owen Posted April 2, 2013 Report Share Posted April 2, 2013 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 of the TS175 piston? i can get them cheap enough but whats the hype all about? Any advise would be great. I dont seem to have much in the way of Left hand engine covers or magneto stuff so is there a way of getting around this easily? Just building up a cheap D1 rigid for trials. Thanks Owen Quote Link to comment Share on other sites More sharing options...
andy m Posted April 2, 2013 Report Share Posted April 2, 2013 Not quite sure what 125 / 175 parts you have (3 speed ??), You may be better off enquiring on the BSA Bantam forum, go armed with engine numbers of what you have got. The majority of Bantam trials riders are using 4 speed engines which many use a TS 185 piston or Rex Caunts replacement, it takes capacity to 186 cc . Can't comment on the Mont head but I know a Fantic one will fit but needs quite a bit of work, it gives the advantage of centre plug head. Best to sort out exactly what you have first then go from there. Quote Link to comment Share on other sites More sharing options...
bezaboy Posted April 2, 2013 Report Share Posted April 2, 2013 Buy a full running engine, it will save you a lot of time and money, sell the bits you have. Upgrade engine when you have funds, but start riding a standard 175cc 4 speed engine. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted April 3, 2013 Report Share Posted April 3, 2013 You really need to use a 4 speed motor as others have said and buying a running motor is always the best option. You could recover most of the cost by selling the 3 speed bits as they are next to useless when building a trials bike. Only bits that I would keep are the left and right covers to help disguise the 4 speed motor if you are bothered about that if not there is a ready market for them from trials riders that are bothered. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.