Creating my own motorcycle scratch

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Old England
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Creating my own motorcycle scratch

Post by Old England »

A few folks have mentioned the idea of building there own vintage style racing motorcycle, possibly using the internals of some modern engine to speed the project along. I did this between 2012 - 2016 working in my home shop evenings and weekends.
I posted a couple of photos in another thread, I wondered if members would be interested in the retrospective build log so to speak?
I'll make a start and if it's not suitable or appropriate please let me know!
Shop machines are a heavy duty varispeed 40INT turret mill of 1970's vintage with DRO and Deckel FP1 clone from 1938 with DRO. Lathes are Bulgarian ZMM and a Myford ML7.
I had built sprint racing motorcyles for my wife, son and daughter over many years in the usual way by buying some old bike and modifying/tuning. At the end of the 2011 racing season my wife said why don't you build yourself a bike at last? Little did either of us know where this would lead! Books were purchased, museums visited and ideas roughed out. I settled on the late 1920's and the bikes that raced at the famous Brooklands Circuit in England, mine would not be a copy but in the spirit of bikes that raced at the track at that time.
I decided on a Kawasaki KLR800 as the donor engine as this had the longest stroke available, combined with a Velocette piston I'd have a long stroke 500cc single.
An engine was bought on eBay but my plans were thrown into disarray when it turned out to be the 750 version with shorter stroke. Unfortunately my Father passed away at this point and by the time things were back on track it was to late to return the engine. Never mind onwards and upwards!
With the crank out I was able to get to work in Turbocad and soon 3 billets of 6082T6 were ordered, these would be the crankcase halves and timing cover.
First up carving out the inside of the crankcases, that was the easy bit! Next profiling the outside of the driveside case, by this time there was a lot of swarf, and much more to come!
OK there you go the first instalment, hope this is of interest and inspires someone else to have a go.
Attachments
crank.jpg
crank.jpg (92.75 KiB) Viewed 3558 times
billets.jpg
billets.jpg (79.01 KiB) Viewed 3558 times
first_step.jpg
first_step.jpg (68.41 KiB) Viewed 3558 times
outside.jpg
outside.jpg (130.69 KiB) Viewed 3558 times
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Harold_V
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Re: Creating my own motorcycle scratch

Post by Harold_V »

Very pretty work!
Sorry to read of your father's passing.
H
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JackF
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Re: Creating my own motorcycle scratch

Post by JackF »

Yes, please continue. you do fine work.
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Old England
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Re: Creating my own motorcycle scratch

Post by Old England »

Harold_V wrote: Thu Mar 30, 2023 2:50 pm Very pretty work!
Sorry to read of your father's passing.
H
Thank you Harold. My father was 90 so not unexpected, I just wish he could have seen this bike as he was a huge motorcycle enthusiast and loved the machines of the 1920's.
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Old England
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Re: Creating my own motorcycle scratch

Post by Old England »

JackF wrote: Thu Mar 30, 2023 4:28 pm Yes, please continue. you do fine work.
Thank you Jack, I'll post some more tomorrow evening.
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Steggy
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Re: Creating my own motorcycle scratch

Post by Steggy »

Old England wrote: Thu Mar 30, 2023 2:34 pmFirst up carving out the inside of the crankcases, that was the easy bit! Next profiling the outside of the driveside case, by this time there was a lot of swarf, and much more to come!
Yes, indeedy! That was a lot of hogging. You could almost make another case half out of the swarf. :D

Those cases look great. Keep posting. I want to see how this engine turned out.
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Old England
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Re: Creating my own motorcycle scratch

Post by Old England »

A lot of time went into profiling the outside of the timing side crankcase half, in the first photo you can see detail emerging, I love working in billet like this, finding what lies within :D I found with a bit of planning I could use the cylinder studs from the KLR750 which was handy as they are high tensile with rolled threads, one is visible in the photos.
Second photo shows an intermediate stage in carving the webs on the case around the timing gear housing. Photo three on my Alexander Master Toolmaker mill, with it's compound table and swivelling head it allowed me to profile the radial webs.
Attachments
roughing.jpg
roughing.jpg (85.48 KiB) Viewed 3509 times
ribs_2.jpg
ribs_2.jpg (130.76 KiB) Viewed 3509 times
ribs.jpg
ribs.jpg (84.45 KiB) Viewed 3509 times
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Steggy
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Re: Creating my own motorcycle scratch

Post by Steggy »

I like how you’ve taken the time to relieve excess material around the gasket faces. Gives it more of a factory look.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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Old England
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Re: Creating my own motorcycle scratch

Post by Old England »

When the cylinder billet arrived it looked pretty massive as the diameter had to incorporating the base flange, but at least it was mostly a straightforward turning job. By this time the crankcases were finished as regards machining and I admit to twirling the crankshaft quite a few times :D After boring and turning the OD of the fins the base flange was milled and then it was on to cutting the fins followed by pressing in the commercial cast iron liner. This liner was fitted and honed by an expert in Bristol who has done all my cylinder boring, honing and crankshaft work for many years.
I fitted a piston from a Yamaha SR500 and things were starting to look promising. However the next step was many tedious hours with needle files, Dremel, abrasive paper and finally bead blasting to give an impression of castings. In the final photo of this group you can see the result and the timing cover taking shape. At this stage I wasn't sure what ignition I was using so the face of the timing cover was left blank.
Attachments
cyl1.jpg
cyl1.jpg (88.05 KiB) Viewed 3456 times
base_flange.jpg
base_flange.jpg (155.89 KiB) Viewed 3456 times
cyl2.jpg
cyl2.jpg (124.55 KiB) Viewed 3456 times
cyl3.jpg
cyl3.jpg (81.91 KiB) Viewed 3456 times
timing_cover.jpg
timing_cover.jpg (79.56 KiB) Viewed 3456 times
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NP317
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Re: Creating my own motorcycle scratch

Post by NP317 »

Respect!
RussN
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Harold_V
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Re: Creating my own motorcycle scratch

Post by Harold_V »

NP317 wrote: Sat Apr 01, 2023 7:06 pm Respect!
RussN
Indeed!
I have been engaged in similar work in the distant past. So many opportunities to make mistakes!

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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Old England
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Re: Creating my own motorcycle scratch

Post by Old England »

NP317 wrote: Sat Apr 01, 2023 7:06 pm Respect!
RussN
Thanks, as you might guess, it was a lot of fun 😁
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