miss on 3-4-5 gear?

[Thornfold]

Have a miss in my mid range on throttle from 3-4-5 gear running wot, does not miss other gears, feels like hiccup, changed up-down jetting and cant clean up, happens only end of riding day as temp cools. Prox350 with esr9 port, 88 bottom end, 195 pounds comp, 188 main, 58 pilot, 2 turns air screw, b8es, 50-50 race-pump gas, 40/1 oil-gas, esr reeds, trx5R pipe, ESR air filter kit, 38 Keihin, 14-38 sprocket, 200 pound rider, dune hill racer & duner.
Need help!

[latheboy]

I cannot comment on your jetting overall because I see you are in CO....but did try adjusting the needle clip position?

[fearlessfred]

when u say mid range,do u mean throttle position is around the mid opening or it is wide open but rpms are mid range .what elev.are u at. im guessing around 2000 feet. cooler temps will will cause it to lean out slightly,but i would think that would cause a bog and not a miss. i would suggest doing a plug reading after running thru the gears ,at the throttle position that it happens at.

[machwon]

Too big on the main and pilot jets. drop them both. What needle are you using? Are you using 6th gear or just not getting there? What is you plug gap set at?

[Thornfold]

Run wot wide open full throttle, miss or hiccup on 3-4-5 not 6th gear, ran jeting up-down and best combo at 188/58, dgh needle 3rd clip, b8es .02 gap, quads fast as hell even with miss. i can jet good, this one bothers me i can not find the fix, do not think jeting is the problem

[machwon]

Yes, jetting is easy and I consider my self very good at tuning. The most difficult thing for a lot of tuners to overcome is dropping the main jet a lot. If you are using the correct fuel and stock timing your motor will survive on a lot less fuel. I'd say a 178 main and 52 pilot would be a good starting point with a NEW spark plug gapped at .02". Once you get past that one you'll likely still need to drop the main.

[Honda 250r 001]

I had the EXACT same problem with mine, turned out it was a combination of the compression being low, and having a fat main jet. Dont know if that is the case with yours or not.

[fearlessfred]

Originally posted by machwon
Yes, jetting is easy and I consider my self very good at tuning. The most difficult thing for a lot of tuners to overcome is dropping the main jet a lot. If you are using the correct fuel and stock timing your motor will survive on a lot less fuel. I'd say a 178 main and 52 pilot would be a good starting point with a NEW spark plug gapped at .02". Once you get past that one you'll likely still need to drop the main. you are spot on with your remarks,but i think he should do a plug reading after running thru the gears at wide open throttle and pulling in the clutch and killiing the motor at the same time. this is just to prove to him self that he is not going to hurt his motor

[Thornfold]

Not the jeting, ran down to 144-40, got worse. runs good with 188-58, 8bes plug gap at 020-024, cant find fix for hiccup. co springs elev 6500 feet, low 50’s temp. happens at end of day when temp cools, ran 7bes no better. going to try different cdi first, & stator second. thanks

[wilkin250r]

I'm not sure what the problem is, but I can certainly tell you what it's NOT.

Most problems like this, as you know, stem from the ignition system or from the carburetor (jetting). NIETHER of these aspects has anything to do with your transmission, they don't know what gear you're in.

You say you've got a problem in 3-4-5, but not in 6th, and not in 1st or 2nd. That can't be possible, your gearing doesn't have any effect on your jetting or ignition system, or any other aspect that is likely to cause this sort of problem.

Forget the gears. You need to find the problem in terms of throttle position, and RPM, because those are the only factors that are going to influence how your engine runs.

[86 Quad R]

whens the last time you had the stator cover off? i've seen a build up of corrosion have a dramatic affect on things. and it could be the flywheel itself.

have you performed a leakdown test on the engine to check for leaks?

[Grande Huevos]

my R did pretty much same thing ran like crap in 1 and 2nd gears then awesome in 3rd and up would somtimes cut out at certain rpms then pick up and hit hard. turned out i had cracked reeds put new ones in and completly fixed the problem!!!!!

[Thornfold]

Called in a sick day to try diferent cdi made no diference, i changed the stator and went way rich, jetted down to 180 then 175 then 168 ended with 170-48. miss is gone, my old stator looks good, no rust. the stator i put in looks old, runs good, made all the diference. high elev run small jets like my budies 370, now she runs clean, thanks

[machwon]

Yes, that is very good jetting for that motor. The only thing else to recommend was a new plug before you change the jets. The stator cover with water in it was another good possibility. Even at 800 ft above sea level here i would have recommended 168 mains and 48-52 on th pilot with a DGH in the middle.

[Thornfold]

The fix was not jeting, it was a bad stator, not a rusted one, old one look good. the diferent stator made the miss go away and the jeting change, at 6500 feet the jeting is 170-48, when i ride at 0-1000 feet the jeting will go to 188-58, i have been riding high to low elev all my life, you dont know how to jet at 6500 feet until you do it 10 times, thanks for trying.