Scooterotica

I'm running a 230cc Rapido with LTH reed valve / 30mm phbh and a BGM clubman.

I'm Wondering if this pipe can cause a build up of heat? The tailpipe is only 17mm , and 48mm plus box pipes I've used are usually 24mm diameter ? Can this cause heat?

I've been through everything , and I mean everything on this engine and it's still "soft siezing" when I cane it up a hill or even slight gradient.

The tuner of my barrel advised this could be an issue and so have a few seasoned riders - anyone looked inside one ? Could this be a cause?

Would appreciate anyone's help

when i got my classic rapido (225cc) i asked the dealer i got it from if it was ok to run it with a 60mm crank and bgm clubman , but he said no, it would put too much heat into the barrel. he said the tail pipe diameter needed to be increased to " get the heat out ".

perhaps a grown up could clarify ?

was reading an article about building a custom expansion exhaust the other day, and the diameter of the tailpipe does have a bearing on cylinder temperatures, so yamlam is quite correct. too small equals too hot, there are formulas to work these things out, you can even buy programes to work out the perfect expansion, after you put in all the info about the engine, thats bore stroke, port timings what revs you want peak power, the programe will work it all out and even print out paper templates to cut up your steel to make all the sections of an expansion, thats from downpipe to tailpipe, hope ive not bored you to death with that reply

holty

Holty and YAM LAM. - great replies and bares out what others far more knowledgeable than me have made me suspect ..... Thank you both
I can't weld so there's no way I can build my own clubman , but my own pig headed approach means I don't want an expansion pipe.
My options are limited - Gori gp50 or another Ron Moss clubman - rarer than a rare thing!!

Any other comments from the experts on here more than welcome

Just to throw a spanner in the works....i run a very similar set up...225 muggello with reed..28 dellorto..bgm clubman..i do not have any heat issues
The motor is a peach to ride....i like my bgm clubman
If your siezing could it be your piston to bore clearance?
Also after setting up 2 reed valve bikes with gamma egts they are jetted nothing like piston port set ups of the same capacity
Whats your carb set up?

camel wrote:Just to throw a spanner in the works....i run a very similar set up...225 muggello with reed..28 dellorto..bgm clubman..i do not have any heat issues
The motor is a peach to ride....i like my bgm clubman
If your siezing could it be your piston to bore clearance?
Also after setting up 2 reed valve bikes with gamma egts they are jetted nothing like piston port set ups of the same capacity
Whats your carb set up?

Hi Camel - it's a phbh 30mm / 140 main /300 float valve/ av268 / x13 needle - 2nd clip / it won't run on anything richer becomes boggy / stutters

I have a 225 race rapido , 30 mil dellorto and bgm, never had a heat seizure and its been driven mainly long long distances , check the bore clearance it can be an issue with rapidos ,

I was told recently by someone that the BGM Clubmans v3 are more restrictive than the earlier versions ....

Mine has only ever been run on a GT186 with the porcupine cylinder head which, I suspect, is pretty good at dissipating heat. However, the area of the silencer that connects to the tailpipe does get very hot, moreso than any other box pipe I have used.

I have never had a seizure though.

Why have BGM reduced the size of the tail pipe? Sounds a bit of a backward step to me.

Could be a case for detuning your engine maybe? Instead of ramming more gasses through the exhaust try a smaller carb so you get a more balanced set up. It would probably go just as well.