the only thing is you need to modifiy your throttle cable or buy one for the PWK.The 44mm or 50mm carbs I think you will have to change the air box setup around or maybe even have to remove it all together.

[gh500]

do you know if you still have yor stock carb or has someone replaced it with a 88-90 carb ? a lot of shops put the newer styke carb on the 87's the 87 carb IMO was a POS you can tell by looking for the model #on the carb it's on the right side on a small square pad the 87's were 43b00 & the 88& newer ones were 43b10 & 43b20 which are both good carbs can be bored larger & keep the stock look

[ThrowinRoost89]

id go with boring the stock carb. about 41 or 42mm. if you buy one, you DO NOT wanna go bigger than 44mm. you will start hurting your hp if you go to big, remember that.

[flotek]

mikuni flatslides are pure junk ,id just get a 39pwk for gas on a non ported cylinder and youll have better response and a few hp too

[gh500]

IMO keihin pwk are junk you cant replace the needle jet to tune them like a mikuni & rebuild them your stuck with what you get when they are used & have a worn needle jet now dont confuse the needle jet with the jet needle which is replaceable in both
depending on which carb you have 87 or 88-90 if it's 88-90
I'd bore your stock carb to 39-40mm to start with you can always go larger 41mm is about the limit on the stock carb they start getting thin

[flotek]

mikuni TM carbs have soft aluminum slides and wear out causing erratic jetting and free rev especially when theyre 20 years ,it is way more likely to have this than a worn seat on a keihin carb plus a pwk is just plain more advanced circutry and design.for alky applications it(mikunis) may be a better choice.i have found the tm series to be harder to accuratly jet

[gh500]

well it all comes down to preference & what you know how to tune i guess thats why i prefer mikuni i've tuned them for years & can dial them right in w/o any problems
for a zilla they fit in the factory location & use a factory cable & intake tract & just make things a lot easier IMO

[emerson]

thanks for your inputs. i didn´t know how to see the replies posted untill a few minutes ago. tommorow im going to check the carburator to see what year its from. I think ill probably go for the 39 keihin because my stock is hard to jet and even has rusted parts in it. If I do go for the 39 keihin will the intake track (i believe its called) need to be changed or does the carb fit right in. im taking off the air filter box so that doesn´t matter. and the same question for the 41 pwk. can i pull off using a 41 u think? hope u don´t mind my silly questions.

[ProTTZilla]

Correct me if I'm wrong.But I think the biggest PWK is a 39MM unless of coarse you bore it.And yes a PWK fits right in the stock location and you have the choice of useing the stock air box as well I did.Actually I think I have PWK 39 smooth bored to 40.5 mm if your interrested I will dig it up.