CR500 Carb Question

[matt14c]

I did some research and found that the carb I have is off a 1986 CR500. The code on the side is PJ24A. I found it on a CR500 riders website. Is this the same carb or as good as the carbs that come off the newer ones like the early to mid 90's? Same size 38mm? Is this the same PWK carb it seems most of you talk about? Thanks in advance. Never had an R before just trying to figure out everything I have to have a starting line for adjustments.

[86 Quad R]

the carb on that year cr500 is a pj series. it is a "oval" slide whereas the pwk series that you hear so much about is a d-slide

[IcutMetl]

I have the same Keihin 38mm PJ carb on my 'wheeler and it runs good. I don't have any other experiences with different carbs though; it came on my motor when I bought the 250r. From what I gather, the 38mm PWK AirStryker carb is the tits and muff for these motors.

[matt14c]

So I have the PWM? The slide doesnt affect how it will be adjusted correct? Say someone had a similar setup as I with the other carb I could use his settings for a baseline or starting point.

[IcutMetl]

No, you have a 38mm "PJ" series carb.- same as myself The stock carb on a 250r was a 34mm PJ series...same thing; just smaller. I believe they've been discontinued, but will still use the same jets and spare parts as most any other Keihin 2-stroke carb from what I've noticed. One thing that a few people don't seem to care for on these is that the choke knob is also the idle adjustment, making consistent idle adjustments a little finicky sometimes...which I notice. They can be had pretty cheap on ebay, and were very popular on a few dirt bikes, including the CR500. Seems to run very well on mine, and is easy to work on. The "PWK" series, especially the Air Stryker 38 seems to be "the one to have" and about the most popular aftermarket one available. Typically, a large carb on a small motor will result in reduced low-end response and power due the loss in air velocity. The air-stryker "PWK" variety combats this due to a different intake tract and the D-slide.

Jetting has SO many variables, that all anyone on here will be able to give you are rough suggestions. From what I've done on mine, and assuming you are on a stock bore , mild compression, and perhaps an aftermarket pipe, I would think that a 48-50 on the pilot jet would be a good place to start, and around a 155-160 on the main jet. The needle can (and was to me) a pain in the nuts, but starting out in the middle clip is always reccomended. I would guess that you'll be able to tune it in w/o changing to a different needle. I have a 175 main, 48 pilot, and DGH needle on 4th clip down, but it could be TOTALLY different for you.

If you have questions or need parts, there's a guy in Cleveland on Ridge Rd. at Carb Parts Warehouse that has helped me out quite a bit- run a net search and it'll come right up. There is also a Keihin jetting suggestion chart somewhere on there that helped me. Search Duncan's website as well for their jetting suggestions- they helped me out too.

Good luck!!

[86 Quad R]

what he said........


the main mostest reason most guys dont like the pj carbs is the fact they have the idle circuit and choke combined, making it a bit tuff to dial in. but once dialed in, they are a fantastic carb. i too run the 38mm pj on my personal quad and actually preferr it over the 38 pwk/as.

[matt14c]

Its not a stock bore though its bored 80 over. The guy had it all jetted and running in the winter he had the motor in his three wheeler. So im guessing it will some some adjusting due to the 50 degree increase in temp. Thanks for all the help guys. Will prolly have many more this is my first 2 stroke other than a sled which those have had efi since 1990 something so I havent messed with 2 stroke jetting.

[regg187]

Originally posted by 86 Quad R
what he said........


the main mostest reason most guys dont like the pj carbs is the fact they have the idle circuit and choke combined, making it a bit tuff to dial in. but once dialed in, they are a fantastic carb. i too run the 38mm pj on my personal quad and actually preferr it over the 38 pwk/as.


I can't agree more with ya 86, I have the 36 bored to a 37 and I like it better than the 38 pwk a/s sitting on my shelf!

[jcs003]

i also agree. i tried an a/s and it would never idle right...it wanted throttle. i use a stock bored carb on my 265 and it is very good. probably isn't best in the high rpms but i ride trails with a trx6 pipe...

[zedicus00]

i do like the PJ series and have used them. MY atv has a 38 A/S PWK and i would not go back. we have trails and wide open stretches and these carbs handle both very well. the PJ seemed like i could run gould flat out and foul plugs in the trails or be o.k. in the trails and power tapered off too fast up top.

my wifes blaster has a 35 A/S on it. absolutly the perfect blaster carb.