85 250R pilot jet help

[Blown 331]

Ok, I've done lots of getting on 3-wheleers, 4-wheelers and dirt bikes but I've never really went any farther than the main jet and needle. So I don't know a whole lot about the other jets. The jet that screws in next to the main jet is what I call the pilot, I have noticed some people call it the slow jet, 2 names for the same thing?
Anyway. I could tell my R was running rich and just thought I needed a smaller main jet, I'm running a 175. I bought a 170 but I haven't put it in yet and decieded to pull the pilot, it had a 75! It runs great under acceleration or WOT but spudders while crusing or at steady throttle, doesn't idle and doesn't have the greatet responce off idle. I pulled the pilot out of my stock carb and it had a 52, I was thinking I needed a 55 but that's close enough. The 2 carbs take different style gets! I had the stock 34mm round slide and went to a Kehin 36mm flat slide. How do I specify which style jet I need when ordering one? My buddy has a 38mm air stryker on his TRX250R and he has some pilot gets that range from 60 to 70. I'm thinking a 60 will be ok for now but do you guys think they will fit? Just looking for some suggestions or tips.

[jmack3986]

well hmm i would have to listen to it but if the pilot was to big it would start and idle great, but if it is to small then you would have trouble starting it. and a 60 sounds about right. but 2 different carbs jets wont usually fit go with the kehin. just go to a dealer and get the jet you need like i said 60 sounds about right. i have a 38mm flatslide on my atc 250r

[x.system]

Pilot (slow) jets are either short or long for the Kehin, you should have the long style in all of your carbs except your 450. I think the 450 takes the short style. If its the long style they will interchange. 60 seems to big to me, I've got a highly modded R and am using a 58 and I could even go lower.

You want your air screw to be between 1 1/2 to 2 1/2 turns out. If it idles really good at 1 turn out you need to go to a larger slow jet, if it idles great at 3 turns out you need to go smaller on the slow jet. When you are adjusting the air screw and it revs just a little higher this is where it needs to be set but I can't see you getting it to idle at all with a 75 in there unless you have a strange needle or something.

85 had a 52 stock where the 86 had a 42 stock on the flat slide carb so it depends on which carb you are going to use. I have mixed pilot (slow) jets from 85 to 89 carbs with no problems, just remember which carb you are working on when you do it. You will get different results with the same jet with the two different carbs.

[Blown 331]

Thanks, that helps a lot. My stock 34mm round slide and my 36mm flat slide take different pilot gets for sure. I tried my stock jet in the flat slide, won't fit. I can't remember which is which but one of them screwed into the carb and the brass along the side of the jet was totally exposed and the other actually slide all the way into the carb, kinda like it's own housing before it screws in and the only brass exposed is the very end of the jet, not the whole sides like the other one. Not sure if that makes sense. The threads are also different diameters.
So basically just compare the 2 and order a new one based on the length. Long or short. I think I'm gonna try a 52 or 55. I'll check if my dealer has one on Monday. I think my buddy is bringing his jets over tomorrow so I can try his 60 from an air stryker, hopefully it fits. Even though it may be too big it should be way better than a 75, that's just insane.

[sandpuppi101]

Hey Blown I don't mean to step all over yourThread but,X you seem to really have a grasp on the flat and round slide concept of these carbs,You say on your modified R you have the flat "newer style" 85-89 carb mixed set.I am thinking knowing you and you going all out ,you have it piped ,ported and some sort of valve or reed cage.OK I have these types of mods on my 85 R and awhile ago I took off the Fatty and 38mm carb to go back to stock just so I would'nt have any problems up North with the DNR.I went back to the stock 34mm and stock pipe,Iwanted to throw them in the trash,Every thing went downhill,Acceleration,Mid,Topend,the whole thing.I know that I should have rejetted but my question is ,Would it be easier to rejet the 34 for stock or just get it done with and monkey with a 36 0r 38,or just forget about running stock again!

[x.system]

Hey Blown I don't mean to step all over yourThread but,X you seem to really have a grasp on the flat and round slide concept of these carbs,You say on your modified R you have the flat "newer style" 85-89 carb mixed set.I am thinking knowing you and you going all out ,you have it piped ,ported and some sort of valve or reed cage.OK I have these types of mods on my 85 R and awhile ago I took off the Fatty and 38mm carb to go back to stock just so I would'nt have any problems up North with the DNR.I went back to the stock 34mm and stock pipe,Iwanted to throw them in the trash,Every thing went downhill,Acceleration,Mid,Topend,the whole thing.I know that I should have rejetted but my question is ,Would it be easier to rejet the 34 for stock or just get it done with and monkey with a 36 0r 38,or just forget about running stock again!

You can jet a stock 34 to run a modded motor, I never use the 85 round slide but I use the stock 86 flat slide on short track courses where its more low end friendly. I also have a 36 and don't see much of a difference. I run a 39 on larger courses like ice racing where I'm into the top end more than anything.

Honda's stock jetting is just a universal setting and its always fat so people don't blow their motors. Try leaning it out on the main a couple sizes and see how much better your performance is. Plug chops highly recomended here

If your worried about the DNR get yourself a fmf silencer with the built in sparky, they know those pipes quite well now and never have I seen anyone get in any trouble for aftermarket. I think they look for fmf more now than anything else. When they see mine they just wave me by. I havn't ran a stock pipe in probably 15 years, don't even remember what its like but it can't be that bad if your jetting is right on.

If you have the 85 round slide and the 36 and 38 flat slide I would just use the 36 and or the 38 and jet it right, I've never like the 85 round slide much. I would use the 36 for trails and the 38 for the dunes.

We're headed for silver lake in a few weeks, we'll have to hook up if you can make it. I have to rejet twice a day when I'm up there, once in the morning and then afternoon once it warms up.

[Blown 331]

That was my entire problem. I took the 75 pilot get out and I had a 52 in an old XL500 carb I had laying around. Runs great, great throttle response, idles. I don't think it could hardly run any better.

[jimeeatc]

hey, wow a 75? not sure if this is any help,-but; i have an 1985 r bored once over, some porting, airbox lid has 2 -1 inch vent holes-(uni) recently installed vforce 3 reed vave, complete dg exaust, but have the stock 1986 -34mm keihin flatside carb (pj03a); which by the holy honda shop manual says and is #42 slow/pilot- #145 main on a stock 86r atc. also clip positon is 3rd groove stock,- have mine on 4th. but i plan on try a size up or 2 on the main , though bike runs great, but sure only a size or 2up on the main would be fine . the 1985 carb had #52 and a #142 on the round slide (pe37a) clip on 3rd groove. my opinion is you dont have to alter change pilot size so much, you can get by with the screw. also anyway, i have just richened the pilot screw 1 turn in, but i think i may try a step up or two on the main. let you know how it goes, i want to play it safe. ---------oh yeah, would like to mention -no to machines or carbs are the same, and there is many other factors like elevation & temp.

[Bad Karma]

Here's a link to an interesting article on pilot jetting: http://www.maximausa.com/technical/l...summer2001.pdf