V-twin mini bike

[noseoil]

Making a little progress again on the bike, finally. The back-ordered parts should be arriving soon. For now, here's a mock-up of the rear swing-arm for the back end. Drilled a 7/8" tube into a 1" tube for the bushing joint, then a 5/8" bolt goes through the bushing for the pivot point. Should work well enough, but it's overkill, as usual. The 7/8" will be welded in place.

[noseoil]

Working on the clutch & jackshaft. These two items are critical for good transmission of the power to the rear tire. Alignment & center-line distance are the two things which need to be correct so it doesn't eat belts & cause too much friction.
The plates needed to hang the jackshaft for alignment & strength.



Here's the clutch, engagement is at about 1800 rpms & I don't want a "hard" shift. It may need a bit of adjustment so it's soft enough to not pull the front end up under hard acceleration.

[twisted lines]

Don't know how you intend to use this beast, but this is where I would.
100 miles.
I think you may need a Check point for a refill.

[noseoil]

Looks like a great place to do a test run! That might work, but the debut will probably be at this year's Run To Raton.

A bit more time on the build, still setting up the clutch, jackshaft & geometry for engagement & run-up to speed. Here's the location of the jackshaft, it sits behind the motor & uses the same mounting plate to keep alignment & the correct distance between the clutch & driven pulley. It's called a CVT, or constantly variable transmission. Subaru, Nissan & some other manufacturers use it, along with Polaris & a bunch of other UTV's.

Here's the rear view with parts assembled & alignment being checked.


The side view of the clutch & driven, it needs 10.990" from the center-line of the motor to the center-line of the driven member. As the rpm's increase, the front clutch tightens of the belt & the driven member expands to give about a .87:1 final drive (12% over-drive). Final output will be at 3.21:1 or "about" 70 mph.


https://www.youtube.com/watch?v=Mn92P4j ... M&index=13

[tony.latham]

but it's overkill, as usual.

That's some serious fabrication skill there, Tim. :thumbs-up:

Tony

[noseoil]

Thanks Tony, there's a lot of trail & error involved in this one, but so far so good (not too bad on errors, at least yet).

I drilled & located the jackshaft bracket, cleaned it up a bit & made sure it's all aligned for later, when it starts to get assembled into an actual bike. This is the basic engine & drive-train setup, it could go into a go kart, mini bike (this application) or a boat at this point. Moving along slowly...

[bdosborn]

Here's the clutch, engagement is at about 1800 rpms & I don't want a "hard" shift. It may need a bit of adjustment so it's soft enough to not pull the front end up under hard acceleration.

You might need some wheelie bars if it does.


Bruce

[noseoil]

I used a friend's tubing bender yesterday for the frame members. He has a shop here in Raton & builds trikes, show bikes & paint. Nice to have friends who share a passion for building things. The frame pieces need to be cut to length, dressed on the ends for fitting & then welded in place for assembly. still plenty to do bet it's moving forward.

[Pmullen503]

I'm really enjoying watching the progress on this project. Keep posting updates!

[noseoil]

A little more work on the frame.

[noseoil]

Redid a bit of framing (changed the height of the front end), but this is what it will be once the rest is done.

[bdosborn]

Did you make the head tube angle a little less steep? It looked pretty steep in the mock-up, I was wondering how well the front shocks would work.
Bruce

[noseoil]

Yes, I should have ordered the 29" set, but instead got the 31" so I made a bit of a change to drop it a little bit. Trail dimension is just over 4" so it will be a relatively slow turner, but good at speed. Definitely a challenging build, but it's fun.

[bdosborn]

I'm always amazed by how different the things I build turn out from what I thought they would be. But I'm with you, that and the challenge is the the fun part.

Bruce

[noseoil]

Decided to see if things fit together correctly. So far, so good. Will need a different air filter, had to cut the plastic shroud to slide things in place, but things line up well enough...