I have a little 'sprinter' mower. Have had it about eight years. It has actually been a great mower for the price. Gradually it has got lower and lower on compression and has reached the point where it just stalls out on pretty much anything. Did a compression check and it seemed very low. Able to turn it over by hand with very little effort. So I took the engine out and tore it down. Is an 8p502 0066 H1. All of the internals seem fine. I planned to do the camshaft and any seals since I have taken it apart. But the problem is the bore. It is worn. It isn't deeply gouged that I can feel with a finger nail but I can see lines in it. I think I could hone it out for some more life. But my question then is do I go with original standard sized rings. Can I even go over size on rings for this little motor in which the cylinder is integrated with the case. Does anybody bother? Do they just throw it away and get another? If I was to replace the engine I would like to go for something older and more serviceable. What is a good engine I am likely to be able to find here in Australia that will match the bolt pattern and ideally have a separate cylinder and parts to service it etc etc etc? I really like the mower. No rust in it. I don't want to throw the whole mower out either. Throwing out things irks me :|
THIS INFORMATION IS WRONG AS WHEN I SAW "SPRINT" I IMMEDIATELY ASSUMED IT WAS THE OLD SIDE VALVE SPRINT ENGINE NOT THE NAME OF THE MOWER MODEL.
There is at least one oversize and you can get oversized rings from places like Total Seal but you have to know the dimensions , bore width & radial depth of the ring.
With side valves, the valve seat wears away so the exhaust valve fails to make a proper seal.
IT is a characteristic of side valves regardless of what engine they are.
So do a seat recut and then shorten the valve stem to get proper valve lash & you should be good for another 10 years
Most mower repair shops ( not big box glass front retailers ) will have a seat cutter .
If you do not add the cost of your labour then rebuilding is viable
For a workshop, the hourly rate of a strip down & rebuild exceeds the wholesale price of a replacement engine .
However Side Valve engines are no longer made
Yeah this little motor is OHV. I was going to lap the valves but aside from this head looks fine. I was hoping somebody might have specific part numbers for oversize rings. I cannot find them on the B&S website.
From the parts list the B&S code for the ring set is : 26 591976 SET, Ring -(Standard)
If I could go 0.010 over I bet I could hone it out and be about right. I've not put a bore gauge in it yet.
That is because no rebuilds these engine any more mainly due to costs vs replacement cost.
Welcome to the world of throw away equipment. I ran into the same problem on Kohler engine on a LB. All it needed was to have an OS piston and rings but none was available so engine got stripped for spare parts and the rest recycled [I hope]. I took to the recycler but that don't mean it got recycled.
What might be a good reliable engine push mower engine that fits this bolt pattern that can be rebuilt? That would be something with a separate cylinder or a sleeve and parts available.
Has anybody thought about boring one of these out and putting a sleeve in?
#7
StarTech
First finding the correct size is problemic, plus costs can be rather high especially for us that would do it for customer.
So after removing my foot from my mouth I went to the parts catalogue to check as I was sure there were O/S B &S pistons listed.
I was right, they were listed , in the 2009-2011 catalogue from one of the local aftermarket suppliers.
Not in any of the subsequent ones & the O/S rings vanished in the 2017-2019 catalogue .
A long time ago I was having a chat to the Tecumseh storeman before Stens closed down the Sydney warehouse.
He showed the spot where the concrete was damaged where the containers full of push mower engines used to stand.
Apparently even back then when labour was cheap most mower shops would simply swap your blower housing & pull start onto a brand new engine, and charge the customer 1 or 2 hours labour for "fixing " your push mower engine rather than trying to actually diagnose & repair the faulty one .
So no surprise that there are no O/S pistons available any more
Now you CAN do anything mechanical if your wallet is thick enough .
For an O/S rebore
You need to find a piston of the correct dimensions & WEIGHT or take your old pistons to a specialist and have it expanded , but I have not heard of this service being available here for the last 30 years .
A new custom piston will have about 1 hour of machining by a 1st class machinist so there is $ 100 to $ 200
Then you need to have the cylinder bored
Now these engine do not have a bolt on cylinder block so you have to find some one who can mount the crankcases & bore the cylinder which will most likely add the price of fabricating a mounting plate .
A standard bore here is $ 60 ( Aus ) , a custom bore can go several hundred dollars if you can find some one to do it .
I had some blind cylinders (no head ) bored a while back and they cost $ 350 a hit because the machinist had to make up mounting plates and customise a boring bar
Even worse he could not hone it so we had to use a bottle brush hone .
And finally you will need to find some piston rings to fit .
You might get lucky but ring catalogues no longer list rings by size, they list them by application so you will have to ask one of the custom ring makers to make a set.
Even if it is a stock size you will be charged the custom ring price because you can not look up bore stroke & radial depth any more .
So a rebore & oversized piston will probably run to twice the retail price of a new engine.
Now fitting a sleeve has the same boring problems as the O/S piston
Next problem is finding a cast iron / steel sleeve in the right size
These are not just a piece of pipe turned down to fit, they are spun cast to achieve the right grain structure .
Down here I have never gotten a liner for small engines ( 250 cc or less ) any cheaper than $ 150 ( Aus ) which is more than the wholesale price of a replacement short block .
Then there is the problem of the head which will not be designed to clamp onto & hold the sleeve in place so it might fail
Then there is the problem of wall thickness in the actual cylinder which may split
IT will now be 3 seasons latter
Your grass will be 10' tall
And the rebuilt engine will have cost you about the same as a brand new Honda Commercial walk behind .
Now if you know a teached in a trade school you could get the whole shooting match done for a case of beer but it will take a full seimester
I've done some sleeves on motorcycles and cars. What makes the B&S motor silly is that you do need a lot of travel to get in on the mill. Otherwise I would go in with a fly cutter and get into it. Bit I don't quite have the height in my mill. What I do see though is that the B&S cylinder does have some meat in it. Enough to get 3mm or more out for a sleeve. It is finding the right sleeve and the cost of it that looks like it will be the decider. Got an idea I might be able to find a two stroke sleeve for cheap and turn it down to the right height. I've also got some old cylinders with sleeves in a box. Keeping it at the same ID though would cut down the cost since then able to reuse the piston and add some new rings. Not entirely ready to give up on it yet.
IF you have the gear & the skills go for it
But for Joe Average it is a big loss maker
Also be careful if trying to take a liner out of an original engine
A lot of them are cast in and have ridges in them so they can not be pushed out
I found that out the hard way
Down side of having a 40T press
Right went off on a tangent. Got as far yesterday as finding room in the mill to mount the B&S motor on a right angle plate. Was about to go into it this morning with a fly cutter. Found a sleeve that brought the motor down in volume but would have fit. but after being grumpy at this extra work decided to try something a bit more fun. Why bother with this nonsense when the future is available. So the silly B&S will go into the recycling. Figured how I have gradually moved to a lot of electric tools over the years after various suspicions. Things like the battery trap. But I have been running a Makita electric chainsaw for about a year. Much to my surprise it goes great. Used it to take out some big fallen trees on property. Built a big chicken coop with it. Has got to the point where my misses is even driving an electric car now and she loves that. So I had a look at what it would cost me to just build up a stack of bits out of an existing electric mower from Makita. This way I am keeping the old sprinter mower bed I like and it doesn't go in the bin. Now this mower isn't going to have to do all the property. Is just to get into verges and do corners etc.
Parts list available and easy to follow. Really very simple. Parts available here in Aussie. Depending on what is needed I will probably just machine up the base plate of this dead B&S motor to take the electric motor. After costing up the parts to do this came to about as much as a decent petrol banger would have cost me new anyway. If I also add the shipping even a cheap Loncin comes in about the same by the time I add the shipping out here in the rural. Now If nothing else I will learn something new and if it wont go well I can always find some other use for the bits.
