ZXR250C exhaust mods?

[mynameis]

I just took the exhaust out for some attention and care, thought I would give it a good sand and paint it with VHT. Now a few other things are popping in mind, so I would really like to hear from some experienced ones on here :)

Sanding it down seems to be a mission on those hard to reach places and I don't want to sit down with sandpaper!! What do I do? Clean it to my best and just paint it or get it sand blasted and then painted? Anyone has done this? Any contacts, good places?

On the same note what are your thoughts on getting a whole new performace exhaust for the 250? Anyone has modified theirs and got better performance? Costs, brands? Recommended ones? Shall I do it? If yes why, if no why not? Pro's con's, do's and don't please? Any other useful tips and comments welcome :)

And please don't say save your money for a real bike as I am having way too much fun on it to sell it anytime soon!

[N4CR]

pretty much the only way to get header systems/full systems for them is off 2nd hand bikes, they are no longer produced (parts) for these bikes unfortunately. custom chambers i'm sure could whip something up but you are looking at 1-2k for that at minimum... cheapest perfomance gains from these bikes is with a straight through (yes proper straight through) can, i de-riveted an alu aftermarket can and stripped it internally including packing for my old bike.. amazing sound and when jetted and tuned accordingly for top end (and valves etc done) it was untouchable. performance wise this meant on a slight down hill (read mt eastern highway to pakuranga) would bury itself at 190k and keep revving to a rough 200k+ indicated... i miss doing this **** on the 250.. for its age and capacity.. amazing bikes. when tuned and set up best of the il4's ever made in my opinion.

anything else just ask away. best person for carb tuning is ricky.. ex mt eden ex city cycles will be in aussi soon, might still be at haldanes. he is the best zxr250 tuner in nz probably...

also if you wanna shine them up dont' forget chemical treatment, probably easiest to do! can get some spray on **** to remove rust from memory... real nasty ****. hpc coatings could be the bizzo also but cost alot too. 250's are a money pit after you've done basic engine work like what i mentioned previously, suspension could be refitted with aftermarket though i'd say.. sallo has a rgv rear shock in her c model.

[mynameis]

Yeah I was hoping for something like a full performance system or even a performance can at least but you rekon they aren't in production for ZXR 250? Would any other bikes one do? Like a ZXR 400, I know someone had a Yoshi can on their ZXR 400. Does anyone know of anyone out there, perhaps with a performance full system. Would it definitely gain a few HP's? Dynoed results?

Ricky is a mate of mine he has well over 25 years of experience and has done my carbs and valves before :msn-wink: What type of chemical treatment? At this point priority is to get rid of that blady rust, so what spray is this??

[N4CR]

pm r6_kid he is the one that told me about it i think satch has also mentioned the chemical at some stage. as with fitting cans the zxr250 as you can see has a 3 lobe system, i used to run a zx9 race can which was about 1-2mm wider diameter with 6mm bolts, just drill the lobes out and it will fit on.. :) i have the all of the measurements somewhere too (triangle lobe distance, diameters etc) but not sure wher ethey are at the moment... i also have the old zx9r can which is dinged up should you wanna have a look at it.
you will need to get ricky to rejet/tune once the new can goes on. you can weld up a yoshi slip on and have an adaptor pipe if you so wish to.. anything can fit just need the metal that goes between and the mounting hardware onto pillion peg.

[mynameis]

Thanks dood now the million dollar question.

After going through this, time, hassle, money am I looking at a definite performance gain or not?

You ever got your ZXR dynoed before and after or know anyone who has?

Chur bo.

[placidfemme]

I've got an aftermarket pipe on my bike (and apparantly aftermarket header pipes too), But I don't know if its helped performance wise or not as they came on the bike when I brought it... sounds mean though :)

[N4CR]

thanks dood now the million dollar question.

after going through this, time, hassle, money am i looking at a definite performance gain or not?

you ever got your zxr dynoed before and after or know anyone who has?

chur bo.

okay, stock can stock tune would just touch 180+ and a bit, with tune for top end + can it would get 190+ if your engine is in good nic. on a good day in perfect conditions i twice worked out to a real 198-200k. 198k indicated (by rpm) on a perfect flat is exactly 190k and an indicated 209 on a downhill which is exactly 200. they red line at 204kmh in 6th on a dyno. mine got 36ps with the zx9r can (not tuned for it as much as the other can...) with 1021hpa pressure in the air that day. without can i'd estimate around low 30's?. speedo was calculated to 4% accuracy, no torque figure availiable though.

with mine i noticed alot of the power was around 14-16k which is where it should be they are peaky *****e smade to scream, stock tuning keeps it quite smooth all around.. tuned made it all top end, almost 2 stroke ish. the straight through can had 0 backpressure i have a sound file somewhere... awesome stuff, i'll post it tomorrow.

edit: and ye si had a magic box from japan so it wouldn't have 180k cut the way aroudn that is to unplug speedo>cdi sensor cables and measure resistance across the two outside lines of the three from the speedo side (not line i dont knwo what it's for) and then put that resistance value back into the ecu side feed and leave speedo unplugged, it will go over 180 that way i'd say as it would nevre detect resistance change. you will have to dismantle the top subframe by instrument clutster to get at it, it's the line that comes outta top of speedo, it has a plug under the neutral light.

[mynameis]

Ok perhaps a slight change of thought, think I will pass on the performance can idea aye. It would probably cost over $800 all up. (New can, jets, tuning and valves done) with little performance gain. But thanks for your input dood.

On the other hand I cleaned the bugger with UN Phosphoric Acid, it did a good job on the rust, brushed with metal brush and sand it down nice and clean then gave it a good paint. Now just have to put it back on.

Does it have to have gaskets? Or some lube type sticky thing before I mount it. Can't recall the name now. Sorry if the pic isn't clear, was taken from my cellfone.

[R6_kid]

looks good bro. The treatment is POR15, im guessing its just a commercial application of the stuff you used, but also includes a preventer and sealer... was going to suggest a wire wheel on a grinder but you got it all sorted.

To be honest, ask around and see if someone in Auckland can give you a little time on a milling machine. I reckon for $200 you could make a mint CF can, re-jetting/tuning isn't that expensive, truth is you main performance difference is gonna be in db not hp... it'll stop sounding like an electric sewing machine and more like a racey little sports bike.

*shouldnt* need new gaskets, but its not gonna hurt (maybe the wallet) if you replace them.

[wallzy]

cheapest perfomance gains from these bikes is with a straight through (yes proper straight through) can

hey u just answered one part of my question lol.
i am wanting to gain some power and thinking of exhuast mods.
i was reading my latest moto mag and saw that most of the motogp bikes are running straight throughs. i was wanting to do this to my zxr250 but didnt know whether it would make the bike better or worse.

i am thinking of goin from 4 - 2 with the tails running out the back of the fairing on either side using no cans. would this make my bikes performance better or worse. I understand that some rejetting would be required and that is no problem.

It would be a fairly easy mod if there are gains in performance.

thoughts would be much appreciated.

ryan