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Rebuilding an F750

All about BMW in racing can be discussed. Sharing of pictures, and other information.
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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

Oil cooler kit mounted. Bike is essentially done except for fluids and seat foam. Next I need to go visit dad and we'll start it up.

Detail
Detail
Oil cooler
Oil cooler

RUBBERCHICKEN
Posts: 1
Joined: Wed Dec 29, 2021 11:14 am

Re: Rebuilding an F750

Post by RUBBERCHICKEN »

Eric-

Looks great! I've been following this build with your Dad since it started. We've had many hours of conversations about fine details. I'm pleased that the Wedgetail Ignition worked well for you. I was confident that it would, as it makes mondo bright spark, a real necessity when the long intake runners are taken off. I think a lot of custom builders will discover this going forward.

Please post some video with sound now that it runs! I can't wait. I was going to ride down to hear it start up, but with Hurricane Ian tearing up the Atlantic coast right now I figured that the riding might not be too pleasant. I hope to get down there before the bike leaves for TX, though. I'd prefer to see you when I get there but Ma Nature has a different idea. :?

Tom Cutter
Yardley, PA, USA
RubberChickenRacingGarage.com
WedgetailUSA.com

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

Finally got bike outside this past week.
Attachments
Side view 1
Side view 1
Side view 2
Side view 2

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

And for those interested in hearing it running....

https://youtu.be/cQNCT-ZnQiA

Ps, it's much quieter than the open pipes of past.

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

I'm pleased to announce the bike will debut at the Revival Handbuilt Motorcycle Show in Austin, TX on April 14th-16th. The show coincides with the MotoGP at Circuit of the Americas.

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

Here are a few pics from the Revival Cycles Handbuilt Show in Austin Texas. There are a lot of BMWs entered. Its interesting to see how many people use these bikes for custom builds.

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20230414_202307.jpg

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

A minor update to the bike since I've last posted...

Turns out the Mikuni TM38 carbs were just too big and there was no way I was going to get them dialed in. The issue is the valves in the R65LS heads are too small resulting in too little airflow to get things moving. Even though the bike is an 860cc, the smaller valves proved too limiting. I went ahead and bought a pair of Mikuni VM34s which was on the original bikes which had R75 heads with 750cc displacement.

The result is everything worked right out of the box with just a little adjustment to the mixture screws. I haven't ridden the bike so some further adjustments may be needed but at least I know i can get there.

We have a set of R100 heads that might go on the bike someday, but for now i think it will be just fine for its intended usage.

I did move the chokes over from the TM carbs. I think the knobs look better than the stamped metal levers that come on the VMs. Luckily the internals are same on both carbs.
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20230707_110636.jpg

mmmotowerks
Posts: 11
Joined: Tue May 26, 2020 9:24 am

Re: Rebuilding an F750

Post by mmmotowerks »

Where did you source those carb bell mouths and filters?
I've run VM34's on our 750 racing sidecar for years they work well once
we got the jetting dialled in.

Mathew

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Ericandchi
Posts: 54
Joined: Sun Oct 09, 2016 10:11 pm

Re: Rebuilding an F750

Post by Ericandchi »

The stacks were from a shop called Speed Moto. They have them in different sizes plus the mesh filters. Link below.


https://speedmotoco.com/mikuni-stacks-e ... ity-stack/

mmmotowerks
Posts: 11
Joined: Tue May 26, 2020 9:24 am

Re: Rebuilding an F750

Post by mmmotowerks »

Thanks!

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