waterbug89

so here is the deal i have had a small issue with this bike for about 2 years when the bike is under a half a tank of gas every now and then on cold starts the bike would fire up no problem run down the road any where from 2 miles to 5 miles would start to sputter and backfire i would pull over and turn it on and off a couple of times would be back to normal, and would only do this at half a tank and under and would not do it all the time just once and awhile.
about a month ago it did it full time could not get it to run again, i never did any work prior to this happening just was out for a ride so i started to pull the bike apart i cleaned the carbs replaced lower carb boots new choke cable put back together ran great for a mile up the road had to push it back. tore bike apart again replaced fuel filters vacuum line to shut off valve put back together same thing ran up the street for a mile pushed it back. so i remembered i have been priming the lines with fuel cause it would not start, so i figured out it was not pulling gas from the tank i think. so i drained the tank blew out the vent lines on tank and still nothing. tried running it with gas cap open to make sure vent wasn't plugged. now i have taken the fuel valve apart diaphragm appears to be in good shape no rips or stretching as far as i can tell now the problem is i just can't by the diaphragm separate and to spend 200 dollars on a new fuel valve and not know if this is it kind if sucks. so if any one has any help it would be great thanks.

CruxGNZ

Sounds like your petcock isn't working correctly. Are you sure you put the vacuum line on the correct nipple on the petcock?

Remove a fuel line, and pull vacuum (suck on the vacuum line if need be) on the petcock. Does fuel flow?

There are pictures here that shows the correct nipple to attach the vacuum line. I'll see if I can find it for you.

EDIT:
Here's the vacuum hose routing: https://www.superhawkforum.com/forum...ix-pics-19843/

Also, why can't you buy the diaphram seperate? The kits are plentiful on eBay.

waterbug89

yeah mine only has the 2 fuel lines and the one vacuum line witch i have on the bottom nipple this is how the bike has bee since i owned it. i was able to find the rebuild kit on eBay, just still puzzled why it would run that way every once in awhile and only with less than a half a tank i just don't get it. although i do remember once on my way out to surges it did do it once right after i filled up but that was the only time with a full tank of gas.

CruxGNZ

What year is your bike? Is your petcock on the tank or on the frame?

FYI - The bottom nipple is the vent. You need your vacuum line hooked up to the back nipple. Read that link I posted. It has pictures to help.

waterbug89

98

waterbug89

its on the tank

CruxGNZ

You sir are another victim of PVLIR - Petcock Vacuum Line Inadvertent Relocation ...

Many here have had this happen. Look at the back of the petcock. Hook up the vacuum line to the nipple on the back of the petcock. It will now work correctly.

CruxGNZ

In this picture, a petcock is split in half. The part on the left is the back. See the nipple? That is where you attach your vacuum line. Do not attach the vacuum line to the bottom nipple.

waterbug89

the crazy thing is i have had this bike apart 50+ times and have a damn good memory and that vacuum line has been on the bottom since day one you can tell the wear marks on the bottom nipple it looks band new from the hose being on it, i didn't even know that nipple was back there till i took the petcock apart the other night so how this bike ran for the last 15,000 miles is beyond me. Anyhow i put it on the back one and it does run so wanted to say THANKS VERY VERY MUCH!!!!!!!

CruxGNZ

No problem

You were a unfortunate and innocent victim of PVLIR.

Your bike will run a lot better now.

VTR1000F

It was running on gravity.