YX140 engine with Keihin Carb

[keaton85]

I'm going to get a XY140 engine but I already have a 26mm Keihin off of a ATC200.

I'm wondering if it will even work and where to start on jet sizing? I know this kind of thing has been beaten to death but this carb is not one of the normal ones that gets put on here correct?

Stock, the carb comes with a 195 main, and 38 pilot for a 200CC engine. Thus I will have to step down the main a bit.

What do you guys recommend for a range to start in? or if this kind of carb would even work! Thanks!!!

 

[my67xr]

hi, welcome to Miniriders,


the ATC200 Keihin looks to be close on the china Mikuni copys, being a 26mm/22mm

i would start by trying a #95 or a #100 Main jet, and see how it runs

 

[keaton85]

Thanks!

I will get a set in that range, or I might even solder and drill until I find a good size. What do you think about a pilot? or is the main going to be the starting point. As this does have a needle to idle adjustment mixture.

 

[timeeh]

36-38 should be fine for a pilot

 

[keaton85]

umm, did a little more research and stock is 95 main and 38 pilot. I thought there was a 1 in front of that 95 I guess.

So should I just try it as is?

 

[timeeh]

umm, did a little more research and stock is 95 main and 38 pilot. I thought there was a 1 in front of that 95 I guess.

So should I just try it as is?

Should be fine, however you are starting to get on the lean side, however a 160 will typically run a 100 main and as yours is a 140 you should get away with a 95-98, i'd just keep an eye on your plug.

 

[keaton85]

I'm just assume that this carb is a better platform then the stock 26mm Molkt? since I will probably spend more on a rebuild kit and jets then just getting a $30 Molkt.

Thanks again guys! this really helps.

 

[my67xr]

the Keihin carby will be a better starting point than a china carby anyday.

the #38 Pilot jet should be pretty good for that motor,
try it and see

why do you need a rebuild kit for it though?

 

[keaton85]

It's an older carb and the float bowl gasket is now rock solid. Maybe I can just find the gasket and not the whole kit, but I have not checked on that.

Again thanks for all your help guys!

 

[my67xr]

does it use a gasket for the fuel bowl or a rubber seal?

if it is rubber, you can gently pull it out, try not to stretch it,
now soak it in some petrol for half an hour or so.
next, take it out an dry the seal off on a clean rag.
this should make the seal expand, most likely back to it's original size/thickness.


another thing to check while the fuel bowl is off, is if it is flat or not.
lightly face it back flat, using some 320 grit W&D paper (used dry) on a flat piece of glass.
give it a few passes across the paper and check that the mounting face is perfectly flat.
you will soon see if it is, or not.

 

[keaton85]

It's a rubber seal. I will soak it and see if any life comes back. The bowl has raised spots which prevent it from being lapped. I can check it over with a straight edge.

Great ideas!

 

[my67xr]

aah ok,
the china copy Keihins' fuel bowls we get here are pretty flat across the base.
only the brass overflow tube sticks up another 1/4",
but if you gently (don't squash it) use some pliers on the tube, they can be turned left and right as you pull on it, it will come out making it easier to face flat

then slip a small nail or something into the tube to stop it flaring it or closing it,
and lightly tap it back in with a hammer, making sure not to tap in in too much


if you can cut/sand back about 1mm or so off the top of the bowl, it helps the rubber seal to seal it off when it is refitted.
dont overtighten the screws when refitting the bowl.