CAM questions

[mr.zxr]

I was dialling in the cams the other day and was a little shocked at the result. The duration of the inlet cam is 15 degreees more than spec and the exhaust is 20 degrees more than spec. I have a second set and they were out too but not by the same amounts. All cams are original and have noe visible wear. It goes to show that in mass production these motors are just thrown together. Anyone else seen similar?? The other thing for the turbo guru's out there. how much should i advance/retard the cams.

[Redmohawk]

Cam chain out one tooth ?

[K6Thou]

I know that the KZ 750 cams are always 5 deg different from the factory.

[mr.zxr]

nah, can't be camchain out. it's the duration, which is the cam grind. i can't believe kawasaki would be that far out.

[Dynomutt]

What figures are you using to measure them at? I always measure at 1mm of lift to get the duration figures. What durations did you get for the cams? Generally the OEM cams will be slighty different grinds, they tend to have much greater quietening ramps to let the valves open and close more slowly, which can affect the duration figures. Generally I would advance the exhaust cam a little and retard the inlet slightly to reduce the overlap. Opening the exhaust early will help to get the gas out, you won't lose anything from doing it as the crank angle is usually so poor at that point hanging the exhaust later won't gain any power.

[ALBI]

I was dialling in the cams the other day and was a little shocked at the result. The duration of the inlet cam is 15 degreees more than spec and the exhaust is 20 degrees more than spec. I have a second set and they were out too but not by the same amounts. All cams are original and have noe visible wear. It goes to show that in mass production these motors are just thrown together. Anyone else seen similar?? The other thing for the turbo guru's out there. how much should i advance/retard the cams.

unless the cams have an adjustment in the gears ""dont know kwakas that much!!"" are you sure you have set up ur degree wheel correctly ???

i didnt use my "crow cam" made degree wheel for about 18 months and i was shocked to find a simular set up in a range rover 4.6lt i built ,to be out by 13 degs ,then i re-set the piston to true top dead centre with a dial gauge ,redone the pointer for wheel.
and re-set lifter dial gauge, only to realise ihad set dial gauge incorrectly.

it may pay to walk away and have a cuppa and re-set !!

[mr.zxr]

checked and re-checked. used a piston stop to get TDC and it lines up with original mark i had on the crank. I measured at 1mm lift to get the cam centrelines and duration, but the kawasaki manual gives duration from zero lift so i re-measured. the cam sprockets are pressed on which is a bit of a shit to adjust. i'm not too concerned about the whole thing, but i just can't believe they are so far out. i spoke to a mate who was a mechanic at a kawasaki dealer and he said that they are all different. he said he builders in kawasaki just try to get the overlap correct but the duration of the cams were all different. Lets face it, how many people dial in the cams on a production road bike..most wouldn't even know that they are out of spec.

[EXBEN]

probably why some bikes feel stronger than others

[Dynomutt]

When I was teaching, I used to do a demonstration for my students with a stock B12 motor, the cam timing and ignition timing were out by 9deg IN 7deg EX and 5deg Ign compared to the figures given in the factory manual. All production bikes will vary quite a lot by virtue of the production tolerances, each motor will be different which is why some bikes feel stronger than others as Exben has said. The B12 can vary by upto 10bhp on the dyno between individual bikes, I've usually seen around the 118bhp to 122bhp mark on most B12 that I've fitted a Dynojet stage3 kit to with dual K&N filters and aftermarket linkpipe and can. I did one recently which was a smidge over 127bhp, which is unusual.
You can buy the adjustable cam sprockets from APE which press onto the cam, I have a set on order for the ZX9R cams that I'm using in my Z1000 carbed motor. Dialling the cams in will find you an increase on virtually any production engine.