when it is hot, she stubles.
Posted: Wed Aug 28, 2013 3:50 am
What are you stoking (heh)?
Criswell
Sent from my iPad
On Aug 27, 2013, at 5:10 PM, "revmaaatin" wrote: > An update to my own post about high OAT stumbling- > > Just back from a test ride before I do the final loading of the mule. > 96F (car at the gas station on board temp) > 20 miles at 5500rpm. 75mph/GPS > nary a stumble. > I am stoked. > > revmaaatin > > --- In DSN_KLR650@yahoogroups.com, "revmaaatin" wrote: > > > > Finally, I think I got the bike to stop stumbling. > > > > Jeff Saline and I have been chasing this phantom for over 3, tiring years (at least tiring for me) > > > > 3 years ago the 1998 KLR650 presented with a problem that only manifested itself with 90F+ temps that seemed like the bike was running out of gas...except when you went to reserve of 'enricher-full' position, it did not get better. At the worst case, > > > > The bike would barely pull itself at 35mph if the temps were above 90F; a tedious proposition at best. > > > > > > I was pretty sure it was a fuel delivery problem; but what? > > > > > > I drained the fuel bowl. > > > > I wrapped the fuel line with foil bubble wrap > > > > I changed fuel brands > > > > I Seafoam-ed treatment of the fuel in the tank until the stock price went up... > > > > > > Jeff Saline tore down the gas cap (it had sticking valves) > > > > I went to premium gas > > > > Made sure it was not ethanol gas. Again. > > > > > > changed the spark plug > > > > Tore down the gas cap again: rubber valves not perfect but flowed air. > > > > I changed the gas cap in June to a brand new gas cap from my bone pile. > > > > Stumbled along as soon as it hit the 90F+ again; so I changed back to the old gas cap. > > > > Then, changed the vacuum line to the petcock > > > > checked the float bowl fuel level > > > > serviced the air cleaner. > > > > all the while, > > > > each correction was a tedious process as we don't have a lot of consecutive 90F days...so make a change and then wait for the next hot day. > > > > It could be weeks! Sometimes months. > > > > shrug. > > > > = the temp would decrease and not have a problem for 100s of miles. shrug. > > > > > > But the dog days of summer are upon us, so we got some hot days ahead. > > > > Riding 10 days ago near Williston North Dakota, we were bumping 90F and the bike began to stumble again. sigh. > > At least I know it is not solved. cough. > > > > > > So fast forward to last, Saturday--the wx forecast is HOT. > > > > Like to hot for the Cat on a tin roof, hot > > > > To Hot to fish. > > > > To Hot for most Harley riders, hot. > > > > you get the picture.... > > > > > > > > After much knashing of teeth, and process of elimination, > > > > I (convinced myself) was being very methodical about the checking process as I wanted to know, what the actual item that was the ultimate fix. > > > > = only one item at a time changed, > > > > then verify: > > > > it appears/and verified at this time the only item remaining has to be a bad petcock diaphragm. > > > > > > So, I got busy and pulled the tank, > > > > tore down to petcock; (best done with the tank off, least you drown your work area with petrol.) > > > > > > During the p/c teardown, the diaphragm was wet on both sides of the diaphragm, which indicates (to me) extra fuel was being sucked into the intake and 'drowning' the bike vs. starving the bike. > > > > at least that is my present understanding...that the fuel was only supposed to be on one side of the double diaphragm. > > > > > > Fortunately, I possessed a new petcock diaphragm (takeoff part) purchased from the F 1 builders of the USMC diesel bikes. > > > > > > 70 plus miles of spirited riding today at 90F+ and nary a stumble. > > I am pleased, to say the least. > > > > > > As a side note, > > > > It appears that the diaphragm life on this petcock is ~25Kmiles +/-. > > > > The previous petcock diaphragm failed to external leak at ~25K. The bike now has 52K and has been stumbling the last 5K at temps above 90F; > > annoying in view that the 'sister' 36Kmilr KLR650 in the garage has nary a stumble and often drinks from the same pump/hose. > > > > Go figure. > > > > > > A complete OEM rebuild kit (as I recall) is ~$30. Includes all the moving parts and O-rings. > > The alternate fix to all this is a $20 manual petcock block off plate that Jeff Saline makes. > > I have that part in my pocket, and will make that change if necessary. > > > > > > Another item of note, > > examine the plate that contains the vacuum nipple. > > It has two holes on the inside to the plate. > > The center hole must be able to 'draw' vacuum easily; that is what makes the petcock flow fuel. > > > > Then there is the tiny, tiny, tiny hole must flow a tiny, tiny, tiny amount of air when you blow into the vacuum nipple; that lets the pressure off the petcock when the engine is shutoff. > > > > > > Jeff Saline and I checked a couple of these backing plates from our 'bone-pile' and some did not flow air. > > > > > > Does your bike stumble? > > Is it the diaphragm? > > You just won't know until you tear it down and look at it. > > > > > > Pay close attention to the parts orientation as you tear down the petcock...there is a little spring under the outer plate that is just dying to jump off your bench and run across the room and fall into a deep crack. cough. > > > > Launching on Wednesday for 3Ksmiles; right into the teeth of a South Dakota-Iowa-Missouri heatwave. Will know for double dog sure on Wednesday afternoon if this IS the cure. smile. > > > > > > revmaaatin. > > > > [Non-text portions of this message have been removed]