a new member and new builder plus progress so far

i have an amal mk2 on mine 34mm, it has a 108 needle jet , 320 main and 2d1 needle set in the third groove, also the pilot jet in the bowl s a 30 ,
The slide is a 2 1/2 , hope this helps. Are you having trouble?

We run an amal 34mm also, will check what the setting are. It's always a pig to start and usually have to put the choke on and partially cover the bellmouth.


Eddie

I've removed the choke altogether, and also have to cover the bellmouth to get it to kick in. I build a set of starting rollers , couldnt be doing all that shoving it up and down!

We have a set of starter rollers also, we have other bikes but im just unfit!



Eddie

my wife said I spent too much money already, on my return, so Im not allowed to buy rollers, so I run every morning instead.

! but I have to say, not sure I need them, as at the moment, my bike "usually" starts after one or two steps, I always believed a good air tight motor with not to over adventurous "inlet timing" (piston port) is key here. "or regular pump up checks".

Derek

just a quick word to a very big thank you to all i met the weekend at lydden for the help and advice and taking time to explain , it nice to put face's to names and finally turn the wheels , had an awful lot of fun . hopefully i'll be fixing the problems quick , really cant wait to get back.

Hi Dan
Great to put a face to a name, love some of your idea's, lookforwards to seeing you at another meeting, having just returned myself, its hard for others Im sure to realise what a big hurdle it is to start racing again the bike the gear and all the stress of racing for the first or returning. welcome and well done.


regards Derek

just some pictures of the weekend, nipped up , some how my maths had a day off , must have halved something as it later transpired i had double the compression i was aiming for (16.5:1) so gave sundays run a miss, head is now re-skimmed and will be fitted shortly . still had lots of fun though ,even enjoyed taking it all apart!

Hi DAN I do not know how come I did not get to look at your bike at lydden or have a chat . I was a bit busy on my 175, yours looks great in the photos. May be I had to many free beers. Thanks to all who made it a good weekend for many reasons.

found this on the net . nice pic

Hi Dan.

I only saw your bike when it was in bits at Lydden and didn’t put 2 & 2 together. Having looked at your pictures from Lydden I know why your engine seized. You are running a pressurised air box. The faster you go the higher the pressure of the air entering the carb. The float bowel is at atmospheric pressure & the discrepancy between the two will cause the engine to run week when the bike gets up to speed. To get around the problem you need to put ALL carburettor vents into the air box. The best way is to put the whole carburettor into the air box. Having the whole carb in the air box eliminates any chance of discrepancy of pressures. When the float bowel is pressurised the fuel coming into it also needs to be pressurised. You can chose to pressurise the fuel tank, but all the manufactures use a fuel pump when the air box is pressurised.

Great bike by the way, keep up the good work & hope to see you racing soon.

Mick.

hello mick , i think maybe i'll be cutting a the end of the hose that goes over the carb so it only goes near and use it to sort of funnel cool air in the direction of the carb, having seen a few bikes in the paddock this seems the normal "bantam way", the seize was i think most likely me making a cock up with the compression calculation, some how i made it right but sunday with robbie's and tom help it was measured again and was way too high(16.5:1) i'm surprised it ran as well as it did!

head is now skimmed out, and i had a second look at the ports too, managed to nibble these nearer to where i wanted them , a while ago tom snows engine was on here with a pencil rubbing of the ports, and having seen this engine perform i thought i'd try and copy it, my exhaust timing is 94 degrees and trans 65 , inlet 80 .

got the piston back on last night and be setting the squish , it was 0.040" , was not sure if i should go a little less, maybe 0.030" , with the port timings i have does anyone have a advice for the ignition timing ?

thanks dan

Hi Dan,
Depending on the efficiency of your engine you could run any timing from 1.60 mm BTDC to 2.0 mm BTDC you will find that the more advance you use then the more bottom end power you get, but loose it at the top end!! and vice versa... so it is a matter of what suits the circuit you are at at the time. Mainly done via a dyno or by experience once you get used to the bike.
Hope that helps.
Alan

Thanks Alan, I had a few folks ask about my barrel and ports etc at Lydden , here's a few pictures , . I

A very nice piece of engineering Dan. I particularly like the dual transfers.

dansofield550 wrote:

made a start on fuel tank , need to weld in the tunnel to clear the top tube, rear set part done and converted the engine to left hand gear change as i don't think i'll be able to change a habit of a life time

Can you explain, how you converted the gear change to left side, I too won't be able to change the habits of a lifetime, and this is the big big issue that i have that is stopping me getting started on a bike. Everytime I decide to take the bull by the horns and do it, I always come back to the gear change issue.
An article on 'how to convert to left foot gear change' would be brilliant , (well to me anyway)
Pete

Gear box mods ,having been after a close box for a while it seems I'm getting nearer to one,I've managed to get hold of a part set, I was how ever missing the shaft with the 19 tooth gear, I found all the different mods a little confusing to begin with especially as there are few pictures on the forum, here's what I had to do ,hopefully this help other new builders.
The standard shaft I had has a 15 tooth (we need it to be 19 for close ratio box)
gear as an integral part of the shaft, this can be cut back and a spline formed In its place, a standard road box has a 19 tooth gear pressed on to the end of the layshaft,we can press this off and fit it to the modified shaft that was modified to have the same slpine as the 19 tooth gear we pinched off the layshaft, ill be having to make a 28 tooth gear for the layshaft , that next on my to do list. Here's some pictures of the shafts and gears in progress




I the pictures is an unmodified shaft to show the difference next to the new shaft ,also a layshaft to show the 19 t gear removed from standard layshaft . Hope this help someone. Obviously the older hands will know all this I guess ,

I have some new old stock 28T layshaft first gears, if you would like like one and can not find one in UK.
e mail me direct: johnS.bantam@xtra.co.nz
cheers
John

thanks john thats a very kind offer,
i was going to make one as i only have a standard 25 t gear and these have a different ( sharp cornered ) drive dog, the close 25 gear has the round drive dogs to match the 28 oval drive holes, i've got to grind my standard 25 t drive dogs down in diameter and make the holes to suit in the 28t cog. lucky i like making things really!

heres the gear after i modified the drive dogs , and the gear in the process of being made and the finished gear, just needing heat treatment .

You do like making things Dan!! And you have the kit to do it too.... Excellent!
I know a lot of bantam folk are busy 'planning' 'thinking' and 'doing' with
gearbox's to make them more avaiilble and at a reasonable price.

One thing i'm thinking is why did BSA go for round dogs/holes on the c/r box
when a road cluster has (i'll call them square) dogs/holes? Wonder if the square
holes may be stress raisers? Shame BSA didn't go for 3 elongated round dogs..
Thinking again was the box a BSA re-design or a DKW design and therefore
pre-war!

Regards Mike

Having made the 28t gear and sent it and other bit to the heat treaters , fitted the gear and rebuilt the motor , and fitted it all back in the bike , I then found the heat treatment to be wrong rather annoying as I was hoping to test at Lydden, this ment a full strip down, thinking about this as I made more gears and bined the others I came up with this idea, it'll let me remove the clutch cover and clutch with primary chain etc , then undo a cover holding the bearings and then I'll be able to change the box with the engine still in the frame , shown here minus a ball bearing that'll replace the bronze bush , bearing is on order , the cover is a very tight fit in the machined out case and has screws to hold it in place etc.

very nice i like it dan! very simular to a casstte gearbox, makes life allot easier at meetings if you have gearbox failures

That was the idea, especially ad I'm trying new home made gears , it'll make it so easy to just have a peek inside to check up on the condition .

Thats different Dan, never thought of doing this 'mod' from that side? But with the layshaft
bearings and a bolt up -'no end float' type its the only way to do it. I know of 2 casette? type
side loading set ups but both on the other side.

Hope you get your gear issues sorted...