Kohler engine tuning issues, smokey full rpm

[Oldtoolsnewproblems]

So my 80s era Ariens rideon has a Kohler K3610s 18 hp engine in it. The K3610 i believe is a higher compression version of the K341, making 18 instead of 16 hp but running a much hotter exhaust and larger carb. I've been running it the last year ish with a spare carb from a K341 becasue I lost a piece of the original carb during cleaning. the smaller carb worked ok, great idle and great high end, but always hunts in the mid RPMs (i didn't want to tweak the governer) and the biggest issue was the huge backfire i would get EVERY time i shut it down, bad enough even I couldn't live with it. I finally found the missing carb part and now my issues begin.

The K3610 carb has a shut-off solenoid to stop the backfire and dieseling, I've never seen a replacement carb that still has that. I put the original carb back in, set the float and tuned it. it idles great and revs up way smoother than the little carb did, but as soon as it hits the high range, it starts spitting black smoke, running pig rich. I had replaced the float seat so i suspected that, but hooking up a fuel line to it, pouring gas in until the bowl was full and then putting my mighty vac on it it held 5-10 psi with only a slow leak down. unless that is supposed to be a perfect seal, which seems unlikely, I don't think it's the seat. what else could I be missing? I can't imagine its too much fuel pressure, as the other carb did not have this issue. i have hte main screw turned basicly fully in, theres nothing I can do with the screws to get this into spec. I can see a clogged passage making it run lean, but pig rich?

unless anyone has a magic 8 ball I fear I'm just gonna take it apart and together again and hope for a change.

 

[Oldtoolsnewproblems]

i had a breif second of "wait did i fofrget to put the main jet back in but no, i can see it poking up in the throat. I'm not even 100% sure i pulled it, those things are often quite stuck. you can see on the side there the cut-off solenoid that makes this carb seemingly impossible to replace, i don't want to try drilling and faceing my own one into a standard carb!

 

[Aknutter]

I have a Kohler motor that came out of an ariens gt19 mower. It's a 84/85 year 19 hp motor but don't know if it had the fuel solenoid but I can check to see if maybe , next few days.

 

[Oldtoolsnewproblems]

appreciate it. I pulled the carb again and am fully cleaning it one last time, i just remembered i replaced the float and seat on this one, something I've never done before, I've always jsut re-used the seat. I wonder if there was some subtle way of screwing that up available to me...

 

[Mad Professor]

Is the float set correctly?

 

[Oldtoolsnewproblems]

yeah, that was the only thing i could think of. it was actually running really underpowered, thats when i realied the float was set SUPER low due to the replacement seat, the bowl was like 1/3 full when it cut off. set it correct and now i have black smoke. It's in the solvent now soaking, gonna put it back together today. Fortunatly i can recall when i first got this thing this carb did work, it was just missing the solenoid thats why i pulled it out. in a freak accident i found the missing solenoid (a 1/8x1.5" piece of steel!) in the layer of grease caked on to the top of hte mower deck 4 months later. what the heck are the odds of that

 

[Oldtoolsnewproblems]

ok yeah, it's me, I'm the problem. i had the main jet half way out and it got stuck so i left it there. with the high speed screw all the way in the needle was still not even in the seat. time for some lube and heat to get it freed up and back into its home

 

[Sidecarflip]

Not trying to be insulting but.. do you know how to set the correct float level?

 

[Oldtoolsnewproblems]

I've always set it level but I guess the briggs calls for 11/64 height, which is what I got. I pulled the main jet out and put it back, but it landed in the same place spot. that wasn't the issue, when i looked more closlely i saw the main adjusting needlehas the tip broken off. hope somoene has a spare theye want to sell me.

 

[Oldtoolsnewproblems]

I've always set it level but I guess the briggs calls for 11/64 height, which is what I got. I pulled the main jet out and put it back, but it landed in the same place spot. that wasn't the issue, when i looked more closlely i saw the main adjusting needlehas the tip broken off. hope somoene has a spare theye want to sell me.

 

[Sidecarflip]

Level to what and how did you determine that? Far as the pilot needled is concerned, try Jacks Small Engine parts (so long as it's not a Chinese knock off carb.

 

[dboyd351]

Have you used an ultrasonic cleaner to clean the carb? I would try that - they are very good at cleaning inaccessible places and getting off deposits you can hardly see.
Can you use the needle off the other carb?

 

[Sidecarflip]

Have you used an ultrasonic cleaner to clean the carb? I would try that - they are very good at cleaning inaccessible places and getting off deposits you can hardly see.
Can you use the needle off the other carb?

All I use actually. I have a heated ultrasonic cleaner and I use Berryman's B12 in it for cleaning carbs and Berryman's gets everything squeaky clean in 15 minutes or so. Mine has a drain on it so I can change out solutions for different things too.

 

[Oldtoolsnewproblems]

i want an ultrasonic, but the minieral spirits and tce do a real good job on their own, and i keep buying welding gear instead...
the culprit btw

 

[Sidecarflip]

Actually, I use mine more for cleaning my hand guns. I remove the furniture and optics (if any) and give them a swim for about 30 minutes. They come out squeaky clean and a quick blow off with compressed air and the a light oil on the triggers and I'm good to go.

 

[Oldtoolsnewproblems]

wow i forgot that the cluprit was a snapped needle tip. i actualy dug up this post to respond with it 6 months late "oh hey guys, turns out my head gasket was going" but i guess I had two problems.