I'm in the process of rebuilding a mikuni I just picked up. It was varnished up HORRIBLY. The attached 1st pic is the part of the pump assembly and it appears as though there is varnish still on it. The weird thing is that all other parts I let soak overnight came clean so I'm not sure if this part of the pump assembly (1st pic) is supposed to look like this or whether I should let it soak longer and maybe use something else to clean it out?

Trochoid I'm glad you suggested pulling this apart because the person I purchased it from said that I might be able to get away with just some carb spray ... but as you can see there is no way!!! This was in need of a serious rebuild. Anyway the 1st picture is the part I'm wondering about. You can see the yellow blotches that look like varnish... but the weird thing is everything else came clean except for the 1st photo. I could probably scrape away gently but I just want to make sure that this is not intentional plugged by mikuni and that it is indeed varnish.

This is my 1st carb rebuild.

 

thats a common view of the fuel bowl. funny , you called it first rebuilt...rebuilt means you take everything apart including bearings, shaft etc etc, and not just the top cover.

 

Something like this (prolly not but I gave it my best)?

I've got a bunch more pics. I'm no pro.... far from it... but I think I removed everything that could be disassembled and gave it a good soaking. I took a shot of each part I removed. Just cant post that many pics.

The fuel bowl isnt supposed to have that yellowish stuff on it though is it wacky?

 

few more

 

that just looks like old gasket residue, not to worry. get some of this and box blade to scrape, careful not to gouge the soft aluminum.

 

wow that is one dirty carb. make sure you get ALL the varnish out or it will gum up the jets.

 

thanks guys

 

Worked like a charm! soaked for a day in gumout carb cleaner. Sprayed carb cleaner through every hole afterwards and reassembled. Just bolted it on and it kicked right over. A few air adjustments and now it idles as good and steady as my Nikki did at 800 rpm except a HECK of a lot more responsive. Now I need to find a filter for it before I take it out for a run (hopefully I can find a local shop with one)

 

Yep, that's a gooey one, lol. As bad as it smells, I prefer using Berryman's carb cleaner, don't get it on your hands. The spray can stuff is ok, but for soaking parts, buy a gallon can, (it's much more concentrated). Soak everything for a day or 2 except the floats and the ap diaphragm. Then use the spray can, with the straw in the spray head and blow out all of the passages. For the stubborn buildup, use a brass bristle brush and a scotch pad.

I remove the main and air jets from both ends of the E-tubes for better cleaning.

Good to see you got it running. The last Mikuni I rebuilt for a member wasn't varnished, it was corroded. The corrosion was built up so thick that I had to lightly beadblast the parts to remove it.

 

Wrong thread. Cool carb though!