13 replies to this topic

[B40RT]

Chain / tyre clearance on my B40 is minimal, I dont think the rear whel can be dished enought to give adequate clearance. Has anybody put a spacer between the sprocket and hub, then made new axel spacers to effectivly move the wheel away from the chain by a corresponding amount ? There is plenty of clearance to the right of he tyre. While I'me picking your brains, I've noticed that if I leave the bike with piston at TDC that it doesn't wet sump as quickly, is this something to do with where the oil pump positon in its stroke ?Thanks in advance for any thoughs / observations. Ross

Edited by B40RT, 27 September 2008 - 01:34 PM.

[Big John]

Yes, I have done this, ace wheelbuilder George Spence sorted the problem for me.

We offset the rear rim 6mm further to the right (when looking from the rear of the bike), no change to the sprocket or spacers as this has to maintain chain alignment.

Can't help with wet sumping, what oil are you using Ross?

Big John

Edited by Big John, 27 September 2008 - 09:35 PM.

[B40RT]

Hi John
Is George Spence in Fife ? Have you a tele' no. Will contact him and see what he says, I think he built the wheels originally. I'me using 20/50 and changing it every 2 - 3 trials.
Ross

[Big John]

B40RT, on Sep 30 2008, 01:37 PM, said:

Hi John
Is George Spence in Fife ? Have you a tele' no. Will contact him and see what he says, I think he built the wheels originally. I'me using 20/50 and changing it every 2 - 3 trials.
Ross

Hi B40RT,

20W50 is what I use too, just wondered if you used a straight monograde in her.

Yes indeed Ross George Spence is in Cupar. In my opinion, he is the finest wheel builder in the land, he built all the racing wheels for Jack Gow of Dundee and I've known and recommended George for many years. No-one has ever said to me that George built a bad wheel for them. I must have had about 20 wheel sets built by him over the years, without a wheel failure or as much as a broken spoke.

My 350cc Matchless has done 14 Pre-65 Scottish trials (plus some others of course) without tightening a spoke since George built the wheels in 1991!!!

01334 654602 will get the man himself, provided of course he is not out having a game of snooker!

Big John

[PeterB]

Hi B40RT,
By wet sumping do you mean the sump is filling up with engine oil as the bike stands overnight? If so then the oil must be passing through a non return valve of sorts, usually a ball bearing held onto a seat by a spring. Sometimes, this ball bearing requires a tap to assist it to seat properly, or there may be dirt under the seat. I haven't stripped the motor down on my own B40 yet so am only speculating. Just had a quick look, there is a pressure non return valve and a scavenge non return valve, both ball bearing types. My guess is the scavenge NRV which is located in the sump housing at the bottom of the motor. This should prevent returning oil from draining back into the motor from the oil tank. Remove, inspect clean and refit, may need tapping to seat properly.
Bye, PeterB.

[B40RT]

Hi John
I thought he was in Cupar, but could'nt think how to spell it ! Thanks for the number. Like you're self, I've never had to touch a spoke in the twenty years I've had it.
Regards
Ross

[B40RT]

Hi PeterB
Yes, the engine fills with oil, but will fill over a few days if left at anything other TDC, if left at TDC will take 2/3 weeks. There is a ball valve as you say just in font of the timing cover, which is not really accessable with the engine in the frame, so as yet I,ve not touched it. I will give a tap, I,me all for percussive maintenance!
Thanks
Ross

[PeterB]

Hi B40RT,
That ball v/v in front under a big hex nut is the pressure non return valve, the scavenge one is under the bottom of the crankcase accessable under the little plate held on with 4 studs, may be accessable between the bottom frame tubes, mine is. This is more likely to be the problem. Having the motor at TDC overnight may be just aligning the oil pump in a best postion to help prevent the oil draining through/past the NRV, it would still be the NRV that is the problem. Need to be stripped out, cleaned and gently re-seated with a tap.
Bye, PeterB.

[B40RT]

Thanks PeterB
Will give that a try, last time I was in there I found bits of red hermatite and a small piece of piston ring ! mind you it was years ago, so I'me not to worried.
Regards Ross

[Big John]

Now then, interesting discovery made today!

I said earlier that I was running my B40 on 20W50 multigrade engine oil...

The B40GB motor as supplied to British Army should be run on Monograde 40 oil (summer) and Monograde 30 (Winter). This fits in with what Gordon Jackson (the Scarborough one!) told me when he visited recently, he always ran my bike with straight 40 monograde oil! Looks like an order to Promopac for a 25 litre drum of Castrol XXL40 then!

Also the gearbox should be run with EP 90 gear oil.

Big John

[B40RT]

Hi John
That would make a differance. Just looked at the Haines manual which doesn't mention WD B40's.
Engine Castrol GTX 20w50
Gearbox Hypoy EP90
Primary 10w30
Forks 10w30 or TQF

Dont think I'll be using EP90, tried it in a 350 Bultaco - turned it into a 250 !

Thanks for the info

Ross

[charlie prescott]

Hi Guy's

Hi "Big "J"
Am I right in thinking your New bike for the Pre65 Scottish has a GB B40 engine.
I have a Guy from Aus, that would like to compete , and I have offered him the use of our B40 which has a GB engine fitted, and frame modified like the 1964 production C15T's, forks and wheels are from the WD B40, BSA loaf tank fitted, the only outside Mod is a Triumph alloy back brake plate. Do you think this bike would be OK for him to enter on?

Regard's Charlie.

Edited by charlie prescott, 03 October 2008 - 05:17 PM.

[Big John]

Hi Ross (B40RT) & Charlie,

My Matchless when I bought it many years ago had a reasonably thin oil in situ, it wet sumped like crazy!
I had the motor rebuilt before I used it and filled it with Castrol Classic GP50, which was just available and to be honest that bike has never wet-sumped even after sitting idle for months.

My B40 'smokes' on start up (a true sign of wet sumping) and it was only after checking with the previous owner (Gordon Jackson, Scarborough) that he confirmed he always run the bike on a straight 40 grade. So be it!

Charlie, yes my proposed 'new' Scottish bike is fitted with a B40GB motor as supplied to British Army, countless numbers of B40 riders over the years have ridden the Pre65 Scottish with these motors and have not been turned away. The one thing that has turfed them out is Dellorto or Mikuni carbs and BSA 4 stud type front forks!

Check the specification sheet along with the entry form of the Pre65 Scottish!

By the way, due to a couple of phone calls since my last postings, I can confirm that my 350 Matchless is not for sale, eldest son wants to ride it in 2010, or so I am told! Besides, I may be tempted one day to ride my 1964 short stroke AJS! You never know...

Regards,

Big John

[B40RT]

Hi Charlie
I would agree with Big John, although virtually all WDB40's are 1967 (correct me if I'me wrong) they are of a design which is pre 65, which is the essesence. As John says, it's worth down loading the regs which are now available, these will give you most of the information required. Critical parts as John said are forks, engine (not square barrel) carb, though a new Amal Mk1 is acceptable, frame, (some arguement about oil in frame) Hubs (cub hubs are period) shocks, anything goes. Purests don't like alloy rims /levers etc, but ok. NO tubeless tyres, unless fitted with tubes. No hudraulic clutches ( a cub turned up a few years ago with one) Boyer ignition ok. What goes on inside engines / forks, read else where.
Hope this is of some help.
Ross (MyB40 is WD)

Edited by B40RT, 03 October 2008 - 07:32 PM.