A Blast from the Past

Bevelheadmhr

Member
DTT BOTM WINNER
Meanwhile work on the Honda CB72/77 engine is progressing well, its now got a homemade billet block which will take it out to 400cc, while its Eaton supercharger is being remade with matching billet end cases and centre case, the latter is being made at the moment. No performance reason for making a new case, but it'll look cool..
 

Attachments

Bevelheadmhr

Member
DTT BOTM WINNER
This project has been waiting for space to work on it, but its finally coming together. One point that isn't obvious is that the crank centre has been moved 4mm inside the engine to allow for the 400cc big bore conversion. That meant machining out the crank bearing mounts which also meant using bigger / strong crank bearings. A lot of work to say the least.
 

Attachments

Bevelheadmhr

Member
DTT BOTM WINNER
Found a couple of old photos of the bike when my mate first built it in the early 80s..

Here's a video of us talking about progress with the bike.. starts here... since I made the video, Jeff has been busy making a tool to fold sheet aluminium which is needed to make a new fuel tank for the bike.

https://youtu.be/dPAxnpEkP4E
 

Attachments

Bevelheadmhr

Member
DTT BOTM WINNER
Because of the way the supercharger needed to be mounted behind the engine, and with the constraints imposed by the frame etc, it was decided that the best solution, if not the easiest, was to make a new supercharger case. This new case would have its inlet and outlet moved from the standard location, to one ideal for the bike. Making a supercharger case isn't an easy task to say the least, but its almost done now. Actually once the fixtures and machining steps have been worked out to make one, its not much more work to make another, so that's what we've done.. 4 made so far.
 

Attachments

Bevelheadmhr

Member
DTT BOTM WINNER
This rear wheel came off a Yamaha R1, its been painted and polished to be used on the Honda. But its also had its cush drive removed and an alloy plate welded onto to the hub in its place to mount the sprocket. This was done to keep the wheel as narrow as possible and also because a drag bike doesn't need a cush drive.
 

Attachments

Bevelheadmhr

Member
DTT BOTM WINNER
The Honda CB72 drag bike project took one step forward and two back when the new 17 inch rear wheel got its drag slick and was fitted to the bike. The frame was build to take a 18 inch wheel and drag tyre, the latter being no longer available, so a change to a 17 inch wheel was needed. But the new tyre is much taller than the original and raises the back end way too much, and being a hard tail there's not that can be done. Except make a new back end for the frame, cut the original frame in half and weld the old front half to the new rear..

Also the billet supercharger is almost finished, now with its mounts and drive snout base machined.

https://youtu.be/4OABajaPaRc
 

Bevelheadmhr

Member
DTT BOTM WINNER
Its now time to take the new frame rear end and the original frame front end, and combine them to make a whole frame. To do this, the frame tubes of both need to be heated and bent before being welded together. In the pic below the bike is just loosely held together to check for clearance issues etc. But the frame needs to be mounted on a frame jig to ensure everything is straight and true before any welding begins.

That will happen in a week or so, as the frame jig is currently in use, with an old Kawasaki frame of mine being heavily modified to take a bigger engine, wider back end etc..
 

Attachments

Luugo86

'73 CB350, '78 XS650 Cafe Killer
This project is bad to the bone man.. I really love the smaller displacement engines and pushing their limits.
 

Bevelheadmhr

Member
DTT BOTM WINNER
The bike is now on the frame jig, though progress had to wait while Jeff recovered from falling a few feet off a step ladder...

https://youtu.be/w5hoCmtsjbI
 

Bevelheadmhr

Member
DTT BOTM WINNER
The frame is off the frame jig now, and since the vid was shot, work has started on the alloy tank and seat unit... who knows it may even be finished ready to run on the track next year..

https://youtu.be/s3HaoJQt7IA
 

Attachments

DTT Sponsors

www.dimecitycycles.com
www.cognitomoto.com
https://www.townmoto.com/collections/vanson-leathers
www.speedmotoco.com
www.CITYLIMITMOTO.com
www.jadusmotorcycleparts.com
www.lostapostlejewelry.com
www.sparckmoto.com
Top Bottom