engine losing insane power

C

CRazy250

Member
May 28, 2006
334
1
today i finally got to fire up my 93 cr250 after putting it back together,i put new rings in it and rehoned the cylinder,i drove it for the first time and it was horrid. it had a little bottem end power but once it moved to midrange and up it would go flat no power what so ever.wenever you let off the gas it just wants to completly die like its being suffocated from fuel and air,its got a fmf fatty and silencer and boysen reeds,i went thru the carb and it was clean.im thinkin itss in the powervalves linkage.i picked the bike up from aa pawn shop with a 02 yz125 for a major 2800,it was in bad shape wen we got it but its clean now,this is terrible i cannot figure this one out,my 82 suzuki rm125 will crush it right now.im thinkin its losing atleast 20 hp but idk.anybody have a clue?
 
D

dirt bike dave

Sponsoring Member
May 3, 2000
5,348
3
The power valve could be stuck.

On the left side of the cylinder there is cover that allows you to check the operation of the powervalve while the engine is running. Under the cover is the end of the powervalve shaft. Remove the cover and start the motor. Rev it up. The slot in the end of the shaft should move 90 degrees as the valve goes from fully closed to fully open.

On the CR250, when you put the cylinder back on, you need to line up a little fork on the bottom right front corner of the cylinder with a peg. If that peg and fork don't fit together just right, the power valve will not work.

If you did not line up the fork and peg just so, you will need to remove the cylinder again.
 
C

CRazy250

Member
May 28, 2006
334
1
well i havent been on here for awile and my bike still isnt running.now it wont even start.im starting to believe its the whole ignition because my merc sno twister snomobile is having the same problem and the only thing i havent replaced on it was the ignition system.its running rich badly,wet exhaust coming out,bogs out once throttle is twisted,and no power.
 
D

dirt bike dave

Sponsoring Member
May 3, 2000
5,348
3
On the CR, were you able to verify the powervalve was operating before it stopped running?

The reeds could be shot, preventing it from starting.

Are you 100% certain you put the new piston in facing the right direction?
 
C

CRazy250

Member
May 28, 2006
334
1
yes, i dont know how good the reeds are but i looked at the carb and still had the stock 175 jet in it,i put in a 165 and a nw plug and it started right up and it ran better but no power still and its running rich. im sure of everything else on it.its got a little bottem end power cuz it will pull wheelies in 3rd gear but after that it drops off and has less power than my 82 rm125.ill check the powervalves soon.
 
C

CR2FIFTYR

Member
May 18, 2006
42
0
I definitly call powervalve on this one...Sounds like the same problem my friends RM had when the rod dropped out of the clip in the bottom end that operates the powervalve. I say thats it, let us know.
 
C

CRazy250

Member
May 28, 2006
334
1
my valves are not working,i had them set in right and somthing in the linkage is not doing its job.....what parts are most likly to break on powervalves? some guy wants to buy it for 1200 but i dont wanna sell it cuz i wont have a beasty 250.hmmmmmmm itssss so annoying
 
D

dirt bike dave

Sponsoring Member
May 3, 2000
5,348
3

99% sure you will have to pull the cylinder.

There is a very small chance that some of the allen head bolts in the linkage were not tightened all the way.
 
C

CRazy250

Member
May 28, 2006
334
1
i already did that to double check the fork thing and it was lined up but still it wasnt moving.ill check for loose linkage tomarrow
 
C

CRazy250

Member
May 28, 2006
334
1
i already did that to double check the fork thing and it was lined up but still it wasnt moving.ill check for loose linkage tomarrow,the crank case lever that sits on the bottem end is not moving,could it be a gear or somthing?
 
C

CRazy250

Member
May 28, 2006
334
1
i have the clymers manual,they are not working i have checked and i manually held the valve open and it had better throttle responce but i didnt drive it.im thinkin its whatever is inside the crankcase that turns the valve isnt working. i dont want to split the case,can i acess this thru the water pump?
 
C

CR2FIFTYR

Member
May 18, 2006
42
0
On my 1995 you dont have to split the case for anything to do with the powervalve. Chances are the peg isnt in the slot on the cylinder so you are going to have to pull the cylinder...Well that is if you have about the same PV system which I think you do.
 
C

CRazy250

Member
May 28, 2006
334
1
i already re aligned the peg 2 times so then the problem is on the upper part of the cylinder,but what does the valve work off of,its a gear in the case or somthing like the thing shows......i dont know but i need to get my new chain on it because its 1 link too short and will end up toasting the motor bearings if not fixed
 

MikeT

~SPONSOR~
Jan 17, 2001
4,095
11
Do you know anyone who has some experience working on bikes that might be able to take a quick look at it? Maybe you might have unknowingly overlooked something...
 
You must log in or register to reply here.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…