the irreplaceable carb gasket/oring

My 03 yz250 has been running poorly for a while so yesterday I began the diagnostics. Checked compression, and it was good @ 210 psi. Took the carb of for a good cleaning. I figured I had better do a thorough job and disassembled most of it for cleaning. I removed the piece the jets screw into and the needle sits in. There was remains of a gasket stuck to it. The whole gasket was rotted away and crumbling. I went down to motosports today and apparently this gasket is not available. He even showed me the fiche it was not there nor was the part that the jets screw into. What do I do now? I bought some gasket paper and I'm going to attempt to cut out my own. Any thoughts?   I can put up pictures if my description of what this part is is unclear.

 

 

Here's an exploded view I got from the keihin website that still doesn't show this part 

Can you take a pic of your carb? Might be something jammed in there? Either that or buy an eBay carb.

Edited by poldies4

The only gasket I know of on the carb is the one between the float bowl and the main throttle body...is that the one you mean? That's just an o-ring type gasket. Maybe you should post pics of what you are describing because it doesn't sound like it's the same gasket I'm thinking of.

Is it possible you are talking about the gasket for the reed valve assembly on the intake?

Is it from the rubber tip on the float valve??

the guy at motosport said he has never had anyone ask about it. It is the part in the centre of the carb the needle and slide sit on top and on the other end has the jets. The second picture is the bottom of the carb.

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Edited by Hutch1

Sorry but I'm still not sure what it is you are describing. If it isn't in the part schematic I'm not sure what it could be because those things are super detailed.

I'm only aware of the o-ring between the float bowl and carb and the top cap and carb.

Edited by MXRider72

Sorry but I'm still not sure what it is you are describing. If it isn't in the part schematic I'm not sure what it could be because those things are super detailed.

YES this is what is so frustrating. I cant find info on it anywhere.

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You aren't supposed to take that part of the carb apart.  There are no replacement parts available.  Since you've already done it.  Pick up some anaerobic gasket maker and put it together without a gasket.

call carb parts warehouse

i have used jetsrus several times with no problems. quick shipping..good luck

Thats it! So im guessing there is not a way to order it through yamaha as they dont have it in their parts catalogue. Is that a reputable site?

 

I'm not sure about the site, it's just the first thing that popped up on my phone in a search.

its also $25 to ship to Ontario Canada. I bought a huge sheet of gasket material today and I have a tube of rtv gasket maker so I will attempt to make my own.

Rtv might work but be careful not to use too much or else it'll ooze all in your carb.

Rtv might work but be careful not to use too much or else it'll ooze all in your carb.

Yeah that was my main concern. One of the very small ports got plugged but I managed to blow it out with hpa.

its also $25 to ship to Ontario Canada. I bought a huge sheet of gasket material today and I have a tube of rtv gasket maker so I will attempt to make my own.

 

 

O rings are fuel resistant - Gasket maker isn't.

Been down this road.  That generic o-ring from jets-r-us and other places does not fit correctly.

 

The part you removed is called the "Jet block" and the seal you are looking for is the Jet Block O-ring.

 

Look at the OP's picture of his Jet Block.  Notice that the one small hole by itself is smaller than the 2 that sit side by side.  Also notice that it is directly "siamesed" against the main D-shaped part, unlike the other 2 that are set off a little.

 

Now look at the pic from Jets R Us.  Notice that all 3 small holes are the same size and all 3 are set off from the main D shape by a little tab.  It ain't right.

 

Good luck finding the REAL CORRECT mysterious Jet Block O-ring for the YZ250 PWK carb and be sure to let us know when you do!  :thumbsup:

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