18hp opposed twin model 422707, older model

Hey all first time posting here. Love it here so far!
The engine was running ok, and it would idle fine, however it needed the choke out about half way (when warm) to run properly. I also run it without the governor, although all the linkage is still there but not hooked up.
So I replaced both head gaskets, completely cleaned all the carbon deposits from the combustion chamber and the head, and totally cleaned and rebuilt the carb and fuel pump (walbro 3 screw carb). Now it will only run with full choke and revs very high, even though the throttle is not moving from idle. If i just move the choke a hair it will stall out, so literally the it only runs on full choke but revs TOO high, and even moving the the throttle does nothing. I am at a loss here, and any help or ideas would be GREATLY appreciated.

Thanks

Carb not adjusted properly??

there is only one adjustment and thats the low speed adjustment. and well there is also the idle adjustment but thats it. ive messed with both...

You said you bypassed the govorner, where did you hook the throttle cable up to? A picture or two would help a bit.

Like AllisKidD21 said, shoot a pic so we can see what you got going on. Also, sure you got all the ports and holes cleaned up well? Also, any cracks in the input manifold or even the plastic adapter between?

mightyraze wrote:

Like AllisKidD21 said, shoot a pic so we can see what you got going on.  Also, sure you got all the ports and holes cleaned up well?  Also, any cracks in the input manifold or even the plastic adapter between?

well i was working on it again today and i noticed smoke coming from the bottom of the carburetor....well mightraze you hit it right on the head...unfortunately its not the plastic part but the bottom of the carb itself where it bolts to the plastic has got a nice crack in it....glad i wasted money on the rebuild kit...lol

thank you all for your help...much appreciated.

That kinda sucks, but hopefully that'll fix the issue you're having!

well its definitely the cause...lol...but gonna need another bottom end of the carb or a whole carb. here are a few pics of the setup i had and the carnage...lol...

Wow haha, that ain't right. I wonder what caused it to crack like that..

That sux.  Looks like an impact or stress fracture. The original carb for sasquatch had the same break. I was planning to jbweld it, but the internals were too far gone to recover it.

AllisKidD21 wrote:

Wow haha, that ain't right. I wonder what caused it to crack like that..

well it needed the choke out about half way before i rebuilt the carb so it must have had a small crack already in it...and when i went to bolt it back on i probably did to tight and the rest is history..lol...and after looking at it more the plastic piece actually has a crack in it too...well i guess you live and learn.

Oh yeah, that makes sense. Yeah that would've been sucking a lot of air haha. It's too bad you found out AFTER re-building it.

AllisKidD21 wrote:

Oh yeah, that makes sense. Yeah that would've been sucking a lot of air haha. It's too bad you found out AFTER re-building it.

tell me about it...haha

Haha yeah, hopefully you can get the new carb and spacer sometime soon. And relatively cheap!

i hope so too...but was thinking of maybe putting a mikuni style carb on it. my current offroad mower has one on it and it makes a big difference. I basically used fearless fronts ideas that he has on the murray. i love it.

Yeah I'd be interested to see one of those carbs on an oppy, naybe the broken carburetor was a sign... you should do it hahaha.

2 carbs or make a 90* flange?  This could be interesting.  Mr.modified did a dual carb setup on an oppy, in Mr.modified's GTR Four Zero !

u can get the molkt carbs (chinese knockoffs) from ebay, which i have on my current offroad mower, and they come with the 90 degree flange...just have to file the holes a bit so they line up with the intake manifold. i may just do it...u get the carb, air filter, and intake flange for about 45-50 bucks canadian.

Definitely keep us informed! I have several OPPY's that may look to an upgrade. :-)

well here is some progress...got the 90 on there and fuel pump mock up.

this is my current setup with my offroad mower.

Looks a lot like FearlessFront's setup with the catch can, fuel pump, return line, etc. Pretty high tech looking! Hahaha

ya he's where i got it from...haha...i just wanted little more power.

Yeah that'd do the trick haha.

That's a lot of wasted fuel vaporization(cant think of the right word) and flow with all those bends and long intake manifold. If you could find an intake manifold for a horizontal opposed twin and just made an adapter plate to mount the slide carb to it'll be a whole lot more efficient. I don't think that little carb will feed the oppy as it is.