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[Dampking]

Les H - That's a lot of info but I didn't get the last part where you said "Better to go bigger if you can rather than rev it faster." So you mean to say it's better go for a better con-rod? also assuming that the Electra X's should have a bit more longer rods? or am I totally wrong? DAM I am such a newb when it comes to such technical stuff

[Les H]

All I meant is that if you can get a big bore kit (Bigger capacity) then you can get the extra power without unduly stressing the engine. The piston will be slightly heavier but by keeping the revs lower the ultimate big end loading will probably be less. Higher lift cams even with the same timing should help with engine breathing, and with the right valve timing you can get a decent power increase without needing to go to higher revs, but every aspect of the engine has to work together to get real benefits. Anything too extreme which is not matched by the other engine parts will quite often reduce power. Extra capacity is virtually guaranteed to give more oompth, unless the carb and inlet is way too small to start with....Now you are going to tell me there's no big bore kit for the AVL engine? Oh well.

[Dampking]

But I also heard that the 535 kit will raise the compression? So instead a normal compression raising work on 500 might help? Also heard that when a friend tried 535 on AVL.. compression raised to 175 from 150psi of what he had. So after installing "S" cams the compression went down and it was perfect it seems. So I thought lets save up for the cams and then go for the big bore kit.

[Les H]

For the more tech minded here is an explanation of cam design and lift:......http://www.peterwilliamsracing.com/pw3cam.pdf.....I still haven't found the other article and I have a feeling it was by Mick Hemmings rather than Colin Seely....it'll drive me mad untill I find it...

[Dampking]

Thanks for sharing Les H. Good info there

[Nico]

On the subject of cams.
If you want to rev higher rpms, there are to reasons why to go for a wider profile, i.e. a cam that opens for a longer time. There is obviously the breathing that gets more time thus more charge into the cylinder. The higher you rev, the later you normally want to close the valve. Basically while the piston is already gonig up, the accelerated air with its inertia is still travelling into the cylinder. When it starts to be pushed back by the pistons, the valve needs to close. Due to this, a late closing inlet cam like that will show mist out of the carb when run WOT at low speed.
But there is also a mechanical reason for the wide cam profiles. As you can imagine, if you have a narrow cam - even with low lift - and you want to open/close it faster and faster, the valve will lose contact to the cam. If you give it more time, the mechanical stresses due to the accelerations (the second derivation of the valve travel over crank degree for those who remember their school days..) actually become smaller and you do not necessarily have to run a harder spring. If you want to increase the lift as well, you will normally have to increase the width as well otherwise the stresses just go through the roof, with our engines certainly a lot of trouble.
Modern turbo charged engines, tend to have very narrow cams but have means to swing the timing, so that they can run early or late closing/openings.
For our engines, the width and the lift will have to be a compromise between tractability (narrow, low lift), power (wide, high lift) and stresses (wide, medium lift).

[Norm]

Dampking, I looked at the AVL versus Bullet cams a few years ago when I was building the crossbred and although the profile is similar the AVL cam is about 2mm higher in the lift and this is due I think to the fact that the AVL rocker arms are longer therefore requiring more lift. I doubt the Bullet cams would work very well in an AVL

[Bullet Whisperer]

Norm,
I actually fitted and tested [road and dyno] many different cams in the AVL, including standard Indian 'Classic' types. Most, if not all of them gave an improvement to some degree, but only the 'S' types cured the valve bounce and allowed the revs to carry on past 5,800 rpm.
The AVL cams have a higher lobe, but also a greater base circle than the older Enfield cams and in fact give slightly less rocker movement than the 'Classic' types.
Incidentally, although the engine could reach 7,000 rpm, there was no need to go there, max power was around 6,000 rpm and 103 mph [the most I got from it] was at 6,200 rpm.
Paul.

[Dampking]

WOW! That answered my question! So 6000 to 6200 rpm did wonders for you. I think 6200 rpm won't be that bad for an Electra X Worth the try! :