EC250 suddenly won't rev on to pipe

[Mattnzl]

Hi guys - had a fantastic ride today at a local club ride (http://www.ttbrc.co.nz/) bike was on fire for the first two loops - two mates on 450's and no way could they out gun the EC

On the last loop I hit a hill climb in third and the bike rocketed up as normal. Puttered down the other side then went to climb again and the bike would only rev to the point where it starts "getting on the pipe" (I guess thats how to describe it - the point where it goes from medium to high revs, and the exhaust note changes to a nice snarling sound).

Stayed like that for the rest of the loop. Bike will pull/lug just as normal if I short shift nor problem. Just won't rev out, even in neutral.

Hmmm, any ideas? I initially thought stuffed plug or maybe a some grit got into the main jet, but could a broken/stuck power valve cause this?

Thanks, Matt.

[noobi]

Originally Posted by Mattnzl

Hi guys - had a fantastic ride today at a local club ride (http://www.ttbrc.co.nz/) bike was on fire for the first two loops - two mates on 450's and no way could they out gun the EC

On the last loop I hit a hill climb in third and the bike rocketed up as normal. Puttered down the other side then went to climb again and the bike would only rev to the point where it starts "getting on the pipe" (I guess thats how to describe it - the point where it goes from medium to high revs, and the exhaust note changes to a nice snarling sound).

Stayed like that for the rest of the loop. Bike will pull/lug just as normal if I short shift nor problem. Just won't rev out, even in neutral.

Hmmm, any ideas? I initially thought stuffed plug or maybe a some grit got into the main jet, but could a broken/stuck power valve cause this?

Thanks, Matt.

Could be gunk in the carb but you're more likely to block the pilot than the main.
Could be the PV not opening, ie stuck closed for some reason. You can run the bike with the RH PV cover off (but the pipe on), to confirm whether its opening or not.

[Jakobi]

You're on the right track. Throw a new plug in. Pull the carb jets and have a look, and check the powervalve action as Noobi said.

Does it break up or just fall flat and not rev any further?

[Mattnzl]

It runs like it is cold and kind of 4-strokes/blubbers if revved above about half throttle. Doesn't "clear out" like it would do if cold though. Starts fine and potters around at low revs fine too.

Thanks chaps, I'll start pulling apart things tonight. I was totally knackered last night, was such a buzz of a ride!
It's been raining for two weeks here & yesterday was the first sunny day. The hill climbs were muddy but they are high speed climbs so it was a blast ripping up them throttle pinned in 3rd

[arminhammer]

Sounds like the main jet fell out.

[bchatt]

Maybe check the muffler as well. A while ago the perforated tube up the center of my muffler fractured and fell out of alignment, causing the packing to partially block. The symptoms were similar to what you describe.

[skid jackson]

Originally Posted by arminhammer

Sounds like the main jet feel out.

this happened to me. .....

[desertgasser300]

Had the same symptoms on mine a month ago. On a fluke chance i pulled the PV cover on the right side of the bike. The nut holding the actuator arm came off an the rod fell off. Put it back on all is good.

[Mattnzl]

And the winner is... power valve!

Took the cover off and it's pretty obvious, the small bolt in the middle has fallen out, phew! Nice easy fix. And as a bonus I get to try and fix my rattley pipe at the same time....

Thanks for the help everyone, really appreciated

[Jakobi]

Did the nut fall down the hole??