Jump to content

Yz 250 powervalve question

Recommended Posts

hi all, just a quick question  i got a yz250 2001 model. just rebuilt it but need to now one thing. does a dowel pin go in here? there wasnt one when i bought the bike as it was already stripped? any help appreciated 

20170315_072127_zpsrtkzchgn.png

Edited by wardy123
link didnt work

Share this post


Link to post
Share on other sites
4 hours ago, mikeylikesit said:

link doesn't work

done, thanks for the heads up

Share this post


Link to post
Share on other sites

You place a rod in there to hold the powervalve while  loosening and tightening. Drill bit or a screw driver that fit will work well.

  • Like 1

Share this post


Link to post
Share on other sites

Noticed no power down low, but decent pick up, up top.  Pulled the cover off and see this.  I've taken the clutch cover/crankcase cover off before, but did not use a dowel to loosen or tighten the push rod bolt.

When prying up on the "lower leg" of the push rod, it needed some good leverage to get it to move.

 

Does this look right? (attached)

 

 

powervalve.jpg

Edited by j cal

Share this post


Link to post
Share on other sites

That's not right.

It should be sitting counter clockwise where you can insert the dowel without turning anything.

  • Like 1

Share this post


Link to post
Share on other sites
14 minutes ago, mikeylikesit said:

That's not right.

It should be sitting counter clockwise where you can insert the dowel without turning anything.

Thanks for the reply.  Do I need to get to the governor to correct this?  Or simply in unbolt and adjust?

Share this post


Link to post
Share on other sites

It also needs a collar on the shaft under the top arm. Top arm should be bolted on with the shouldered hex head bolts not a Phillips head. That whole connection up top looks suspect.
If the lower arm does not return all the way when you disconnect the top arm checked the governor. The little dowel pin that holds it together may have come halfway out when you pulled up on it with a lot of "leverage".

  • Like 1

Share this post


Link to post
Share on other sites

Thanks guys, I'll check it out tomorrow.  as I started taking things apart on this bike, you're definitely right about things being suspect.

Share this post


Link to post
Share on other sites

Alright pulled the powervalve cover off to find that the pin that follows the cam/guide was off the track.  This was keeping the powervalve open the whole time.  This may explain why the top end was fine but no low end torque.

I didn't pull the clutch case/cover off to check governor, since the push rod seemed to move freely when it was disconnected.

 

A little late to fire her up to check if  works as it should, good thing I have the day off tomorrow.  I'll report back.

 

Thanks for the help!

 

  • Like 1

Share this post


Link to post
Share on other sites

That would do it.

When I bought my 2000 the side PV actuators were switched so they were open at idle. It had no low end power, couldn't even lift the front wheel until the midrange.

Share this post


Link to post
Share on other sites

Alright, so started the bike up with the push rod cover off, and it appears that she's opening when revv'd up.

Few things that I've noticed is that there is a lot of vibration on the push rod (actually the whole bike vibrates a lot lol).  Also, there seems to be a slight lag/delay if I chop the throttle off.  I'm guessing that's due to the exhaust gasses keeping it from closing.

Thanks again for the help!

Share this post


Link to post
Share on other sites

Power valves are controlled by the governor, governor is controlled by revs. You chop the throttle but the motor is still turning so they will not close with the throttle, they close as the revs decrease.

  • Like 1

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:


×