Breaking up prob..

[FL-R]

I have a 86, punches out to a 265 running 110 race gas, with a 38a/s. Well I just put a new bottom end half and it had a +4 degree timing advance and also a new set of V-Force reeds.. I didn't touch the jetting and now its breaking up real bad on top end.. wont rev out for crap... could it be too lean and I need to up the main or what.. I'm also running a B8es plug. Thanks.

[reconracer64]

yea man im having the same problem my motor is all stock though...i just have an exhaust and air filter and i can get it jetted right for anything...it always breaks up on top end like you are saying...so if people could help out im sure we would both be greatful and sorry man not trying to steal your thread

[mx91a]

Try closing the gap on your spark plug to 0.018-0.020" if you haven't already. That will help if you have increased compression and are still running the stock ignition. Also make sure the engine is getting plenty of air, clean filter, no restrictions in intake tract, etc.

[265 sleeper]

What compression ratio you running . What pipe and jet size

[FL-R]

Its like 190-195.. and its the stock ignition, but the filter was kinda wet from all the water. And the filter is beat to hell and back from the chain.. its one of those junk K&N's hanging off the back of the Carb that ESR sells... and this Florida sand dnt help.

[wilkin250r]

There seems to be a recent epidemic of this, and I've suffered myself from the same affliction.

I've seen it attributed to bad connections in the ignition wiring, bad flywheels (the magnets inside were broken), bad CDI, air leaks, and my own problem seems to be attributed to the actual pipe (because I've changed everything else, including the entire motor).

I don't have an easy answer for you, but if you find YOUR answer, please post it up!

[265 sleeper]

Could have a bad carb it happened to me . I could tune ether top or bottom and only one would tune . Never a smooth power . I used a friends carb and she tuned in perfectly .

Your jetting seems to be too fat .

[leager-n-ky]

If your filter was wet, it will suck the water into the carb, the water will look like little bubbles in your gas, they will go up and block off the main jet, and if they do pass through, they will not burn.

drain your carb, dry your filter, try again.

[trx/lt500r]

Happened to me as well. Had 38 mm AS...played with jetting, inake, ignition (replaced with new), etc. but would still break up.
Changed my pipe from FMF (yes i know this was on the quad when i got it) to LRD then rejetted. Bike then ran well.

what pipe are you running?

[265 sleeper]

Originally posted by leager-n-ky
If your filter was wet, it will suck the water into the carb, the water will look like little bubbles in your gas, they will go up and block off the main jet, and if they do pass through, they will not burn.

drain your carb, dry your filter, try again. X2 I over looked his question .

[wilkin250r]

Originally posted by trx/lt500r
Happened to me as well. Had 38 mm AS...played with jetting, inake, ignition (replaced with new), etc. but would still break up.
Changed my pipe from FMF (yes i know this was on the quad when i got it) to LRD then rejetted. Bike then ran well.

what pipe are you running?

Odd. I had an FMF that ran great, and I now have a Duncan Racing Eliminator pipe that seems to be my problem, and I plan on getting a new FMF pipe to correct the issue.

Of course, I can't confirm it's the pipe until I swap it out, but I've come to this conclusion based on a variety of factors.

1. I rebuilt the motor, did a compression and leakdown test on it. I tried three different carbs, two different reeds, and all manner of jetting. Still won't rev out.

2. Swapped the ignition and all wiring with a brand-new CR250 ignition, and even ran separate dedicated ground wires to make sure it wasn't a grounding issue, and tried multiple carbs at the same time. Always the same issue, won't rev out.

3. Complete new engine, with it's own stator and flywheel, and reeds, coupled with my existing CDI and wiring. STILL won't rev out, all tried with different carbs.

4. The only pieces common to everything are the fuel tank (two different types of fuel) and the pipe. And I'm starting to think I even have the same problem on my 340PV because I have the eliminator pipe on that one, too, and it won't rev out either until I run it for a while and it gets up to temp. But I never paid much attention to my 340 because it has so much low-end torque, I never needed it to rev out. But the more I think about it, I think I have the same problem on both bikes, because they are the same pipes.

[FL-R]

I have a ESR trx 5 or 6... every thing ran till the water ride... I'm gunna strip the Carb and put a new filter on it and see what happens..

[slamdak8782]

Did you ever try new CDI or Coil? Maybe the coil is having issues

[slamdak8782]

found a trouble tree in the manual for high speed problems

1. Check Ignition timing if bad cdi or pulse generator

2. Check fuelflow at carb clogged fuel full? Breather tube clogged? fuel valve? Fuel strainer?

3. Check air cleaner Is it clean

4.Check jets. Clogged or improper sizing

[265 sleeper]

Originally posted by FL-R
every thing ran till the water ride...

[C-LEIGH RACING]

Believe it or not, I'm in the same boat.

I've tryed everything I know to do from all my years messing with these 2 strokes & still the engine wont rev out.
My daughters 350R, went to the Sikeston MO race & you would think somebody was pouring gas in the carb with a bucket it was flooding out so bad .

350 Pro-x, TRX5 pipe, Cr250R ignition, Rad Valve with RL-19 reeds, 39mm PJ carb, 48 pilot 200 main, DGH needle on top lean clip groove.
Went all the way to a 190 main, one jet at a time & still wouldnt rev out, so left it like that & just ran it.
We get back home & run a local the next weekend, jet down to a 185, still wont rev out.
Plug set at 0.18 even though we have CR ignition & even put two washers on the plug thinking the plug tip might be sticking out to far in the dome cause it not to rev, still wont rev out.
This past weekend race, everything set just as it was, still wouldnt rev out so pulled the carb off, took apart, vent tubes open, went from 48 pilot to 42, 185 main to 180 main, still DGH needle set lean, re-set the float level a bit leaner, put it all back together, still wouldnt rev out. Got a whoop whoop as it revs into the upper rpms going through the gears.
As a last resort, last race, I mixed 50/50 race & 89 pump gas, just to get a little faster burn rate in the head, dang fool thing started to clear up mid way through the race, now explain that.

I'm about to think its something to do with the race gas these days.
It is like we have had trouble with the gas ever since Nascar dropped Unocal 76 race gas.
The Sunoco they switched to, I tryed it, nothing but trouble, so I switched to 112 Rocket Fuel & it has done good up untill now.
Rocket fuel brand, is made by the same guys made the Unocal 76 race gas.

Wonder if the base gas stocks all of them are using has that stupid ethanol in it ???, but then if it does I would tend to think it would lean the engine out instead of rich.
Neil

[FL-R]

Hmm, didnt think of the fuel, But i did pull the carb and all down the inside if the intake tube was dirt. I hate the ESR airbox eliminator kit,

[400man]

this might be a little off topic, but I was having trouble with my 250r not to long ago, it would not even rev out into the powerband and it felt like a bad fouled out spark plug, but I was getting plently of spark when I grounded the plug out against the cylinder. then one day when I was opening the doors of my storage shed to roll the bike out, I noticed a dirt dobber fly out of the silencer :mad: . I look inside and about 6 or 7 inches inside it was almost completely sealed up with a dirt dobber's nest. I take a long screw driver and break up the dirt and crap all in the silencer and fire up the bike........it runs perfect and revs to the moon. and the day before it would barely even run :grr: . talk about feeling stupid. I have now learned to plug my exhaust up when im not riding for a few days. I even ended up buying an extra cdi box and coil for nothing it turns out.

[C-LEIGH RACING]

Originally posted by 400man
this might be a little off topic, but I was having trouble with my 250r not to long ago, it would not even rev out into the powerband and it felt like a bad fouled out spark plug, but I was getting plently of spark when I grounded the plug out against the cylinder. then one day when I was opening the doors of my storage shed to roll the bike out, I noticed a dirt dobber fly out of the silencer :mad: . I look inside and about 6 or 7 inches inside it was almost completely sealed up with a dirt dobber's nest. I take a long screw driver and break up the dirt and crap all in the silencer and fire up the bike........it runs perfect and revs to the moon. and the day before it would barely even run :grr: . talk about feeling stupid. I have now learned to plug my exhaust up when im not riding for a few days. I even ended up buying an extra cdi box and coil for nothing it turns out.

That same thing applys to your string trimmer, weed whacker, weed eater... what ever people want to call them. You take it out of winter stroage building in the spring & those dirt dobbers have built a nest in the muffler, so go ahead & first thing run a screwdriver up in the little muffler hole & get the nest out.

Those mud atvs or 4X4's, I've seen them with all the vent tubes plugged up with dobber nest as well. Ol thing wont run right & sure enough those vent tubes are stopped up.
Neil