Crm 250 mark 3 1994 runs fine at low revs but not top end??

djstormman · Post by **djstormman** » 16 Nov 2008, 14:43

I have recently purchased a 1994 crm250 mark 3 and have a problem regarding correct running. The bike runs fine at low revs i.e ticks over and revs to about half throttle (Start of Power band). The bike will not run at high end revs and just coughs and splutters. I have tryed removing the airfilter and the airfilter side casing and the bike runs 100%. I have tryed smaller/main pilot jets and larger main/pilot jets but to no result. I have had the carb off and cleaned it out throughly & also tryed a BR8ES and a B9EGV spark plug. Any ideas about this would be most appreciated as this is driving me crazy lol....

djstormman · Post by **djstormman** » 16 Nov 2008, 22:33

Forgot to mention, Airbox is drilled, Snorkel from airbox removed, moto air filter, 150 main / 45 pilot jet and a full dep pipe.

Post by **knackeredMk1** » 17 Nov 2008, 09:06

Sounds just like my Mk1 when I forgot to connect up the powervalve servo.

Take the cover off the powervalve on the cylinder and start the engine. You should see the arm on the powervalve move as the engine is reved. If not then work through the options. Is the powervalve stuck

Are the cables being operated by the servo

(take the cables off the valve and see if they move when the engine is run). Take the servo apart and check to see no damaged gears........................

djstormman · Post by **djstormman** » 17 Nov 2008, 13:32

Hi & Thanks for the suggestion but the power valve is functioning and setup correctly..
I have had the carb sat in carb cleaner for the last 2 days and I'm going to blow everything out with the airline.
Inlet rubber is ok, reeds ok, If this clean out doesnt sort it, Look out on ebay as I am completely fed up with this heep of Sh*t lol..
Dont really mean that but I am getting very frustrated & desperate to have her on the road..

wb · Post by wb » 17 Nov 2008, 15:47

Have you done a plug chop on it? If, as you say, it was better with the airbox opened up more and the filter removed it sounds like it may well just be running rich at the top end to me. Have you cleaned the filter? Have you got an un-cut airbox and a stock size main jet you can try? - assuming the 150 is bigger than stock that is?

djstormman · Post by **djstormman** » 17 Nov 2008, 17:06

Thanks for your input guys but the long soak in paraffin and an aggressive blow out with the air line and she is running top notch!!!
Hardly believeable but anyone else with this problem, Please take note as the carb has been blew out twice to no avail..
Thanks again, Stevie.

Crm 250 mark 3 1994 runs fine at low revs but not top end??

Crm 250 mark 3 1994 runs fine at low revs but not top end??

Re: Crm 250 mark 3 1994 runs fine at low revs but not top end??

Re: Crm 250 mark 3 1994 runs fine at low revs but not top end??

Re: Crm 250 mark 3 1994 runs fine at low revs but not top end??

Re: Crm 250 mark 3 1994 runs fine at low revs but not top end??

Re: Crm 250 mark 3 1994 runs fine at low revs but not top end??