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Message started by rocky on 11/15/07 at 17:57:22

Title: petcock only works on prime
Post by rocky on 11/15/07 at 17:57:22

If I put my petcock on prime my bike runs fine. If I put it on reserve or run it pumps fuel out the vacuum hose and the overflow. Is it bad diaphram?

Title: Re: petcock only works on prime
Post by Reelthing on 11/15/07 at 19:08:12

overflows do not - the vaccum line sounds like it - and be really careful you can end up with a crankcase full off gasoline - not good - eats the bearings and cam in no time

search a bit - quite a lot of postings on the matter

Title: Re: petcock only works on prime
Post by T-Mack1 on 11/15/07 at 19:17:27

Like Reelthing says, read the posts, but it really sounds like it's bad.

Fuel coming out the vacuum hose it a big clue.

Note: Check your oil. Probably should change it to be on the safe side.

Title: Re: petcock only works on prime
Post by barry68v10 on 11/16/07 at 03:15:41

Some here really like the vacuum actuated petc0ck, but when I started having problems with mine I converted it to manual operation and haven't had a single problem since. There's a post in here on how-to convert it...

Title: Re: petcock only works on prime
Post by serowbot on 11/16/07 at 10:11:51

If the diaphram were bad, you would run way rich and stumbly even on prime, because gas would be sucking down the vac line.
Running good on prime says that your vac line is leaking air and won't pull enough vacuum to open the diaphram.

Replace the vac hose and you should be O.K.

Title: Re: petcock only works on prime
Post by barry68v10 on 11/16/07 at 14:20:42

serowbot wrote:

True dat! But the petc0ck conversion deletes those pesky vac lines... ;D

Title: Re: petcock only works on prime
Post by rocky on 11/16/07 at 16:29:25

I replaced the vacuum hose and gas is still running out the 2 tubes that are on the upper part rear of the carb. they run behind the little side panel. I don't have a problem converting petcock to manual but I would like to be doing the correct repair. As soon as I put the petcock on prime it runs great and there is no stumble and perfect idle and running. switched to either run or reserve gas comes out the 2 tubes. help!

Title: Re: petcock only works on prime
Post by rocky on 11/16/07 at 19:23:59

I just realized the vent tubes are hanging down well below the carb could that be the problem?

Title: Re: petcock only works on prime
Post by barry68v10 on 11/16/07 at 20:13:32

rocky wrote:

I just realized the vent tubes are hanging down well below the carb could that be the problem?

No, I don't think so. My vent tubes hang below the carb, as do the one's on my dirtbike. It's kinda sounding like your float need is worn out, except for the whole bit about PRI petc0ck position seeming to cure all. So I'm gathering there's no gas leaking at all on the PRI position?

Title: Re: petcock only works on prime
Post by rocky on 11/17/07 at 04:12:18

there is no gas leaking in the prime position, everything is good and runs fine

Title: Re: petcock only works on prime
Post by rocky on 11/17/07 at 08:09:58

I raised the carb vent tubes up to the frame rail and after about 30 secs the vent tube starts to spew gas. As soon as I swith the petcock from run to prime it quits. Does anyone have any suggestions?

Title: Re: petcock only works on prime
Post by serowbot on 11/17/07 at 09:17:21

Time to do the petc0ck conversion. Info on how is in the tech section.
I did it. It's not to hard.
Good luck,

Title: Re: petcock only works on prime
Post by barry68v10 on 11/17/07 at 12:15:39

Hmmm, so after all this, we're back to my original post. :D

Quote:

Also, I would consider removing the internal fuel screen and adding an inline fuel filter...that change added about 30 miles to a tank of gas for me.

Title: Re: petcock only works on prime
Post by Trippah on 11/17/07 at 17:44:13

I don't think this is going as well as it could. If rocky wants to keep the vacumn system in place, then the real question is; why is the fuel leaking out the vent tubes when he is using the vacumn vs the gravity feed position. He has replaced the vacumn lines, it still leaks. Next check, I would think is to open the top half of the carb and see if the diaphram is okay, or if the needlejet whatever is hung up? Yes?

Title: Re: petcock only works on prime
Post by verslagen1 on 11/17/07 at 18:05:14

First, (sorry) is the carb hosed correctly?
Vacuum to petcork, vents pointed up?
check with pictures in clymers, SSM or tech section.

If you're overflowing it has to be a needle valve problem.

If all else fails, remove carb and clean the he!! out of it. You got some demon in there. ;D

Title: Re: petcock only works on prime
Post by Trippah on 11/17/07 at 18:46:20

Amen.

Title: Re: petcock only works on prime
Post by rocky on 11/17/07 at 18:49:28

I dont have a problem converting to a maual petcock. I just want to know if that will solve my problem. I did not want to convert the petcock and then it be something else. I did not think it was a needle or jet problem if it did not happen on prime. If you guys think the petcock conversion will solve my problem I will do it tomorrow.

Title: Re: petcock only works on prime
Post by Reelthing on 11/17/07 at 19:15:19

This sure seems odd - the only way for fuel to come out of those vents is for the float to not cut the gas off - sounds like a float failure.

This PRI stuffs,,, no offense but your sure? there is a arrow on the fuel lever showing which way - so you really just point the long part of the handle - not top of handle - to PRI and such

Title: Re: petcock only works on prime
Post by Savage_Rob on 11/17/07 at 22:47:06

barry68v10 wrote:

Also, I would consider removing the internal fuel screen and adding an inline fuel filter...that change added about 30 miles to a tank of gas for me.

How would that effect mileage?

Title: Re: petcock only works on prime
Post by rocky on 11/18/07 at 07:35:17

I went to drain the tank to convert the petcock and when in prime or any other position fuel wiil not run out. I thought fuel would drain from the tank on prime position. I put the lever in all 3 positions and it will not drain in any. If i start the bike it will run fuel out in prime but in run position the fuel pulsates noticeably. Am I correct in assuming it is definitely the petcock?

Title: Re: petcock only works on prime
Post by Reelthing on 11/18/07 at 07:43:38

like both - an odd acting petc0ck and a float the does not close the needle - fuel does pulse on run with the engine at idle - but pri should stream fuel engine running or not - at least drain the tank and pull that petc0ck - may just need to clean screen.

Title: Re: petcock only works on prime
Post by rocky on 11/18/07 at 08:40:54

I forgot to mention that I had pulled the fuel line off of the carb at idle to see the fuel flow. It pulsed at run and reserve but flowed smoothly on prime. The vacuum must be what pulls the fuel even on prime? If it flows smoothly on prime why would the float have anything to do with it. Also the guy I bought the bike from supposedly replaced the diaphram. Is it possible he reversed the position underneath the petcock lever when he put it back together?

Title: Re: petcock only works on prime
Post by serowbot on 11/18/07 at 10:22:08

Prime position should flow constant, all the time, no vacumm needed. If it does not, the screen must be plugged or you're tank is empty.
Run and reserve should not flow without the engine vacuum pulling the diaphragm in the petc0ck open.

"I forgot to mention that I had pulled the fuel line off of the carb at idle to see the fuel flow. It pulsed at run and reserve but flowed smoothly on prime."
"I went to drain the tank to convert the petthingy and when in prime or any other position fuel wiil not run out. "

The combination of these two statements and the fact that the bike runs on prime, defies logic. I am totally stumped.

That being said,... the problem has to be in the petc0ck, so pull it, take it apart, and see what's going on in there.

Then let us know what you see.

Title: Re: petcock only works on prime
Post by Max_Morley on 11/18/07 at 10:45:59

I think you need to check the clearance on the valves, particularly the intake. It appears to be pressurizing the carb/intake manifold on the compression/power events. Max

Title: Re: petcock only works on prime
Post by Dr_Jim on 11/18/07 at 12:49:00

Title: Re: petcock only works on prime
Post by barry68v10 on 11/18/07 at 15:48:54

Savage_Rob wrote:

How would that effect mileage?

Rob, the internal fuel screen only picks up fuel about 1/2" from the bottom of the tank, no lower. My MPG was not affected, but my usable fuel WAS. Now I can COMPLETELY drain my tank. ;)

Title: Re: petcock only works on prime
Post by barry68v10 on 11/18/07 at 15:52:20

BTW, the internal fuel screen is very susceptible to plugging up if the m/c is not properly winterized, that was one of the problems my Savage was having.

Title: Re: petcock only works on prime
Post by rocky on 11/18/07 at 16:09:18

I tried to convert the petcock but it leaks not only around the lever but around the bolts that connect it to the tank. I put a new oring on lever and black rtv sealant around mounting surface on petty connection surface. What type of sealant should I have used? If new oring how can petty lever leak?This bike is only supposed to have 1300 miles even though 98, stolen and wrecked.Is there a way to tell if this bike really has a lot more miles than the speedo indicates. I guess I messed up because it ran perfect and did not leak on prime and the carb did not flood. Obviously for me the petty convert was not that easy!

Title: Re: petcock only works on prime
Post by barry68v10 on 11/18/07 at 16:28:12

I didn't use any rtv on mine. If the O-ring is good, you shouldn't need any rtv. I suggest taking it off, clean the rtv off, ensure the O-ring is good and try again.

There's 1 O-ring that seals the petc0ck to the tank, and 1 O-ring that seals the lever inside the petc0ck. The only place to use rtv in the conversion is to ensure the hole you seal with a screw doesn't leak, so if you have a bad float needle, the carb won't flood with the petc0ck turned off.

Title: Re: petcock only works on prime
Post by rocky on 11/18/07 at 17:42:52

I am going to get a new oring for the petcock as it does not look good. I put a new one in the lever and the first time I did not use vaseline so it did not get seated far enough. This time its fine. What keeps the fuel from leaking around the 2 bolts that hold the petcock on?

Title: Re: petcock only works on prime
Post by barry68v10 on 11/19/07 at 05:23:57

rocky wrote:

An o-ring around the base of the petc0ck seals to the base where the petc0ck bolts into the tank.

Title: Re: petcock only works on prime
Post by verslagen1 on 11/19/07 at 11:17:54

rocky wrote:

What keeps the fuel from leaking around the 2 bolts that hold the petcock on?

Each bolt has a o-ring or gasket.

Title: Re: petcock only works on prime
Post by rocky on 11/19/07 at 14:29:10

I am waiting 5 days from the local dealership for oring and washers for petcock bolts, thanks to everyone for their help