jlo440 seems to not want to run

[Bazooo guy]

Thanks Mike so we dont need to worry about that.
Chris did you modify the exhaust system?
Pull the spark plugs again and see if they are soaked with fuel.

[chris lewis]

I will check compression however it has to be very good. I replaced the pistons with NOS Wiseco units from Richards and I had the cylinder checked out by our in house CMM guy. The cylinders were not noodled out and were still very much in tolerance for standard bore.

I did have a JLO 400 in it which I bought thinking I could run it until I got hte 440 done. It had the same symptoms....so the only parts that are the same are the intake and carb...so I am leaning towards the carb as the culprit.

If I go to a Mikuni carb, I guess I will need the adapter plate, an air filter, some way of hard mounting the carb (I think the adapters are rubber necks...correct?). It was mentioned that I need to change the angle of the carb as well....anyone know the exact angle that the carb would need to sit at?

Thanks
Chris

[hydromike]

From your very first post, if you can spray starting fluid into the carburetor and it fires and runs well (until it's out of ether), and with all the other properties you've described, the problem is more than likely rooted in the carburetor itself somewhere.

Some folks have gotten the Walbro and Tllotson diaphragm carbs to run very well, but at the end of the day a Mikuni is more suitable/tunable for this application. A float style Walbro is another option; they were stock equipment on many Cuyuna (JLO) powered Scorpion snowmobiles. I ran one on a racer for a while and had no problems with it. Float style Walbros have the fuel pump built into the top of the carb and have a float bowl with a butterfly style throttle plate rather than a round slide like a Mikuni VM series. A Walbro float-style and a Mikuni carburetor will need to be mounted level.

There are Mikuni VM32s that have the flange cast right into the carburetor (many Attex machines had these), VM32s that are rubber-boot mounted and most, if not all of the VM34s I've seen are rubber boot mounted.

EDIT:: Here's an ebay auction for a Walbro float-style carb. 1980 Scorpion Whip 440 Carb Walbro Carburator Cuyuna 80 Sting TK | eBay

If the link is dead, it's item number 110819218810. I ran this same carburetor on my 440 Cuyuna my D/stock Attex for a couple years, and it was great. I caught a bad case of Tinkeritis and threw the Mikuni on just to do it.... No noticeable difference in performance when I got the Mikuni tuned in well. Just an option...

Oh 'nother edit. Here's a picture of how that carburetor mounts to a 440. That's the fuel pump with the pulse line on the top of the carb. Butterfly style throttle and butterfly style choke.

[chris lewis]

Thanks for the great information. I am very new to this (I bought this on a whim after having wanted one ever since I was little) and really am at a loss on it.
I have to be honest...I really do not want to buy any more used up stuff. I have over 1800 in this thing and I still do not even know if it drives. I bought it with the engine locked up.. I rebuilt the carb and it seemed like it was all OK... I "wish" there was a simple retrofit that was cost effective.

I will do some more poking around tonight and see if I can squirrt bottle it and adjust the carb to get it running. I have spark, I have compression and it will fire on ether....so it MUST be the carb.

I will let you konw what I find out.

Thanks!
Chris

[hydromike]

I have over 1800 in this thing and I still do not even know if it drives. I bought it with the engine locked up.....Chris

Okay, how's this for cost effective?

I'll send you my old (float style) Walbro carb off my 440 if you want it. I don't *think* I have a spare manifold lying around though, and you may need it for your engine. What are the numbers on the tag on the bottom-rear (intake side) of the engine? Something along the lines of 2F440-6? Six head bolts on each cylinder or four? I admittedly don't know if the JLO is mounted level on your Max, or if it's tilted forward. If the engine is mounted level, we're in good shape, and there's at least one $10.00 manifold waiting for you on ebay.

Don't give up, Chris. We can get you fixed up cheaply one way or another. It's our specialty.

Mike

[chris lewis]

hello all,
i did a quick compression test and both cylinders read 135 which i have to thk is very good. my vw bus engine has less than that and it runs...dangit!

the engine is sitting on a mount that tilts it towards the rear of the machine. i think the engine is a 440-7. i have two standard intake manifolds for single carbs. i am going to get the mikuni carbs offered to me and will try those. they came from a running engine and they come with the manifolds and cables.
they come off of a attex.

thanks for all of the input....

chris

[Bazooo guy]

Before you replace the carb you should determine if thats the problem.
Is the engine not getting fuel or getting too much.
If you spray gas/oil mix into the carb will it fire?
When you spray it hold the throttle wide open so the fuel gets past the throttle plate.

Sometimes the crankcase has a drain plug that could be missing or an open fitting or is just leaking somewhere.
If the case has a leak it will not run properly and spit gas out the carb and exhaust and backfire in both directions.
2 strokes will foul plugs quick if not tuned properly and spraying fuel into it doesnt help.
If you pull the sparkplugs and they are wet its flooded. If they are dry its probably not getting fuel.

[chris lewis]

hi all,

i checked for vac leaks etc a nd found nothing to report. i did find that i mistakenly identified my carb as a wda 52... it is a wda4. i really do not know wht the difference is specificationwise. when i got the machine the carb on it was the wda 52... but the engine i purchased (400) had that wda 52 on it. i used that carb since it seemed more complete and i rebuilt that one. the wda
4 seems to be missing the high speed needle.

i did get it running by squirting some gas into the carb throat...but again, it just seems to run up in rom, then die. if i keep it choked it seems to run a little bit longer but not much...leading to the ida of an air leak...
i pulled the carb off and tore down the wda4 to compare it to the wda52....that is as far as i got.

chris

[Bazooo guy]

Wda-4 is for the Jlo 440cc

Wda-30 is for the jlo 400Cc and 440cc

Wda-52 is for a kohler 440cc

Is your impulse tube external or part of the flange on the intake side?
Is the return line connected to the tank above the feed line?

[chris lewis]

great...thanks... do youknow if there is supposed to be a needle for high speed on the wda4 carrb? Mine has a screw where that needle would "normally"be. on the wda 52 there is a high speed needle and it inserts into a brass tube as you look into the venturi of the carb. my wda4does not have that part.

the impulse tube runs from the bottom of the crankcase up to a nipple on the carb diaphragm stack. it does pump...as there is gas getting pumped into the filter bowl ...a plastic filter that is screwed onto the carb inlet side...and therre is gas...and bubbles...pumping out of the carb into the return line going back to the fuel tank.

are there any good shots or parts breakdowns for the diffent carbs? i have a generic walbro manual that has a generic walbro parts diagram.

can i use the 52 carb? what is the difference between the kohler and the jlo that dictates the use of different carbs?

thanks again.

chris