Hitchcocks Forum

Hi guys-----am in the process of fitting a 32mm AMAL Mk1 Concentric carb.this winter to my 2005 Classic 500. It has an 8.5:1 piston fitted but is otherwise standard...What jet settings, plug and ign. timing would be a good starting point ?? It will be breathing through a paper element "Pancake" type air filter, and has a semi-free-flow exhaust....Thanks for any help-----------

Hi Alan, I would go for somewhere around the 220 size to start with and you might need a slightly more advanced ignition timing than standard, or else your engine might seem a bit 'flat'. 38 deg BDC, as opposed to the usual 35 should do it. If you get pinking, try either a bigger main jet, 107 needle jet or raising the needle.
Regards, Paul.

Hi BW, -------- thanks for the quick reply and tech. info.--------- Will be making a start fitting this week-end so should have some feedback for next week.... Haven't forgotten about the crank re-building etc. which will be sometime in FEB or MARCH 2013....Mr Xmas has promised a new con rod and forged piston from Mr.H (I hope).

No problem, Alan and, as you may have spotted my first reply should have read 38 deg BTDC and not BDC as typed above.

Hi BW---- I'm used to double-acting pistons on steam reciprocating engines---- would be interesting to get an internal combustion engine to do the same !!