www.zxrworld.co.uk

Does anyone have a detailed guide on best practice for setting up SP cams? I have built quite a few ZXR race engines but have never used adjustable cams. Any links or info most appreciated.
Cheers shaggy

Got this Sussed now due to a few amazing websites. Now I just really need to find what best options are for cam centres. The old F3 manual ends up at 105/105 as do the Kent Cams. Anyone have any info that says different? This engine is for Manx GP so reliability is most important.
Cheers Shaggy

What cam, what carbs, what air box, what exhaust......
Not a one size fits all but 105 105 is a good starting point.

Shaggy, what websites were of most help? Doing something similar with my bikes and could do with some help. I have one engine with what I think are Kents and one with either SP or 'kit' ...both types adjustable but obviously different.

cheers Hammy

shaggy geez a bell....

I tried m8 but no reception up here lol

Mick current setup is SP cams, 32mm cv's, ramair, head skim, porting work done, hopefully beet exhaust and full RTD ignition. Standard pistons

Eddy,
Here are three i found pretty useful although one is for cars the principle is same. Do a search for either 'how to degree motorcycle cams' or 'motorcycle cam lobe centres'

http://www.muzzys.com/articles/lobe_centers.html

http://www.zx-10r.net/forum/showthread.php?t=84083

http://www.motoiq.com/MagazineArticles/ ... -Cams.aspx

Cheers Shaggy..now my head hurts lol. Just in case you didn't realise its Hammy (#39) speaking. Just set up my timing last night, but either I've royally fecked up and missing something big time or the person who set up my engine originally has located the cam marks (that you align with the head) 180 deg out. With cyls 4 & 1 at TDC and #4 cams facing outward as per the manual, my cam marks are facing towards each other rather than away from each other. Got everything set up as per the manual (apart from the marks of course) so hopefully its good. Next job will be to swap the pulse rotor with a kit to suit the Mitsu CDI. All going well I'll be at Knockhill in 2 weeks reverse direction...thats me not the engine!

cheers Hammy

Shaggy, start with 105 105. If you start to get reversion at 8-10k roll over to 110 108. If you run flat slides inlet can come back to 103 for a bit more punch out of corners without losing top end.

Mick, cheers for that, when you say reversion, what would the symptoms of that be other than obvious poor running caused by fumes spitting back through the carbs. Are there any known symptoms at certain points of power curve that would show on dyno run. ie that bullocks to iron out dip around 7,000 lol

Hey hammy, I can never remember which way the lobes point as iv always had fixed cams so never really notice. I dare say, unless the holes are offset, then someone coulda had pulleys off and put them back on wrong. I guess that means you need to centre your cams so that you at least know what your starting with. Out of those links the zx10 forum one was easiest to follow and it does all make sense...eventually lol. I tried all the 'what if' calculations and questioned all the simple points...and you know what? It bloody works I couldn't figure that if you always ended up with 140 (35+65+180/2) how you would end up with anything other than the same number. But eventually Sussed that you are always going to be subtracting a different number from that based on the opening point (btdc) of the valve. Then I queried the reference point of dti, 40thou? 50thou? Calculations show it doesn't matter a jot so long as you use same indication for after opening and before closing of valve. Clever stuff, and I celebrated my new found knowledge with a beer

Mate you will feel it on track, but best seen on dyno. Run with tank & air box off you will see the carbs start to spit fuel back out at certain rpm. Thats reversion. The fuel gets sucked back in & in the process carburetor adds more fuel to air mix so gets double carbed.
Different length inlet trumpets & cam timing can move this about. Problem with cv's is that it fucks the vacuum circuit at this point & makes the slides dance about a bit. Thus you get that real bog down that is hard to pull through.
Have you done the main air jet mod to the carbs, often best way to get rid of that al mid range flat spot on carbs. What needle are you running.
MB

Shaggy, hope you will celebrate your new found knowledge with a win rather than a beer lol...

To be honest all this stuff is fascinating in theory but just havent the time to do anything about it in practice. If I could get my engine running mid-70's and reliable I would be happy. Being even more honest, I confess to standing on the shoulders of giants as the cams I refer to are untouched since I removed them, and are the way they were since I bought the bike. When I removed them I set the marks up as per manual but didn't even bother to check the actual position of the cams hence the original confusion..doh! But it was running like a sweetie for 2 seasons before I stripped it (to replace the head gasket) so sure it will run fine again. I double checked to make sure I didn't have the inlet on the exhaust etc (don't laugh I've seen it done before by people that should know better) so the only conclusion I can make is that the marks are wrong.

I'll be putting it back in this weekend so will let you know the results.

cheers Hammy

Mick,

The carbs are standard needled 32cvs, ill get a look and see if I can read numbers off them this weekend. In fact scratch that, the slides and needles are outta my old 30.5 mm jap spec carbs. I also have dynojet needles. When u say main jet mod, what mod do u mean, blocking the air correctors?

Cheers Shaggy