Kohler cv13 Command issue with carb spitting at 1/2 to 3/4 throttle.

[coop402]

I bought a 93 Toro T bar walk behind. It is a nice big mower.

I knew when I tested it that is needed a valve job.
I ordered new valves, all parts, springs, retainers. I used Chevy 350 lifters, as I have heard on many forums this is acceptable.

I tore the entire engine down to clean and inspect it. I found the crank to be smooth and used plastigage and got a 5 thousands reading.

The cylinder looked exceptional, you could see the factory crosshatching. I did run a fine hone to just to possibly break glaze.

I was very very careful, replacing seals, cleaning. Things look good.

I spent a ton of time making sure that I matched the marks on both the camshaft and balancer.
I am sure I nailed this. Checked it three time (however I am human).

My particular motor does not have the adjustable type of lifter mechanism.

As it stands, the motor is a little hard to start, but runs PERFECT at 1200 rpm idle, as smooth as any motor I have ever heard.
In fact I can work all the mower functions and gears. It is very strong.

I can rev it up to maybe 2200. Right at the same rpm every darn time it starts spitting out of the carb and almost dies unless I set it to idle.
It sounds excellent at 2000.

I keep thinking that I need a way to adjust the lash. The other thing might be the Chevy lifters pumping up too hard.
Right now I am just frustrated.

Oh, I did rebuild the carb, as well.

I find it strange that it is a the same rpm range every time. Seems like right at the point where the valve floats or no longer seats.

I am sure it is something silly.

I am using 10-30 quaker state synthetic.

I would appreciated any advice.

 

[Rivets]

Here is a service manual, so you can check your steps against theirs. It seems that you have done everything according to the book, but not being there I can't tell for sure. The only thing that I can see where you might have gone wrong is the following. Did you set the valve clearance 1/4" PAST TDC? This is different than autos which don't have a compression release system. Post back what you find.

http://www.mymowerparts.com/pdf/Koh...13-CV14-CV15-CV16-CV460-CV465-CV490-CV495.pdf

 

[coop402]

Here is a service manual, so you can check your steps against theirs. It seems that you have done everything according to the book, but not being there I can't tell for sure. The only thing that I can see where you might have gone wrong is the following. Did you set the valve clearance 1/4" PAST TDC? This is different than autos which don't have a compression release system. Post back what you find.

http://www.mymowerparts.com/pdf/Koh...13-CV14-CV15-CV16-CV460-CV465-CV490-CV495.pdf

I have been using this same manual, all the torque specs and procedures.
The problem I have is (see page 11.15, picture 11.45) that my valve train is non adjustable.
The only way I would know to set valve lash would be the old school grinding of the end of the valves.
Kind of itimidated to go that route.

I have found, however, that I can put a serious amount of pressure on an old push rod, in order to bleed the hydraulic lifters, as I don't want to do a complete dissambly just to adjust lash. But how do you actually know if you have properly bled the lifters? That could cause a major problem if I ended up grinding away.

Too bad they do not make a series of custom washers for the base of the rocker arm. So you could mechanically add lash.

 

[coop402]

I have been using this same manual, all the torque specs and procedures.
The problem I have is (see page 11.15, picture 11.45) that my valve train is non adjustable.
The only way I would know to set valve lash would be the old school grinding of the end of the valves.
Kind of itimidated to go that route.

I have found, however, that I can put a serious amount of pressure on an old push rod, in order to bleed the hydraulic lifters, as I don't want to do a complete dissambly just to adjust lash. But how do you actually know if you have properly bled the lifters? That could cause a major problem if I ended up grinding away.

Too bad they do not make a series of custom washers for the base of the rocker arm. So you could mechanically add lash.

Just as an update. It looks like the pressure from the intake valve spring has bled the lifter,
I have not measured it, but I do see a reasonable gap at the valve when pressing on the back of the rocker.

Right now the exhaust valve seems tight? I am trying to bleed that right now to make sure I am not seeing things that are not there.
I do not see how a tight exhaust valve could cause spitting.

Oh also, I did check the flywheel and key. It looks good and is properly torqued.

Question? Knowing how well this motor runs and below 2000 rpm, would any of you expect that I missed the mark on the cam gear?

 

[coop402]

OK, I tore it down again. Replaced the lifters with factory units.
I then set the valve lash by grinding the end of the valves to factory specs an 1/4" past tdc, as mentioned.

I triple checked the marks on the cam an crank. All is well.

Engine started right up, idled well.

Just like before, it is spitting at higher rpms.

Flywheel key is fine.

What else could cause this condition.
I did notice that I have an exaust leak at the gasket, seems trivial, but could that do it?

I suppose timing, but it is fixed? I there any way to adjust magnet position, or fine tune the timing.

Everything looks so pristine, I am at my wits end..

All opinions welcome.

 

[Rivets]

I just got done rereading this thread and getting out the manual. Without having the unit in front of me I'm also lost as to which direction to proceed, the best I can do is to offer a few suggestions, but I have to warn you I'm just guessing here. You say it is coming back through the carb, so here's a few things I would try.
1. When you installed the new valves, did you recut the seats and lap the valves in?
2. Are you sure that the governor is set properly?
3. Are you sure that the float level is not set too high, allowing the unit to be running too rich?
4. Do you have an adjustable carb, where you can lean out the high speed mixture screw?

I know that these may be redundant, but I'm at a lose also. Hope this does some help.

 

[coop402]

I just got done rereading this thread and getting out the manual. Without having the unit in front of me I'm also lost as to which direction to proceed, the best I can do is to offer a few suggestions, but I have to warn you I'm just guessing here. You say it is coming back through the carb, so here's a few things I would try.
1. When you installed the new valves, did you recut the seats and lap the valves in?
2. Are you sure that the governor is set properly?
3. Are you sure that the float level is not set too high, allowing the unit to be running too rich?
4. Do you have an adjustable carb, where you can lean out the high speed mixture screw?

I know that these may be redundant, but I'm at a lose also. Hope this does some help.

I really appreciate your help.

1. Seats were recut, and I lapped them. You can see a nice clean ring.
2. No, I set it a couple of different ways, then exactly by the book. on my last attempt, I swung the thing to wide and dropped that push mechanism into the pan. No *****. I am gonna have to take it apart again! hahahahah
3. Float level is not adjustable, but looks parallel to the base as I have seen many in the past.
4. No adjustments on the Walbro carb.

I am feeling pretty comfortable about the valve train. I had gap with the new stock lifters, as they were empty from the factory. I ground the ends of the valves carefully to the numbers written in the manual for the other adjustment style. When I heard it start up I had a lot of valve noise. It went away quickly as the lifters pumped up.


I did notice something strange. I know that the governer is centrifugal. It is easy how to see how it works. I did notice that once the engine started, and the rough condition happened, the governer would become wildly erratic. In fact, I thought enought about it that I replaced all of the governer parts last time I was in the case.