1980 GS550L Petcock Questions

[cdaniel0808]

Does anyone know if the KL18-4358 petcock has the prime function? My stock 1980 GS550L petcock has not been opening once in a while. If I pull the vacuum hose off and suck on it the fuel begins to flow and I can drive again - no problem. Rather than rebuilding the petcock I'd like a new one with a prime function.

The stock petcock shows a pri position, but it doesn't let fuel flow unless it has a vacuum on it. Turning the slot in the petcock with a screwdriver actually doesn't do anything at all. It's really annoying to have to suck on the vacuum hose to get the bike to start when the gas dries out of the carbs (after not riding for 2 weeks or more).

Does the KL18-4358 petcock mount to the tank with the barbs for the gas line and vacuum line facing to the right or left when looking at the side of the tank?

http://www.z1enterprises.com/Petcock...zuki-1715.aspx

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It only takes a brief puff of vacuum to get your petcock to PRIme.
Move it to the PRIme position, bump the starter, turn the key OFF while it PRImes.
Move the petcock back to the RUN position, start it, ride it.

No need to pull any hoses, just let your engine do the sucking to start the process.

.
__________________

2000 Honda GoldWing GL1500SE
1980 GS 850 GK? "Junior"
hers: 1982 GS 850GL "Angel"
hers: 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300
#2 son: 1981 GS 850G

Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
(Click on my username in the upper-left corner.)
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...unless it's broken and the vacuum won't hold on prime (which is what goes wrong with the things).

The KL18-4358 tap won't fit as the mounting bolt spacing is wrong. In fact, the only 'standard' tap that'll fit your bike is what you've got on it already or fit an adaptor plate and the tap of your choosing. __________________
79 GS1000S
80 GSX750
80 GS550
80 CB650 cafe racer
75 TS100 - being ridden (suicidally) by my father

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oh, thanks! I didn't know that the prime worked like that. I thought that it should allow the gas to free flow even without turning over the engine. My petcock handle is broken off I think. It only has a small slot that I need to put a screwdriver in. Any ideas of what I can use for a handle?

I have a picture, but I'm not sure how to post it here.

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Would it be possible to widen the holes in the KL18-4358 to fit my hole spacing. It's 44mm and I assume that is center to center. My bolts are about 51mm and so it's only 7mm or about 1/4" off. If I could reem out the untapped holes on the KL18 without getting into the seal, it would work, but I can find a picture of the KL18 that shows the seal pattern.

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[cdaniel0808]

I don't understand how the prime function works in the petcock. I have it taken off of the tank and I can rotate the setting know 360 degrees and no matter where it is I can suck on the vacuum line and the diaphram will not stay down (open). Does the check valve in the vacuum line need to be working to have the prime work? My check valve is just an orifice because I can pretty easily blow air in either direction through the vacuum hose.

Is it possible to buy a vacuum operated petcock that would be used with an adapter plate? I don't see any on Z1.

Your help is really appreciated! This GS needs to get back on the road!

[hampshirehog]

Here's how it works:

[hampshirehog]

Here's your adaptor plate:

http://www.z1enterprises.com/Petcock-Adapter-Plate---Pingel--50mm-38-NPT-2718.aspx

I think Jeff is looking at sourcing these a bit cheaper as at that price I'd like a bit of gold in there.

Plus Pingel make a vacuum tap:

http://www.pingelonline.com/powerflo.htm

[cdaniel0808]

That graphic is great! So my problem seems to be that the 1 way valve does not work. I can easily blow air in either direction through it even when I have the orifice plugged.

[cdaniel0808]

So the one way valve flapper is almost completely gone. That's why the PRI doesn't work!

Origional problem was PRI not working - I now understand why, but don't have a fix except for a new petcock.

Origional problem was also the diaphram sticking closed once in a while. I think it's just kinda old and brittle and doesn't flext like it should. A solution would be a rebuild kit, but that still doesn't fix the PRI issue.

Sooo... I think this means I need to buy the adapter plate and new petcock to get both of these issues solved. The Pingel vacuum petcock is about $200 and then a $25 mounting bracket! I think the best solution is to buy an OEM part for $94 from RideNow

http://www.ridenowpeoria.com/fiche_section_detail.asp?section=93277&category=Motorcycles&make=SUZUKI&year=1980&fveh=2111

Agree?

[cdaniel0808]

I guess I can buy the OEM part from a few places.

Z1 and OldBike Barn have it for about $45

[hampshirehog]

I've pfaffed around with various combinations and the only (reasonably) satisfactory solution I've arrived at is to use the OEM style. Others will disagree but I think Pingels are overpriced and the o rings don't last. I've also tried other styles of manual tap but keep coming back to OEM - they work fine when they work is all I can say.

Give Z1 a ring btw - they used to stock the OEM tap and it was a lot cheaper than the price you quoted.

[cdaniel0808]

The OEM part is on order from Big Bike Barn. Thank you all again for your help!

[cowboyup3371]

Be careful about that place. Although there are threads about Old BIke Barn being very dishonest I don't know if this is the same place.

[DUSIEK]

Petcock problem

I have an old 1980 GS550E. There was no petcock present when I purchased that bike a few weeks ago. The new petcock cost around $60, but according to many previous posts causes lot of problems. I decided to machine down an aluminum adapter ( simply half inch thick piece of aluminum with two 50mm apart holes and 3\8" hole for petcock) and purchased Harley petcock (3\8" thread) , $12 on Ebay (all chrome). The petcock hole in the adapter has to be little off from the center ( abo0t 1\4" to 5\16" to the side of airbox. The hole in the gas tank need to be enlarge a little due to off center adapter hole.Works like a charm and costs far less than the original petcock.

[chef1366]

I replaced that POS on my 80 with a Pingel.
Why mess with it?
The prime on that POS needs vacuum to activate it.
Never made sense to me why they put such a piece of junk on an otherwise solid vehicle.