250R engine cuts out at full throttle

[cheesecake]

what's up R riders. I could use some help. '87 250R full throttle 1st, 2nd, go to hit 3rd and engine cuts out. Just like turning the key off. Back off to 1/2 throttle and the engine comes back alive, but barely running. Let it idle a couple seconds and it smooths out. I can run 1/4 to 1/2 throttle all day long, open her up 1st, 2nd and it cuts out. R and R the carb, it was clean inside. I put in a new plug also. HELP

[350ROOST]

sounds like an air/fuel ratio problem, by your description I would guess it is running to rich. First make sure your air filter is clean. If it's dirty, the motor will not get enough air at full throttle and it will go really fat. If the air filter is clean try going down a jet size, but the way you described the motor shutting off at half throttle sounds like jetting might not be the problem. Has this ever happend befor? If not, have you changed anything to the motor?

Hope this helps.

Roost

[JTRtrx250r]

I posted in your other thread in the Open forum, but forgot to mention the kill switch, try unhooking it and see if that does anything for you,my nephews cr would run just like you described, we did everything possible to troubleshoot the prob, as a last ditch effort...I unhooked the killswitch and she ran like a raped ape, ya just never know

[Roostin250R]

sounds like you may be running out of fuel, is your float level set correctly? Mine actually ran like this once because I forgot to put the main jet back in. it ran great from 1/4 to 1/2 throttle but as soon as I went WOT it fell flat on its face As 350 Roost asked, did you make any recent changes? jetting etc??

[wilkin250r]

I posted in the other thread in the open forum, but I'll re-post here.

Originally posted by wilkin250r
None of this makes any sense. I cannot think of one single reason that your quad would run in WOT in 2nd gear, but not in 3rd, unless your tranny was shot.

Have you tried running WOT in 2nd gear for long periods of time? Is it possible that your carb is running dry, but you coincidentally try to shift to 3rd gear at the same time, so you associate the problem with 3rd gear?

Have you determined that you actually have "power" in 2nd gear? If you're running like crap with no power in the higher RPMs, it would "seem" like it is running better in lower gears because you aren't loading the engine as much.

Your engine, carb, coil, intake, all of this stuff doesn't "see" gears or ground speed. If you are running WOT at 8000 rpms, you have the exact same airflow through your carb and reeds, the exact same fuel flow, and the exact same coil rotation speed whether you are in 1st gear or 6th gear. The components that affect jetting and how your bike runs DO NOT SEE GEARS. So it doesn't make sense to say your bike runs good in 2nd gear, but not in 3rd gear.

[250rpilot]

im with the first part of wilkin's response. it sounds to me like your carb is running dry, maybe from a clogged fuel screen inside the tank or dirt in the passages in the petcock.

the only other logical reasons would be a dirty or improper main jet, or a weak ignition system (your stator may be on its way out).

[beerock]

I dont think its the carb, sounds like ignition related. are you running high compression?

[cheesecake]

Originally posted by beerock
I dont think its the carb, sounds like ignition related. are you r
unning high compression?

I ran the bike tonight and it ran fine 1st, 2nd, 3rd, than ran out of room. I made 6 blasts up the driveway. My compression is 230psi. I check this tonight also after I made my runs.

[beerock]

Originally posted by cheesecake
I ran the bike tonight and it ran fine 1st, 2nd, 3rd, than ran out of room. I made 6 blasts up the driveway. My compression is 230psi. I check this tonight also after I made my runs.

ding ding

what kind of gas are you running? i hope its race gas!! if not you better switch.

also with 230 psi you will need to gap your plug down to like .20 with a weak ignition system

[cheesecake]

Originally posted by 350ROOST
sounds like an air/fuel ratio problem, by your description I would guess it is running to rich. First make sure your air filter is clean. If it's dirty, the motor will not get enough air at full throttle and it will go really fat. If the air filter is clean try going down a jet size, but the way you described the motor shutting off at half throttle sounds like jetting might not be the problem. Has this ever happend befor? If not, have you changed anything to the motor?

Hope this helps.

Roost

First time its happened. Ran it tonight, 6 blasts up the driveway, just to 3rd gear then I ran out of room. Ran GOOD!