Hip to be square

MG fi­nally gets his Us-sourced ‘square cam’ in the FXR. It even ticks over. Just…

BIKE (UK) - - LIFE - Mark Gra­ham Editor at large Been rid­ing for: 45 years An­nual mileage: 4000 Owns: seven bikes in­clud­ing H‰D FXR Shov­el­head, Wom­bat…

RUN­NING IN PLEASE PASS. You don’t see that so often, if at all, th­ese days. It’s re­fresh­ing to know that some things stay the same with old V-twin knock­ers – you have to run things in. Es­pe­cially when a 1340cc mill has been treated to a wild cam, new fol­low­ers, a glaze bust on the bores, and new rings. It’s been a long time com­ing this re­fresh of a tired Evo en­gine in its first gen 1984 FXR chas­sis, but it al­ready feels like it’s worth the long-ish (two year) wait. All down to me. The Leinewe­ber E4S cam is by no means the most brutish this longestab­lished line of cam grinders pro­duce. But it goes some way to re­in­force Jim Leinewe­ber’s rep. as the ‘man who makes square cams’. By square we mean a ramp that gets the valves off their seats as rapidly as pos­si­ble, holds them close to max­i­mum lift for as long as fea­si­ble, and then dumps them back on their faces in short shrift. And this cam has lift too: 0.528in of it. ‘Our high­est lift bolt-in cam’ they say. It’s not ex­actly bolt-in. Rich at Skull­chopa (sic) had to re­lieve the cut-outs in the pis­tons for safe valve-to-valve clear­ance and Alex at Fast­lane Heads was most con­cerned we might not have enough crank­ing com­pres­sion to make it work prop­erly at a con­ser­va­tive 9.25:1 static ra­tio (ide­ally it wants 10:1), but it seems to be work­ing sprightly enough for me to have to clamp up the clutch springs a few times to stop it slip­ping even at well un­der a 4000rpm (ish) run­ning-in ceil­ing. It feels like it wants to go. I’ll change oil and fil­ter af­ter 400 miles and then gen­tly get it to­wards the 6000rpm max we’ve di­alled-in via the Crane Hi-4 ig­ni­tion curve. Next stop dyno fine-tun­ing and the roller of truth. Feels good. Real good. It even ticks over. Just.

MG’S new square cam. Not ex­actly bolt-in

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