KLR650 Manual Petcock
Year, Make, Model
1987 Kawasaki KLR 650
Service Manual
See this post for FREE service manuals for the KLR.
Diagnosis
The motorcycle stalls during a high RPM deceleration with throttle closed. Vacuum levels are very high in this situation. The fuel petcock diaphragm was tested and an internal fuel leak was found. During this high vacuum situation, the engine would suck in excess fuel through vacuum line connected to intake boot and cause the motor to run rich, and eventually stall. Above, the video shows how to test a vacuum actuated fuel petcock.
Solution
Rebuilt kits are available for the stock KLR petcock (K&L Supply Fuel Petcock Repair Kit 18-2723), however, it costs $30 and you still have to spend time reconditioning the old petcock. Also, chances are that the fuel filters are long gone, and I haven’t been able to source these separately. As you can see below, someone attempted to use RTV to repair the leaking diaphragm.
It turns out that a manual petcock (ON, OFF, RES) from a 2001 Yamaha Raptor 660, part number 5LP-24500-01-00 fits perfectly, and can be purchased from Cheap Cycle Parts for $20. The stock petcock is shown on the right above. The Raptor manual petcock is on left above and installed below.
I believe why street legal motorcycles have a vacuum actuated petcocks is safety reasons in the event of an accident. If the bike were to be laid down, once engine stalls, all fuel flow will stop. This is not true with a manual petcock, where fuel will continue to flow. Please keep this in mind when making your decision whether to keep it stock or go manual.
Also, make note that the Raptor ON standpipe is shorter than the KLR, which will increase range for ON, and decrease range for RES. Many owners have shortened this standpipe on stock petcocks anyway to increase pressure and flow.
Now, with a vacuum actuated petcock, it can actually mask a bad float needle and seat since fuel flow is off when bike is parked. Make it a habit to turn the petcock to OFF when done riding, you definitely don’t want to end up with a crankcase full of fuel!
Lastly, you’ll need a vacuum cap and clamp to cover the port on the intake. Don’t forget this step or you’ll have a large vacuum leak!
The right and safe solution is to rebuild the original petcock, I got the rebuild kit from my local Kawasaki dealer for $26.00. The in-line fuel filters were also all destroyed by the alcohol in the gasoline, I found in e-bay these filters for a Triumph, seller steadfastcycles, cost $12.00 for a pair, plus $6.00 shipping, they fit right in the tubes of the petcock, but if the one for the reserve side is missing you will need to remove the remaining of the filter with an 8 mm tap, trim the thread of the filter with a moto tool and seal the connected area with epoxy.
Diameter of the filters are larger by 1 mm than the hole in the tank, just careufully trim, in the side of the reserve filter, the hole in the tank with a moto tool, your tank has the be drained and rinsed with soapy water. You don’t want to mix a spark with the fuel fumes.
Now, it is working perfect. A plus the filters are made of a brass mesh.
Luis,
I’ve rebuilt these petcocks in the past, and it takes a quite a bit of time. Sometimes you can spend at least an hour polishing all the surfaces so it operates smoothly again.
In this case, I opted to go to a ON/OFF/RES manual version since it was only $20, cheaper than a rebuild kit. Also, I removed potential vacuum and fuel leak failure from the petcock.
You do have a good point on safety, though. With a manual petcock, if someone were to dump the bike on the street, fuel would spill and create a fire hazard. Although I’ve seen wrecks where the rear wheel was still elevated and engine was running anyway.