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HS Replica

Posted: Thu Mar 14, 2024 4:04 pm
by simon.holyfield
Inspired by Ben Mitchell's splendid article in the February Cheval, I'm contemplating an HS replica as a long term project - unless by some miracle I can find & fund a real one.

Many folk must have done this before and know the pitfalls?

Re: HS Replica

Posted: Thu Mar 14, 2024 4:27 pm
by will_curry
The petrol tank doesn't give you much of a range between petrol stations.
Back tyres don't last very long either.
My right foot gets covered in oil courtesy of the raised oil level in the cam
chest when the oil seal between the timing case and the magneto has a
bad day. Difficult to silence with Mk1 setup without killing the performance.

As for getting the grin off one's face at the end of a run . . .

Re: HS Replica

Posted: Fri Mar 15, 2024 6:29 am
by nevhunter
Might have missed my chance for a run with a HT (Trials) unless someone has an unfinished Project. I have the forks wheels and mechanicals and Hagon AMC gearbox Need clutch and kicker mechanism. Nev

Re: HS Replica

Posted: Fri Mar 15, 2024 8:48 pm
by Vincent.vanGinneke
Just buy any late VH and swop the iron barrel for a alloy one.
Fit chrome mudguards + 1954 rear chainguard and 19" WM3 rear rim and 21" WM1 front rim.
and your'e as good as done :D

Re: HS Replica

Posted: Fri Mar 15, 2024 10:49 pm
by nevhunter
Had some of those but I've got the ducks disease so thought I'd go the Bartram Ht5 way and it's 132 KGs. Thanks for the reply. Nev

Re: HS Replica

Posted: Fri Mar 15, 2024 11:07 pm
by simon.holyfield
nevhunter wrote: Fri Mar 15, 2024 10:49 pm Had some of those but I've got the ducks disease so thought I'd go the Bartram Ht5 way and it's 132 KGs. Thanks for the reply. Nev
Ducks disease?

Re: HS Replica

Posted: Fri Mar 15, 2024 11:27 pm
by will_curry
I believe it to be a reference to one's stature - or lack of it.

Q.v. 'Lawn Ornament'.

Re: HS Replica

Posted: Sat Mar 16, 2024 1:14 am
by nevhunter
Duck's disease refers to having your bum too close to the ground. Nev

Re: HS Replica

Posted: Sat Mar 16, 2024 6:36 am
by david.anderson
Simes
It depends on whether you want the looks or the performance. If you want the performance then fit polished steel flywheels balanced to 65-67%, a HS 9 to 1 piston, machine .040” off the base of the cylinder and the compression ratio will go to 10 to 1, then fit a 1956 mk1 cam preferably run with VH followers to improve low down tractability over the HS followers, and fit a 32mm concentric carb, and a non restrictive muffler. It is possible to build an unbaffled reverse cone megaphone inside a slightly larger diameter Ariel type barrel muffler, with the reverse cone being constructed as per the Dunstall decibal silencers. My muffler constructed as such is quieter than a standard muffler, but performs much better. For snappy performance fit a 21 or 22 tooth engine sprocket.
The downside is the alloy head (whether VH or HS) which will continually have the exhaust guide come loose. Yes that has happened to me yet again today, and I have lost count of how many times the head has been repaired. Not sure whether to have the guide bore welded up again and rebored or to go to a new head. Unfortunately the new heads that Budgen was retailing were not redesigned a little to provide more support for the guide, and the machining near the valve seat detracts from performance.
David

Re: HS Replica

Posted: Sat Mar 16, 2024 9:49 am
by nevhunter
I think you'd be flat out getting a good alloy barrel.. The Velocette 500's went back to iron as did the 500 twin ARIELS. Just having a good alloy head will reduce detonation but they need a complete redesign with a shallower combustion chamber and a bigger inlet than exhaust valve and properly flowed Ports. Nev