4hp briggs cruiser project

[Deleted member 25783]

Pat and his products are great. I love the frame and tank he built for me. I don't know how anyone could hate on him.

It is not hate, jealousy is a better and fitting description.
Pat is the real deal.
A package came from Speedy Metals yesterday. Four lengths of 314 stainless .187 dia. to make early Harley fender stays.

 

[RocketJ]

6/19/18 update:

I hit a bit of a block since work picked up and my funds dried up, but I'm back to the grind. Finished a working mock up of my belt drive. The belt may have to br stretched however. I also cut away more of the seat stem to give a better feel of sitting IN the bike, not on it. This feels so much better.

I still need to fasten the exhaust to the bike and install the foot brake. Finally, a new inner tube needs to be ordered and a new carb cable needs to be installed.. Other than that, the bike is coming out pretty well. I'm glad to finally get back into the build.

 

[RocketJ]

6/29/18 update:

Tons of progress made!

I finally got the carb working again. I simply swapped the cable around and threaded the big end through the jet needle.

I picked up a longer belt for the jack shaft. I'm still filing out the mechanism, but it's working better.

I started on a mock up of foot pegs. I think they look okay. I'll bolt them on this coming week.

I started drifting away from a proper design and dove into a slightly home brewed look. Honestly, that's fine. I knew i was never going to create a perfect indian powerplus or whatever. When bikes werw first built, they were made out of scavanged parts in a person's shed. That's exactly what I'm doing here and I'm proud of it.

 

[Deleted member 26224]

Nice build. You are losing a lot of power in that exhaust. See my post on your thread in the other forum.

 

[RocketJ]

Nice build. You are losing a lot of power in that exhaust. See my post on your thread in the other forum.

Thanks for the tip. I don't quite understand what you mean by matching the port size though. If you mean the exhuast diameter then the pipes already match it.

 

[Deleted member 26224]

Thanks for the tip. I don't quite understand what you mean by matching the port size though. If you mean the exhuast diameter then the pipes already match it.

I mean that you are making a 3/4” or 7/8” ID exhaust port run through 1/2” pipe, with a lot of steps and such inside. Better to use a flange bolted to the two 1/4-20 holes at bottom left and top right of the port with a smooth pipe to the back, and grind down those exhaust threads in the port, also grinding out any bumps and smoothing the exhaust port as much as possible. Also with the intake port you can grind it such that the intake charge has almost a straight shot at the spark plug, however the intake porting is not anywhere near as critical as the exhaust. For you engine that is probably almost 1hp worth of power to be gained. Look up msrfan’s builds for some ideas on pipes for flatheads. Also for that motor it would be good to advance timing about 6 degrees, by shaving a .030” step into the flywheel key and clocking the flywheel forward slightly. “The edge”

 

[Deleted member 26224]

Like this key but this is way too much advance for a stocker.. looks like about .085 which would be like 13-15deg. Gotta measure the diameter of the crank there to figure out thousandths per degree think it was about .0055”/deg

 

[RocketJ]

I mean that you are making a 3/4” or 7/8” ID exhaust port run through 1/2” pipe, with a lot of steps and such inside. Better to use a flange bolted to the two 1/4-20 holes at bottom left and top right of the port with a smooth pipe to the back, and grind down those exhaust threads in the port, also grinding out any bumps and smoothing the exhaust port as much as possible. Also with the intake port you can grind it such that the intake charge has almost a straight shot at the spark plug, however the intake porting is not anywhere near as critical as the exhaust. For you engine that is probably almost 1hp worth of power to be gained. Look up msrfan’s builds for some ideas on pipes for flatheads. Also for that motor it would be good to advance timing about 6 degrees, by shaving a .030” step into the flywheel key and clocking the flywheel forward slightly. “The edge”

I'll see what I can do. The exhaust is actually a 1/2 diameter. Maybe i'll try increasing the pipe size to 3/4

 

[Deleted member 25783]

RocketJ , flow reduction per 90degree bend is another consideration.
Look at Pat's solution.

 

[RocketJ]

RocketJ , flow reduction per 90degree bend is another consideration.
Look at Pat's solution.

Do you have a link? That sounds interesting.