F2 Tech Tech Subsection (for any mechanical, repair, and DIY threads)

Bypass vacuum on petcock.

Old 06-21-2012, 10:40 PM
Thread Starter
Join Date: Jan 2012
Location: Central IL
Posts: 30
Default Bypass vacuum on petcock.

I do not take credit for writing this but, I found it very useful and feel that it deserves to be reposed on here. http://www.valkyrieforum.com/bbs/ind...?topic=37577.0
Old 06-22-2012, 12:43 AM
Senior Member
Join Date: Aug 2009
Posts: 577

Yeah you just reverse the spring so it stays open, and you can leave the plastic disc in there to hold the diaphragm in place.
Mine was like that for over a year until I realized the PO had reversed it.
Old 06-22-2012, 09:14 AM
Senior Member
Join Date: May 2011
Posts: 842

wont that just end up clogging the carbs if left unnoticed
Old 06-23-2012, 02:39 AM
Senior Member
Join Date: Aug 2009
Posts: 577

no they won't clog up anymore then usual, but if your needles leak and you forget to switch the fuel off the engine will hydrolock.
Old 06-23-2012, 06:59 AM
MadHattr059's Avatar
Retired Super Moderator - At large E=MC2
Join Date: Feb 2011
Location: Tulsa,OK
Posts: 2,299

Keeping in mind his warnings, as to when this is an appropriate mod, it's a nicely
written post.

I would reserve this as information for an emergency-temporary repair.
It could lead to fuel vapor leakage (and subsequent fire hazard) for any long-term
and/or enclosed-space storage of the vehicle.

Old 07-09-2019, 02:29 PM
Junior Member
Join Date: Jul 2019
Posts: 4

My '98 CBR900RR died on me while driving down the highway. I had to leave the bike there, came home, did some research, found this post, then went back to the bike and did the mod posted on the Valkyrie forum. The bike started right up and I was able to get it home without having to pay for a tow! I guess putting the spring on the other side of the diaphragm kept it from having a good seal when putting the petcock back together so gas poured from the vent hole in a steady stream (I left the vacuum hose disconnected and plugged the hose with a screw). Probably not the safest conditions to ride with, but as MadHattr059 said, for a temporary emergency mod, it worked good enough to get me home and saved me a couple of hundred for a tow.
Related Topics
Thread Starter
Last Post
F2 Tech
12-31-2012 01:09 PM
Street Fighters
10-13-2012 06:43 PM
CBR 600F3
07-20-2012 08:56 AM
F2 Tech
05-09-2011 12:25 PM
CBR 600F3
03-11-2011 03:49 AM

Thread Tools
Search this Thread
Quick Reply: Bypass vacuum on petcock.

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.