Hi All,
prompted by the 80 MPH topic, I thought you might like to see what can be done with the 500 Lean Burn head. My apologies to those of you including Ric and Tiny Tim who have already seen this elsewhere.
My Electra already had one of the UK importer's PHF 32 Dell'orto carb from new, but having played with unit single BSA's in my past biking life I was keen to get in and er... mess with my head! I bought a new spare head from the UK importers, have a look at these:
Nice modern combustion chamber design, room for a 2nd spark plug too...
That exhaust port is unbelievable! Surely something can be done?
What's happening with the inlet? That's quite a large hole already, 1 1/4" (32mm) at the narrowest part. Are you thinking what I'm thinking?
Anyhow, that exhaust port cleans up nicely:
You're ahead of me on this one, but here's the picture anyway. With VERY little work you can get a nice shiny 36mm inlet port, allowing you to fit the Dell'orto/Mikuni/Keihin of your choice. There's just enough metal to take it out to 38mm if you have a spare Amal 1 1/2" GP carburettor lying around
With the head finally fitted I experimented with the 32mm Dell'orto before parting with my money for THIS,
a TM36-31 Mikuni flat slide pumper carb. It just about fits under the gas tank, though I had to lop a spare bracket off the carb first!
The ally sleeve is the same one used for the Dell'orto kit as it lines up with the airbox, though if I put the bike back in Woodsman trim I'll use a pod air filter
Performance has improved noticeably in the mid range, though it is now crying out for a smaller countershaft sprocket to get max revs in top gear. Down one to 17T should do it. Porting the head and fitting the 36mm Mikuni hasn't spoilt the low-speed riding in town or guzzled lots of extra gas, I'm pleased to say.
I would be very interested to know what else is going on in Electra-land. The CMW big bore conversion looks promising, is there any more news? What are our Indian friends doing with their 500 Machismo Lean Burn engines?
Hope this is of interest to somebody...
Regards,
Adrian