new bike need carb help

[kiser1991]

hello all, picked up this gem yesterday and it is a sweet bike. when i bought it the seller told me the carbs back fired shot the filters off and started to burn wiring but he got it out. it hasnt ran after that . i would like to use these carbs if i can, they are locked up right now tho. i was hoping someone could tell me the best rebuild kit for them? i believe they are vm34s.

 

[kiser1991]

carb brand

 

[fredintoon]

hello all, picked up this gem yesterday and it is a sweet bike. when i bought it the seller told me the carbs back fired shot the filters off and started to burn wiring but he got it out. it hasnt ran after that . i would like to use these carbs if i can, they are locked up right now tho. i was hoping someone could tell me the best rebuild kit for them? i believe they are vm34s.

Hi kiser,
you sure it's the carbs themselves that are locked up and not their cables?
I'd suggest that before you spend money on parts you dismantle those carbs, check what size jets etc. are there compared to what should be,
free everything up and re-assemble. You may find that all the carbs need is some TLC.

 

[kiser1991]

just pulled them off the bike and the throttle cable wasnt locked up, both throttle sleeves in the carbs were completely locked up. i got them out tho. so what would you recommend at this point? do you have a thread on the form you could reccomend me to for cleaning?

 

[5twins]

I don't think there's a specific thread on cleaning those because they are aftermarket VM slide carbs. But there's lots of info on the web about them, they're a common carb. Basically, you just take them all apart, clean all the jets and the passageways that run through the carb. Here's a manual .....

http://www.mikuni.com/pdf/vmmanual.pdf

There is a write-up about tuning them for 650 use around here somewhere. There is a jetting baseline that has been found to work. You'll need to check what jet sizes you have to see if they match. If they came directly from Sudco, I think they set them up a little differently than the accepted baseline.

 

[lakeview]

Looks like someone spent a lot of time and money on putting that machine together. I like a lot of what was done, but not sure of how the chrome front end works with the patina'd metal. Also like the rear fender mounts. Are you willing to let us know how much you paid for it?

 

[kiser1991]

i paid 1350 and got a additional about 250 in parts. it was a hell of a deal, she looks rough but out side of paint the work put in it and the welds are very good!

 

[grizld1]

Sudco sells a lot of VM carbs with generic jetting. Their application specific jetting for the XS650 involves a rich 2.0 slide with a lean 17.5 pilot jet, and retains the 2.0 air jet in the intake bell. That's a very expensive way to go; for a baseline combination that's effective and more commonly used, click the Tech button and follow the menus to the VM section of the XS650 Garage USA Carb Guide. Consider inspecting ignition components and timing before you try to start the motor.

 

[kiser1991]

thanks for the replies guys, i went ahead and completely dissambled both carbs and clean them the best i can but i noticed this and wanted to see if there is a problem. in the included picture at the base where the screw starts to screw in is cracked and has a small gap. it this a problem? also there was some kind of sealant used on the screws, it was white and i thought was teflon at first but couldnt find any on the screw threads.

 

[kiser1991]

here is the screw.

 

[grizld1]

Looks like some PO tapped the spigot for a vacuum barb and plugged the hole with a screw; that hole wasn't there from the factory. Can't see the crack in the photo, but if it goes through to the inside of the spigot you'll have a vacuum leak that needs to be sealed. Use JB Weld (original formula, not JB Quick).

 

[kiser1991]

here it is.

 

[5twins]

That screw should be just long enough to reach through the carb bore wall. It shouldn't stick into the inside like that. It should be screwed in tight and have a soft sealing washer on it. Then you don't need any sealing "goop" on the screw threads. It appears someone made quite a mess of a fairly simple mod. And that's a $400 set of carbs they did it to, lol. I'd be looking the rest of the bike over carefully for more examples of the P.O.'s inept handiwork. The welds look good probably because he didn't do them, lol.

 

[kiser1991]

for sure lol i thought that screw was long

 

[grizld1]

A sealing washer will only help if there's a good surface under it. Don't know how the PO broke that chunk out, but you can restore the surface with JB Weld and a file. Run a screw into the hole from the inside to keep the stuff out of the threaded hole.