the irreplaceable carb gasket/oring

[SellYour4Stroke]

Heres Sudco's take on the situation. Its still a better reply than I got from Keihin, which was nothing.

Haha that sucks. Sudco is awesome though.

 

I would have made my own by now if its such a pain. 

[Hutch1]

And rb designs... 

 

RB Designs <rblack66@comcast.net>

1:03 PM (13 minutes ago)

to Bobby, me

Hi Nick,

You are right, no one sells the jet block gasket/0-ring for the ASII carbs. When I do our carb mods and run into this problem, I have come up with a way to make one using other o-rings and making it up and install it. I do not sell these out right as they are built in place...

Thank you, Ron

www.rb-designs.com

 

 

Edited July 23, 2014 by Hutch1

[FGR01]

What a PITA.  That makes 3 parts of this carb that are "non-serviceable" and result in big bills and hassles.  The jet-block o-ring, the pressed in needle seat, and the small rubber tip on the powerjet solenoid.  Are there any others?

[hallsy]

Not a member of KTMtalk so I can't see the link above but I assume it is the same as others have said:  cut off the one small o-ring and replace with a different o-ring from an RC plane, etc.  This method seems hit or miss.  I've seen others try this with no success.  They couldn't get the loose sinlgle o-ring to seal properly since it was not attached to the main D-ring.  Ultimately, hoping we can find a source for the correct part and not have to cobble something together as a workaround.

Sorry about the link, didn't realize one has to log in for it to work. It is the same as others have said, the trick may be to get the right size o-ring, thickness may be more important than the fit in the grove. The o-ring seals the little hole it surrounds, shouldn't have anything to do with the seal of the D shaped ring it's attached to. Most likely they are all attached to each other for ease of installation. Question would be if they had trouble before they replaced the o-ring and it persisted afterward how did they know it didn't seal? Maybe the o-ring wasn't the problem to begin with? I can't really see this thing failing very often unless someone has tampered with it or subjected it to a harsh chemical. Submersing the carb in carb cleaner would likely be the #1 cause for this gasket to fail. My experience has been that neither the float bowl o-ring nor the the drain plug o-ring fail that often and those are removed on a regular basis. I've removed the jet block from my 99' KX 250 short body PWK a then reinstalled it with the old o-ring, and it worked fine. Same with the jet block out of an keihin FCR 4 stroke carb. Doesn't mean I'll get away with it the next time though so yes it would be nice to find the correct replacement. It could happen though as I don't think the o-ring for the long body carb was available up until a few years ago. 

 

To the OP... it's a long shot and I doubt it, but try James Dean at JDJetting. He sells the jet block o-rings for most of the 4 stroke Keihin carbs used by the O.E.M.s. Just like the short PWK, the FCR o-rings aren't available anywhere else. The difference is JD sells a modified part for the FCR carb that requires removing the jet block, so either he's found a way to get them from Keihin or he's having them manufactured. http://www.jdjetting.com/xcart/product.php?productid=142&cat=1&page=1    

[Hutch1]

To the OP... it's a long shot and I doubt it, but try James Dean at JDJetting. He sells the jet block o-rings for most of the 4 stroke Keihin carbs used by the O.E.M.s. Just like the short PWK, the FCR o-rings aren't available anywhere else. The difference is JD sells a modified part for the FCR carb that requires removing the jet block, so either he's found a way to get them from Keihin or he's having them manufactured. http://www.jdjetting.com/xcart/product.php?productid=142&cat=1&page=1    

 

Heres what JD had to say

 

jdjetting@comcast.net

3:31 PM (2 hours ago)

to me

We do not carry any internal carb parts for the PWK models.  You may try Sudco.com.

Thanks,

Dee

JDJetting LLC

 

The one company(Keihin) that could help me in this situation has not replied to me, I wonder why that is?

 

I did manage to make a gasket out of gasket material. Weather it will work or not I don't know yet.  

Edited July 24, 2014 by Hutch1

[SellYour4Stroke]

Heres what JD had to say

 

 

The one company(Keihin) that could help me in this situation has not replied to me, I wonder why that is?

 

I did manage to make a gasket out of gasket material. Weather it will work or not I don't know yet.  

 

 

Haha. Told u sudco is awesome! 

[mugen571]

Hi,

 

I tried several different ideas to try and address this problem.  Didn't quit until I found one that worked. I ended up making a gasket out a piece of Sea-Doo carb intake gasket.  1 year and 1/2 later and it is still working great!  I've done several others since then.

Do you have a leak?

You can test for the leak "bad o-ring" by getting the carb really soapy and blowing low pressure air through the air bleed jets on the air filter side of the carb.  Providing you did a good job plugging off the pilot, main, and fuel screw passage, if you have a leak it might look like the attached photo.  But just because you don't get "leak bubbles", it doesn’t mean you don’t have a problem.  The carb pictured didn't have the "leak bubbles" at first.  This carb had a pilot bypass port that was completely stopped up with debris.  I cleaned the debris out (at that time I didn’t realize it was o-ring) then tested again to check bypass flow, and of course it was good, but the body sprang a leak as shown.

You find a leak or make a leak cleaning out debris:

I stopped looking for ways to fix it when I found one that worked for me.  Disassemble the carb body and clean the old o-ring and gunk out. Clean it very good as your stencil depends on it.  I found copper spray works best for stencil making in this case.  Spray the carb o-ring surface with a dusting of copper spray.  Wait a few minutes then press the gasket firmly on top of the copper spray. You don’t want to press very hard or move it at all.  The o-ring sits in a recess and when done correctly the gasket will be absent of copper spray exactly where the o-ring recess is.  The gasket needs to be big enough so pins can hold it as you make the cuts but small enough to get a good stencil.  If you're satisfied with the transfer, pin the gasket to a piece of soft wood that is small enough to be spun easily on your bench. Spinning the gasket itself always ended in failure. Have a lot of brand new thin razor blades on hand. The thinner the better.  Utility knife razors present a challenge because the degree of taper is too great, it spreads the cut open too far. Start cutting by pressing through the gasket into the wood. Then lift it out completely and do it again and again moving slowly down the line. Don’t smear the copper spray.  I haven’t tried it but maybe freezing the gasket after copper spray but before cutting might help. Dragging the razor through the gasket always ended in failure.  Always start in the middle of the stencil furthest from your pins. Always cut inside holes and lines first. Take your time. If a cut goes to far, start over the gasket is really fragile as you near the end and mistakes must be avoided completely.  I use a stereo microscope when I have to make one of these. When its finally separated keep fitting and cutting until it lays perfectly. And before you start cut a test section to make sure you have the gasket thickness correct.

Seal the outside body upon reassembly with Hylomar, Use nothing on the gasket. Soap test. Done. Worked for me.

Good Luck!

[cj_wai]

after the copper spray sets up,try spraying it with hair spray...........that should fix it so it doesn,t smudge.

[deafrider250f]

Just looked at JD website and they have the midbody gaskets for the fcr...

[mugen571]

Hi Deafrider250f, 

Your comment "The MXoN officals should have pulled a fast one and said at the last sec just before the 5sec card went up that they are now racing on ice..." was funny.   You remind me of a parts guy I once worked with…… He couldn’t spell either. JK 

Or, was it that he couldn’t read…. doesn’t matter. 

Point is:
Unfortunately the mid body gasket that they sell will not fit:
FCR-MX carburetor versions with a removable intake flange.
The gaskets will not fit KTM model years 1998 thru 2005.
The gaskets will not fit Yamaha model years 1998 thru 2002.

Says so on the web-site. The picture isn’t even close….. Or was it that he couldn’t see……

Anyway thanks for giving it your best!

[Hutch1]

I was never able to find a replacement part. I emailed around and nothing. You have to make your own or buy a new carb. Sold the bike now so hopefully the buyer doesn't make the same mistake I did.

[turbo dan]

Bumping this since I just went down this road with the PWK38S on my 05 KX250.  I made the screw top jet block oring work.  I cut off the too-large oring from the main, D shaped portion.  Then I cut a section out of the removed oring so it was U shaped.  I trimmed the ends of the cuts down just until it could be stuffed down into the recess of the jet block with the cut ends of the oring butting against the main jet block gasket.  It was snug enough that it would not drop out of place when turned upside down. 

Bike runs great again.  Very crisp, pulls hard.  The failure was gradual at first but it failed completely in about a week of sitting.  Bike loaded up on fuel severely and was almost unrideable.  There was no response up to about 1/8 throttle.  It would just plain bog until the throttle was opened further.

Another potential source for the correct oring seal is the manufacturer of the STIC jet block.  I have not contacted them yet but I know they are making their own.  Hopefully they are willing to sell them.

[kenpowell]

The jet-block o-ring for the screw top PWK's from Jets-R-Us (http://www.jetsrus.com/individual_parts/021_532_su.html) is a start to the 'fix' but the little o-ring is in the wrong position and is to large. The smallest o-ring in this set on Ebay (Traxxas 4047 Carburetor,O-Ring Set) does fit. Cut the small o-ring off the core and substitute the small Traxxis o-ring. 

[turbo dan]

You can also get a gasket from the guys at STIC super torque.  They told me it is a larger cross section than the stock oring so it may not fit the stock jet block.  As soon as I have it I'll find out.

[turbo dan]

Looks good.  As good as the bike is running with the current gasket I don't have any plans to take it apart anytime soon but I'll have a spare if it does.