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Re: profiling head, why, how..?
Posted: Fri Aug 17, 2012 10:56 am
by GP Kevo
Btw, what's a good way to reduce the fan cowl to fan clearance? Mine is more than 2 mm. Quite a bit more.
Re: profiling head, why, how..?
Posted: Fri Aug 17, 2012 3:32 pm
by rosscla
looking at bolting an old bit of chopping board inside the cowl...
Re: profiling head, why, how..?
Posted: Fri Aug 17, 2012 5:18 pm
by warts
rosscla wrote:looking at bolting an old bit of chopping board inside the cowl...
Might help if you are cutting up other road users.
Re: profiling head, why, how..?
Posted: Fri Aug 17, 2012 5:38 pm
by Muppet
GP Kevo wrote:Btw, what's a good way to reduce the fan cowl to fan clearance? Mine is more than 2 mm. Quite a bit more.
big hammers sorted mine not all on there own i also had a block o'wood and a big cardboard tube twas same size as fan: i put tube on cowl: put block of wood on top: and hit wood while bolted to engine: 1mm gap sorted, :fb:
muppet,
Re: profiling head, why, how..?
Posted: Fri Aug 17, 2012 6:15 pm
by rosscla
warts wrote:rosscla wrote:looking at bolting an old bit of chopping board inside the cowl...
Might help if you are cutting up other road users.
Barooom chaa
Re: profiling head, why, how..?
Posted: Sat Aug 18, 2012 1:53 am
by Terrible Taff
You need to use a Yamaha YFS200 Blaster 89-02 66mm Std Piston kit.
Various prices on Ebay - just need to know the piston size normally standard comes as 65.95mm giving 0.05mm clearance (0.002") on a 66.0mm Bore.
However I replate the RB20 Cylinder to 66.02mm so there is about 0.003" clearance which allows for the cylinder/Piston assembly to run hotter without seizing, thats if the jetting is set on the rich side so as to use the fuel as a coolant!
This also allows for night time running when there is much more cold air about & moisture which leans off the jetting compared to daytime warm weather use.
Most of the RB scooters I have built end up running between 220'C-240'C at high rpm, checked using a CHT unit with a Mychron 4 Kart Data logger.