I have an H70 with scoring and it had a stuck pushrod ... Pics ...

Sixpac440

Sixpac440

#1
#1
Looking for some input .. is it worth fixing?

It had a stuck open exhaust valve due to a stuck pushrod ..



Possibly tied in with the breather being plugged with mud ..



The piston is scored both front and back ...



The cylinder is also scored up front and back ..



I have an H60 on the shelf that ran on starting fluid but I know nothing about it other than that ..
It might be a good candidate for all the lighting and starter stuff from the H70 if she is deemed to expensive to fix ...

So what do you think?!!
 
ole4

ole4

#2
#2
If it were me I would disassemble, clean then measure bore taper and out of round. Do you have a good hone? If so you could just hone out the bore to straighten and clean up any slight scoring if the bore measured OK to begin with. It looks pretty dirty so the clean part is probably going to take a while. If you have a portable sandblaster you can get a 50LB bag of baking soda at Harbor freight and blast clean the carbon from around the valves, ports, and head. I guess If you have the tools to recondition the bore and valve seats it looks rebuild able. Does it have Ball bearings on the crank? If it is a bushing on the magneto side you need to make sure it is in spec as well.
 
Sixpac440

Sixpac440

#3
#3
Always good to hear from you ole4!

It has the crank bearing ... I can measure the bore .. I do not have a sandblaster tho I have been pondering it ... I believe I do have access to a hone ..
Its all do able ...

My concern (assuming its not to far out of round) is the scoring .. the back is worse than the front .. its worse near the bottom and fades as it gets to the top ... I would venture a die makers guess and say some scoring is at least .010 deep but not more than .015 ..

The piston and rings are easy ...
 
T

the beekeeper

Active Member
#4
#4
If you can't clean with a light hone I would bore it, that way you will start with a fresh bore and 0.10-0.20 over piston/rings, get it apart and check the rod to crank surfaces........Report back brotha!..................Tom.
 
ole4

ole4

#5
#5
.010 is a deep score and would require .020 overbore if you wanted to get rid of it. It did not look that bad in the picture, so you can feel it easily with your fingernail?
 
Dr. Shop Teacher

Dr. Shop Teacher

#6
#6
Follow Ole's advice and get her cleaned up first. PB blaster is a good substitute around the valves and I've found aircraft stripper will also cut the carbon quickly (5 minutes or less). Then get some good measurements. Start searching for an oversize piston...it might take a bit. If you don't have access to a machine shop, PM me. I used a guy in North Carolina that did a great job for me and he charges 49 bucks + shipping one way.
 
FirePowerMinis

FirePowerMinis

Active Member
#7
#7
My partner does dozens of bore jobs every week, exclusively powersports type stuff.
Sleeving too, if needed/desired. Clio, MI, just north of me.
When I was young and stupid, I'd drop them in a pail of kerosene to clean. I'm older now.



Oh, and I keep seeing these 7hp engines, but don't have one. Side-poop, HS50s and HM80 & 100, but the service manual shows several different bores for 70s?
2.750
2.9375
3.0625
3.125 on certain Solid State ones?
 
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FOMOGO

FOMOGO

#8
#8
I agree on the clean part. You really cant tell a hole lot with it dirty like it is. The dark in the score marks just makes it look way worse than it really is. It will look a lot less damaged when it is clean. But what I see so far calls for boring to clean it up. If its as bad as it looks you wont ever stop the oil consumption.

Get her clean and post some more pics.

Doug
 
creia

creia

#9
#9
Don't even THINK of buying an OS piston/ring set until you have PRECISE bore measurements top, middle and bottom checking for an excessively worn, tapered, or out-of-round bore. Visible scoring is bad enough, but these 3 conditions can greatly contribute to the need for reboring. Then, have a reliable and qualified machine shop tell YOU how much they will have to overbore it and what OS piston/ring set to get. You may be surprised how much OS they will have to rebore it.
Michael
 
Sixpac440

Sixpac440

#10
#10
Too much money would go into it for me ... I will look into the H60 as the replacement ..
I will pull the head and make sure its up to snuff .. if it looks ok I will move all the goodies over to that block.

I will box and save the parts ...
 
Dr. Shop Teacher

Dr. Shop Teacher

#11
#11
creia said:
Don't even THINK of buying an OS piston/ring set until you have PRECISE bore measurements top, middle and bottom checking for an excessively worn, tapered, or out-of-round bore. Visible scoring is bad enough, but these 3 conditions can greatly contribute to the need for reboring. Then, have a reliable and qualified machine shop tell YOU how much they will have to overbore it and what OS piston/ring set to get. You may be surprised how much OS they will have to rebore it.
Michael
Click to expand...
While knowing you're going to shelve it, Michael is exactly right here....My H60 required much more than an 0.020" which pushed it to an H70 stock bore piston. My machine shop called me after trying an initial 0.020 overbore which did not fix the problem. Secondly, since parts for these engines are getting harder to find...locating a new piston (or X part) may not necessarily mean buying immediately (even though I am frequently surprised at how many people are searching for the same part at the same time).
 
H

Havasu Dave

Moderator
#13
#13
Sixpac440 said:
Too much money would go into it for me ... I will look into the H60 as the replacement ..
I will pull the head and make sure its up to snuff .. if it looks ok I will move all the goodies over to that block. I will box and save the parts ...
Click to expand...
Another way of looking at it. Ole4 uses a very nice hone, and probably does more with it than I (or others) do. If you keep in mind that this is a lawn mower engine, and use that perspective, honing to get to a mediocre place of joy and happiness is enough to make a good running engine. It is not a high compression, automotive engine, where a cylinder chunk means the wrath of the hell hounds from Chuck's Machine and Boring are about to be unleashed in a fit of oil-smoking pestilence.

Hone it carefully, clean up the crap, lap the valves, settle on some .020 over rings, slap on a Chingchong Chinaman Carbonator, and go out and mow some grass.

It shouldn't hurt to be a mini biker.
 
Sixpac440

Sixpac440

#14
#14
Haha .. Dave, your a funny guy .. that's mostly where my thoughts were.
The main reason I would put extra effort into it is because its original but at the end of the day it is just a lawn engine.

I was having coffee with the wife in bed this morning and told her about it .. I said if it was a motor for me to use I would clean it up, buy a new piston and rings and call it a day. But its going on a mini for my adult daughter who lives 30 miles north of me and she will use it a lot! It will likely be used daily more often than not (very small town, Coral Michigan). It needs to not burn oil like crazy and shy of major surgery it going to.

I have the garage warming up now and am going to pull the head off an H60 I have and see if its up to the task ...

I 100% respect and believe ole4 when he speaks.
I have a NOS H50 Powersports motor with a tillitson that he has been a wealth of information for and I'm just getting started. That one I will put effort into ...
 
CLH

CLH

Member
#15
#15
I wish you the best of luck finding .20 or even .10 over rings for a 7hp tecumseh. Im pretty sure they are very obsolete, and most have been bought up by the tractor and rototiller crowd a long time ago. I don't believe there are any aftermarket 7hp oversize rings made. I have found standard size made by Stens.

I have one (cast iron block HH70) that I made the unfortunate mistake of letting the piston rings sit in the middle of the bore with no oil in it while working on it (didn't think that would hurt it), now it has a few nice gall marks where I let it sit for a few days…frustrating. It also has long gall marks where the piston rings come together. I figure its not THAT bad (I've seen worse) and I won't ride it that much to make a difference.
 
Dr. Shop Teacher

Dr. Shop Teacher

#16
#16
CLH said:
I wish you the best of luck finding .20 or even .10 over rings for a 7hp tecumseh. Im pretty sure they are very obsolete, and most have been bought up by the tractor and rototiller crowd a long time ago. I don't believe there are any aftermarket 7hp oversize rings made. I have found standard size made by Stens.
Click to expand...
^^^^ain't that the truth. I found 0.010 rings and they just barely brought the ring end gap to 20 thousandths. Nowhere could I find 20s.
 
Dr. Shop Teacher

Dr. Shop Teacher

#17
#17
Sixpac440 said:
Agreed ... looks like it could be a can of worms.
The motor was going on my daughters VT-8 because she wanted a starter. The H60 will do the same job nearly as well and possibly at no cost.

I see there is a snow blower motor that may work if the H60 is a bust ...
https://battlecreek.craigslist.org/grd/6042444716.html
I bet $75 would buy it ...

We will see tomorrow ...
Click to expand...
The H60 will surprise you, if you haven't used 'em before. My 70 H60 on the Trail Bike is a stump puller (and it was a complete rebuild with 20 over rings).
 
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