www.zxrworld.co.uk

Any experience here would be much appreciated. I have a standard engine (l5) which with a Beet exhaust was putting out aroung 67bhp (with air filter installed). I am installing ram air and SP cams plus a bit of profiling of inlet and outlets which I hope will add around 4-5bhp. Fueling (from the dyno) on the pre-mods bike was v good but i am clearly pushing a lot more air thro the system. Any experience on carb jet sizes to keep the fueling reasonable or is this a "suck it and see" moment?

As I am installing race ram air the carb de-icing has to go but I dont expect that is significant - or is it??

Ive got a similar spec spare motor what your about to do, sp cams a bit of porting etc.. upped comp.with a beet and standard airbox with no filter, i used 102 keihin mains in and blocked off air correctors. apart from a slight zxr rich mid it was very nice.
when i added a full ramair box, and plate bellmouths i got an extra 9/10hp... it really does make a difference.get in touch with dynoproracing and see if they will send you a bellmouth plate, work very well.
you will need to get it on a dyno tho, very hard to get right without. need to fook around with different needles/jets/springs.
never had carb icing

Sounds a bit 'stong' 67bhp with a stock motor Dave but if thats what the dyno shows thats all you can go by. We can usually take a (say 60bhp) stock motor and port and cam it and get minimum 72bhp. It depends then largely what you have bolted on the outside...carbs--exhaust--ignition--airbox? You have the best exhaust available,flatslides give 2bhp and are by far the best to use and as for programable ignition...a waste of time and money. The rpm limit is the draw back with standard ignition but this can be lifted for about £100 and is a big advantage. As for ram air...no way on earth does it give 9-10 bhp, 2-3 usually and this has been developed by ourselves along with Mark from Hobbsport(he no longer runs it) who have or had the best dyno in the country with ramair variable from 0mph--180mph...so when we used to come away from there we had the bike set up spot on with genuine figures So onto your jetting... 108 mains...blanked main air correctors...pilot airscrew two and three quarter turns out and a good set of aftermarket bellmouths (i can supply them if neccessary) and a good ram airbox which i can supply if neccessary...Front exit ram air, as we supply actually showed 1.3bhp more over the short(radiator top finish)trackt. Hope this is of help.

his 67 hp may be on a dynojet? maybe around 61 on a dynopro?
I am no expert, not even close,i know you know yr stuff roger as ive seen your bike... but we had 8hp(peak) up with the airbox and bellmouths and thats on a fully tuned motor aswell. I just guessed that you might get 9 to 10hp on a standard motor with these added.
I only use one dyno(a dynopro), so all the changes we have made are noteable.
These are figures from my bike, which was running a hacked up h airbox with no filter with h bellmouths..maybee this was a restrictive setup to get the gains we got when it was removed... who knows.also, first reading was from a fresh build, then had 2 races on it, the airbox/bellmouths added, then another reading... so maybee loosenend up a little? im not sure, but i was impressed with the difference

All i can suggest Jake is get a good 'Dyno man' not just some someone you think is good but someone who comes highly reccomended and has set up proven bikes for proven winners. Not everyone that owns a dyno can use them and set bikes up spot on. Ive been on lots of dynos in my time and now could only reccomend two. ' I could buy a pair of footballboots and a ball but it doesnt neccesarily mean i'll be good at football' !

Who would be the best to modify a cdi unit? And what revvs can you safely go to on std valves? Cheers leon.

Well, I was thinking of a reply as I read... until I saw Rogers reply, so no point other to confirm what he says, and all my knowledge/experience comes from Dynotech. The only think I would comment on, and I'm not going to argue(cause I can't), is Dynotech have tested all sorts of airboxes, and found no adavantage of having air fed to the same kit box from the front of the fairing compared to the kit type above rad, but having said that, Rogers airbox is a different design, and that could explain the differnce in power given the different routes of the air.

And Jake, in my experience you could gain up to 3bhp on a 'run in' zxr race engine over a just refreshed engine. I very much doubt you'd gain 9bhp with just a ramair box and bellmouths, I just don't beleive it, that's just too easy, there must be something missed!, just my opinion like

That must be it then Greville, i must of got around the 5hp mark with the airbox and bellmouths and rest from a settled in motor.. It was still nice to see such a gain either way

I guess everyone has there choice of tuners/dyno operators... agreed most choose, with good reason im sure dynotech. Bit far away for me, I go to dynopro in runcorn... firstly because i can rely on him. after being let down and missing the first race of the season, thats most important to me! second, there great dudes and get good results(them, not me ,not down to the bike tho)

If its an SP CDI I can mod it to 16,200rpm which is the ( factory kit ) F3 rpm limit. the standard SP is 15,200rpm and the standard non SP is 14,800rpm (although you guys in the UK got lower rpm on the stock units, i think 14,500rpm ).

I can also change the PWM solenoid output to a simple on off rpm based bracket switch ( on between 1500 - 5000 RPM ) This makes it a little easier to jet using the solenoid in place ( rather than just disconecting it ).

cheers TK400

guys -just logged on aftr a coule of days away and stunned by the help -unbelevable. thanks

cargo/roger thanks for the steer on the jets - will go with 108's jets as suggested - at least as a starting point and see how itworks out. -roger -I have a box from AMS but will need a set of bellmouths so will pm you on that

roger - i was surprised by the dyno result. it was dynod at Bob Grants Dynotech centre at knockhill and id be surprsed if they were way out on theaccuracy of the result howerver Iidnt aprreciate that there could be a difference between a dynopro or dynotech machine and that the difference could be as much as 5bhp!!

will be dyno'd again after the work is comlpete so will let you know what sort of result achieved

thanks

dave

my h1 with a beet system, pipercross filter and #105 main jets showed 66 on the dyno with no internal mods except a lack of base gasket... was on a dynojet dyno operated by a clumsy ape though.

fwiw i didnt beleive claimed output of Jake's bike either till i saw the printout, and how quick it is.

re programmable ignition, I bought an ignitech box for less than the cost of chipping the stock box and its a definate improvement