Hey Pedro - tuning question

[diamondj]

Hey Pedro,

I saw your quote in the crank lightening topic:

Can I just say, I rev my engines to 11000 rpm with my lightened cranks and GT750 rods with less vibration than a std crank, and regularly get mid 80's bhp with good power spread, so clearly I am doing something wrong

Mid 80's bhp with a good power spread is impressive to say the least and would certainly hold off the hordes of RD's that tend to dominate the 500cc classes here in the States. In fact, it would explain why several race organizations seem to be afraid of the T500 getting into the GP500 classes (AHRMA and the VRRA come to mind). I don't suppose you would be willing to outline what you do to get these numbers out of a T500 engine? I'm not looking for any of your tuning secrets, just a general idea of what you do for race prep. I had always thought the oddly placed transfers on the T500 kept it from ever reaching it's full potential. Also curious as to what an 80 bhp engine would cost me? Not that I can afford it right now but I AM in the lottery pool at the office and you never know!

Jim

[pedro]

Hi Jim

Sorry for the delayed reply, dont get much time to do forums, and this kept logging me out after 30 secs for some reason

Anyway, not all engines I build reach those figures, as with most thing specification depends on wallet, I have in the past built a almost 100 bhp motor, but that was purely a sprint engine with reeds and would have been unridable with bendy bits in the tarmac.

Often its better to have a lower power but more tractable engine for short twisty tracks, but then I am probably teaching you to suck eggs

Most power is derived from good port and exhaust design, generally my own design which I have been doing for some 30 odd years when I had to do it with a calculator and formulae, but have to admit to having aid of both bimotion and mota programs these days.

I remove liners and put boost ports in then reline with altered timings (which I am not giving away ) the std ports as you rightly say are rubbish but with the liner out you can reangle but are still restricted by the port wall that is right next to the stud holes.

I run lightened cranks reduced dia and reduced thickness of the fly wheels...... with NO stuffers and GT750 rods and cranks are balanced, as I run PVL ignition I also shorten the timing side cranknose, I do this as I use GT cranks because as you probably know the centre main shaft is part of the c/wheel on one side (less bits to twist) and machine taper to suit the pvl rotor.
Wiseco pistons balanced and matched, my own cast heads with squish to my own ideas, close box, straight cut primarys, the thing that most people forget about is tuning the inlet side of things, this has to be tuned in lenth due to pressure waves just like a expansion chamber and work best at the same time as the exhaust, more power can be gain with reeds but we are no allowed to fit them for classic racing in the uk or the IHRO series.

I could waffle on for ages but that will give you some idea, oh yeah cost, mine has cost me 3.5k and thats me doing 90% of it, subbing out casting and liner manufacture, buying in g/box and primarys and ignition etc.
Bit brief and in a nutshell, but this is an epic for me on a forum

[pedro]

Anyway Jim, you cant be that skint as you beat me to that TR MK3 barrel on ebay lasy year

hopefully we are getting the loan of a mk3 TR top end soon with a view to reproducing them, with the long term plan being to reproduce complete watercooled TR replicas along side our aircooled Seeley reps.

[diamondj]

Anyway Jim, you cant be that skint as you beat me to that TR MK3 barrel on ebay lasy year

hopefully we are getting the loan of a mk3 TR top end soon with a view to reproducing them, with the long term plan being to reproduce complete watercooled TR replicas along side our aircooled Seeley reps.

Hey Pedro,

My racing/parts funds are like the tides - they ebb and flow. The tide just happened to be in when the MK3 barrels were on ebay so I got them.

I do need a cylinder head for these barrels so please add my name to the list once you start reproductions please.

Jim