Converting Walbro to Mikuni on JDX 4

[69camaro]

My walbro carb is giving me fits on the the JDX 4. Has anyone refitted with a mikuni? Any insight would be much appreciated.

Thanks Duane

[mikehjd]

I had one that had been converted to a mikuni and it worked fine. It was like that when I bought it, they put an aftermarket foam silencer on it.

[mike817o]

Last winter I changed my jdx-8 over to a mikuni and it's a little work but well worth it. only way of telling is the choke lever. It starts and runs great. Good luck-- Mike.

[69camaro]

Thanks Mike, do you remember what the throttle cable was from and did you find a mikuni that bolted up or did you need a adapter.

Thanks Duane

[mikehjd]

All that was on mine was a carb adaptor off of a cyclone or something. The choke lever was the same as the cyclone and fire series.

[69camaro]

I bet i'm going to have more problems with mine to convert. It has the Kohler 290cc motor.

[mikehjd]

You should be able to get a rubber carb mount that should bolt right on to the kohler.

[mike817o]

i used all the parts off of a cyclone except the fuel pump i used a newer square one. hope that helps. mike.

[69camaro]

I'll do some snooping and see if any Mikunis I have are the same bolt pattern or if a flange will adapt. Thanks

[Mr300]

Just finished putting a Mikuni on our 300, same Kohler 290 as yours. I used a 34mm Mikuni off a Cat, used the flange mount that the carb came with. Just had to drill the mount holes in the flange bigger to fit over the studs the Walbro mounted on. Used cables from Dennis Kirk, measured to find a length that we'd need to follow the original routing. Had to enlarge the hole for the choke cable in the dash, mount up a fuel pump, and plug the return line on the tank. Pretty easy all in all. Starts quick, idles nice, good throttle response. Will do some fine tuning once the right weather gets here.

[iceygears73]

just out of curiosity, what problems are you having with the walbro ? I too have a jdx 4 and keep loosing the fuel on the supply side after it sits awhile. The supply out of the tank is tight but the return where the line pushes on is loose. could this cause the gas to siphon back to the tank? , or is just the walbro carb? Thanks for any info.

[400brian]

just out of curiosity, what problems are you having with the walbro ? I too have a jdx 4 and keep loosing the fuel on the supply side after it sits awhile. The supply out of the tank is tight but the return where the line pushes on is loose. could this cause the gas to siphon back to the tank? , or is just the walbro carb? Thanks for any info.

It's a good idea to clamp all the line connections. You can use spring clamps, worm clamps, or a double wrap of small zip tie.

Commonly, the reason fuel runs back to the tank is a leaking check valve on the end of the pick-up line in the tank.
Unscrew the tank fitting, replace the pick-up line, and inspect the check valve. You can try cleaning it, or replace it.
It seems that the replacements don't seal all that well, allowing the fuel to run back over a inactive period.
It has been suggested that they seal better if they are hanging straight down, rather than lying on their side.
Other options might be a primer, or electric start.

If things are reasonably correct, the Walbro isn't that hard to live with.

[69camaro]

Mine needs more gas than the choke will supply and then when it is running it floods unless it is running WOT. Unless you are worried about originality a Mikunui is 10 times the carb. Mr 300, does the pull on the throttle of the 300 open the Mikuni carb completely open? Thanks Duane

[Mr300]

With the idle set where I want it and the slack taken out of the cable, I can feel may a 1/16" of the slide in the opening at WOT. I'm thinking it's not enough to matter. If you were to look into the throat of the carb, you'd see just a bit of the slide at the top.

[iceygears73]

The tank fitting is what I meant to refer to. After you tighten it in to the tank, the return port ( tube ) can be moved around like it was soldered at one time or how ever they press them in there. thought that might cause it, but I will check the pickup as it was laying down. Thanks !