Briggs 3hp Restoration

[Poboy kartman]

They look okay to me..

Looks like you got some gasket cleaning to do.tho....

 

[landuse]

Looks good to me too

 

[Tomahawk27]

Been a while but finally got around to working on it again. I had planned on buying a valve spring compressor this Christmas but after seeing how expensive they are, I decided not to go that route. After a couple minutes with some screwdrivers, I got the valves out and took a few pictures of them, the head, and the cylinder:









I planned on lapping them but how does the cylinder look?

 

[OzFab]

The valves appear to have been sealing but, definitely need (AT LEAST) lapping...

Cylinder looks fine; is there a lip at the top (feel it with a fingernail)?

 

[Tomahawk27]

Checked it today and there is a small lip at the top of the cylinder

 

[Poboy kartman]

Checked it today and there is a small lip at the top of the cylinder

What that means is that whatever lip is there....is how much that cylinder has been worn away....see...the rings dont go all the way up....at assembly...the bore was smooth and consistent from top to bottom......

 

[jeeperjoel]

wow, that engine takes me back to my minibike as a kid, though it had a decent amount of bailing wire holding it together, front tire was so hard it didn't need air, not much for looks, but on that thing i was unstoppable

 

[Tomahawk27]

What that means is that whatever lip is there....is how much that cylinder has been worn away....see...the rings dont go all the way up....at assembly...the bore was smooth and consistent from top to bottom......

Just so I'm on the same page, the lip I was feeling for was this:



The red markings are small but you can see the silver band at the top of the cylinder; that was the lip I felt. If we are on the same page, how much of an issue is it/what do I do about it?

wow, that engine takes me back to my minibike as a kid, though it had a decent amount of bailing wire holding it together, front tire was so hard it didn't need air, not much for looks, but on that thing i was unstoppable

Ha, I just looked up the year and apparently it was made in 1990, before I was born actually. For now it's probably going back on the plastic cart it was on, although minibike's are a lot of fun...

 

[jeeperjoel]

wow, think my 3 hp engine was made in 70's lol, but same design, only difference i see is my choke lever was on carb, no lever plate, and the kill switch was a metal tab you flipped to contact top of spark plug where there was no boot... one time riding at my uncle's house in lake berryessa made it a few miles from home, big hills threatening to burn up clutch, carb/gas tank assembly rattled loose and fell off, bolts were gone, i was a loooong push home on a hot summer day, dad was pretty angry when i showed up like 2 hours later.... then that time my mom grounded me to room for a week, snuck in minibike and tools while she was in shower, did all kinds of repairs, but when done wasn't getting a chance to sneak it back out of house, had a small rope in toolbox, got bike up on bed, then managed to lower the bike out of window with rope... ahhh the good old days, when life was sooo simple lol

 

[Poboy kartman]

LOL........Except....I would have been out the window with it......"See ya mom.....I want spaghetti for supper tonight! "......

Yes.....I was a problem child.....but I grew out of it....now I'm a problem adult.....but you'd never know it here.....

 

[OzFab]

See the distinctive line adjavent to the green arrow in the pic? That's where we're referring to; that's as far as the rings travel so, over time, the rings wear the bore & leaves a lip here...

 

[jeeperjoel]

LOL........Except....I would have been out the window with it......"See ya mom.....I want spaghetti for supper tonight! "......

Yes.....I was a problem child.....but I grew out of it....now I'm a problem adult.....but you'd never know it here.....

are you sure about that? if your mom was anything like my mom and you did something like you'd get whooped with a belt, buckle end!

 

[Poboy kartman]

are you sure about that? if your mom was anything like my mom and you did something like you'd get whooped with a belt, buckle end!

My mom wasn't that patient.....she would just grab whatever was handy and beat the crap out of me....I still remember getting cracked over the head with my own bb gun......I'm only alive because I could outrun her and she threw like a girl......

 

[Tomahawk27]

See the distinctive line adjavent to the green arrow in the pic? That's where we're referring to; that's as far as the rings travel so, over time, the rings wear the bore & leaves a lip here...

Ooh . I just ran my fingernail around the cylinder and there was only one spot that had a lip to it, the rest was smooth

 

[OzFab]

That's good news

 

[Tomahawk27]

That's what I like to hear.

So assuming I can leave the cylinder alone then, and after I get the valves lapped, what would be the next course of action?

 

[OzFab]

Well, you need to clean all the old gasket from the head & the block surface & remove all the carbon buildup.

However, before you lap the valves, do you have a dremel or similar tool? Have a look at the pic below; where the green lines appear, take a dremel (or die grinder) & remove the sharp edges, don't go nuts & be careful not to knick the valve guides or seats...

This will promote better air flow which will improve performance...

 

[Tomahawk27]

Well, you need to clean all the old gasket from the head & the block surface & remove all the carbon buildup.

However, before you lap the valves, do you have a dremel or similar tool? Have a look at the pic below; where the green lines appear, take a dremel (or die grinder) & remove the sharp edges, don't go nuts & be careful not to knick the valve guides or seats...

This will promote better air flow which will improve performance...

Would you just recommend a wire wheel for that?

Its funny you mention a Dremel and the sharp edges; I'm hoping to get one for Christmas and after I (hopefully) get it, was going to post a pic looking down the passageways from the side, asking if it would be okay to shave those down a bit

 

[OzFab]

Would you just recommend a wire wheel for that?

For the gasket & carbon, yes but, you'll probably need to go over the gasket area with a flat scraper to make sure you remove it all; it's also a good idea to run a straight edge across both the head & the block surfaces...

Its funny you mention a Dremel and the sharp edges; I'm hoping to get one for Christmas and after I (hopefully) get it, was going to post a pic looking down the passageways from the side, asking if it would be okay to shave those down a bit

Well, question answered then...

 

[Tomahawk27]

Had some time to work on this again. I decided to go back to school this semester (and for the next couple years unfortunately), so time is going to be more limited than I had anticipated. Anyway, I did end up getting a Dremel for Christmas, so I started grinding down some of the rough edges in the intake but stopped short because I wanted to see just how far I should go. You can see the difference from the 1st picture compared to the last one. In the 4th picture, am I okay to grind down that big lip?