Pre-65 Bikes

Has anyone grafted a later type k/start on to a Bantam B175, they are a bigger spline than a D14. There are folding levers about for the 14s but can't find anything for the b175?/ Thanks in advance...

Hi, I'm new to bantams and are looking for a bit of advice. I have a bantam b175 trials bike that I have just bought as a non runner,I started by checking the points and timing, I could not get the timing correct and took off the points cam as it seemed to be in the wrong position to get the timing correct. The cam fits on a taper but there does not seem to be any way of holding it in the right place, there is a small groove in the back of the cam but nothing on the crank for it to slot on. Should there be a peg or something for it to fit on? I would be grateful if anyone could offer any help. Thanks Alan.

Hi I am new to the site & to trials too, though have built from scratch many British Frame based specials over the years. I have a couple of old Bantams, one based on a 69/70 B175 Bushman,which has been Trialled for 2 or 3 years, t'other is a D10 engined D7 & its gonna be a Trials style road runabout! I have a friend who is going to rebuild the Wheels for me shortly, & for the rear I wondered if anyone could advise what offset from central to have the rear wheels laced. I have 4.00 x 18" rear Trials Tyres, & was intending to use WM3 Rims, though it has been said that WM2 Rims should be used? I have some thicker rear engine plates from Rex Caunt Racing,…

I have a 175 Bantam and was wondering if anyone has any port timings to improve the power a little as it is a little lacking at the moment, would fishy06 be able to help ?

Hi there Im after some advice on my sons Bantam It has a D7 Engine, standard Amal carb and standard style Air Filter. Currently it doesnt have electronic Ignition. We have only had it a few weeks and took to first trial today. Up to now its been tried out in the street with no problem. First couple of sections if was fine - then started to bog badly when opening the throttle - also a bit of backfire ? Got to the point it was difficult to ride was boging so badly. Changed the Air filter for a foam one I had in the tool box but the problem was the same. Got home and after an hour or so on the trailer, fired it up and it ran spot on (albeit only for a few minutes). I …

As per pictures below, I have fitted engine (which is offset to give clearance) - and have widened swinging arm. Ive got the rear hub in what I think is the correct alignment measuring as best I can, I can then measure to get correct spacers manufactured. Is there an easy way to check front to back sprocket alignment ? cheers John

As some of you know i have finally succumbed and gone over to the dark side and am in the process of building a Bantam. So a few questions as i am a bit confused. 1. Have any of you used the new conrod assemblies, obviously Chinese, from Rex Caunt ? If so what are your experiences ? 2. The popular, and cheap which i like, mod is to swap 2nd and 3rd gear over. Do you find this adequate or do you wish you had spent the extra and fitted a low 2nd gear ? 3. Again the popular mod is to fit the Suzuki 185 piston but i notice that Rex Caunt sells a piston with a correct size gudgeon pin for the Bantam small end so you dont need to make a bush to fit. Has anybody …

Hi there I was wondering if any one could offer any advice on my BSA bantam I have a problem getting it to tick over even once it's warmed up I have cleaned the pilot jet and all of the air ways and it just won't tick over like it did help much appreciated thanks

Hi, Im just finishing a Bantam for pre65/twinshock. Ive fitted a C15 swing arm and tyre clearance is fine. The only problem seems to be the chain touching the tyre. I have a 4" IRC fitted. Has anyone else experienced this? Im thinking the simplest option is to offset the rear sprocket and engine by a bit - I can use spacers on the back mount and cut/re-weld the front. Does anyone know if others have had to do this or am I missing something?? The wheels are central and in line etc (all checked with jig). any help welcomed! thanks Stu

My D14 still has the original rotary clutch actuator that is about worn out , with an 8 spring 4 plate clutch it's starting to be an issue .I've seen some custom built lever type , but no good pictures , I'm open for any ideas . This is about the last area that needs to be improved then I can't blame the bike for all those points cheers , Bruce

Hi guys, Can anyone help me with a starting point for the idea compression ratio for a d14 Bantam with a b175 centre plug head. Thanks, Prelit

Hi, Just wondering if anyone has played with higher comp ratios on trials Bantams. I notice the 1980s Fantic 200s were 11.7:1 (geometric). Anyone any experience of changes? I haven't measured my standard Bantam yet but I think they were about 10:1. Also, is anyone running a different ignition timing than standard? cheers Stu

A common mod on the Bantam is to fit a crank weight usually brass, I am going to build a B175 engine which apparently has a heavier crank, does anyone know if, a. the weight is needed / used and b. who makes the weights. Thanks.

Hello Am I right in thinking that to remove the front chain sprocket on a D1 Bantam, I need to remove the left side cover that houses the point and flywheel thing or am I missing something that will allow me to remove it without the cover coming off? If this is the case, the manual states to lock the flywheel in place you have to lock the engine via the conrod, there must be a better easier way surely?? thanks

Couple of Bantam build questions please, Is it a good idea to swap around the existing 2nd and 3rd gears, I found a diagram of how to do this on the web but if that lowers second then what happens to third gear. Is it instead better to buy the aftermarket second gear set which is I believe 20/27 ? Which ignition system and crankshaft weight is the one to get All BSA Bantam engine build hints and tips welcomed

Anyone suggest a suitable decompressor for a Bantam cylinder head? The only one I can think of is a RE Bullet item.

I am considering building a bantam for pre 65 trials, what is the standpoint on eligibility of four speed bantams, I know that they were not made before 67 so how come I see them in some big pre 65 trials ?? what is the standpoint of the scottish two day, the manx two day and the the yorkshire classic club ? (these are the organisers I would most likely be entering trials with). want clarification before I start spending my few quid (I am a yorkshire man !)

I’ve just acquired a bantam D7 bottom end (everything accept a barrel piston & head) I would like to fit a D14 top end, I presume it’s a straight fit. But did the D14 have any difference to the crankshaft, crankcase volume or transfer port alignment? Basically what I want to know is, will I get the same power output as a D14?

Im needing to put a bantam engine together and i have some questions to help me just in the right direction, this is not a open cheque book build so no stupid suggestions but i have a set of 175 crank cases, a 175 barrel and piston, a 125 (i think) complete bottom end with a loose 125 head and barrel/ I was hoping the 125 bottom end internals would fit into the 175 crank cases so i can make it a 175 using the 175 barrel and reboring it to suit the TS175 piston that seems popular, my questions are will this work, is there any other mods to consider and im told i can use a montesa 200 head (as i dont have a 175 BSA one), is this a striaght swap? Whats the main advantage o…

Not familiar with this one, any ideas. http://cgi.ebay.co.uk/1959-RARE-BANTAM-TRI...%3A1|240%3A1318