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dmoore

1958 KOHLER 4HP CARB

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dmoore

So I have been battling what appears to be a carb issue on my 58 RJ. New needle/seat, both float settings set. Idle & high speed adjustments set correctly. Points set at 0.25, New plug, Great spark, Good fuel supply from tank with new fuel bowl. It tries to start after numerous pulls.  If I choke it only once it wants to wet the plug. It may be time to replace this 65 year old carb. Is there an exact replacement available? Any and all help appreciated!

Edited by dmoore

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Achto
7 minutes ago, dmoore said:

Points set at 0.25,

 

According to the manual, your points should be set a .020. .025 maybe too far advanced timing for a good cold start.

 

I turned a hard to start K91 into a 1 pull wonder by static timing the points. I now use this method on all my Kohler engines that have points.

https://www.mgonitzke.net/cubcadet/tools/static_timing.pdf

Edited by Achto
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WHX??
8 minutes ago, dmoore said:

It may be time to replace this 65 year old carb. 

Or maybe not. The only thing that can really wear out is the throttle bushings which can often be replaced. 

Since you say a new bowl one can only guess it was cleaned and float checked?

13 minutes ago, Achto said:

 

According to the manual, your points should be set a .020. .025 maybe too far advanced for a good cold start.

:text-yeahthat:Try cutting it back to 018 to 020 and see what shakes. 

Plug gap should be 25 not confusing the two? 

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dmoore

I misspoke on the point gap...they are at 0.20...I will try the static method. Float bowel is pristine, Float adjustment perfect. The float drop as well. While I have spark its orange and not a blue color.

Edited by dmoore
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953 nut
21 minutes ago, dmoore said:

spark its orange and not a blue

Condenser

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dmoore

What I was thinking.....I have not removed the flywheel yet but the plug lead looks to be original. I guess the condenser could be as well.

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WHX??
12 hours ago, 953 nut said:

Condenser

Wouldn't hurt to try anyway. 

Wasn't that the McClean @Achto  that went for a 30 puller to a 2 with closing the gap to 018?  

 

I had a 401 that was a real pain to get going so put a offshore carb on it and it started much better. For 15 bucks I wasn't afraid to roll the dice ... just sayin.

Edited by WHX??
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siebenaler

Does it have a fuel pump or gravity feed ? Sounds like it's getting to much gas try starting it with  gas shut off .dry out the wet plug first. If it runs it's your needle/seat.

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WHX??
7 hours ago, Mark siebenaler said:

fuel pump or gravity feed

Most if not all Ball Bakers & 90/91s were gravity feed. Always had to keep mine above 1/4 tank to get them to feed. 

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wallfish

An engine will start without a carb on it at all just by spraying fuel into it. So if you can't get it to start with just a spray into it and no fuel in the carb at all, then the issue is most likely ignition assuming the compression is good. No fuel in the carb and a spray eliminates flooding as a non start cause and spraying carb cleaner eliminates bad gas as a cause.

A bad condenser will show a weak spark and no start or not running above idle.

Some of them just wouldn't ever get to a nice snappie blue spark no matter what, but still ran good. 

Older K90s and some K91s are very temperamental when it comes to the points gap setting.  .020 is not always the best setting. I've had some that will spark with the plug out and sitting on top but then no spark when it's installed and under compression. VERY frustrating and solved through adjusting the points gap. Closer to .018 might be a good place to begin.

:twocents-02cents:

 

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dmoore
10 hours ago, Mark siebenaler said:

Does it have a fuel pump or gravity feed ? Sounds like it's getting to much gas try starting it with  gas shut off .dry out the wet plug first. If it runs it's your needle/seat.

It's a 1958 RJ so yes tank slightly above carb.

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dmoore
10 hours ago, Mark siebenaler said:

Does it have a fuel pump or gravity feed ? Sounds like it's getting to much gas try starting it with  gas shut off .dry out the wet plug first. If it runs it's your needle/seat.

I think I am fouling the plug by choking too much.

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dmoore
56 minutes ago, wallfish said:

An engine will start without a carb on it at all just by spraying fuel into it. So if you can't get it to start with just a spray into it and no fuel in the carb at all, then the issue is most likely ignition assuming the compression is good. No fuel in the carb and a spray eliminates flooding as a non start cause and spraying carb cleaner eliminates bad gas as a cause.

A bad condenser will show a weak spark and no start or not running above idle.

Some of them just wouldn't ever get to a nice snappie blue spark no matter what, but still ran good. 

Older K90s and some K91s are very temperamental when it comes to the points gap setting.  .020 is not always the best setting. I've had some that will spark with the plug out and sitting on top but then no spark when it's installed and under compression. VERY frustrating and solved through adjusting the points gap. Closer to .018 might be a good place to begin.

:twocents-02cents:

 

Wallfish I believe your right on the points gap. I will close the gap a bit and try again. Thank you all for your input! Dave

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dmoore

Ok, set points at 0.18..timing marks are aligned perfectly @ TDC. 

 

I removed the carb to re-check everything since it floods so easily.  Look at the erosion on body where bowl contacts.  I had this engine running shortly after buying last year but it was always hard to start. I'm not sure if this is my problem or not. You guy's?

 

20250208_120109.jpg

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dmoore

.

20250208_120026.jpg

20250208_120118.jpg

20250208_120137.jpg

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dmoore

I'm also guessing that bowl held water and eventually corroded away that portion of the carb. Would this cause excessive fuel level knowing needle & seat are new?

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dmoore

.

20250208_121720.jpg

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dmoore

20250208_122357.jpg

20250208_122426.jpg

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dmoore

I removed the throttle linkage to check shaft play and there is a lot. 

 

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dmoore

I think it's time for a new carb. She had a good run.

20250208_124825.jpg

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squonk

Air leaking by the throttle will cause it to be lean not rich but yes looks like it's time. Brian at K&B Horse Parts had some nice looking carbs at the show last year. Maybe he has one you could use.

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dmoore

Good first choice!

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dmoore

I went back to the points again because I lost fire at the plug. Pulled the cover off again and watched the opening while rotating the crank. They didn't seem smooth and would not open on every rotation, sporadic if you will. Removed the point assy then removed the point plunger. It appears to me as if this plunger is worn down and maybe shorter although I have nothing to compare it to. Are these supposed to be a certain length? One end (crank) looks to be a little mushroomed. As far as I know it could be the 65 year old original.

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dmoore

Crank end is on right.

 

 

 

20250208_172906.jpg

Edited by dmoore

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pfrederi

Kohler used 2 different point plungers over the year.  Have to think a bit an look to see if there were measurements...

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