FR691V can I reuse this scored cylinder?

T

TexasMowerMan

Member
I started a small engine repair business and still have a long way to go to build up my knowledge and skills. I could use some experienced advice. One of my knowledge gaps is internal engine repairs.

A customer brought me a Huster Rapter 54" zero turn with a Kawasaki FR691V engine. He said that she was smoking a lot and that he had taken her to the local repair place that had said... Looks like something broke inside the engine, we recommend replacing the entire motor, it will cost at least $3000. The customer brought it to me hoping I would be willing to be a little more thorough and be willing to do the necessary internal engine repairs. I told him I would take a look.

Fast forward to today. I have the engine in my shop dissassembled and cleaned. The 2nd cylinder was jammed at an angle midway in the cylinder. The rod was broken and the there is a lot of aluminum transfer on the crankshaft.

I did my best to remove the jammed piston without doing additional damage. I ended up having to cut the piston out with a hand saw and a drill. The drill slipped once and did some additional damage.

In an attempt to quote my customer the lowest price, I would like to reuse the cylinder.

Questions:
Do you all think I can sand down the nicks, rehone it, replace the other damaged parts (pistons, rings, rods, crankshaft, etc.)? Or do I need a new cylinder?
Are there ways for me to be more quantatative about wether a cylindar is saveable, specifically in regard to nicks?IMG_20260622_063042854_HDR.jpg
 
Looks pretty deep. All you can do is ridge hone the cylinder to .020" over and see if it cleans up. If doesn't then you are SOL and its time for a new crankcase.
 
no. You might see if oversize pistons are available, and a machine shop near you can bore it oversize. The cost will probably be as much or more than a new engine from HF
 
Piston and Ring just for one side will set you back as much $121 each. Of course you would need both.

Now a short will be between $1200 to $1800 depending the spec.

Costs can be lower if you have a distributor that sales Kawasaki parts.

No way this going to be a low cost repair for one that ran the engine without oil or a failed oil pump.
 
Just swap an LS motor in there. Chevy guys do it all the time. Much cheaper too.

Going with no as well. Those are some deep gouges.
 
Update...

For what it is worth, I had two different experienced people look at it in person. Of course, they got to see the cylinder up close and personal and got to run their fingernail over the nicks. One of them was the guy at the local machine shop who I brought it to hoping they would bore it bigger so I could use the 0.5mm oversized rings and piston. Both people said... "it doesn't look to bad, just run some honing stones through it, but not too much and should be good to go".

The first guy, a motorcycle restorer, said, "what you need to worry about is damage that goes the length of the bore" and "the worst that is going to happen after you clean it up a bit (as long as it is still within spec) is that you might get a little more blowby when passing over what remains of those nicks" and "a lot of the nicks are at the bottom of the piston where they won't have much effect"

The guy at the machine shop was very confident it would be fine he said "the rings are pretty resiliant and will handle those nicks just fine, just hone it, put new rings in, and you should be fine"

Today I honed it and measured the cylinder in 6 locations, it was in spec, but on the very end of the servicable spec. I'm going to put new rings onto both pistons, new seals, new rods, 1 new piston, new crankshaft. The customer OK'd $1500 to $2000 in total cost and I should have less than $500 in parts (I've already ordered all the parts).IMG_20260624_205646101_HDR.jpg
 
TexasMowerMan said:
Update...

For what it is worth, I had two different experienced people look at it in person. Of course, they got to see the cylinder up close and personal and got to run their fingernail over the nicks. One of them was the guy at the local machine shop who I brought it to hoping they would bore it bigger so I could use the 0.5mm oversized rings and piston. Both people said... "it doesn't look to bad, just run some honing stones through it, but not too much and should be good to go".

The first guy, a motorcycle restorer, said, "what you need to worry about is damage that goes the length of the bore" and "the worst that is going to happen after you clean it up a bit (as long as it is still within spec) is that you might get a little more blowby when passing over what remains of those nicks" and "a lot of the nicks are at the bottom of the piston where they won't have much effect"

The guy at the machine shop was very confident it would be fine he said "the rings are pretty resiliant and will handle those nicks just fine, just hone it, put new rings in, and you should be fine"

Today I honed it and measured the cylinder in 6 locations, it was in spec, but on the very end of the servicable spec. I'm going to put new rings onto both pistons, new seals, new rods, 1 new piston, new crankshaft. The customer OK'd $1500 to $2000 in total cost and I should have less than $500 in parts (I've already ordered all the parts).View attachment 73743
Click to expand...
Why would a customer pay up to $2000 for a used, partially rebuilt engine? An engine they can buy new for around $3000.
Most likely you will find as you get busier and build your customer base that going in this deep on engines is not worth the time, effort, focus, and risk.
 
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