OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 3HP - M#80202

That I can agree with as even here for automobile engine I can't even find a machine shop that can do them.

Anyway the last time I had a small Briggs 12.5 hp done outside my shop, the shop that did it fouled the cylinder so bad that it was junk afterwards and they still wanted their money. That why I brought my own hone to do cylinders but I mainly only do horizontals and none replaceable engines get rebuilt now as you said replacement on so engines are nearly equal in cost.

Yeah I've got a friend of mine who's a mechanic. I'll see if it's something he can assist with. Alternatively, I'll buy the hone and measurement tools and do it myself - not before purchasing an oversize cylinder and ring set.

Chris, you can't hone to +20 it has to be bored. AVB we still have a few machine shops that do this sort of work but they are booked ahead for months, these places do jet skis and outboard motors and that being the leisure industry people expect to pay big money for any work done on these machines. These places can't be bothered with a one off mower rebore. As for car engines, cheaper to just grab one from a wrecker, or just buy another car

Hi Norm,

Any chance you could clarify what you mean when you say you can't hone to +20? Accordging to AVB you can and he says he's done it before. A quick search online and youtube has come back with a very simple tool for doing this on minor scratches and so fourth.

I'm assuming you mean that the oversize piston that is available is too large to hone and using such a tool would be near on impossible to increase to +20 perfectly without imperfections and such in the bore?

Would another option be to hone the bore, reuse the same piston and clean the scratches up on the piston and try get some new rings to suit?

Chris you can hone it to clear the scratches but as AVB says the hone will follow the shape of the worn bore. For what it is worth and probably the amount of work you are likely to give it, probably a hone,new rings and see how it goes. Problem is with a +20 piston you need to bore the barrel to suit the piston and get the correct bore clearance or you will find the piston will nip up in the bore (sieze)

G'day folks,
Norm, honing is actually the B&S specified procedure for doing bore oversizes up to 0.020"!
See B&S Service Manual P/No CE8069, Section 9. They do strongly recommend setting the job up on a drill press, and require the use of a good quality 3-stone hone, though.

To clean up that scoring properly, you'd have to remove a significant amount of metal. Which most likely will take it up to .010" oversize or more, and preclude re-use of the piston.

There are a few options here, and parts cost very much comes into play.

Option 1 is to hone it to oversize, and fit a new oversize piston kit. As AVB says, 0.010" OS piston kits are NLA through the trade, but New Old Stock [NOS] ones are still around, in the US. FleaBay US is the best place to look, as you can see at once if the seller will ship internationally, and the estimated shipping cost if they will. Many US parts shops won't ship outside the US, but it can take a bit of digging on their websites to find this out. Shipping can get exy, too.

The P/No for those is 295588, and a search on FleaBay US brings up a cheapest option that will cost around AU$85 delivered. For comparison, a new standard piston kit #295587 is $147.49 + postage from the ODK Shop [genuine B&S]. 0.020" oversize is in the same ballpark.

Option 2 is to give it a very light hone, clean up the piston a bit, and fit a new standard ring set. The ODK Shop has #294232 ring sets for $42.21 aftermarket or $82.15 genuine.

Option 3 is as for 2, and fit a new standard Chrome ring set, #297201. Once more, these are only available as NOS; the advantage is that Briggs' chrome rings can tolerate up to 0.005" oversize bore. FleaBay US cheapest is ~AU$40 delivered.

In addition, you'll need a full gasket set #297275, and I'd strongly recommend replacing the crankshaft oil seals.

G'day Norm,
Even back in the 1970's, it wasn't worthwhile reboring an alloy bore Briggs. It was cheaper to fit a new short block, after the 1973 Whitlam government import tariff reforms.

Fitting exchange rebores was standard practice with Victa 2-strokes though. As I recall, our shop was paying about $18 trade for these [including piston kit] from ER Nason in Elizabeth St Melbourne. They were a superb job; hot-tank cleaned and phosphate passivated, and they had the piston fitted, ready to install!

Then Victa decided to undercut the independents, and offered changeover rebores for ~$12 including separate piston kit. The barrels weren't cleaned at all, but that didn't take long to do.

Gadge, ER Nason, they were the days, like a kid in a lolly shop

G'day Norm,
Yep; back then there was WL Ryan & Co on t'other side a bit further down. Truly a mechanic's Aladdin's Cave! Then there was their antique Lamson overhead wire cash handling setup...

Gadge, I could watch the Lamson for hours at WL Ryans but being young and having to rush around I was not able to fully appreciate how it all operated, but it sure was a classic and I guess there was other stores using that system but by the mid/late sixties they had all gone. I remember Dimmies in Richmond had the vacuum system still running in the 70's, maybe even later

Actually the Briggs Hone and the Lisle hone are setup the same way. Two stones and two wipers. The stones does the honing and the wipers both stabilize the carrier and cleans the bore wall. Now this cleaning is not completely done so once the oversize piston drops in you want to clean the bore and check it size by either using a micrometer or inserting a ring and measuring the end gap for minimum clearance. Also cleaning the cylinder will you know if you have good clean hone job as the grit will fill in the imperfections. I have hone cylinder to oversize to only find that there was a hidden air pocket in the cylinder wall left when the cylinder was cast.

Lisle 15000 Ridge Hone

It does require a low speed 1/2" VSR drill (0-500 rpm) or drill press. You definitely want to keep the max speed down as it will gall the bore if ran to fast. You will also need to secure the engine to it from rotating as quite a bit of torque is involved. Both hones has a micrometer adjustment to set the stone pressure and to increase as bore enlarges and the stones wear. Using drill will make your back hurt as it takes a long time to hone these cylinder to the oversized and I would highly recommend using a drill press.

The ridge hone picture is the Lisle 16000 which is for smaller bores 1.75"-2.75" depending which stone/wiper set you use and there is the Lisle 15000 which uses different racks as you do bores from 2.75" up to around 10" diameter bores when appropriate racks and stone/wiper set.

I don't know where to go with this now. I've been given an information overload (it's amazing).

the piston has minor scratches, but there is one scratch that I can slide my finger nail over and it catches. I've been told by a mechanic and my old boy that given it's usage that it won't be a problem and to just put it back together and away you go. At the same time, a huge part of me still wants to get the O/S piston and so fourth.

I guess given this is my first time doing this, I could put it back together and give it a new paint job and focus on the restoration of the mower. Worst case buy a new B&S if it fails and then rebuild it with O/S when time and costs permit.

I'm not too sure.....

I made a few calls to motorbike and go-kart mechanics and all say that you cannot hone an alloy block as the stones play havoc on the alloy, and insist it requires a re-bore, but given it's not a sleeved cylinder that it's tricky to do properly. Don't get me wrong, I do believe them to a degree, but given their background, I can't help but take their advice with a grain of salt as their boring and build jobs are for high performance engines of which require such precision. I admire their passion and so fourth, but I want "real" advice based on the application this motor and the low rev's it's to be used. In any case, the information you blokes have given me is unbelievable and all those I've spoken to about these forums, I've held this place in high regard due to this wealth of information and experience.

In the end,

Someone be real with me.... What should I do? Should I be concerned with what I've got and just put it back together along with new seals and gaskets and focus on the external aspects of the motor? Or do these scratches warrant further work?

Chris, just put it back together and hopefully you haven't taken the rings off the piston and if you have you know which way up they were

Chris86, Apparently they were using the wrong stones as it does take different stone materials and grits for aluminum, cast iron and Nikasil. Using the wrong stones will definitely mess things up and as well as previous mention running hone too higher of a rpm will also gall the aluminum cylinders.

Even if the cylinder is bored it still got to be honed to produce the appropriate 45 degree cross hatching.

These guys are probably the same guys that say you can't hone 2 cycle cylinders because they don't know they got use ball type flex hones because regular flex hones catches on the ports. Yes some cylinders can't be honed or bored due to ultra thin chrome or Nikasil coatings and the honing ears right through that coatings. The problem is that equipment like chainsaws and trimmers is even if you hone to remove the scoring oversize pistons and rings are not available so there is no point in doing it. Now larger 2 cycle engines which I have not worked on may have OS pistons and rings available.

AVB, thanks for the rundown on the hone type, and pic. As you'd gather, commercial workshops here don't find it worthwhile to resize Briggs bores! And 'backyarder' repairers generally don't shell out for the special tools required.

Chris86, the benchmark on cost is, that a 550 series 3.5hp sloper Briggs can be had for under $300 new, with 2 year warranty. And that gets you an OHV engine with cast iron sleeve bore. 'Chondas' are even cheaper, but it may be difficult to find one with the right shaft size for the SB clutch.

So it's just not worth putting a lot of coin into parts for the old Briggs, as I see it.
As a guide, the gasket set will cost $30-60 [quality aftermarket vs genuine]. That, plus seals, carby pump diaphragm and a ring set, will get you to around $100 or so - personally I wouldn't be inclined to go any further. Put it back together with those, set the points, do the valve clearances, and it will run for years. Oh, replace the spark plug too.

I'd agree with you that motorcycle, and even go-kart, mechanics are used to dealing with much higher-tech engines than this low-compression alloy bore side-valve! So there are things they just don't get, about what can and can't be done successfully on these.

Thanks guys, I really appreciate the input.

Chris86 as Gadge noted it is probably as a cost effective to replace the engine with a new one than to rebuild it if it is an one off rebuild as tools are expensive for such projects. Not only you need the hone, you probably would the valve guide replacement tools and hopefully you don't need the valve seat cutters. So far I have manage to avoid buying the valve seat cutters.

We here in shops don't do much on rebuilds either as noted rebuilds vs new are simply too close to justify the costs. Most times we can buy and install a promo engine for less. The only time around here it cheaper to rebuild is went it come to horizontal engines as they are usually more costly on larger engines. It is still cheaper to rebuild a $2000 Kawasaki v-twin engine than the replacement cost just depends how quick the customer need the equipment back up and running.

The reason I have my hones is from a couple antique horizontal engine projects that the customer wanted me to rebuild which I did then the customer stuck with repair costs. Next time I will insist on at least 50% of the rebuild up front on an approved rebuild. It cost me more than I was charging for the rebuilds as I had buy the two hones and the stone sets. I was hoping to more rebuilds so I could offset the tools cost. I still rebuild engines for myself as you don't count the labor when doing it for yourself and also to keep in practice.

Repair costs is why I don't repair and sell used equipment anymore, I just do repairs now. Customers simply won't pay a fair amount for the equipment when it repaired. I got several pieces here that I did repair and I can't even sale them for what it cost me in parts to repair.

AVB,
My motorcycle mechanic has sworn off doing even engine restorations for customers, for the exact same reason, after getting stuck with one or two. No way to make a worthwhile hourly rate, particularly if any chasing up of rare parts is needed!

Even though he has no shop overheads to speak of [has a big concrete floored shed on his rural block], apart from electricity, just isn't worth doing. And he has a home workshop that's better equipped than any of the local MC shops - up to date Dynojet chassis dyno, lathe/mill, top end tyre changer etc.