BSA Engined MX4 Challenger

[scott151]

Hi All,

Did you all see the BSA engined mx4 in the new leading link?

What a beauty,the bike looks very competitive

I wonder if we will see the bike in the metal in next years championship?

Being a big mx4 fan i would love to see some more pictures of the machine and in colour, it even looks lovely in black and white

Scott

[Colin Sparrow]

There ya go, Scott! 441 Victor, should go like stink!

[scott151]

Thanks Colin,

I think im in love

Thats Gorgeous, Whoever it is that has built that has made a lovely job..

Scotty

[Kim275]

Beautiful finish - and just shows how good a Greeves looks - when somebody does a similar high standard restoration to Cheyney BSA's etc......reminds me that my bikes always look tatty - but then they do get raced hard....

But note as well as a beautiful finish - looks like well kitted out - decent racing shocks Reynolds mx chain and possibly a VM Mikuni carb?? - (although resolution not good so can't be sure) - which would mean destined for pre74 class. If it has typical 'new' BSA internals - then it really would fly - as weight would be closer to the Greeves engine - so it should still handle well. Cheers Kim

[Brian Catt]

Funny you should mention "new" BSA internals, there were a few BSAs yesterday that sounded a bit different to most of the others. I thought it might be down to different cams, because they sounded sharper than the norm.

[Kim275]

Hi Brian - good observation - and probably a different thread........If you wonder why in the pre65 class a 350 BSA walks all over a Greeves 250 - when in its day it was the other way round - the reason is down to what a 4-stroke BSA rider can get away with in classic scrambles...and it is a lot.

Modern BSA's rev a lot higher - due to developments in modern 4 stroke motocross bikes (I have a YZ250F and have ridern YZ450f's - so I know a little bit about it ) . A top BSA can fit a slim profile piston - an alloy liner, titanium valves and CCM cam's - all resulting in a lighter faster revving engine - and will burm methanol to boot !!

A 2 -stroke - is not allowed to change its barrel port config - or fit a reed valve - so is more limited than a 4-stroke in terms of tweaking.

I don't know how you could govern this though - as it is probably too late - (maybe a minimum weight limit for 4-stroke engines?)

This is why the Greeves series is so brilliant - as it gives the hawkstones and challengers a chance to be competitive!! - without having to spend a fortune like a BSA rider !!
Cheers Kim

[Brian Catt]

Yes, it's a problem that can't really be got round, much like the same sort of problems in Classic Car Rallying, where cars that were only competitive as works cars because of the component attrition rate, are suddenly up there with the best, because of modern materials and revised designs.
I've got this theory about self-adjusting pistons that will elongate inlet timing........! No it's great that the Greeves Championships are well regulated and fair to all.

[dave higgins]

Hi kim & brian, there is something in what you are saying about modern technoligy boosting power out put, & it is a case of the more you spend, the faster you go, but it does not have to be that way.
My own bike, built by myself has no components built into it that were not freely available during the pre 60 period, except electronic ignition.
Many hours spent machining, filing, measuring, using better pistons & other parts from the likes of triumph etc. went into building a very powerfull light weight 250.
It finished 2nd in the pre 60 unlimited at mortimer, beating seven 650 triumphs a few 500`s, & about ten 350`s, so money does not always win the day. dave.

[druid]

BSA/Greeves

Kim,
What "new" internals are you talking about?
I know the current crop of fast 350 BSAs use light clutches and electronic ignitions and modern replacement bottom ends, no different to the current crop of Challengers with Griffon clutches and Rex Caunt ignitions together with Simon's modified bottom end. Any performance boost from cams and valve sizes could be replicated on the Greeves by changes to port timing, all totally within the rules.

In the mid 60's the only unit 350 BSAs in top competition I remember were works ones (i.e. Smithy on Black Bess).

I think the main reasons that the current 350's are faster than they appeared to be is because they are well prepared and have fast guys on the loud handle.

I've run Challengers, Griffons, 250 and 350 unit BSAs, they all have plus and minus points but none were obviously superior engine wise over the others.

Druid

[Kim275]

Hi guys I think there is sense in all of this. There are other changes made on 4 strokes like alloy nicosil liners but I guess we could do the same . Our only limitation is port configuration and piston height. And no reed valves ....maybe the reality is that BSA's are more fashionable and attract owners with money to burn ( with methanol presumably !!) .... And to Daves point having a faster bike does not mean you are faster round the track ... A fast rider wil still do better on a stock bike than a slower rider on a fast bike!! ( well done on your Mortimer result Dave by the way ! )
Based Daves and Druids feedback I Need to alter my previous statement " I like the Greeves championship because I can be competitive without spending a fortune !! Must point that out to the missus next time I hole a piston!!"
Cheers Kim

Cheers Kim

[Colin Sparrow]

Just to wind Scotty up a bit, here's another offering from the same mystery genius...

(It's a 500 - and I want it!)

[Phil Hyde]

Wind up

You've grabbed my attention as well as winding Scotty up!

Colin, please reveal all. The Griffon looks really good. Are there any more photos? and what about posting a few in an album?

[Kim275]

I agree with you Phil another cracker ! Love to see/ hear more
Cheers Kim

[Colin Sparrow]

You've grabbed my attention as well as winding Scotty up!

Colin, please reveal all. The Griffon looks really good. Are there any more photos? and what about posting a few in an album?

The builder just enjoys the challenge of building them, and shuns publicity.

That's the only photo of that bike he's sent me so far, but I'll ask.

There's a couple of other mouthwatering machines in his collection too...

[Phil Hyde]

Cheers Colin

Clearly we must respect this man's desire for anonimity. His engineering skills look very good with the factory finish a nice extra.

Phil