ms250 wont accelerate properly

[1953greg]

im working on a ms250 that wont accelerate properly. starts ok and will run and cut wot ok. but between idle/fast idle and 3/4 throttle i have to use the choke to get it to accelerate.
as long as i keep it above prolly 10k it runs like a banshee.
fuel fire and plug are good.
definitely not carb adjust problem
this one has me stumped

any ideas??

 

[Evan]

i wonder if the L jet is pluged up and runs at idle because the choke richens the fuel mixture

 

[1953greg]

the L adjustment has effect on the idle. the spread is wider than most like 3/4 to 2 turns out is the idle range. idles great but wont accelerate. just bogs and dies unless i use bout half the choke while accelerating then turn choke off when it gets to hi rpm.

 

[lovetheoutdoors]

maybe a air leak

 

[willsaw4beer]

maybe a air leak

:agree2: Maybe check the hoses/ intake boot.

 

[lovetheoutdoors]

:agree2: Maybe check the hoses/ intake boot.

yep i should have explained....also the tank vent.

 

[1953greg]

tank vent is good.

intake boot is a possibility i guess. i didnt remove it but its only couple yrs old.

i still think its in the carb but cant figure out exactly what.

 

[willsaw4beer]

tank vent is good.

intake boot is a possibility i guess. i didnt remove it but its only couple yrs old.

i still think its in the carb but cant figure out exactly what.

Well then put in a carb kit, make sure the needles are clean, etc...

 

[lovetheoutdoors]

are you sure the carb is tuned right?

 

[1953greg]

are you sure the carb is tuned right?

sure as i can be but ive been wrong b4

accelerates best between L 3/4-1.5 out. but still will die if throttle is opened w/o choke

never had this trouble b4.

 

[lovetheoutdoors]

sounds like a small hole in gas line ...its starving for fuel

or the h jet may be clogged

 

[Griffbm3]

Chased a problem like this one, put in a carb kit, messed up the crb, bought a new one, put it in , and it ran great...

Good Luck, I say at least do a kit and let it SOAK for a long time before re-assembly.

Jason

 

[willsaw4beer]

Probably the best thing to do is inspect the lines/ intake, clean the jets, then start replacing stuff after it's established it's not something stupid.

 

[1953greg]

sounds like a small hole in gas line ...its starving for fuel

or the h jet may be clogged

definitely starving...............will check the h jet

tachs 15k with the h maxed out

 

[willsaw4beer]

definitely starving...............will check the h jet

tachs 15k with the h maxed out

What do you mean maxed out? That saw won't last long at 15k... Sounds like a lean problem.

 

[lovetheoutdoors]

What do you mean maxed out? That saw won't last long at 15k... Sounds like a lean problem.

yep she wont last long at 15k

 

[1953greg]

What do you mean maxed out? That saw won't last long at 15k... Sounds like a lean problem.

ccw against the plastic stop

 

[Griffbm3]

So I will describe a different problem that sounds remarkedly similar. Had a Husqy 55 that would spin up to WOT with hesitation, but would hit the limiter. Couldn't stop it from happening even with H adjustment. Nearly roasted the piston. Thought it was an air leak. Did everything to it. Turns out it was the carb all along. Despite doing the kit, I didn't let it soak long enough.

Good soak, new kit, try again. Good luck with this one. Pressure/Vac test as well. Just wanted to say it though.

Jason

 

[willsaw4beer]

Out of curiosity, what mix ratio are you using? Probably not enough of a factor to make as much of a difference to bring the rpm's down to where they need to be. Air leak sounds to be most likely culprit. If there is no air leak and the carb is fine, I guess you'll need to modify the stops. It sounds to me like your carb is out of adjustment, that you need to get the low idle and l jet adjusted so the wot rpm is manageable without hacking out the stops on the h.

 

[1953greg]

So I will describe a different problem that sounds remarkedly similar. Had a Husqy 55 that would spin up to WOT with hesitation, but would hit the limiter. Couldn't stop it from happening even with H adjustment. Nearly roasted the piston. Thought it was an air leak. Did everything to it. Turns out it was the carb all along. Despite doing the kit, I didn't let it soak long enough.

Good soak, new kit, try again. Good luck with this one. Pressure/Vac test as well. Just wanted to say it though.

Jason

havent done a pressure/vac test. starts really easy. first pull every time when warm.

will clean out the h jet, check intake boot, then carb kit if needed.
i have never soaked carbs. what do you use??
mix is 100LL w/ mx2 45:1
thanks guys