Frame Rebuild for 212 Engine

Hey MotoMagz,

Thanks for the rope starting tip, that will help a lot.

For the race motor, I am allowed governor removal, billet flywheel, and 18lb. valve springs, straight pipe exhaust, and new air filter. I have to keep stock piston and rod, stock cam, stock carb. So I have done that to this engine.

For mikuni carb, I originally used the copy mikuni that sells on eBay for cheap. It worked fine, but I had a nightmare of a time once at a race at Grange track. I needed to change the main jet, but in order to do that, you have to take off the fuel bowl, then the little rubber gasket that fits in a groove swells up from exposure to air or something, and it wouldn't fit back in its groove. That was a pain in the booty!

I then bought the real mikuni from Sudco, a lot more expensive, but totally worth it because it has the main jet that can get screw out of the bowl without removing the bowl. Brilliant!

Gilbert

Thanks for the replies guys.

Buba, bike is still not rideable. Have to work out throttle linkage for stock carb, then fabricate a new exhaust, but when I do finish I do plan on visiting the DTM crew on a Sunday.

Jeff, the Briggs did work out well, won a couple races with it, but those darn gc190s just kept breaking down. I wasn't riding the Briggs on the street because my old Briggs seemed to overheat in stoplight driving, so I rode the gc190's but they couldn't handle it. I do still have a soft spot for the Briggs 5hp engine. They are cool.

I basically went with the predator for reliability and a little more oomph. The built motor with new cam, piston, rod should work well on the street. Do you think I could throw a stock rod with this set up? I do like to run hard.

I have been watching the Harley Davidson mini series. It's pretty good, but I have to admit I tuned out early last night, to much lady stuff and marriages and whatnot. It also seems a little inaccurate. That dude Eddie Hasha died at some other race after they had been going on for a while. His bike and himself went flying and took out four other spectators, all died. It is cool though to get a glimpse of the early days. I wonder if Joe Merkel and Hendee were really that big of a-holes.

Bow, just PM me any questions about frame building. I used a prewar women's bike frame, chopped it all up and fabricated a new down tube, top tube and under tank crossbar, as well as stretching the rear triangle. I used rudimentary tools, angle grinder, cut off wheel, acetylene torch, and a bench vise. To bend the down loop, I used an EMT conduit bender tool. Hand bending cold.

Thanks guys,

Gilbert

Hey Everybody,

Update on the re-build. I got the engine started, not without a few hiccups along the way though. I really wanted to go to this vintage motorcycle show in Venice, CA last weekend, but I just couldn't get the motor working before Saturday. I got everything together and made up a temporary exhaust of my own by brazing a flange, short pipe, and pipe fitting for a muffler. I went to pull start the bike using a rope, and I remember Motomagz mentioning the amount of compression on the motor when trying to pull start, but that rope was yanking out of my hands, flying across the shed and actually snapping the rope in half!. I tend to get tunnel vision in these situations and just kept going at it, even though I should have realized something was off. I broke off the carb fuel shut off, and ruined my velocity stack with the rope ricocheting off the starter cup.

The next day I got wise and checked my valve lash. I had adjusted them after changing the valve springs, but I guess I didn't tighten things down good enough, because the valve lash was crazy loose, thus negating the compression release feature. After fixing this, I did get the motor started, but it would only run for 1 second and die. I then investigated the stock carb and realized there were air vent holes that I was closing off with my custom intake and air cleaner mount. I modified the air cleaner mount to accommodate the vents, then I ended up using the stock plastic spacer between the head and the intake manifold and that fixed the carb problem. It runs now, but I have not got a chance to ride it yet. It seemed to rev through all the ranges of the throttle pretty well though.

Then on this last Sunday, Culvercityclassics let me come over and work on my exhaust pipe that I had pre-bent and cut to be welded. He laid down some very tidy tig welds for me and the pipe turned out exactly how I hoped. Thanks Jeff, that was very kind of you. And the icing on the cake was I got to see his briggs bike build start for the first time, super fun.

Here are some more pics of the most photographed bike on this whole forum, including close-ups of the exhaust, and my funky home made starter cup.

I look forward to testing it out both on the street and on the track this October.


Thanks for looking,

Gilbert

More pics, 5 photo limit !

Hey Harold B.,

Well I just took my maiden voyage with this set-up on a lovely Santa Ana wind-warm-no jacket-ride this evening around 9:30, so I can give a first impression of the seat.

Pros and cons.

Pros, love the look of the seat, very springy, lots of travel, comfortable to sit on out of the box.

Cons, it does sit too high, and that's as low as I can figure out. My other vintage seat, the springs sit below the top of the rear triangle, probably almost 2" lower, but I have not yet measured the difference, also it might be too springy. It never bottomed out, which is what I was looking for, but it bounced a lot after a suspension event. It almost started to pogo in an amplified way. My vintage seat bottoms out, but it recovers to neutral much faster than the Lepper.

I will ride it for a while to get a feel for it, and report back.

If I can figure out a way to mount it lower, I think it would work out quite well.

Gilbert

Thanks for the comments guys,

Tony, I guess great minds think alike on the intake manifold. And yes, the stock carb throttle arm makes for a very short range of motion on the twist throttle, that's why I ripped off the stock arm and made my own with a longer arm. Now the twist throttle is spun almost all the way at WOT, instead of just half way with the stock arm.

Harold, I am still very interested in getting my lepper saddle to sit lower. It looks like you made a bent seat post in the shape of kind of the number 2? I would very much appreciate some more detailed photos and a how-to, if you're up for that.

Oh and Tony, with the stock carb, have you ever revved the motor to 5,000+ rpm's? I was trying to set up the stock carb to race with a 2 disc vortex clutch, but at 5,000+ rpm's, the motor would sputter and lose power. I couldn't figure it out, do I had to switch to a CVT clutch for the race.

Thanks everybody,

Gilbert

curtisfox said:

What is that rope start cone off of? Need to find a couple.........Curt

Click to expand...

Hey Curtis,

I made the starter cup using a 1 1/2" copper plumbing cap, then I brazed a large washer to the outside edge of the cup.

Gilbert