Need help w/ jettting???

[1promodfan]

O.K. guys here is what I have. '89 long rod motor, ESR 310...(actually a 293)...pump gas, boyeson rad valve, 36pwk, stock airbox no lid, K&N filter, running close to sea level. I checked my carb. and it has a 155 main, and a 55 pilot jet.

Does anyone......(that knows what they are talking about) have any recommendations on what my jetting should be, or close to?

[bluetrx]

......(that knows what they are talking about)

well i cant honestly say i know what im talking about in regards to your motor but i can tell you what im running.

stock cylinder a little over ported by someone who didnt know what they were doing.

bored to 69mm. 4mm stroke. 284cc displacement.

38mm pj (dang i just realized in not even running the same carb)

no airbox. k&n filter

pro design cool head

fmf fatty pipe

cr250 ignition

high compression. 110 octane

anyway im running a 185 main and a 55 pilot. i hope this isnt just irrelevant information. when i first looked at your post i thought the 155 main was way too small on a 310 but i think the 36mm carb could make that diffrence.

[312R1]

Originally posted by bluetrx

anyway im running a 185 main and a 55 pilot. i hope this isnt just irrelevant information. when i first looked at your post i thought the 155 main was way too small on a 310 but i think the 36mm carb could make that diffrence. [/B]



I would say that the pilot is on the rich side and the main is lean..On my OEM jug engine I use a 36MM PJ and my jetting is 52 pilot, needle on the 3rd clip and a 175 main.


-Steve

[bluetrx]

the sectional area of a 38mm carb 1134 sqmm
the sectional area of a 36mm carb 1018 sqmm
the diffrence 11.39%

185
155
the diffrence 19.35%

185
168
the diffrence 10.11%

does it make any sense what ive done here? anyway it looks to me like if i were running your carb i would probably be using a 168.
always start rich. the worst you can hurt with too rich is your spark plug. if your shooting in the dark i would start with a 190 and work down untill it stops bogging. then do some wot plug chops to tell better.

sorry if this is just a waste of your time.

[gojk]

Originally posted by bluetrx
the sectional area of a 38mm carb 1134 sqmm
the sectional area of a 36mm carb 1018 sqmm
the diffrence 11.39%

185
155
the diffrence 19.35%

185
168
the diffrence 10.11%

does it make any sense what ive done here? anyway it looks to me like if i were running your carb i would probably be using a 168.
always start rich. the worst you can hurt with too rich is your spark plug. if your shooting in the dark i would start with a 190 and work down untill it stops bogging. then do some wot plug chops to tell better.

sorry if this is just a waste of your time.


This logic does really work to well because the velocity through the carb on the 36 mm will be greater closing % gap between the 2 carbs.

[jhtrx250r]

dont guess, call sudco, look them up on the web they will tell you the base jetting they recomend when selling your perticular carb.
your jetting looks to rich on the pilot and to lean on the main, but what needle do you have? that is the most important key to a good running carb.

[1promodfan]

Thanks for the help guys. Bluetrx, your not wasting my time........I put that because I've seen some guys post stuff that even I knew wasn't right. Most time I don't even know what I'm talking about:D Very useful stuff here, and feel free to post more.

jhtrx250r, I have no idea what needle I have......how do I tell??

[Honda 250r 001]

im thinkin a 36 pj is a little small for that motor you got. hell stock the cr 250's have 38's on em i believe. you should get a 39 pwk or a 38. but i would start off with a 165 main and go from there. slide on the middle, and around a 55 pilot.

[1promodfan]

I've got a PWK not a pj......from what I've been told the 36mm will work.

[Honda 250r 001]

well yes it will work if you want a bottom end motor. but a bigger carb would be better for a dune machine.

[Honda 250r 001]

250rnut has a nice pwk 39 mil for sale for a steal at 75 shipped. you should get it.

[CorvetteZ06]

as far as carb size... my buddy just had his motor rebuilt by tony kellner, and we asked him what carb he recomended for a ESR 310 and a 265 PC2000. Tony told us he actually ran stock, yes STOCK carbs in his pro racers LRD 300 motors!!! so, the 36 can def. handle a 310.

[Honda 250r 001]

prolly doesnt know what hes doing or something a 36 pj would not even come close to being a mid-top end carb for a trx 250r with a 310 big bore. a 38 would be a way better choice. IMO

wow, i woulnt run a stock carb even on stock motor! my cr 125 has a friggen bigger carb than the stock trx R!

[1promodfan]

I think Tony Kellner knows what he's doing!!......(hint: pro racers) and again its not a PJ!!!

From what I've been told a 36pwk will be really "peppy". For now I'm going to run it, if it don't work right....I'll go bigger.

[fulltiltrider]

That 36 will work awesome on a low end 310. I have a 39pwk on mine, it works great but, I have DAYS involved in jetting to get it where I wanted it. I run a pretty lean needle, cej, a48 pilot, and Im down to a 182 main. I think I might be able to go down a jet or 2 on the main yet but Ill wait till it gets a little warmer. Im close to the ragged edge as it is.

[dunatic]

Originally posted by 1promodfan
I think Tony Kellner knows what he's doing!!......(hint: pro racers) and again its not a PJ!!!

From what I've been told a 36pwk will be really "peppy". For now I'm going to run it, if it don't work right....I'll go bigger.

great idea.

Start with:

DEG or DEJ needle, clip in middle position

175-180 main jet (depending on porting, timing, elevation, pipe and fuel type)

50 pilot if over 200 psi cranking compression

52 pilot if under 200 psi cranking compression.

1.5-1.75 turn outward on the air-idle mixture screw.

New spark plug gapped at .018"

Adjust needle clip up or down for crispness in the mid range.

This will get you close and is a great baseline to adjust from.

[05LSR250R]

Tony Kellner knows his stuff!
He was Barry Hawks mechanic back in the good ole days!
I've worked with him before...........he knows his way around a 250R!

[Honda 250r 001]

i just dont see how a 36 pwk could be enough to feeed a hungry 310 esr kit.

[CorvetteZ06]

trust me, when Kellner told me he ran stock carbs on barry hawks machine, i could not believe it!

[Honda 250r 001]

well hell ya you could run it. that does not mean it would make the most horse power. im pretty sure if you switched from a stock 34 pj to a 38 stryker on a 310 kit you would gain hp.