2T Engine gear ratio's?

[ADickerson]

Does anyone know if Villiers produced gear ratios other than those offered as standard. I'm restoring a 25SA for use in Pre65 meetings, but have no idea whether the standard ratios are suitable or if anything else might be available?

[John Wakefield]

2T/4T gear ratios

Adrian
Yes Villiers produced a wide ratio set of gears for the 4T/SK & 4T/SRK Siba Dynostart engines as fitted in the Bond Ranger mini car. The ratios are as follows: 1, 1.556, 2.240 & 4.0 to 1 (standard are 1, 1.32, 1.9, & 3.06 to 1)
The 2T & 4T gear box is the same (on later models). Presumably though you require a close ratio set for an SA. The wide ratio set would be OK for the the 25TA though. I think these are the only ratios made by Villiers.
John W

[ADickerson]

Hi John, many thanks for the info. It looks like I'm limited to the standard ratios then, although I suspect that will be the least of my worries. For now I'll be perfectly happy if I can just get it up and running. Who knows, the power band, limited as it maybe, might cope perfectly well with the standard set up!

[John Wakefield]

Might be better to use a 4T engine as these have greater scope for tuning than the 2T (piston transfer ports & squish central plug heads). & also will not be so suseptable to overheating, (bigger fins). They give 17 bhp as standard as against 15 for the 2T & could probably be got up to about 25 or more. Not sure though if the rules will allow a more modern engine.

[dave higgins]

2t or not 2t

Hi adrian, this sounds very interesting, is it a period resto or a special, you are working on?
Can`t help with the g/box, i`m afraid, but it would be good to hear a little more about this restoration, a secret weapon for next season, i fear....!!
Why don`t you stick a thread under projects, with a few pics?, one i`m sure, will keep us all interested over the winter months, dave.

[Stuart Baskill]

Hi adrian, this sounds very interesting, is it a period resto or a special, you are working on?
Can`t help with the g/box, i`m afraid, but it would be good to hear a little more about this restoration, a secret weapon for next season, i fear....!!
Why don`t you stick a thread under projects, with a few pics?, one i`m sure, will keep us all interested over the winter months, dave.

I heard that the rear chain could foul on the speedo bulge on the gearbox and come off the sprocket when scrambling.It might be worth making the rear wheel sprocket bigger.I had to lower the standard road ratios on a road 2T as it struggled to pull my excessive weight up steep hills from a standing start.

[dave higgins]

Standing starts?, i don`t think thats going to be a problem for adrian, he only weighs the equivelant of two wet twigletts... dave

[ADickerson]

Thanks all for informative responses, even wet Twiglets. I'd no knowledge of the chain issue Stuart so will check that out thankyou, could save a lot of anguish especially if I ever get to tackle "Runnacles dismount" at Theale with it. The 4T sounds interesting John and would be eligible for Pre65 events, but the SA was from '58 so would like to keep it eligible for Pre60 class if I can. I've no illusions about it's limitations as I'm sure that, if the engine did have any potential, then a certain Mr Stonebridge would have spotted it and wrung the necessary additional bhp from it to make it competitive. From my own limited knowledge of engines the 2T doesn't look that robust, but it would be good to get one running and circulating at Pre65 events. I say one, but it was brother Rob's enthusiasm which should take the credit for initiating the project and who is keen to complete a second. Don't hold your breath though I doubt we'll have either running, if at all, before the latter part of next season.. Keen to hear from anyone with experiences of competing with the 2T.

[riflegreen]

Adrian ,

when I started in The Comp Shop , there was still the remains of Stonebridge tuned 2T engine there .

Porting had been altered and fitted with twin carbs . It obviously wasn't up to scratch and never used .

Eventually got thrown out .

Chris

[John Wakefield]

2T chain issues

There should not be a problem with the chain fouling the speedo drive protrusion as long as you use the standard 1/2 x 5/16 rear chain. The modern DID chain has slightly wider links & will just rub but I have been using
this on my 4T 25DC & have had no problems although a few thou of alloy may have been removed.
As long as the chain line is correct it should be OK even with a large rear sprocket.

[Brian Catt]

I think it more likely that Adrian may need a smaller front sprocket, will this cause any problems?

[John Wakefield]

2T/4T gearbox sprockets

I think it more likely that Adrian may need a smaller front sprocket, will this cause any problems?

I would not think so, 5 available, smallest is 15 largest 19

http://www.isdm.co.uk/VI62/_VSF6.asp?ID=TXG024&fun=F2

[Stuart Baskill]

Thanks all for informative responses, even wet Twiglets. I'd no knowledge of the chain issue Stuart so will check that out thankyou, could save a lot of anguish especially if I ever get to tackle "Runnacles dismount" at Theale with it. The 4T sounds interesting John and would be eligible for Pre65 events, but the SA was from '58 so would like to keep it eligible for Pre60 class if I can. I've no illusions about it's limitations as I'm sure that, if the engine did have any potential, then a certain Mr Stonebridge would have spotted it and wrung the necessary additional bhp from it to make it competitive. From my own limited knowledge of engines the 2T doesn't look that robust, but it would be good to get one running and circulating at Pre65 events. I say one, but it was brother Rob's enthusiasm which should take the credit for initiating the project and who is keen to complete a second. Don't hold your breath though I doubt we'll have either running, if at all, before the latter part of next season.. Keen to hear from anyone with experiences of competing with the 2T.

I think I mentioned this before.I was told that the fins caused overheating when clogged with mud and it was slower than a single out of corners even though it was fast at the end of straights.I dont remember ever seeing a 2T raced in vintage or classic so I think its hard to extract much performance.Please dont "butcher" a rare bike !

[dave higgins]

Stuart, have no fear, adrian is a well respected, professional engineer & butchery is not in his vocabulary, i`m sure the bike he is building, will be well in line with the greeves style & spirit.
I also agree with adrian, in that it would be great to see a mx based twin doing the rounds next year, something different & a challenge to build, which is half the fun.
It gets my vote & if anybody can get a 2t flying, it`ll be the dickerson bro`s.
good luck mate. dave.

[ADickerson]

Adrian ,

when I started in The Comp Shop , there was still the remains of Stonebridge tuned 2T engine there .

Porting had been altered and fitted with twin carbs . It obviously wasn't up to scratch and never used .

Eventually got thrown out .

Chris

Thanks for the encouragement Chris it's just as well then that we're not attempting to wrestle the European championship or even Greeves championship from present encumbants! We've seen the odd 2T turn up at meetings over the years but never with any degree of regularity. The last one was a couple or three seasons ago and I'm not sure it even made it to the start line, in spite of the considerable efforts of the owner and several helpers in pushing it up and down the pit lane to get it going. Thanks for additional info and encouragement each, we're under no illusions about their potential or reliability but it would be good to get them going, even if not particularly competitively. After all, it's just as much fun at the back of the pack as it is at the front. Not that we won't be trying should we succeed in getting them running. After all, we can always race each other for last place.