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Millyard Kawasaki S1 Four Cylinder Engine
Posted: Wed Dec 01, 2021 2:51 pm
by Triple Parts
EPISODE 1 - CRANKCASES
https://www.dropbox.com/s/d4k1ecz042w2g ... S.mp4?dl=0
In this video I show how I converted a pair of Kawasaki S1 250 crankcases from 3 cylinder to four cylinder and fitted Kawasaki S3 400 barrels making the engine around 550cc with +0.5mm pistons.
The process is carried out in my home workshop and shed using mainly hand tools and a 1950's vintage milling machine and my TIG welder which is a 15 year old 240V, 200A, DC/AC machine, and I use 5% silicone filler wire for welding cast aluminium.
Hope you enjoy the video
Best Regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Wed Dec 01, 2021 9:18 pm
by TallyB
I thought he would have cut the cases as 2 and 2 rather than 2 1/2 and 1 1/2. I'm sure there is a engineering reason why he did it that way.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Wed Dec 01, 2021 10:17 pm
by Roy R
Loved that video, wish my engineering skills were that good.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Thu Dec 02, 2021 6:07 am
by Olde Coney
The mans a bloody genius .... well he is to me - a self confessed engineering numpty 
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Thu Dec 02, 2021 6:19 am
by Eric
TallyB wrote: ↑Wed Dec 01, 2021 9:18 pm
I thought he would have cut the cases as 2 and 2 rather than 2 1/2 and 1 1/2. I'm sure there is a engineering reason why he did it that way.
I would think its to do with the gearbox.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Thu Dec 02, 2021 7:56 am
by Nigel S
Eric wrote: ↑Thu Dec 02, 2021 6:19 am
TallyB wrote: ↑Wed Dec 01, 2021 9:18 pm
I thought he would have cut the cases as 2 and 2 rather than 2 1/2 and 1 1/2. I'm sure there is a engineering reason why he did it that way.
I would think its to do with the gearbox.
As Eric said
But also the weld bead is then inside where the crank webs run and not where the bearings run. Mine is a 2 1/2 + 1 1/2 configuration.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Thu Dec 02, 2021 8:08 pm
by TallyB
Interesting, knew there had to be a reason.

Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Fri Dec 03, 2021 7:39 am
by Wolfie
He cut the cases by hand..

Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Mon Dec 13, 2021 9:12 pm
by Triple Parts
EPISODE 2 - CRANKSHAFT ASSEMBLY
https://www.dropbox.com/s/tl8hfn8h8bpah ... Y.mp4?dl=0
In this video I show you how I made a four cylinder pressed up crankshaft with a 90 degree 1 - 4 - 2 - 3 firing interval.
This crankshaft is for my 550cc four cylinder engine that is based on the Kawasaki S1 250 triple engine.
Hope you enjoy the video
regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Mon Dec 13, 2021 9:27 pm
by Triple Parts
EPISODE 3 - GEARBOX OUTPUT SHAFT
https://www.dropbox.com/s/i0lmxqgf0ger5 ... T.mp4?dl=0
In this video I am making the gearbox output shaft out rigger support bearing and extended sprocket for my four cylinder Kawasaki S1 550cc engine.
This modification allows the engine to be re positioned centrally in the frame and for the chain to line up with the front and rear sprocket.
Hope you enjoy the video
best regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Mon Dec 13, 2021 11:00 pm
by Roy R
Loved those videos.
Wish I had seen the one about the crankshaft rebuild a couple of years ago before I embarked on learning to rebuilt a crankshaft, it would have saved me months of research and learning how to work without the special Kawasaki crankshaft rebuilding tools.
All I had to go on the old Kawasaki crankshaft rebuild manual which I downloaded from the Internet.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Sat Dec 18, 2021 9:09 am
by Triple Parts
EPISODE 4 - GEAR CHANGE SHAFT & SPROCKET COVER
https://www.dropbox.com/s/md9h0hfpssmkw ... R.mp4?dl=0
In this video I show how I extend the gear change shaft and sprocket cover for my Kawasaki S1 Four Cylinder engine.
When I was rummaging for the parts to assemble the bottom end for the next episode I realised that I hadn't modified the gear change lever so this is an extra episode .
Best regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Mon Dec 27, 2021 11:17 am
by Triple Parts
EPISODE 5 - BOTTOM END BUILD
https://www.dropbox.com/s/3f3232s7o4kw2 ... D.mp4?dl=0
In this video I will be putting together the bottom end of my Kawasaki S1 550cc four cylinder two stroke engine.
Hope you enjoy the Video
Best regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Mon Dec 27, 2021 12:24 pm
by Nigel S
TallyB wrote: ↑Wed Dec 01, 2021 9:18 pm
I thought he would have cut the cases as 2 and 2 rather than 2 1/2 and 1 1/2. I'm sure there is a engineering reason why he did it that way.
The reason is simply that the welded join is where the crank webs run and not where the bearings run. Also easier the keep things aligned when welding
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Tue Dec 28, 2021 1:25 pm
by Mitsui Spy
Tony_d123 wrote: ↑Mon Dec 27, 2021 11:17 am
EPISODE 5 - BOTTOM END BUILD
https://www.youtube.com/watch?v=Nk9BW0FQW7s
In this video I will be putting together the bottom end of my Kawasaki S1 550cc four cylinder two stroke engine.
Hope you enjoy the Video
Best regards
Allen Millyard
.
Standard S1 clutch with a 550 top end? I don't think so

Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Tue Dec 28, 2021 3:23 pm
by Mitsui Spy
Mitsui Spy wrote: ↑Tue Dec 28, 2021 1:25 pm
Standard S1 clutch with a 550 top end? I don't think so
Needless to say he has it in hand and is on the lookout for a s3/KH400 clutch if anyone has one available.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Sat Jan 01, 2022 7:43 pm
by Craig T
So he has widened the cover by 48mm but that still leaves a 48mm gap to the end of the gearbox...where the cover fixes too...or am I missing something here
Screenshot 2022-01-01 at 19.40.02.png
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Sun Jan 02, 2022 6:35 am
by Eric
Just keep watching
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Tue Jan 04, 2022 7:20 pm
by Craig T
Eric wrote: ↑Sun Jan 02, 2022 6:35 am
Just keep watching
.....latest video showing top end rebuild now posted. On one shot you can see spacers across the gap so it looks like he will leave it open...not sure I like that with all the cr*p from the chain flying around.
Screenshot 2022-01-04 at 18.50.28.png
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Tue Jan 04, 2022 9:37 pm
by Triple Parts
EPISODE 6 - TOP END BUILD & CYLINDER REBORE
https://www.dropbox.com/s/xpcw7zsfx4gix ... E.mp4?dl=0
In this video I'm putting together the top end of my Kawasaki S1 550cc four cylinder engine and showing how I re-bore the cylinders using my mini bore cylinder boring machine to fit over size pistons.
regards
Allen Millyard
.
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Tue Jan 11, 2022 10:51 am
by Craig T
If you have a few minutes to while away, take a look at what this guy gets up to !..
https://www.youtube.com/channel/UCYzXoH ... shelf_id=0
Re: Millyard Kawasaki S1 Four Cylinder Engine
Posted: Thu Feb 03, 2022 10:25 pm
by Craig T
Latest Millyard video..... .......skip to end of vid to see it running...... it does sounds pretty sweet !
https://www.youtube.com/watch?v=-1ETYWSJNnM