Oil burning on an HS40

[gwoods27]

I’ve got an HS40 that I had someone do work on. They said they replaced an exhaust valve, piston rings, honed the cylinder, new lighting flywheel, He said the valve guide looked worn but seemed ok with a the new valve. When running the engine, it always seemed to take a few tries to get it going, but one it startled would idle just fine. However when putting any kind of load on it the engine seems to bog down and sputter. Then idle fine, but just had no power under load. Opened it up to see this:

Am I looking at oil getting past the rings here or past the exh valve guide. I can feel the scoring on the wall of the cylinder by the valves. It’s only been run a handful of times since I got it back. Never seemed to have the power it should have. Feel like I’ve been had.

 

[1971_MB1A]

I’ve got an HS40 that I had someone do work on. They said they replaced an exhaust valve, piston rings, honed the cylinder, new lighting flywheel, He said the valve guide looked worn but seemed ok with a the new valve. When running the engine, it always seemed to take a few tries to get it going, but one it startled would idle just fine. However when putting any kind of load on it the engine seems to bog down and sputter. Then idle fine, but just had no power under load. Opened it up to see this:
View attachment 289296
Am I looking at oil getting past the rings here or past the exh valve guide. I can feel the scoring on the wall of the cylinder by the valves. It’s only been run a handful of times since I got it back. Never seemed to have the power it should have. Feel like I’ve been had.

Wow...looks and sounds like very shoddy workmanship to me.

 

[creia]

How many hours runtime since the "rebuild"?
Michael

 

[Bigjake]

That don't look like anything has been done to that wall
Or wrong rings in it not a expert i know enough to de carb them
Maybe they didn't clean all the old oil off the piston id be pissed

 

[canuk]

Looks like the valves are switched valve with the centre crater should be intake

 

[canuk]

Correction valves are correct sorry I was thinking h series

 

[gwoods27]

How many hours runtime since the "rebuild"?
Michael

Prob 20 minutes, tops

 

[gwoods27]

That don't look like anything has been done to that wall
Or wrong rings in it not a expert i know enough to de carb them
Maybe they didn't clean all the old oil off the piston id be pissed

I know, I do also have the billit forged connecting rod from ARC. Could that have caused the issue? I have a oversized piston I acquired, I’m not sure a .010 over piston will be enough to fix it though. I have someone that can do the boring for me. I just want to make sure I’m not looking at oil coming thru the valve guide. I also have an oversized exhaust valve. Is it as easy as just reaming the guide with the 9/32 reaming tool and using the over sized valve, or do you need to do something else to the guide after you ream it?

 

[creia]

Prob 20 minutes, tops

A (PROPERLY done) honing will display the characteristic "Cross Hatching" pattern on the walls of the cylinder- I am not seeing any in your photo which suggests it was not done properly, if at all.
You say they replaced the rings- Why? Was the cylinder worn oversize, out of round, or tapered? The only way to determine that is with precise measurements of the bore using the correct tools, then compare that with published Tecumseh "reject" sizes. Furthermore, if they replaced the standard size rings with just another set of standard size rings it will do nothing to correct the bore issues. (The aluminum bore wears out faster than the cast iron rings).
Michael

 

[gwoods27]

Wow...looks and sounds like very shoddy workmanship to me.

I know, it’s the first time I ever sent a motor to someone to work on, I was having ignition issues that we’re driving me batty and ended up striping the crank shaft flywheel side threads. It’s for a Rupp roadster2 so I needed a 3” PTO shaft replacement. Sent him the motor and he said the flywheel was bad, so he replaced that also along with rewiring the secondary circuit on the lighting coil. The guy is on facebook building these engines all the time, figured he knew his stuff. Don’t know how he could have missed a cylinder gouge like that, or what could have caused it in the 20 to 30 minutes that I ran it for when I got it back.

 

[massacre]

Post his info? Or his FB page?

 

[Mariah]

Those gouge lines have been there for a long time, you can tell by the soot stains that are embedded in them. I call bs on cylinder honing because it would take many, many, many hours to wear off the hone marks where the rings ride against the cylinder. The truth lies at the top ridge of the cylinder where the rings don't travel, There are NO hone marks at all. Case closed! One exception, IF that would be a chrome bore cylinder it can't be honed. It would have to be overbored to remove the chrome and sized to fit oversize piston and rings.

 

[creia]

Post his info? Or his FB page?

I would not do that - YET.
Now that you have done some forensics on the "rebuild" of this engine, and revealed some things, the seller has some explaining to do. You have the most leverage right now getting him to make it right (maybe a refund?), if you state that you will out him on an international minibike discussion forum (and also Facebook) if he does not satisfy you.
Michael

 

[gwoods27]

Those gouge lines have been there for a long time, you can tell by the soot stains that are embedded in them. I call bs on cylinder honing because it would take many, many, many hours to wear off the hone marks where the rings ride against the cylinder. The truth lies at the top ridge of the cylinder where the rings don't travel, There are NO hone marks at all. Case closed! One exception, IF that would be a chrome bore cylinder it can't be honed. It would have to be overbored to remove the chrome and sized to fit oversize piston and rings.

It’s an HS40-55356C Ser: 11590 so 1971?
What year did the HS40 have a chrome bore?

 

[gwoods27]

I would not do that - YET.
Now that you have done some forensics on the "rebuild" of this engine, and revealed some things, the seller has some explaining to do. You have the most leverage right now getting him to make it right (maybe a refund?), if you state that you will out him on an international minibike discussion forum (and also Facebook) if he does not satisfy you.
Michael

Agreed, I really need to contact him and see if he’ll make this right.

 

[markus]

They never made/used a chromed bore, Depending on if the bore itself isn't too far out as a whole you should be able to get past the scratching with .010 If that scratching is caused by heavy piston rock and not something else passing through the rings, it may be out pretty far out though. Hard to say without running the gauge down in it.

Exhaust side valves in the Tecumseh world are sloppy by design and Ironically on a new old stock 29313 replacement valve, the stem usually measures smaller than one that came in the engine from the factory. I have resorted to refacing the original valve when the guide still measures in spec rather than replacing the valve if the valve is still good overall. I feel thats better than increasing the stem to guide measurement by usually .002" if not needing to go OS. to answer your question though on going OS if needed, you will also have to recut the valve seat to re center the valve to the seat after cutting Tecumseh recommends a 3 angle be done when doing that.

If things don't work out with your builder I will be happy to help if needed, I would prefer not to get into the middle of this otherwise though.

Best of luck with it.

 

[f4radar]

Is that black soot on top and around the valves a sign of running to rich or burnt oil?

 

[Havasu Dave]

Is that black soot on top and around the valves a sign of running to rich or burnt oil?

No, that is how they get. There is zero precision in valve guides on these, mostly because there aren't any. That combustion area is probably the only part of that motor in the photo at least, that doesn't look AFU.

 

[gwoods27]

They never made/used a chromed bore, Depending on if the bore itself isn't too far out as a whole you should be able to get past the scratching with .010 If that scratching is caused by heavy piston rock and not something else passing through the rings, it may be out pretty far out though. Hard to say without running the gauge down in it.

Exhaust side valves in the Tecumseh world are sloppy by design and Ironically on a new old stock 29313 replacement valve, the stem usually measures smaller than one that came in the engine from the factory. I have resorted to refacing the original valve when the guide still measures in spec rather than replacing the valve if the valve is still good overall. I feel thats better than increasing the stem to guide measurement by usually .002" if not needing to go OS. to answer your question though on going OS if needed, you will also have to recut the valve seat to re center the valve to the seat after cutting Tecumseh recommends a 3 angle be done when doing that.

If things don't work out with your builder I will be happy to help if needed, I would prefer not to get into the middle of this otherwise though.

Best of luck with it.

Ok one more question, I was able to aquire a .020 over piston, had the cylinder bored .020 over so, cylinder issue should be resolved. However, looking at the fly wheel and crank mating surfaces, the guy used lock-tite red on it, as well as the threads, when he torqued down the flywheel nut. Replacing the crank and flywheel was part of his repair work. Looking at the keyway, it looks like there a gap on the back side of the keyway trench.

Is this something that can be repaired? Weld on some metal and smooth out the surface?

 

[ELT]

Does the key rock side to side when it's seated in the keyway?