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

Hi All,

I've recently acquired a Rover Thoroughbred 16" mower. I'm going to restore this (first time).

the motor on it is a B&S 80202. It's a 1975 build. I'm curious as to how available parts are and whether they're still made? As much as I could easily just bolt on a new honda and be on my way, I'd like my hand at restoring the motor also.

The pulled the motor off tonight and started stripping it down. The choke and accelerator springs have gone and will need replacements, however, if I can buy a new carby complete it might be easier to deal with knowing I won't have to fuss about anything else.

The also pulled the tank off and emptied the fuel out which was a lovely shade of red no thanks to the rust in the tank. It doesn't look too bad, so I'm hoping I could possibly de-rust the tank, but once again, are these still available at all? The rubber grommets for the breather are not much chop and are rather hard, so they'll need doing.

The pull-cord starter assembly I believe is rat Poo. The cable can be pulled, but doesn't retract and at times slips when pulled. Not sure if these are fixable, or are a replaceable part. I have the complete parts manual for the motor, but the part numbers don't mean much to me if they're not available nowadays.


I've attached some pictures for reference.

Many thanks in advance

G'day & welcome, yes to parts either from here or overseas.

Oh I forgot to ask - Where are the best locations to buy parts for these? Local mower shop, or is there a go to location?

Ebay has a few good sellers that are mower shops selling on there. Google is your best friend when looking for parts.
sent you a PM..

Hi Paul, thanks for the info. I'll give ebay a look over

G'day Chris86,
Before you tear it down any further than as shown in the pics, do a basic compression check. Spin the flywheel backwards, and see if it bounces back off compression.

Parts availability for these small side-valve Briggs engines is generally good, as they didn't change much over ~30 years.

However, it can be pretty annoying to have one that has had minor external parts ratted off it, as some of these parts are priced a bit extortionately.

And you may get a shock if you price a new Honda, good though they are. The current Briggs 'sloper' engines are nearly as good, and a lot cheaper.

Keep in mind that it would be very easy to over-capitalise this machine, given its rarity. Even common wear parts like drive sprockets are not likely to be available.

Also the pull starter is fully serviceable & easy to repair.

I have a couple of these engines (stand alone) with various carby/tank set ups

Hi Gadge,

Yeah it certainly has good compression. The bloke I grabbed it off said it was running and continues to run although difficult to start due to issues he suspected were related to the carby, but given it's poor maintenance, I dare say there was more to it than that. With that said, compression appears to be great. Parts appear to be rather cheap and I can completely understand the reasoning behind over-capitalizing (I was originally going to replace the motor), but at the same time, a huge part of me isn't concerned about the cost more so than I am the learning experience by doing this. By the sounds of the information you have provided along with others, it's obvious it's likely to be cheaper in the long run to buy a new motor, but having never having done this to a motor before, the cost of learning is cheap.....at least that's my reasoning, as twisted as it may sound.

EDIT: The engine had less than 100mm of oil in it - dirty at that. I believe these are alloy blocks and they don't like low or dirty oil?
Not sure what damage if any is done, or whether it's worth just pulling it apart and giving it a good clean up and rebuild from scratch?

I wish I knew this when I threw an Echo garden vac on a verge pick up one year...I had too much going on, and never gave it a second thought. I'm sure I'm not the only one guilty of such silliness over the years

LMAO, I fully relate to that reasoning Chris, by doing it, It's allowed me to help many others who wont do it or not mechanically minded..

Looking on the B&S website for my specific motor model, I can't find it. They have a 80202-0535-99, but mine is a 80202-0535-01. Unsure of the difference between the two? Assuming probably nothing as specs look the same.
According to the site, the carby is no longer available OEM.

The common parts list covers your variant anyway; this is the one you want:
http://bsintek.basco.com/MDEXResultsPages/PDFDisplayPage.aspx?fileName=Z6jmyBVJ1DajI

As to the carby, yours doesn't look butchered, so why would you need the complete assembly?

These Pulsa-Jets are a very simple carby. Unless there is excessive slop between the throttle butterfly shaft and the body, it will be easily repairable. Most of them only need a pump diaphragm and a new carby to tank gasket, along with cleaning out the tank and checking the pickup tube screen.

If the compression is OK, there's no real need to open up the crankcase. Cylinder head off to clean off deposits, and check/adjust valve tappet clearances at the same time, should be all that's needed there.

It's true that they don't take kindly to being run with low oil, but as it hasn't 'thrown a leg out of bed', so to speak, its most probably OK for further use.

Being a '75 it would hurt to check your valve clearances as when these close up can make them hard to start as you have too much compression release at start-up.

Yeah I will likely pull off the head tomorrow for a gander and check the condition of the bore also. I still haven't ruild out a complete rebuild just for the sake of it.

I've taken the head off. The bore is in beautiful condition. Piston has little carbon build up, but valves have quite excessive carbon build up.

I'm trying to get the crank case open but not sure whether I should take the magneto off first?

Managed to get the crank case open, but how do I get the flywheel off? Not sure how to get the clutch assemblyou off

Alright, I've been at it a couple of hours and having being the first time pulling one apart, I kind of did it backwards at first, but in the end I got there. Lesson's were learnt to say the least.

Anyhow, I managed to get the head off and pull the guts of her out. The carbon deposits on the valves were quite bad, and there was obviously presence of carbon on the piston. Initially the bore looked to be in great condition, and I guess in the scheme of things it is, however, after closer inspection upon removing the piston, there is scarification marks on the bore. They're not deep, but can be felt using a finger nail across the surface. The piston also doesn't look much chop. My best guess is that it was run without the filter on. It doesn't appear that the carbon deposits did the more so than grains of sand as a result of the motor being run without the filter housing on (that's how I picked it up).

The major thing I wasn't aware of is how to remove the flywheel and starting clutch assembly. I wasn't aware there are special tools for this, and I'll certainly aim to pick this up since this experience, however, with a little bit of ingenuity, I managed to remove it without damage. What occurred was that I removed the crank case housing prior to removing the clutch which made it extremely difficult to hold when trying to undo the clutch assembly. It was frustrating, but I found it quite funny in the end.

I'm an electrician, and am certainly no mechanic, but given my fault finding and problem solving skills, I managed to get through the process rather smoothly all things considered. Given how easy it is to take a part, I'm more than confident putting it back together. The timing marks are rather simple to follow also. No doubt I'll have questions upon putting it back together, as my aim in all this is to build a very smooth sounding little motor.

I have attached some photo's for you all. I'd love some input





























Moving forward, what's the best way to hone the bore to give it back a smooth surface? I'm going to try locate a new set of internals and this is where I start entering uncharted waters; it's all well and good pulling something apart and putting it back together, but doing work on the block itself has me scratching me head

Well it going to need over sizing. Now the old IPL may indicate sizes other than .020 over but usually only the .020 over is available nowadays.

As doing the honing it take a ridge hone to true up and resize the cylinder; flex and ball hones won't do it. They will only amplify any oval and/or taper of the cylinder. The cylinder appears to be aluminum only so you need stones for aluminum 180-220 grit. My Lisle 16000 uses 180 grit stones.

Truing means the removing all scoring, tapering, and oval (Egg Shape). One or more of these can be present on worn cylinder.

Now the crankshaft journal looks good from what I can see especially for an engine as old this one is.

Trying to find a shop that can bore small bore engines is getting very difficult these days, even in a big city like Melbourne they are few and far between. They have either retired, died or just given up because it just isn't economical to rebuild motors these days, cheaper to just replace

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