Jump to content
Sign in to follow this  
Xjchief

Kohler k91 troubles

Recommended Posts

Xjchief

I need help i have a 4hp k91 that i have done points condenser coil new plug carb tune up kit cleaned flywheel magnets everything is gapped properly compression is good. Once its running it runs like a champ idles the whole bit but to get it started takes alot of pulling with the old style rope start sometimes i have to put a drill on it to do most of the turning. If anyone has other ideas i am open to ne suggestions thanks

Share this post


Link to post
Share on other sites
 
MarkPalmer

What color spark do you have with the engine cold?  Other than a weak coil, or if the choke isn't closed up fully or there is an air leak at the intake, I can't think of any reason why it shouldn't start on the first or second pull.  I encountered loads of these engines at a go-cart track in the early 1980's, and they always started up quick. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
Xjchief

Its a nice bright snappy spark i replaced the coil due to inconsistant spark but now its much better. There is fuel on the plug so i know its getting there

Share this post


Link to post
Share on other sites
 
Fordiesel69

Is the flywheel magnets getting weak?

Share this post


Link to post
Share on other sites
 
WH nut

You say compression is good, What is good, Need PSI

Share this post


Link to post
Share on other sites
 
MarkPalmer

That is a good idea to get a compression reading.  The K91 doesn't have a compression release so a standard compression tester can be used to get a good indication of the internal condition of the engine. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
VinsRJ

You said the plug

 

Its a nice bright snappy spark i replaced the coil due to inconsistant spark but now its much better. There is fuel on the plug so i know its getting there

 

Initial carb adjustment correct? The plug should not be wet with fuel.

Share this post


Link to post
Share on other sites
 
Xjchief

Ill check that i figured the old 1.5 turns should b good jus to get it to pop but im gonna play around with it today. Thanks

Share this post


Link to post
Share on other sites
 
Xjchief

90 psi compression

Share this post


Link to post
Share on other sites
 
MarkPalmer

I'm drawing at straws now, but one thing that has me wondering is that it does start when you spin it over with a drill.  This is telling me the problem might be in the spark timing.  Try setting the points gap a little tighter, to say .015-.017. There could be some wear on the cam for the points push rod.   See if this helps. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
Xjchief

Is that the only timing adjustment here?

Share this post


Link to post
Share on other sites
 
MarkPalmer

Yes, that is the only way to make a small adjustment in the ignition timing.  You usually have to set the points a bit tighter if there is any appreciable wear on the cam lobe that drives them.  If this doesn't make any difference, set them back to .020. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
WH nut

It might not hurt to pull the flywheel and check the key. If its dinged or bent even a little it will throw the timing off. 90psi should run it

Share this post


Link to post
Share on other sites
 
Xjchief

Still nothing im going nuts here replaced the coil under flywheel got a new plug nice spark at plug. Coul someone tell me the wiring diagram / order of operation of the ignition system?

Share this post


Link to post
Share on other sites
 
Hodge71

If you have spark at the plug then your ignition is operating correctly... at least I think so.... 

Share this post


Link to post
Share on other sites
 
wallfish

I had one K90 that would fire off spark at the plug when it was laying on top of the head (so It would pull over easier). When the plug was installed, no spark (using an inline spark tester). It turned out to be the points gap setting. An old timer told me to close the points and then open them just a hair each time you pull it over until it fires up. It didn't make sense to me either,how it would spark out of the cylinder and no spark when it was installed but... The old timer was right because it worked. ?????

Share this post


Link to post
Share on other sites
 
buckrancher

is your float level set correctly and when you rebuilt the carb were the all small holes in the main needle open and is your carb mounting flange flat (check for air leaks)

also when you rebuilt the carb did you blow compressed air thru all ports and passage ways?

Share this post


Link to post
Share on other sites
 
WH nut

Have you tried dumping a little gas in the plug hole to see is he fires, that will narrow things down quite a bit.

Share this post


Link to post
Share on other sites
 
Don1977

Try a different spark plug I have found plugs that would not fire when installed under compression. Not all new parts are good.

Share this post


Link to post
Share on other sites
 
MarkPalmer

One other thing I can think of, have you checked the cold valve stem to tappet clearances?  Should be .005-.009 intake and .011-.015 exhaust on the K91. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
Xjchief

Is it possible to install the magneto coil wrong cus there were no instructions and i cant seem to find ne thing online?

Share this post


Link to post
Share on other sites
 
MarkPalmer

You can download PDF manuals from this page: 

 

http://www.kohler-engine-parts.opeengines.com/kohler-engines-parts/manuals/free-engine-service-manuals/free-kohler-service-manual-downloads

 

You'll see the link for the K series singles manual there, it discusses magneto installation in section 8 Electrical Systems and Components. 

 

-Mark-

Share this post


Link to post
Share on other sites
 
Xjchief

Well I got it to run today I did a new plug and it started with the drill. Once running the motor couldn't run any better its strong no smoke idles from full throttle to the lowest of low idle and any where in between. I'm baffled!! Once running I checked for air leaks on the carb and carb gasket got nothing. Now I think it's safe to assume that if I installed something wrong it shouldn't run but it does it just doesn't want to start.

Share this post


Link to post
Share on other sites
 
stevebo

I have a 58 RJ with a k91 and OIL BATH !!!! I believe the float level may be off because the oil bath fills up a bit with gas when it sits a while. When this happens i cannot get it to start at all. What i found is that the gas is preventing the air into the carb which is why it does not start. When I pull the oil bath off it fires right up. So..... do you have an oil bath ai cleaner on it?

Share this post


Link to post
Share on other sites
 
Xjchief

No standard round air cleaner

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...