Leaky LC-4 petcock question for ya

micio · 04-01-2007, 06:16 AM

I've got a slooooow leak on my '02 Duke ll petcock (it's the Mikuni CK-69 '96).

I haven't had it apart yet but I'm guessing that there's a lil' seal in there that needs replacing. Trouble is, I can only find the petcock assembly complete for about $50...

Anybody know if an automotive gasket will cure it?

Or do I need to man up and buy the whole thing?

bmwktmbill · 04-03-2007, 12:02 AM

I took mine off and cleaned it and put in a new O-ring.
It leaked just the same. It is a bad design, take it apart, you will see.
Better to cut an old piece of fuel line with a plugged end and stick that on the petcock outlet when the tank is off.
IMHO.
bill

micio · 04-03-2007, 01:42 PM

Thanks, Bill. If cleaning and a new o-ring won't fix it, and it gets to be real bad, I'll kick down for a new one.

lvdukerider · 04-03-2007, 08:51 PM

The one on my 00 Duke II just started leaking last week. I guess the 50 bucks I spent to order a new one wasen't wasted then.

ktmMike · 04-06-2007, 07:29 AM

Lengthen the fuel line a bit and add an aftermarket in-line petcock, then just leave the stock one open.

lvdukerider · 04-06-2007, 08:19 PM

I hear what your saying but mine is leaking around the outside of the part that you turn. Plus I just picked up the new one up from my dealer today. Thanks for the idea though.

bmwktmbill · 04-10-2007, 01:41 AM

The petcock can leak two ways, one is to the outside and the other is through the petcock.
If you take one apart you will see it is built like a bung. There is an o-ring that keeps it from leaking to the outside. That can be replaced to stop that problem.
I can't see how to fix the through leakage but someone might know more.
Bill.

biensur22 · 04-23-2013, 02:11 PM

Sorry for the thread revival, but anyone ever use the raptor petcock on the LC4 tanks? I know a lot of people broke the petcocks off their tanks on the 640As, so there must be a decent replacement. Both sides of mine lead on the outside, but replacing the o-rings didn't fix the problem.

bmwktmbill · 04-23-2013, 07:43 PM

Quote:

Originally Posted by biensur22

Sorry for the thread revival, but anyone ever use the raptor petcock on the LC4 tanks? I know a lot of people broke the petcocks off their tanks on the 640As, so there must be a decent replacement. Both sides of mine lead on the outside, but replacing the o-rings didn't fix the problem.

Did you use metric o-rings?
b

Reinhold · 04-23-2013, 10:02 PM

I just eliminated mine. Put a blocking plate on where the petcock was on my Adventure. Ran a T connector with fuel line from the tank crossover to the carb. Works like a damn!

biensur22 · 04-24-2013, 08:52 PM

Quote:

Originally Posted by Reinhold

I just eliminated mine. Put a blocking plate on where the petcock was on my Adventure. Ran a T connector with fuel line from the tank crossover to the carb. Works like a damn!

What? no fuel pump? What do you do when you have to take off the tank? Ride 300 miles then pull it? Empty it into a bucket?

RE: Metric o-rings. They were metric, but they still leak. Possible i used slightly the wrong size, or PO did and I matched them. I'll check again soon.

04-01-2007, 06:16 AM	#1
micio ^OP stress kitten Joined: Aug 2006 Location: New York Sh***y Oddometer: 338	Leaky LC-4 petcock question for ya I've got a slooooow leak on my '02 Duke ll petcock (it's the Mikuni CK-69 '96). I haven't had it apart yet but I'm guessing that there's a lil' seal in there that needs replacing. Trouble is, I can only find the petcock assembly complete for about $50... Anybody know if an automotive gasket will cure it? Or do I need to man up and buy the whole thing?

04-03-2007, 12:02 AM	#2
bmwktmbill Traveler Joined: Jul 2005 Location: Traveler Oddometer: 4,006	I took mine off and cleaned it and put in a new O-ring. It leaked just the same. It is a bad design, take it apart, you will see. Better to cut an old piece of fuel line with a plugged end and stick that on the petcock outlet when the tank is off. IMHO. bill __________________ '02 KTM 640 Adventure-lowered "On the road there are no special cases." Cormack McCarthy-The Crossing The faster it goes the faster it breaks. And high performance=high maintenance. Bill Shockley

04-06-2007, 07:29 AM	#5
ktmMike Coordinator Joined: Aug 2005 Location: NC/TN Mountains Oddometer: 1,093	Lengthen the fuel line a bit and add an aftermarket in-line petcock, then just leave the stock one open. __________________ KTM MIKE . . . . . . . KTM EQUIPPED SINCE 1999 three 640's (sold), two 950's (sold), 530 EXC, 690 SMC, 990 SM-R

04-10-2007, 01:41 AM	#7
bmwktmbill Traveler Joined: Jul 2005 Location: Traveler Oddometer: 4,006	The petcock can leak two ways, one is to the outside and the other is through the petcock. If you take one apart you will see it is built like a bung. There is an o-ring that keeps it from leaking to the outside. That can be replaced to stop that problem. I can't see how to fix the through leakage but someone might know more. Bill. __________________ '02 KTM 640 Adventure-lowered "On the road there are no special cases." Cormack McCarthy-The Crossing The faster it goes the faster it breaks. And high performance=high maintenance. Bill Shockley

04-23-2013, 10:02 PM	#10
Reinhold No, not Messner Joined: Jun 2006 Location: Chuck City Oddometer: 184	I just eliminated mine. Put a blocking plate on where the petcock was on my Adventure. Ran a T connector with fuel line from the tank crossover to the carb. Works like a damn! Reinhold screwed with this post 04-23-2013 at 10:08 PM

04-03-2007, 01:42 PM	#3
micio ^OP stress kitten Joined: Aug 2006 Location: New York Sh***y Oddometer: 338	Thanks, Bill. If cleaning and a new o-ring won't fix it, and it gets to be real bad, I'll kick down for a new one.

04-03-2007, 08:51 PM	#4
lvdukerider Las Vegas Nevada Joined: Oct 2003 Oddometer: 523	The one on my 00 Duke II just started leaking last week. I guess the 50 bucks I spent to order a new one wasen't wasted then.

04-06-2007, 08:19 PM	#6
lvdukerider Las Vegas Nevada Joined: Oct 2003 Oddometer: 523	I hear what your saying but mine is leaking around the outside of the part that you turn. Plus I just picked up the new one up from my dealer today. Thanks for the idea though.

04-23-2013, 02:11 PM	#8
biensur22 Gnarly Adventurer Joined: Oct 2011 Location: San Diego, CA Oddometer: 183	Sorry for the thread revival, but anyone ever use the raptor petcock on the LC4 tanks? I know a lot of people broke the petcocks off their tanks on the 640As, so there must be a decent replacement. Both sides of mine lead on the outside, but replacing the o-rings didn't fix the problem.

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