Question about 1979 Yamaha XS 650 F

1 Answer

I have completely rebuilt the petcock but I still have a serious gas leak. Can you help?

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert whose answer got voted for 500 times.

  • Master
  • 1,978 Answers

Did you replace the vacuum diaphragm on the back of the petcock? That is usually the cause of fuelcock leaks on Yamaha's. Yamaha only offers the diaphragm in the complete petcock assembly. The only way to get a diaphragm separately is in the K&L petcock rebuild kit. Unless your leak is dirty carb/bad needle related and not petcock related.

Posted on Aug 25, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

My harley is leaking gas @ the reserve switch

Either the gasket/o-ring that seals the petcock where it screws into the tank is bad, or the petcock needs new seals/rebuilt (there are kits for this), or you could just replace the petcock.
You need to get down there and see where the leak is actually happening.

Nov 16, 2013 | Harley Davidson Motorcycles

1 Answer

I have a 1992 yamaha seca 2 it has a gravity/ vacume gas pump not sure witch one but its not a electric one it doesnt seem to get gas to the carbs

Considering the age of your bike the vacuum valve on the fuel petcock may have failed. The vacuum valve uses vacuum from one of the air intake manifolds to allow fuel to flow only when the engine is running. But if the valve develops a leak, it fails to open when the engine is running. Some valves can be rebuilt, others require changing out the entire petcock.


Sep 12, 2013 | Yamaha Motorcycles

2 Answers

Overflowing Carbs again!!!

recheck and clean /adjust floats pet **** doesnt stop fuel in bowl if floats out of adjustment or valve sticking/debris will allow fuel to constant flow

Jun 04, 2017 | Suzuki Motorcycles

1 Answer

Is it possible to fix a leaking petcock

Not sure if this will fix your problem but.... we had a 454 LTD with a leaking petcock. we had to replace all the seals and rings in it. stopped the leak. not sure if honda still makes parts for that old of a bike, but kawasaki does not and getting a new petcock was not an option.

Apr 21, 2012 | Honda Motorcycles

1 Answer

Lets see if this works... I have a KTM 450 EXC 2009. It has 500 miles on it, so pretty new. I rode it all day yesterday(a little hard I must say) and all went well. I left it in my garage and during the...

Thank you for contacting FixYa with your KTM inquiry.
This happens sometimes. Usually it's one of two things:
  • You forgot to turn the gas lever off under the tank (Petcock).
  • The float valve stuck in the open position and allowed gas to drain out of the open petcock.
Bikes bounce around quite a bit sometimes mounted on the trailer on the trip home and if the petcock is open this happens. Sometimes the float valve sticks open. Noting serious just smelly and annoying and gets you in trouble with the wife. Tap on the float bowl with the handle of a screwdriver and it usually will shut off.
Hope this helps.
Kind regards,

May 15, 2011 | 2008 KTM 450 EXC-R

1 Answer

My 1993 fatboy seems to leak gas. It didnt for a few days then it did. I turned off the gas and it leaked a little. The next day i left the gas on and it didnt leak.So this isnt a constant problem,however,...

it sounds like you petcock vavle ( your fuel shut off valve) is the problem its easy to change i would really keep a i on it no fuel leak is a safe thing to have.

May 05, 2011 | 1993 Harley Davidson FLSTF Fat boy

2 Answers

What would cause gas and oil to come out of the air filter

Hello check your engine oil level to see if it is over filled.
Also if it is smell it to see if there is gas in the oil.
what some times happens with older motorcycles the fuel petcock o-ring or diaphram goes bad and fuel will weap into the cylinders and into the crankcase. raising the level and pushing into the air box via the crankcase breather hose.
Also check the vacuum line from the petcock if it has gas in it the diaphragm is leaking.

May 31, 2010 | 1994 Yamaha FZX 750

1 Answer

I have a 1987 yamaha warrior

the only thing i can think of is that you might want to take the carb off and really clean it good where it bolts down and around the entire area if thats where its leaking from. Hope i was of some help to you.

Jul 27, 2009 | Sport & Outdoor - Others

Not finding what you are looking for?
1979 Yamaha XS 650 F Logo

Related Topics:

285 people viewed this question

Ask a Question

Usually answered in minutes!

Top Yamaha Experts


Level 2 Expert

281 Answers

Steve Sweetleaf
Steve Sweetleaf

Level 3 Expert

1144 Answers


Level 3 Expert

2600 Answers

Are you a Yamaha Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides