Scooterotica

Hi all,

Thinking about getting the head skimmed on my std SIL GP200 with clubman.
Book says the std comp set up should be 7.3 to 1, what could I take off without giving myself any pre ignition problems?
Just looking for a bit more grunt and nothing too daft seeing as the engine just has Indian bearings etc.

Thanks and regards,
Eric.

does the scooter start and run well?will it cruise at 55 and 70 on the flat?

ah.....High Compression Heads! Takes me back.

Used to be able to buy HC heads back in the day.

FWIW the old Work Shop Manual by G Beresford stated that you could do away with the head gasket and also remove 25 thou to increase compression.

This was, however, before the demise of 4 star fuel and the advent of unleaded containing Ethanol.

I think do so at your own risk- but it is tempting to try it.

Chris

70!!!
I wish!
Starts and runs very well, will hold 55/60 without too much trouble and not too bad at climbing hills, best I've done on the flat with no wind is 65 (I'm 6 foot and 14 1/2 stone.
Remember its standard, except for Clubman, matched inlet/barrel and matched exhaust manifold/barrel.
Reason I'm asking is I've just ordered a 19 tooth front sprocket, I'm not looking for super speed, just a little less work for the engine at top speed.

Good old 4 star! I can get Avgas from a local airclub if I wanted too, put 1 litre of avgas per 9 litres of unleaded and you have 4 star (but still got the ethanol from the unleaded). if you read the RON spec on Avgas it looks very similar to old 5 star, but, Avgas uses a differant RON scale, its much higher and loaded with lead. So much lead it fouls the oil up in aircraft engines and exhausts are all stained white.
Thing is if you set the engine up on it you're limited to how much Avgas you can carry if going on a run, plus its £2 a litre.

I add a litre of Avgas to every 10 of unleaded to my little Daf 33, yes there are still some left!

Used to be one of the first things I did back in the day (late 70s early 80s) does no one do high comp heads these days then?

Best regards,
Eric.

Which book says 7.3 to 1 ?

AF do one that's 9.5 :1 but I'm not sure how they work that out, I can only guess it's an estimate / average.

http://www.afrayspeed.co.uk/index.php?p ... buteID=HEA

It says in the Indian SIL handbook that they're 7.3 to 1, the one with the silly pics in it.

Thanks for the link Rosscla, I see they do an 8.1 to 1 too, I'll give them a call and see what they say.

I run on 97 ron anyway so might get away with it.

Whats the squish ?

I add a litre of Avgas to every 10 of unleaded to my little Daf 33, yes there are still some left!

I drive a Daf YA66, had it about 4 years

cancel the 19 tooth sprocket,try a better carb and exhaust(borrow one) dont bother with the head at this moment you have a reasonable scooter messing about will only result in failure!