Need Restrorob or Expert Help. Kaw 15

[Jason Pallas]

OK here's the background. This engine has been the bane of my existence for the last month - fixing it for a friend. His employees cooked the left head by not cleaning the fins and cooling ports. The head was messed up (valve guides, bent push rods, etc..). I replaced the head - now the second cylinder has developed problems all of a sudden.

I've set the valve gap on both cylinders. Both cylinders have spark. Both cylinders have good compression 90-100psi. However, the engine runs rough - especially at lower RPMS. At lower rpms (about half throttle), if I unplug the good cylinder (left), the whole engine dies (as if it's only running on that one cylinder). There IS spark though and it will run on the "bad" cylinder only at higher RPMs.

So, I'm still left with this - the right cylinder is definitely NOT functioning right. There is spark (I've even swapped coils to make sure this is not ignition related). There appears to be good compression. The valves appear to be set correctly and functioning.

My next move is to remove the second head and look for carbon deposits or something else - however, I'm reluctant to think this may be the culprit - as the compression tested so well.

Rob or anyone have any other suggestions? Any thoughts would be really appreciated. This whole engine has just been one problem after another. Thanks in advance.

[QualityLawnCare4u]

Would this by chance be a 23hp Kaw.?

[dutch1]

You didn't mention that you installed new plugs. If you didn't, give that a try. I don't remember the specs on checking out the resistance in the coils but as I recall there is a method to do so--maybe Restro will slip by with the info. Likewise check for any breaks or wear in the plug wires where juice could be leaking to ground. Sometimes those wires get pinched between the top engine shroud and the lower cooling fin shrouds. At this point, if you have valve lash set properly, it would appear to be an electrical problem.

Dutch

[Jason Pallas]

It's a 15 Kaw. Yes - I looked for any obvious signs of wear on the coil wire and areas where I could be loosing power to a ground. Couldn't see any - swapped out coils to see if that was it - still the same results. It sure acts like an ignition problem - but I just can't find any culprits. Keep suggestions coming - they're helpful. Thanks.
I haven't tried NEW plugs - but have used several different near new plugs that all fire well in other equipment or show a good spark.

[Restrorob]

Jason,

When You installed the new head, Did you replace the intake gaskets as well ?

Have you tried applying the choke SLOWLY while it's running rough to see if it smooths out ? If not try it and see what happens.

The model AND spec numbers may be helpful.....

[MowerMedic77]

Intake gasket leak?.......spray carb spray were the intake manifold bolts to the head(Entire area) while the mower is running and see if your engine rpms change.

[Jason Pallas]

Will post model and serial numbers tomorrow. Will also try carb spray trick - forgot that one. I did not replace intake manifold gaskets. I did check to make sure it looked good on the side I'm having trouble with - gasket was in good shape - and tightened down well.

Rob - choke is linked to the throttle (older exmark style) - so, I can't apply choke separately very easily. However, at higher RPMs, the choke does begin to close and the motor does run better.

[Restrorob]

If spraying the intake yields no change, You should be able to get to the choke shaft on the carb instead of up under at the throttle control assembly to apply the choke at lower rpms.

[Bill Kapaun]

You might check for a cam lobe that got "wasted".
Measure the amount of valve "travel" and compare to the other cylinder to see if it's the same.

[Jason Pallas]

Ok guys - here's the update. Been busy with the snow side of the business over the weekend, but finally had a chance to get back to this issue (and solve it!) today.

First - thanks for the help. It really got me to think things out better and eventually solve this. I pulled the OTHER head off. No visible signs of problems. Cleaned it, lapped the valves, seats, etc.... ( I didn't think I was going to find anything by doing this - but was getting desperate and needed to eliminate things). After reassembly, the engine worked a "little" better - but still had the same type of problems.
I had previously cleaned the carb and made sure that the carb was not an issue. However, as I began to play with the choke and throttle, I became convinced that the issue was with the carb. There are very little adjustments on this carb. HOWEVER, on closer inspection, there was what looked like a small jet adjustment on the right side (standing in front of the mower). I figured that the issue was a lack of fuel, so I opened the jet adjustment a half a turn. IT SMOOTHED ENGINE OUT and SOLVED THE PROBLEM!

I would not have thought that this would have done it - as I expected an adjustment like this would affect both cylinders (instead of just the one). However, it did. I didn't think to check this previously. This mower had been a nightmare. It got cooked from not being cleaned all year. This guys employees ran it all year without once cleaning it - so there was no air cooling going on. It just looked like one big ball of dirt and grease. As I fixed one problem, it would only bring another one into clearer view.
It truely was an odyssey or repair work. I just wanted to post a follow-up. To thank you guys. And, also to be able to add this to the lawnsite library of knowledge for the next guy that has this type of problem.