Any suggestions?

[rrobert]

I have a Kohler CV15.5s that will start on choke and run on low idle when cold(30-40 degrees). But, it needs to warm up for about 5 minutes before it will run on high throttle.

The carb and intake gaskets looked ok inside. Did I miss something?
 

[G1355]

I'd clean the carb, after that mess with your fuel and idle screws on the carb. And maybe it's just really cold blooded. Does it do it when it's warm out
 

[joe csuti]

Two possible causes,1-main jet/hi-speed passages partially restricted due to dirt/gum & hi-speed supply too lean for eng when cold,after eng gets warm it will run on a leaner mixture.

2-carb iceing possibly caused by consensation buildup in venturi when eng at rest or a damp/wet paper filter element.When eng started any moisture in venturi/air filter is deposited on walls of venturi,due to design/shape of venturi this causes air to accelerate thru same,air also gets colder when it accelerates thru venturi causing any moisture in venturi/air to frost/freeze on venturi wall/hi-speed jet,after eng starts to warm up heat is transfered from block to carb body & prevents frosting/iceing.

I had this problem on a K301 on a tractor used with a snowblower,at temp 35 deg/below & high humidity carb would start to ice up,I cured problem by making a heated intake for carb,most small engs suffer fron this problem below 35 deg,this is why all walk behind snowblowers have heated carbs.
 

[rrobert]

Thanks, I kind of understood some of it.

I just fired up one of my K301 and it did the same thing. So, I think it is a temperature issue.

I inspected the carb a second time. Looks like someone might have made the small holes in the sides larger when they were cleaning it before.

There are no adjustments on the carb. There is a brass plug on the top of carb, nothing adjustable.

It runs fine after 5 minutes of idling.
 

[JT]

some of the command engines had a choke lever that was kinda of a spring to compensate for what you are running into, it will allow the choek to close a little ways
 

[joe csuti]

I made up this setup in about 2 1/2hrs,it's not pretty but it works to cure iceing problem,for 3 yrs I've been telling myself I'll make someting better looking & this setup just keeps on working.Same was made from whatever I had on hand(1" copper pipe & fittings)the 1/2" partical board spacer is for choke plate clearance.
heated air

 

[rrobert]

Looks good to me. I might try something similar if running the engine is a hassle this winter. Thanks for pics.
 

[joe csuti]

This pipe setup was actually made 5 yrs ago for a tecumseh hh100 eng,the spacer plate was added for choke plate clearance & also as a simple way to mount pipe on kohler carb due to fact carb larger than tecumseh carb as steel plate that 90 deg elbow brazed to was made to mount directly on tecumseh carb useing air cleaner backplate screws,also at angle pic taken you can't see that the 45 deg elbow is actually about 1/2" away from muffler shell & about 1" off pipe,you just want to heat air to about 70-100 deg so as not to cause a lean hi-speed mixture/vapor lock by overheating carb body,if I were to make a new pipe I would make a lighter setup out of aluminum pipe/fittings & shorten up pipe to reduce wt on carb mount & just pull heat off pipe rather than pipe/muffler.