Jump to content
Sign in to follow this  

98 CR250, boggs then surges in low end

Recommended Posts

just rebuilt my engine and now when i start it to go break it in, it will idle fine with choke on, but when you crack teh throttle it will bogg then surge. havne't gotten it past 1/2 throttle cuz it's still new...any tips on what might cause this/

Share this post


Link to post
Share on other sites

Air leak? My 250 was doing the same thing. I didn't notice any cracks on the reed valve rubber intake port, so where else could an air leak be coming from?

I guess I could get a compression tester too since I need one for my Bandit as well.

Share this post


Link to post
Share on other sites

Air leaks can be all over the motor...the gasket between the reed valve assy & the cylinder...base gasket...head gasket....crank seals. After a top-end job was done I would suspect the base gasket or head gasket, especially if you didn't use a torque wrench or used a knife or razor blade to remove old gaskets...aluminum is soft & can be damaged by anything that sharp. Good luck :thumbsup:

Share this post


Link to post
Share on other sites

hmm, air leaks..i'll have to go around and check everything this weekend and make it's sealed up well. Thanks in advance you guys...this will help

oh yeah, i read somewhere that you turn the air screw in to make it richer..is this ture or did i dream it or read wrong??

Share this post


Link to post
Share on other sites
hmm, air leaks..i'll have to go around and check everything this weekend and make it's sealed up well. Thanks in advance you guys...this will help

oh yeah, i read somewhere that you turn the air screw in to make it richer..is this ture or did i dream it or read wrong??

In for rich, out for lean.

Share this post


Link to post
Share on other sites

HUMBADADA!!! it's fixed. I went back and checked and the rings that hold teh carb in the rubber boots where both loose...then the powervalve was bound up so i loosened the cylinder and it popped free and works great now. I broke the engine in and it runs like a champ now. no bogg whatsoever and it will sit and idle nice and smooth. thanks you guys, it helped a lotl.

Share this post


Link to post
Share on other sites
HUMBADADA!!! it's fixed. I went back and checked and the rings that hold teh carb in the rubber boots where both loose...then the powervalve was bound up so i loosened the cylinder and it popped free and works great now. I broke the engine in and it runs like a champ now. no bogg whatsoever and it will sit and idle nice and smooth. thanks you guys, it helped a lotl.

You mean the exhaust valve? Did you check and see if the forks on the lower stem were bent or not? I did that on my first installation and saw I cracked it.

Also, you can pop the cap off the left side of the cylinder to see if the exhaust valve is working correctly.

How'd ya break your engine in? What method?

Share this post


Link to post
Share on other sites
You mean the exhaust valve? Did you check and see if the forks on the lower stem were bent or not? I did that on my first installation and saw I cracked it.

Also, you can pop the cap off the left side of the cylinder to see if the exhaust valve is working correctly.

How'd ya break your engine in? What method?

Yeah, exhaust valve, power valve..i've heard them called both. Yes, the forks where fine. using the view port on the side is what showed me the exhaust valve was not moving.

I let it idle for about 10 min. so it got good and hot then i went out and did roll on's(up to 3/4 throttle) from 2-4th gear for a while then up to WOT and added 5th gear. it seems to work great. has great compression, starts first kick EVERYtime, idles perfectly and has no bogg anywhere...i'm happy with it

Share this post


Link to post
Share on other sites
Yeah, exhaust valve, power valve..i've heard them called both. Yes, the forks where fine. using the view port on the side is what showed me the exhaust valve was not moving.

I let it idle for about 10 min. so it got good and hot then i went out and did roll on's(up to 3/4 throttle) from 2-4th gear for a while then up to WOT and added 5th gear. it seems to work great. has great compression, starts first kick EVERYtime, idles perfectly and has no bogg anywhere...i'm happy with it

Awesome! I'm going to give mine a whirl tonight and see how she goes!

*Cross your fingers!*

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×