Recent Posts

Pages: [1] 2 3 ... 10
1
British Bikes / Re: Triumph 650 twin unit gearbox outrigger bearing
« Last post by Rex on May 22, 2023, 09:09:01 AM »
How much stick would you have to give it to flex the mainshaft enough to cause gear-changing problems, especially as these engines have been used in all sorts of competition work for decades, and this mod isn't common or usual.
Sledge hammers and little tiny nuts?
2
British Bikes / Re: Triumph 650 twin unit gearbox support bearing
« Last post by iansoady on May 21, 2023, 04:15:05 PM »
Somebody on the fb unit 500/350 group is prposing similar and meeting the same response.
3
British Bikes / Re: Triumph 650 twin unit gearbox support bearing
« Last post by beemergb on May 21, 2023, 02:09:06 PM »
To stop the gearbox mainshaft flexing when I give it stick and have probelms changing gear , and yes it does work , I did this on my Thruxton Bonni way back then , it worked a treat .
4
British Bikes / Re: Triumph 650 twin unit gearbox support bearing
« Last post by Rex on May 21, 2023, 12:30:20 PM »
Why would you do that?
5
British Bikes / Triumph 650 twin unit gearbox outrigger bearing
« Last post by beemergb on May 21, 2023, 10:12:39 AM »
Hi folks , I am looking for parts to put a outrigger  bearing setup  behind the clutch , where there is now just a seal .Ive seen it many times and thought one day I will do that ! And now cant find it ! Can anybody out ther share there wisdom please ? Hope so
6
British Bikes / Re: Spark, Bownian, Warrior, Torpedo... who made the frames?
« Last post by john.k on May 14, 2023, 04:19:02 AM »
The slipping drive on the magdyno was claimed to protect the against a violent backfire .....generally restricted to sporty singles ........twins didnt have this problem .........the fibre gear was to reduce gear noise .......most twins had fibre mag drive gears ...........Incidentally,its not generally realized the fibre was very expensive ,and a steel or iron gear would be much cheaper .............i have a sheet of the fibre about 1m square X 1/2" thick  ,that cost over $1000 ...(its a compressed and vulcanized bakelite resin and cloth material ...and some variations have the property of running heavily loaded lubricated only by water ....steel mill rolls.......its also use in ship stern tubes with alternating rubber and fibre strips which run in sea water.)
7
British Bikes / Re: Spark, Bownian, Warrior, Torpedo... who made the frames?
« Last post by R on May 12, 2023, 10:55:58 PM »
Nortons early dommie twins had the fibre gear thusly mounted on the camshaft.
If anything goes wrong in the drive dept, the timing cover has to come off.
If anything goes wrong with the fibre gear, the debris goes into the engine oil !!
In spite of which, it does work reasonably well.
(I always wonder if the genny is actually spinning )

And, the fibre gear is fractionally different (but almost identical) to the magdyno one.
Woe betide anyone who uses the wrong one, the tooth count (form ?) is not quite the same. ?
Dunno who's genius idea that one was ??
8
British Bikes / Re: Troubleshooting a JAP Special
« Last post by R on May 12, 2023, 10:47:56 PM »
Compressions are ALWAYS tested hot, with the throttle wide open.
Otherwise the results are a little haphazard.

Any idea/inkling of the compression ratio ?

75psi seems a little low - for a healthy ohv hotrod. ?
Tipping a teaspoonful of oil down the plughole, kicking over a few times and retesting is advised.
If the number jumps upwards, then the ring seal is not so good.
Either new rings or more running in is required.
Or testing hot, with that throttle wide open ...
9
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on May 12, 2023, 06:57:26 PM »
What sort of compression should i be getting?

I realise that it's a hard question to answer given that the engine is a bitsa with 350 and 500 internals rounding out to about 400cc, but any educated guesses would be appreciated.

Currently getting about 75psi.

https://flic.kr/p/2ozWQPH
10
British Bikes / Re: Spark, Bownian, Warrior, Torpedo... who made the frames?
« Last post by john.k on May 12, 2023, 01:08:38 AM »
The slipping gear with a star shaped spring was on Magdyno s long before WW2......Id think Villiers claim was to do with mounting it on the camshaft ..........which is just plain dumb ,as a slipping drive would need the whole timing case dismantled ,just to replace the spring .........the Lucas spring was also adjustable ...In fact ,I see nothing of value in any of those patents..........Anyhoo,my favourite would be the Walter Moore patent of the pivoted gearbox mounting ........BSA refused to pay ,and went to great lengths to avoid the patent by all kinds of workarounds.
Pages: [1] 2 3 ... 10