Forum

[silverfox]

hi ive got an all alloy 1956 bullet trails bike , ive recently fitted a period chair , as above can i upgrade by simply changing the piston and barrel ? , thanks in advance Russ

[Paul M H]

In simple terms no there is a lot more work than that involved including stripping engine right down and machining crank cases for bigger barrel throat & welding up barrel stud holes and drilling in correct place new carb new exhaust reworked crank. Just to name a few things

[Norm]

and a 500 head

[Chris Tindal]

I once did it years ago with some spare 500 cases. As everyone said, different head, barrel, piston, conrod, flywheels, cams and gearbox sprocket. I did it with 500 cases and it was still very costly, to machine some 350 cases (which are the same casting) as well makes it seem not worth it. Its possible, but cheaper and easier to find a 500 engine.

[John M]

You're mad! Have you had it off road yet?........... I had a trials sidecar on an old SP400 Suzuki, loads of fun in the snow, but an evil handling pig the rest of the time.........We managed to roll it at least three times and it always rolled over the front nearside corner, ejecting the rider with the bike coming over the top to follow........My only constructive suggestion would be to gear it down loads, get the smallest gearbox sprocket available and a large detachable rear sprocket as supplied by Hitchcocks......You may lose out on top speed, but it is probable that it won't pull much in fourth anyway.......Good luck!

------http://hoits.smugmug.com/Motor-Sport-Ph ... -3hV7zsh/A

[silverfox]

Thank u guys , not the answer i was hoping for tho , yes i shook it down at canada Hts over the w/e , and yes i nearly had it upsidedown twice LOL , top speed on the road is 35ish , i built it into a outfit for the Arbuthnot in 3wks time , i didnt want to mess with the engine too much and now i wont touch it at all , hitchcocks have told me its a real works bike , 1 of a batch of 24 , i found it in a shed 12mths ago been there 12 years , thanks for ur help Russ

[John M]

Any chance of some pics? I am particularly interested in 1956 works bikes as mine is a 1956 350 with a non-alternator pre-56 500 style bottom end. It has a slim timing chest without the auto-advance bulge and looks like the engine in HNP331 except it is aluminium rather than magnesium.

[Vespa66]

Hi Russ , I actually have a late 50's early 60's 350 bottom end that's been newly converted to 500 already , [email protected] if you want to discuss.
I appreciate this is "parts" guys and not supposed to be used on the site however as this is a unusual spare I hope I am forgiven for posting !

[Vespa66]

I Meant the 350/500 engle with crank and new bearing/twin bearing was for sale Russ !
Thanks guys

[silverfox]

Hi John , yeah im happy to send u some fotos , im looking forward to meeting someone that can go over it cos i dont really know what ive got , it does have Magnesium chain casings tho . Russ