Engine help please!

Thanks for the advice guys, I appreciate it. I haven’t got the C15 as I wanted to check out stuff like this before forkin out the money.

Thread drift alert !!:D
Many years ago I was happily riding along on my BSA A65 Thunderbolt,when I heard a strange noise…thought my engine was about to blow up until I realised it was my mate riding some distance ahead on his C15 fitted with a very short megaphone ‘silencer’…what a racket LOL
Def not worth messing with a C15…keep it standard !
Do you have a C15 already ??

my option would be one of the modern cheap chineese coppies of the old ( bullet proof ) honda 125 four stroke engined bikes

they go cheap engines are prooved bullet proof and long lived

they are a decent nippy machine without being too much of a handfull for the novice

some have classic looks without classic reliability issues

treat it as a stepping stone your first bike is usualy battered when you have finnished with it

as it is not a matter of , if i fall off !! you will , and probably more than once !!

once you gain experience then is the time to get the propper classic

realise it is awful waiting but better that than shattered dreams !!

Think about it.

Learn to ride on something gutless, gain experience and confidence on something you can handle before taking on something that has the potential to cause you and others more damage.

Treat your first machine as a stepping stone, it won’t be forever.

not necessarily the case nowadays !!

a modern 125 in some cases can out perform vintage 500cc machines

a friends aprilia 125 could achieve well over the ton with little tinkering !!

first thing , do not sacrifice an original classic like that (especialy if matching numbered ) the hacking about would ruin it

and even after if you re sleaved etc you then have to start working out your carburettor jet sizes ( it won’t run good on the orriginals )

in short there is that much hacking about involved it just isnt worth it !!

as mentioned a far better option is to learn and take your test pass and plod around for a while on a smaller machine

if you already have the 250 spend time whilst you are on the other to make the 250 a mint unmolested machine

My dad had a Bantam 175cc so i’d love something along the same lines.
I don’t mind the designs of scooters etc, I just hate the noise out of the so called engines. So a 4 stroke may be worth looking at.

Ah, I see! There are some really good four stroke 125s about now, but I’m guessing you want a classic.

What can i say, i’m a novice when it comes to bikes :p

I was looking to see if could get away with getting the bike relatively cheap and still be allowed to ride it on L plates.

Basically i’m trying to find a motorised form of transport which doesn’t cost an arm a leg to insure. I know you can get mo-peds and scooters but I refuse to own something with a two stroke!:diablo:

eh? You’re asking if you can physically half the cubic capacity of an engine, apart from fitting a new 125 engine, or some how sleeving and making new pistons for the original motor, then no you can’t!
Wouldn’t the power output allow you to ride it as it is anyway (assuming you are not on L plates now?), I thought it was all down to kw/h now?

With modern engines you can change the power output by making external changes to the engine (though not the actual capacity) this can help with some of the more recent licence restriction issues.

However with a machine of the vintage of a C15 there are no such options available and certainly ‘limiting’ the capacity just isn’t an option I’m afraid, that’s just down to the mechanics of the engine. The only way you ‘might’ achieve the 125cc capacity is to fit a different engine. Now I’m working at the very limits of my memory here but wasn’t the BSA Bantam originally a 125cc engine? I’m not sure how mechanically feasible or financially cost effective it would be to find and fit such an engine, but I don’t see any other option.