Roadster Inlet camshaft Retard for more high RPM power

Question for the people who have tried.
Claviger Lush Warp etc. Anyone tried skipping one tooth( 9.5degrees) retard on the inlet cam only on a Roadster? Theory says peak HP and torque figures could occur about 400 rpm higher in the rev range with only 2 to three HP losses in the 2000 to 4000 range. Dynoed proof is essential of course Thanks

torki pig said:

Question for the people who have tried.
Claviger Lush Warp etc. Anyone tried skipping one tooth( 9.5degrees) retard on the inlet cam only on a Roadster? Theory says peak HP and torque figures could occur about 400 rpm higher in the rev range with only 2 to three HP losses in the 2000 to 4000 range. Dynoed proof is essential of course Thanks

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The 9.5 degrees are camshaft degrees or 19 degrees crankshaft. This would mean -10 TDC intake opening and 47 degrees after BDC. Very little overlap but lots of late closing moving HP and torque about 800 rom higher?
Engine peak on dyno is now 159 at a mere 5250 with torque at 170. Custom pipe and Ramair the only mods that brought HP up from 125 on dyno. Stock pipes peak at same RPM so cam is probably the thing to work on

I'm not sure I completely understand. How exactly did you get the 34 horsepower increase? Was it from the intake cam retard only or a combination of cam/intake/exhaust? Are these before and after dyno results?

@Penner I believe pioneered the stock cams, using 2 exhaust cams or 2 intake cams (I can't recall)

something is not right with your sums, stock inlet timing is 12/28, if you retard it 9.5 degrees it would be 2.5/37.5. To my mind, this would probably make the bike a turd under 3000rpm, but I have not physically done this, so I may be wrong. The old 'trick" was to use two exh cams and retime, but not sure if Ulf Penner did it or some one else. It was not me, we just made the "street" cams..

Retarding the intake cam one tooth will be about 20 degrees. And I doubt that will work any way. Maybe a small gain at high revs, but i am not even sure about that. Loss in the other areas will be significant. The stock exhaust cam has longer opening than the intake one and it will fit. But it is just something like 5% more area. If you can get one cheap and it is time to do valve adjustment it might be worth a try. (I never did it). If you want some real gain all over, you should go for one or two of Neville´s cams.

Neville Lush said:

something is not right with your sums, stock inlet timing is 12/28, if you retard it 9.5 degrees it would be 2.5/37.5. To my mind, this would probably make the bike a turd under 3000rpm, but I have not physically done this, so I may be wrong. The old 'trick" was to use two exh cams and retime, but not sure if Ulf Penner did it or some one else. It was not me, we just made the "street" cams..

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The one tooth cam retard actually is 9.5 cam degrees which would be 19 degrees crankshaft. So -7 and 47. Sorry I was not clear in my description.
I flowed my heads and entered parameters and all the engine specs into an engine program called Dyno 2000. The program uses hundreds of motor configuratios along with dyno figures to predict performance with typically + or- 5% accuracy.
As I'm sure you know intake cam closing is the single most important event to determine high rpm cylinder fill. The opening delayed 7 degrees ATDC is apparently irrelevant because nothing is happening in terms of vacuum yet. The valve being opened late and not quite as high as in stock timing seems not to deter horsepower from rising significantly above 4000 according to the program. The head flow supports good cylinder fill even though it seems like it would be a good idea to open earlier.
I do have adjustable sprockets not installed yet but I was looking for feedback on 19 degrees retard and planning to actually try 10 degrees someday when I have to adjust the valves and change the head gasket anyway.
Curiously the program indicates that changing the lift or timing of the exhaust will lose horsepower. In other words exhaust cams are good for this engine even into higher rev ranges as is.

What lift are you measuring your valve events at? I use 1mm or .040" like the manual is. I have not used software, but maybe 15 years ago now worked out the mild street cams, for a stock engine, with differences in timing and lift and we gain 9-15hp depending on the exhaust . If your program says there is no gain by lifting the exh valve more, is this before or after the head work? I have absolutely no desire to get involved in an argument, but you did ask my opinion. Maybe put all the data into your computer and see what happens to the cylinder cranking pressure when you retard the inlet close 10 degrees. The inlet close event has a big effect on that as well. There is 38 teeth on a cam gear. I agree the heads are pretty good, we can make 200hp at the tyre with stock head. Good luck in your experiments.