Main jet washer

[r3tro74]

I'm working on my 74 GT550 carburators and the generic exploded parts diagram shows a washer under the main jet. My carbs did not have a washer here when disassembled.
Is this washer necessary? If so, is it a fiber sealing washer or a metallic shim with a specific thickness?
Thanks

[tz375]

It's a brass washer and it stops the needle jet from sliding upwards (locates it vertically). They should be available from any Mikuni stockist such as SUDCO or jetsRus etc.

[r3tro74]

Thanks for the info. I wonder why they were missing. The carbs were clean on the inside I guess someone must have been there before.. Oh well I have plenty of other work to do w/ waiting for parts. At least I'm down to only one workbench with parts strung out on it now.

[r3tro74]

Update..

Went out to the barn this morning for a second look (this time with my glasses on) turns out the washers are there, they fit down into a recess and were mushroomed out a bit.. I was able to pop them out with a pick. Thnaks for the description of what thier purpose is.

[disagt]

Hi r3tro74,

do your carbs a favour and remove and clean the main jet in each carb. What you and the most of us call the main jet in fact is the needle jet. The main jet is the long thing with the female thread under the washer. Take a plastic pin or something like that and carefully push it in the direction to where the slider usually sits. Take care not to damage the little brass pin or the jet's thread.
Usually the space between the jet and the carb body is filled with debris which you can`t remove otherways.

Best regards
Dirk

[tz375]

Pedro, Love that laconic style. Brief and to the point. Not everyone understands that British approach though.

Dirk,
Unfortunately you are not entirely correct. The main jet is the short brass object with male threads. The long thin tube with female threads is known as the Needle jet. it is also the Emulsion tube in a 4 stroke with lots of small holes to admit air to emulsify the fuel before it emerges from the calibrated orifice at the top (needle jet).

So it's a fuel well, and emulsion tube and at the top its a needle jet and spray nozzle, but in a Mikuni it's called a Needle Jet.

You are correct that there is often corrosion (not so much debris) between the carb body and the needle jet.

[disagt]

Hi,

I only wrote, what the german Mikuni Importer told me a few years ago. So if he doesn't know....

@ Pedro: GOOGLE says: Twat = A..hole ? Just a very friendly answer.....expressing great technical knowledge !

Dirk

[tz375]

Hi Dirk,

Unfortunately he seems to have got it back to front. No worries.

[r3tro74]

Thanks for the info. I had not assembled the slides yet, so I took the bowls back off and removed the main jets and the Needle jets. They were mostly clean. One of them had a small amount if tarnish and crust.

The carbs came out really nice looking. I had previously read the earlier posts about the home made soda blaster (thanks to all who posted on that topic). I had this old "Speed Blaster" that is a gun with a sand resovoir on the top of it. I've had it for years and it never really worked very good with sand. I tried baking soda in it and it works excellent.