Jump to content
Sign in to follow this  

RC Valve Troubleshooting

Recommended Posts

Hey guys,

 

i know there have been a lot of threads opened about this topic, but i have a more specific question. i bought a blown up 2003 cr 250 a while back and i just got it back together. Power is OK just off idle then it starts to bog/feel lethargic. upon further inspection i noticed the RC valve was very sporadic, and im not talking closed at idle - shakey in the mid range - open at wo,t im talking the power valve does not function right at all it jumps around even at idle and almost never fully opens but when it does its just for a split second.  After this i noticed the previous owner (or somebody before him) had cut the capacitor that is connected to the regular/rectifier clean off (!!)  :facepalm:  I am just wondering if that could be causing my RC valve control issue or is it possible it is something else?

 

 

Thanks in advance,

 

John

2014-06-11 19.46.57.jpg

Share this post


Link to post
Share on other sites

I would expect the Cap’s job in that situation would be to filter out ripple on the DC side

Fixing that would be a good starting point IMO

Share this post


Link to post
Share on other sites

I dont know weather your around seattle washington if so I could meet up with my rectifier and see if that fixes your issue before you spend 100 bucks on a new one.

Edited by 223hpyhooker

Share this post


Link to post
Share on other sites

I dont know where your around seattle washington I could meet up with my rectifier and see if that fixes your issue before you spend 100 bucks on a new one.

I appreciate the offer but i am in New brunswick so that isnt really an option.

Share this post


Link to post
Share on other sites

So i tried driving the bike around a bit with the powervalve all the way shut, half opened and fully opened. The bike runs good at low RPM with the valve shut good in the midrange with it half opened and good at high rpm with it fully opened but at any other rpm the bike would run like absolute crap which all makes sense but i guess i am wondering if this is normal for the power valve being stuck closed to have that much of an effect on the bikes performance? or is it possible there is something else wrong? Also, i notice this bike will spill gas out the overflow while it is only being tipped at a very slight angle. just wondering if there is anything i could do about that as well?

 

Thanks in advance guys.

 

John

Share this post


Link to post
Share on other sites

The gas spilling out sounds like the floats are not set within specs.

Share this post


Link to post
Share on other sites

On mine with the power valve working correctly there is not much of an in-between. It’s either held shut against the stop or fully open with some flutter at the transition point. The transition point is within the service manual specs. I used a 2t Timing light/tach from Advance auto

 

Like Fenmore said, Check the float height and also make sure carb is level (I use a Level for reference)

Share this post


Link to post
Share on other sites

On mine with the power valve working correctly there is not much of an in-between. It’s either held shut against the stop or fully open with some flutter at the transition point. The transition point is within the service manual specs. I used a 2t Timing light/tach from Advance auto

 

Like Fenmore said, Check the float height and also make sure carb is level (I use a Level for reference)

When you say make sure the float is level what do you mean by that? Mine is far from level it is tilted toward the front of the bike but i cant see any way of changing that and it is perhaps a little off level from side to side, but the front of the carb has a metal tab that fits inside a slot where the clamp attaches the carb so i cant see myself being able to adjust it that way either

Share this post


Link to post
Share on other sites

When you say make sure the float is level what do you mean by that? Mine is far from level it is tilted toward the front of the bike but i cant see any way of changing that and it is perhaps a little off level from side to side, but the front of the carb has a metal tab that fits inside a slot where the clamp attaches the carb so i cant see myself being able to adjust it that way either

No, I mean with the carb installed I put a level parallel with the back side of the bowl gasket. I only needed to do it one time to get a true level reference. I used to think I had the carb level when it wasn’t.

I lost that center notch in the boot/carb when I went to the Keihin / boyesen reed

 

But check the float height first

Edited by AXAxiom

Share this post


Link to post
Share on other sites

better threads on diagnosing the RC valve, but real quick, just disconnect the cables and safety wire the valve in the open position.  WFO should now be great.  If so, then you know the problem.

 

Re fuel overflowing, I doubt it is going to be the float; more likely ethanol has ruined your float-needle rubber tip.  Contrary to popular belief, the tip does not shut off/open, but rather fuel is constantly trying to seep/push past the tip.  ANY thing less than a perfect seal results in fuel bleeding past.

As a test soak the tip in some PBlaster, this stuff will swell rubber up temporarily.

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  

×