CBR 900RR 1993 - 1999 Honda CBR 900RR

Petcock leaking and won’t start.

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  #11  
Old 06-15-2021, 10:56 AM
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Sounds like the guy took out the diaphragm and spring in the petcock (effectively running the bike on prime the whole time) to bypass the vacuum line operating the petcock as designed. The other end of the hose should connect to a vacuum port under one of the Carbs (#3 carb on my 97). I was only able to get 60-65 miles a tank until I got a new petcock.
 
  #12  
Old 06-16-2021, 02:12 PM
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Originally Posted by WilliePete
Sounds like the guy took out the diaphragm and spring in the petcock (effectively running the bike on prime the whole time) to bypass the vacuum line operating the petcock as designed. The other end of the hose should connect to a vacuum port under one of the Carbs (#3 carb on my 97). I was only able to get 60-65 miles a tank until I got a new petcock.
The guy tried to put the line with the screw to close that small hole under the petcock,not the vacuum port on the petcock. But the line didn’t stay there. So I got home, I opened the petcock and the spring and the diaphragm are in the right place. The vacuum line is also connected. Now as the bike runs, it doesn't leak. As soon as I stop the engine, the petcock leaks the gas that is in the lines coming from the carbs.


From that small hole comes out all the remaining gas in the lines from the carbs, after I turn off the engine.
 

Last edited by vanklang; 06-16-2021 at 06:05 PM. Reason: I uploaded more informations. Thank you.
  #13  
Old 06-17-2021, 02:54 PM
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Thanks for clarifying the leak. I was beyond tired when I replied so reading it again I see how and why I read the issue wrong.

Though I may add that I’m not sure at what position that ‘bleeder nipple’ as I call it needs to be in. I tried looking at the fiche diagrams to see if they show it but don’t. An when I look at pictures by part number (whether OEM or AM) I see them in the 12, 6, or 9 o’clock position. I imagine I could be in any one so as long as to bleed of any pressure (or vacuum) left in the line so the diaphragm can return to its neutral (or resting) position when not running.

Another on here may know better than me and please chime in if I’m wrong.
 
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vanklang (06-19-2021)
  #14  
Old 06-18-2021, 03:48 PM
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That hole serves 2 purposes. It lets you know if the diaphragm is leaking and needs to be replaced. Second it's a vent to atmosphere which allows the diaphragm to move back and forth based on vacuum generated by the engine.
 
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vanklang (06-19-2021)
  #15  
Old 06-19-2021, 07:48 AM
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Originally Posted by WilliePete
Thanks for clarifying the leak. I was beyond tired when I replied so reading it again I see how and why I read the issue wrong.

Though I may add that I’m not sure at what position that ‘bleeder nipple’ as I call it needs to be in. I tried looking at the fiche diagrams to see if they show it but don’t. An when I look at pictures by part number (whether OEM or AM) I see them in the 12, 6, or 9 o’clock position. I imagine I could be in any one so as long as to bleed of any pressure (or vacuum) left in the line so the diaphragm can return to its neutral (or resting) position when not running.

Another on here may know better than me and please chime in if I’m wrong.
Thank you. No problem. For the moment I switched that ‘bleeder nipple’ from 6 o’clock to 12 o’clock position and it’s not leaking anymore. But I think I must change the diaphagm or the entire petcock.
 

Last edited by vanklang; 06-19-2021 at 08:03 AM.
  #16  
Old 06-19-2021, 08:01 AM
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Originally Posted by IDoDirt
That hole serves 2 purposes. It lets you know if the diaphragm is leaking and needs to be replaced. Second it's a vent to atmosphere which allows the diaphragm to move back and forth based on vacuum generated by the engine.
As I switched the hole from 6 o’clock to 12 o’clock it’s all good, no leaks but I will put a new diaphagm. I hope I can find an OEM. You guys are awesome!

 

Last edited by vanklang; 06-19-2021 at 08:06 AM.
  #17  
Old 06-22-2021, 02:46 AM
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Nice lookin’ ride!
 
  #18  
Old 06-28-2021, 11:53 AM
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Originally Posted by WilliePete
Nice lookin’ ride!
Thank you.
 
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