Rotax 300 builld

[Craig H]

love it and any details on start/kill switch cheers;)

[TED CRUD]

Any updates ?

[Hotrodlambretta]

It's never going to get finished, he bought a house to fix up.


Jason

[ruevespamad]

What conrod is that mate?

[Minority]

It's never going to get finished, he bought a house to fix up.


Jason

Tell him he needs to get his priorities sorted

[RManson]

Touche! Hotrodlambretta speaks the truth, but don't ask him about his own projects. Those are decades in the works...

The conrod is a Hotrod Cranks unit. Martin mated it to a Lamby crank.

[Hotrodlambretta]

Touche! Hotrodlambretta speaks the truth, but don't ask him about his own projects. Those are decades in the.

Well, that's kind of true however I have been working on the Yambretta every night. I just may finish before you unbox your new garage.



Jason

[RManson]

Update time! A bit past due but life got in the damn way...

Started welding and machining the crankcase to accept the 64mm crank as well as converting the whole enchilada to crankcase induction.

I'm using a Miller TIG welder as well as a spool feed gun on my Miller MIG machine for all the welding. These cases have nearly fifty years worth of oil and gunk embedded in them and it really shows when you try to weld on them in any significant manner, which I definitely did.

First thing I did was to start the buildup of material on the backside of the crankcase. I had all my filler jig pieces I showed earlier in the build installed as well as a few other jig fixtures I've built since then. The goal is to gain at least 1/4-inch worth of material before machining the crank/rod trench.

Rotax Lamby build-065 by PotvinV8, on Flickr


Rotax Lamby build-066 by PotvinV8, on Flickr

[RManson]

Once I got a good layer built up on the backside of the crankcase, I made a few "boxing plates" to tie the mag flange to the engine case to further stiffen then entire area. This tied the intake flange to the coolant inlet at the bottom, essentially forming a much stronger crankcase structure. The lower plate is seen welded up while the second, upper plate is simply set in place. At this point, I've also welded up the barrel adapter at the mouth of the case.

Rotax Lamby build-067 by PotvinV8, on Flickr

[RManson]

From there it was a few days on the mill machining the crankcase (transfer ports, boost port, intake, coolant passages, crank trench) before it was finally time to fit the crank. Ok, so the crank was actually tried a handful of times before it finally fit!

Rotax Lamby build-068 by PotvinV8, on Flickr

Rotax Lamby build-069 by PotvinV8, on Flickr

Rotax Lamby build-070 by PotvinV8, on Flickr

Rotax Lamby build-071 by PotvinV8, on Flickr

A shot looking down at the crank inlet...

Rotax Lamby build-072 by PotvinV8, on Flickr