Take a look and listen (video)

[Wayne S]

Kohler 340, dual Walbro WD 6 carbs

• Hard starting even with engine warm.
• Lots of popping at idle.
• Left exhaust pipe hot after 20 min run time. Welding gloves
• Right exhaust pipe cool after 20 min run time. Bare hand
• Left exhaust leaving an oil trail.
• Right exhaust leaving a small oil trail.
• Left carb vent line seems full.
• Right carb vent tube blowing bubbles.

45 second video below
340 @ Idle Video by Wayne_Shankle | Photobucket

 

[Stangrcr1]

Bad. Running on the left cylinder only.

I would take the motor out. Me thinks its internal.

 

[wjustice]

Could be internal (maybe crank seal) or possibly a bad diaphram in the right side carb.
Those are walbro pumped carbs right? Damn I hate those things. Could just be me but I never could get them to run and start well at all.

Err does it have any compression?

 

[Newoldstock]

I had a manual for that and most of the K motors from back in the day.
As I recall these used Tillotson HR carbs.

AH HA.....

The plot thickens.

I suspect your carbs are the trouble.
Maybe they could use some synchronization and tuning...
And one appears slightly different from the other like one has been modified.

Now as I recall that engine was used in the Tera jets and was a real work horse that ran well.
I think you simply have carb issue...

Remember that Gunson Colortune thread in the tool section?
You would be surprised how useful that is is setting up and synchronizing a set of dual carbs like this.

 

[Wayne S]

Yep the K340 2AS motor was replace with a SK340 2AS and also did away with the oil injection. The carbs came with the motor and I thought I would give them a try.

Before I set them up, I took them apart and the left looked like a new gasket set was installed. I used a gasket kit on the right that came with the carbs because it leaked badly and all the seals looked toast.
I'm not a carb person. That and brakes are the two things I usually leave to someone better, but I thought I would give it a try.

Anyone know where I can get a rebuild kit for these carbs? I've had one order canceled and I don't have any local snowmobile shops

 

[Bill Ellerby]

I looked on partstree.com website and it doesn't list you motor. The closet is the Kohler K341? On ebay there is a parts manual that may help you in the long run, check item 231000098608. You can get free manuals for the motor at www.asberry.net/Kohler.htm, hope that helps.

Upon further research you can contact Classic Snowmobile Sale&Service out of Michigan at 269-561-5404 for help. They showed two kits one for the Tillotson carb and one for the Walbro carb?

 

[wjustice]

Will this do? The complete kits can get real pricey 07-410 - Walbro WR, WD, WDA, Diaphragm and Gasket Set | Snowmobile Parts | MFG Supply

 

[wjustice]

Appearently some parts like the umbrella shaped piece and the diaphragm leaf are no longer available. This makes the.rebuild kits expensive. Can you put the mikunis from the k340 2as on it? I bought the mount off eBay and a new mikuni from pats small engines. Best thing I did for that 2ax engine I have on my trike.

 

[Wayne S]

I am going that route now to put the single carb/intake back in, just hate giving up on something... :censure:

 

[wjustice]

just hate giving up on something... :censure:

Ya know, me too. I fought with a tillotson and 2 different walbro pump carbs on my RTS trike for over a year. Finally I gave up, bought a rubber flange off ebay, a snowmobile mikuni and pump. I had to modify the frame to fit it but it was the best change I've made. It starts easily and runs great. I even got one for my TS290.
Are you sure that the flanges from the original engine wont fit? Just swap everything over. Switching to mix may require a jetting increase I would guess.

 

[Wayne S]

...Switching to mix may require a jetting increase I would guess.

Nuts, nothing easy. Makes me almost wish I was in snow country again just to get this lady back on the road....................almost!

Might just have to make a run to the Yamaha dealership and take the old Mikuni in and see what they have on the 2-stroke 4 runners that may work.

The intake should be the easy part, but the carb itself needs attention as it won't start very well without the starting plunger and that cable was long gone before I got her

 

[wjustice]

That looks like a standard mikumi VM carb. I dont know the size you need but the plunger, starter cables and even new carbs are available at reasonable prices. I got a new 34mm carb, cable plunger assembly and small fuel pump for $100 shipped. Look around here and see if you can find what you need.
Universal Fuel/Intake Acc.

 

[vintagetrike]

Mikuni UpGrade...for kohler 340

Appearently some parts like the umbrella shaped piece and the diaphragm leaf are no longer available. This makes the.rebuild kits expensive. Can you put the mikunis from the k340 2as on it? I bought the mount off eBay and a new mikuni from pats small engines. Best thing I did for that 2ax engine I have on my trike.

Any other Info On Putting the MIKUNI VM On a KOHLER 340-2AX, Carb size,?________
carb jet size...?___________ Flange mount ? number?___________

 

[wjustice]

I'll try to get the info tonight.

 

[wjustice]

Ok, what I did to put a mikuni on my RTS was.....
I had a mount flange but if you look at the Mikuni product catalog they list the flanges available. Just match your bolt pattern to the carb spigot size. Once you get the number, ebay is good.
I bought a carb, pump and button choke kit from Pats small engine. These are snowmobile pre-setup carbs that are made to run with pumps. I got the 34mm. Mikuni Carburetor
Now the problem. The RTS frame shock crossmember is directly in the way for the carb to fit. A buddy of mine made a hoop for over the top and a brace lower, then cut the section out in the way. I made a throttle cable from a standard 100in available at most parts stores. I ground the round down until it fit into the hole in the carbs throttle valve. I silver solderd a 1/4" barrel to the other end for the twist grip.
Right now I have the standard jetting that came with the carb. The only change is the needle is 1 notch leaner. For an aircleaner I just measured the carb flange and got a K&N that fit. I originally used the button choke but later switched to a cable style that mounts in the side of the body. The carb comes with the cable type hookup. Keep in mind that something bigger(36mm) is a bigger carb and will take up more room. There are diagrams available that show all the carb dimensions.