Can I make a 1961 cub 250cc?

Can I use the round barrel?

Whitch sleve do I use?

Whitch piston?

Is a 1961 motor strong enough for a 9:1 piston?

Thanks in advance from Sweden

Hi Penton,

I presume your motor has the round barrel & distributor ignition system, for advice on all things Cub the best people to speak to would be either Serco or Alan Whitton. Many people seem to prefer a 230cc Cub rather than the full 250cc motor because 230cc seems smoother to ride, my own bike is 199cc, low compression piston, R cam, PVL ignition & Del-Orto carb this set-up gives plenty of power & I am no lightweight but it really goes well enough for everywhere i have ridden.

PM me if you require the phone numbers for Serco or Alan.

I believe that both the 230 or 250 routes need a new alloy barrel. Then the crankcase mouth needs machining to accomodate the larger liner. I'm not sure if the new 250 crank needs roller bearings - 230 uses your existing crank.

I have the same set up as TRF and agree that it seems to work reasonably well. If you do the conversion you'll want a PVL fitting, and so maybe it would be best to start with some later cases.

Hi Penton,

I presume your motor has the round barrel & distributor ignition system, for advice on all things Cub the best people to speak to would be either Serco or Alan Whitton. Many people seem to prefer a 230cc Cub rather than the full 250cc motor because 230cc seems smoother to ride, my own bike is 199cc, low compression piston, R cam, PVL ignition & Del-Orto carb this set-up gives plenty of power & I am no lightweight but it really goes well enough for everywhere i have ridden.

PM me if you require the phone numbers for Serco or Alan.

Thanks for the answer.

I have just bought the Cub (non running) and my trialfriends says that 199cc is not strong enough. Maybee i chould try it for one sesong first.

I have Doyer Bransden, R-cam and 7;1 piston and Kehein carburettor. I had not try it in sections yet. So far i have drive my TLR250.

If I find it to weak I start with some later cases as Subira told me, but I like to do it myself as I have the machines.

Hi Penton,

I presume your motor has the round barrel & distributor ignition system, for advice on all things Cub the best people to speak to would be either Serco or Alan Whitton. Many people seem to prefer a 230cc Cub rather than the full 250cc motor because 230cc seems smoother to ride, my own bike is 199cc, low compression piston, R cam, PVL ignition & Del-Orto carb this set-up gives plenty of power & I am no lightweight but it really goes well enough for everywhere i have ridden.

PM me if you require the phone numbers for Serco or Alan.

Thanks for the answer.

I have just bought the Cub (non running) and my trialfriends says that 199cc is not strong enough. Maybee i chould try it for one sesong first.

I have Doyer Bransden, R-cam and 7;1 piston and Kehein carburettor. I had not try it in sections yet. So far i have drive my TLR250.

If I find it to weak I start with some later cases as Subira told me, but I like to do it myself as I have the machines.

I have a 199cc Cub never had a problem with power in normal pre65 trials (im 15 & a Half Stone)

Vinnie

199 cub never a problem with power shortage for this 16 stone lump, climbs owt i point it at and grips for fun (being big boned finally counts for something...)

Hi Penton,

I presume your motor has the round barrel & distributor ignition system, for advice on all things Cub the best people to speak to would be either Serco or Alan Whitton. Many people seem to prefer a 230cc Cub rather than the full 250cc motor because 230cc seems smoother to ride, my own bike is 199cc, low compression piston, R cam, PVL ignition & Del-Orto carb this set-up gives plenty of power & I am no lightweight but it really goes well enough for everywhere i have ridden.

PM me if you require the phone numbers for Serco or Alan.

hi there im planning on fitting a dellorto carb to my cub ,what size have you gone for and what jets are in it please

22mm PHBL I need to check the jets etc. tomorrow

low compression piston,

What compression is it

Vinnie