Briggs 3hp Restoration

[OzFab]

Compare the look of the ports in pic 3, there seems to be excessive casting in the intake port, you can safely remove it but, be careful not to damage the guide hole.

You can also remove the sharp edge around the sides & top of each port, making them a bit rounder...

 

[dengieboy]

Engine

I gotta say buddy that is a nice little engine you have there. Is this your first engine strip? if so take lots of pics clean everything before you put it back together then clean it again crank cases can be painted or if ally they can be polished along with carburetors the tins can be made to look good to with filler and paint. Nuts and bolts that are on show could be swapped with stainless steel items really the world is your limit on what you can do with a little engine and a little time here are a couple of pictures of my little side valve B.S.A which is 110cc its had the full rebuild with everything polished which is going to end up on my trike

B.S.A F12 engine



I wish you all the luck of the spanners my friend the only way we learn this is by doing it and getting dirty hands

Don't think just weld

 

[Tomahawk27]

Haha thanks, it is a neat little engine. Yes, this is the first engine I've torn into and I have to say, it's been a lot of fun and informative at the same time. Sometimes it's a little overwhelming looking at all the parts I've taken off but I have taken pictures along the way and there is a lot of knowledge on here to help me re-assemble it if I can't figure something out.

I don't plan on putting much money into it, at least right now, but a few coats of paint are certainly doable to dress it up. Once I'm done putting it back together, it'll just go back on the kart it came from but in the long run, and this is way down the line, once I have time, money, and space haha, I'd like to get another 3hp and make a twin engine kart. Haven't given it a lot of though but it would have two axles, one engine per axle and two separate throttles. Twice the power but it stays a "dead axle." When making a turn, let off the throttle for the inner engine but keep the outside engine fully engaged. I don't know if this is how twin engine karts normally work but I think it could be fun

 

[Russ2251]

Having built a twin engine kart, I can tell you it would be far less complicated to have one pedal controlling both engines simultaneously. What you are proposing just makes things more complicated and is not at all necessary or desirable.

 

[OzFab]

Furthermore, if both engines aren't exactly the same, you may end up going in circles... literally!

 

[Russ2251]

if both engines aren't exactly the same, you may end up going in circles

Please explain.

 

[OzFab]

If one engine has a higher output than the other (even slightly) & each engine is powering each rear wheel independently, one wheel may move faster than the other, due to the hp difference... Yes, it's a long shot but, it's possible...

 

[Russ2251]

Then by that logic, my one wheel drive kart should be constantly turning to the right.
It doesn't. Not even in theory.
Edit: Noticed my

was revoked. LOL

 

[Tomahawk27]

Again, I haven't given the idea a whole lot of thought but, for the sake of my curiosity, humor me in the hypothetical scenarios:

- I thought of using hand controls for the individual throttles and a regular pedal for the brake

- If the engine outputs were equal, would there be any other factors that would make it pull to the right/left?

- I realize the whole setup and construction would be more difficult and complicated, but assuming the kart was constructed properly and the outputs were the same, would being able to disengage the inner engine would allow for tighter turns?

I know there's a lot of factors to consider, I just think the idea is pretty neat

 

[Russ2251]

If the engine outputs were equal, would there be any other factors that would make it pull to the right/left?

Assuming everything is operating properly, kart should not pull to either side even if engines have unequal output. No 2 engines are identical in any case.

..,would being able to disengage the inner engine would allow for tighter turns?

It might, but think it unlikely. Sounds like a good experiment.
What I have discovered is that engines tend to self synchronize and stay synchronized until rpm drops to the point that clutches disengage allowing them to spin independently of each other. This is a mouthful but is exactly what happens.

I have had an engine coil fail completely and it continued to spin along with the other operating engine UNTIL rpm dropped below the engagement speed of clutch.

 

[OzFab]

Assuming everything is operating properly, kart should not pull to either side even if engines have unequal output. No 2 engines are identical in any case.
It might, but think it unlikely. Sounds like a good experiment.
What I have discovered is that engines tend to self synchronize and stay synchronized until rpm drops to the point that clutches disengage allowing them to spin independently of each other. This is a mouthful but is exactly what happens.

I have had an engine coil fail completely and it continued to spin along with the other operating engine UNTIL rpm dropped below the engagement speed of clutch.

I could be wrong but, perhaps you missed this very important point, which may help clarify a few things...

it would have two axles, one engine per axle and two separate throttles.

Then by that logic, my one wheel drive kart should be constantly turning to the right.

NOt at all; if a single wheel is driven it will move the whole kart; if two separate wheels are driven by two separate engines, at different RPM, the wheels wil obviously turn at different rates... but, I see what you're getting at... logically speaking, it would be constantly turning; mechanically speaking, not so much because they're somewhat governed by the front steering wheels...

 

[Russ2251]

Split axle or solid axle, makes no difference.
The more I think about it, the more I am convinced that little improvement would be realized... if any at all.
Originally, twin engine karts did feature a split axle.
They got away from this practice possibly for the reasons I described.
If there were an improvement in cornering, does it not make sense that the split axle would still be around?
I have not seen one in many decades.

 

[OzFab]

They got away from this practice possibly for the reasons I described.

Is it not possible they got away from the practice for the reasons I described?

 

[landuse]

Maybe we should agree to disagree??

 

[Russ2251]

Right, pointless to run in circles.

 

[Poboy kartman]

 

[Tomahawk27]

Hey everyone, it's been a while but being on break from school, I was able to work on the engine a little bit.

Got the engine torn down and started to paint some of the parts like picture 2 shows. Nothing too great, but considering I wanted to do this as cheaply as possible and just dress it up a bit, I'll take it. The bolts in the picture are after taking a wire wheel to them but I'm still trying to decide if I want them all to look like that, or paint them black (the new intake I made is black).

Speaking of the intake, I decided to use a Honda carburetor (thanks to Kartfab for the idea ) instead of using the old tank and pulsa jet carb. Bought the carb adapter and Uni filter to go with it. Since the kart it goes on is so small, I'll just mount the new tank above the engine and use a gravity fed system. I'll figure that all out later.

In the meantime:

1) Does anyone know the torque specs for a 3hp?

2) To clean up the flywheel, just go over it whit a wire wheel?

3) Haven't looked into a new exhaust yet but since the exhaust port is threaded, would it be possible to use a small section of black steel pipe?

EDIT: Yes, I realize I sprayed over the spark plug lol but I needed a new one anyway and just left the old one in to not get any paint in the threads

 

[KartFab]

rust is not an issue on a flywheel, i wouldnt worry about it.

The threads on all briggs are standard threads, and there are new mufflers you can get that have the threads on them that are super cheap ($5-$7 shipped) just measure the diameter of your hole - im guessing its 1/2" male pipe standard pipe thread muffler, or whatever 1/2" male pipe you want to thread on there would work.

Also, i matched the honda carb to the briggs based on displacement of the engine. So if you are working with this 2-3 hp engine, then the 97cc style honda/clone carb would be ideal i think.

 

[OzFab]

I hope this helps...