Bad petcock diaphragm?

[hueco]

The Ol Girl would not start yesterday. I took tank off and took petcock off and disassembled the  petcock. Could not see anything wrong. I put the petcock back on tank. I hooked up my hand vac to the petcock. So long as I pump the vac fuel flows. As soon as I stop pumping the gas stops and won't hold a vacuum. Does that sound like a bad diaphragm? I called the local Honda dealer for a diaphragm. Was told they don't sell the diaphragm. I would have to buy a whole petcock for $148.00. What are the alternatives? Thanks.

[old2soon]

There are rebuild kits available for a lot less than $148.00. At that price you are at pingle prices. Look on e-bay. Not affiliated no profit yada yada.

[art]

You can take it apart an remove the vacumn parts an block off the opened end with an alum. plate an gasket for $0 .I did mine about three years ago.Just go manual an don't forget to turn it off when the bike is not in use.

[lucky_1_chris]

You absolutely can buy the rebuild kit from Honda. They call it a cover set. #5 in the diagram. About 35 shipped.

http://www.hdlparts.com/fiche_section_detail.asp?section=148545&category=MOTORCYCLES&make=HONDA&year=1999&fveh=3473

You can also get just the rubber, plastic, and spring (no cover and screws) from old bike barn for about 10 bucks less. This is really all you need. In the mean time you can remove the vacuum functionality of the petcock until you can rebuild it so you can ride, just don't forget to turn it off when you park it. Search the board for how to do it.

[hueco]

You can take it apart an remove the vacumn parts an block off the opened end with an alum. plate an gasket for $0 .I did mine about three years ago.Just go manual an don't forget to turn it off when the bike is not in use.

That is what I thought about doing. I would sure not want to get stranded on the road because of a bad diaphragm. Was not sure if ball valve shut off in petcock was enough to keep fuel from going though. I guess vacuum diaphragm is a safety feature. I always turn fuel off.
Does what I described sound like a diaphragm gone bad?

[Daniel Meyer]

Does what I described sound like a diaphragm gone bad?

Yep. Exactly that. When you take it apart hold it up to the light and stretch it a bit...it will be leaking around the "tit" in the middle.

Check 'em with the mightyvac every time you change your air filter (ever 10K, yes?) and it will never leave you stranded.

[garyheskett All 49 x 3 st.louis]

Hueco,  First let me state I sure ain't a mechanic, but....
When I broke down in Colorado this May on a trip with several guys, I had the petcock failure.  I had replaced the petcock with a rebuild kit at around a 100,000 miles just because I read so much about "petcock failure".  So when I broke down in Colorado and realized it was petcock failure and it was a Saturday afternoon and no help from a dealer, we started numerous attempts to fix the petcock with no parts. After numerous attempts, one of the guys just reversed the spring and it now works like an old time petcock. I'm not sure how the spring was reversed (remember I'm no mechanic) but its worked fine ever since. You do have to cap the vacuum line on #6 carb and now I have to turn it off every time I shut off the engine. But there is a "no cost" way to do it.  I'm sure you could get specific instructions on how to do it on this great board.

[Bone]

Here is what I did when my diaphragm started to fail. The #6 plug would foul out becoming sooty.
Guys on the board here told me what had happened. Opening the petcock the diaphragm had a tear. I started switching sparkplugs with #6 and could get 50 miles before fouling I had ordered a rebuild kit but didn't want to park the bike.

About the same time someone posted this link.
It's not a Valk but the same process.

http://www.daughertymotorsports.com/howto/Tankvalve/tankvalve.html

Looking through my files I ordered the cover set
in March 2010. I have the set in my cabinet now.

I'm still riding this setup have been cross country twice. It's manual now and must be shut off to be safe.

[Blackduck]

Unless the bike has been stored for a long time there will be enough fuel in  carbs to start.
Sounds like there is another issue.
Disconnect the vacuum hose to the petcock  and suck on it, hold the suction for a minute or so, this should allow fuel to flow to the carbs.
If you want to check the petcock operation take off the fuel hose from the petcock and apply vacumm to the  hose from No 6 inlet (that is, suck on it) fuel should not flow until vacuum is applied and should stop when the vacuum is released.
Cheers Steve

[Wil]

My OEM petcock failed in the first year I bought the bike. 

I replaced it with a manual Pingle because I didn't want to be stranded in the Hinterlands with no fix available.

You just have to remember to turn it on and off, just like when we were kids with dirtbikes.

[Ricky-D]

The only problem I encountered with my stock petcock was the ball valve mechanism that controlled the "on", "off", and "reserve" function of the petcock.

Having the "off" position of the petcock between the "on" and "reserve" made it imperative to insure you are actually in the "off" position.

The aftermarket petcocks we usually discuss on this forum are different in that the "off" position is fully to the end of the motion of the selector which leaves no room for missing the mark that you can with the stock unit.

***

[hueco]

I feel like I owe a update on my situation. Seems like the diaphragm was ok. The battery was low when I tried to start it. Not enough vacuum I guess. I put a new battery on it. Reassembled the petcock with old diaphragm and installed tank. She started right up and been running great. But. A diaphragm going bad on the road is still in the back of mind. Thanks to all you fellows for your great advice.