Les Miserable

[Mossy]

M/T them old engines had a small cup there where he attached the tube, they had a steel wool type of filter, that you where suppose to clean once and a while. It was mostly meant to relive back pressure, but moister seemed to get the oil Rosado up and and seep out. Then they went to valve tappet cover venting, same thing there, you will always find excess goo on front of these small engines, unless you have really bad rings for ingress back pressure, I don't think there is chance of getting oil up and over his engine, let alone to the bearings.

That Brings up another subject OIL. These engines and most before 1995 are flat tappet, even cars, they took out the ZING additive that lubed these engine. Up until now I have been running Lucas breaking oil and STP in my oil for additive, I belong to https://www.casecoltingersoll.com// and there are some engineers on there, that have directed me to Diesel motor oil, that has the ZING in it. So now I just get 15-40 full synthetic Rotella. And if you are worried about cost you can run it for 2,3 years before changing...............Curt

I've used joe Gibbs and the real deal leaded gasoline... The 79cc predator I've been collecting parts for has a decked head so it gets 98L... Even if the seats are hardened and the valves are stainless plus it smells like 1970... Should make an old school Briggs sing don't forget the cam and lifter assembly lube and the valve train likes it everywhere...

 

[curtisfox]

$15 a gal. for a motor bike, you got to be nuts. We can go to Holiday stations here and get nonethanol 20 cents above regular ethanol. ..........Curt

 

[Oldbiscuit]

I’m not building a racing bike, it probably won’t run a lot over idle. I wanted to build in the board track style with the old school feel. The engine is entirely stock although I did open it up to inspect the cylinder and valves, which looked great. I’m just going to run pump gas like all my engines.

 

[curtisfox]

Sorry, I was just trying to aid, then high tech come along.

I do like you bars and grips, so KOOL............Curt

 

[Mossy]

I sudgest lead substitute or marvel mystery in the gas... On the old engines... I like the leaded gas with Castor oil for the 2 stroke also... More for the nostalgia and the one or two high compression engines... $15 a gallon to me is worth it for gas that won't go bad in a few months and not have to worry about water in the pump gas or winter/summer blend... Used to be $1 a gallon at the pump when I first got started on engines... Makes everything run longer and cooler and start easier... We used it in outboard motors and at the end of the season it would go in the woodsplitter and the Briggs on that splitter lasted 40 years the coupler to the hydraulic pump would go out every 10... The engine actually came off a tote gote then went back on it after some gaskets a coil and rings... The engine that replaced it was a steel sleeve Briggs lasted about 10 years on pump gas and the old engine had to go back on for a season... Is my experience... It's the pump gas made the oil dirty and gumming up carb and top of the piston... Pulling it over several times in the dead of winter... Or having to replace the pull rope because it just got worn out... Everyone loves those Briggs springs

 

[Oldbiscuit]

Well, two steps forward and three steps back ! I fired the engine up, tuned it, had it running like a sweet machine. I took it out for a test ride and and discovered that the Briggs 5S is just underpowered ! It just wouldn’t pull, so back to the shop and another engine. I have a 6S Briggs which has a 1/2 “ longer stroke and has been bored.020” oversized. Pulled it all apart, cleaned, inspected, ordered a gasket set for it and now I just need to get it reassembled. One thing I am going to do is shave .050”(thickness of head gasket) off the bottom of the head to increase compression. This engine should raise my HP from 3/4-1 to around 2-21/2. Time will tell.

 

[curtisfox]

I think I see the problem, your primary drive output pulley is to small, should be about 6" with about 2.5" one the engine, maybe even 2". My old 1.5 hp did about 25 mph. I judged mine after my factory made Monark twin, after engine fail.............Curt

 

[Oldbiscuit]

I think I see the problem, your primary drive output pulley is to small, should be about 6" with about 2.5" one the engine, maybe even 2". My old 1.5 hp did about 25 mph. I judged mine after my factory made Monark twin, after engine fail.............Curt

I was looking at the pull-up set up as well. The 6S has a larger output shaft so I will need a new drive pulley anyway. I’m looking to go from 3 to hopefully 2.5 or 2.75. The driven pulley will go from 3,25 to 4.5. I want to get the engine together and running, check RPMs , and tuned before I make any major changes.

 

[Oldbiscuit]

So just calculating, 2.5 drive to 4.5 at 3100 engine rpm gives me 1722 driven rpm. Take driven rpm from 3 to 26.5 wheel gives me 22.5 mph.

 

[curtisfox]

That sounds better, you will just have to try it and see. ...............Curt

 

[Mossy]

I'm putting together parts for a 79cc predator build from 3 to 7hp @6500rpm... AGK and ARC parts... It's a basket case another member lost interest in

 

[Tom from Rubicon]

I'm putting together parts for a 79cc predator build from 3 to 7hp @6500rpm... AGK and ARC parts... It's a basket case another member lost interest in

Just out of curiosity, care to inventory list the AGK goodies?

Tom

 

[Mossy]

Just out of curiosity, care to inventory list the AGK goodies?

Tom

It's mostly everything... Haven't gotten the engine as of yet

 

[Mossy]

Just out of curiosity, care to inventory list the AGK goodies?

Tom

I ran out of room.... The build specs... Everything came from Degre8 on eBay and AGK and the impossible to find seal from diesel generator shop eBay

 

[Mossy]

I would have loved to do a flat head Briggs... the parts are just non-existent or in very tight hands... Same as the Maytag 72... But I feel better knowing that If something blew up I can find something for it... I don't have a shed full of old motors to paw through

 

[Mossy]

I ran out of room.... The build specs... Everything came from Degre8 on eBay and AGK and the impossible to find seal from diesel generator shop eBay

This was the final order... The engine and 30seres comet is the next bite... Those are plentiful so I go after the hard to find stuff first...

 

[Tom from Rubicon]

Quite the haul Mossy.
For what it's worth, SportsCarPat told me the racing cam in a 79cc made little difference.
Where as the racing cam in a 212cc made a noticable difference.

Tom

 

[Mossy]

Quite the haul Mossy.
For what it's worth, SportsCarPat told me the racing cam in a 79cc made little difference.
Where as the racing cam in a 212cc made a noticable difference.

Tom

Every little bit helps... I'm hoping the 19mm carb and bigger valves make the most difference... I'm looking into 1.2 raito roller rockers for the 212/gx200 and a spacer for the valve cover... There con rod bolts with holes for wire I haven't researched few other things I can't remember polishing compound for the crank... 1/4x 20 bolts for the governor holes... It's always something

 

[Oldbiscuit]

Thanks for hijacking my thread

 

[Oldbiscuit]

Well I’ve been working on my replacement engine and I was in for one mild surprise today. I had the piston out and was inspecting the bore and rings. Bore still had cross hatch patterns from the last honing and the rings and piston looked great. Put the piston back in, went to torque the rod bolts and pulled the threads on one bolt. Pulled it back out and installed a HeliCoil, reassembled and retorqued it !! Found out that it had a 2 1/4 bore with a .020 oversized piston. All along I thought I had a 6S when actually it’s a model 8 which was rated for 2 1/2 hp. Bigger bore, longer stroke, bigger intake valve and intake port. My buddy picked up my head today and is going to mill .050 off the deck, which is the thickness of the head gasket. This should raise my compression a bunch and hopefully raise the HP up closer to 3- 3 1/4. My new pulleys should be here sometime next week or first of the next. Going to have to do some machining on the one pulley to press in a new bearing, and make a spacer to go between the two pulleys before I can weld them together. Getting more excited every day as the weather keeps warming up!!