hardcore tuning - questions :]

[havnek]

Hi everyone. I just bought a zxr 400 a couple weeks ago after my VFR 400 was stolen on new years eve just gone! Im very glad to be joining the zxr owners club I must say, the VFR was definitely quicker, but then I paid £1700 for a top condition VFR (from a garage) and I only spent £850 on my 1992 ZXR 400.

Any way, My ZXR is in the garage waiting for a new chain + sprocket kit to be fitted, as well as cam chain to be adjusted or replaced. My bike has a G-Force Race Can on it, which is literally the best sound i've heard from any 400 (and actually most bigger bikes!).

My question is this: My zxr has 40,000 miles on the clock. Taking this in to consideration, is there any point in me doing any real engine work? Over the next couple months I can either invest ~£1000 in getting a full exhaust system, big bore kit (to 444cc), RAM air system and some nice wavy discs + other various little mods, or I can spend the money on buying a new engine and getting it fitted which will only leave me with enough cash for the big bore kit or ram air. And even then, is a bike of this age and usage going to be worthy/reliable enough to cope with the new bits? Another consideration would be to save up for the next couple months, sell my ZXR and buy a new one for closer to £2000.

I REALLY want to squeeze some more performance out of my 400 because I can't afford the insurance on a 600 for toad, and I know this pocket rocket can give me more UMPH having owned a VFR 400. When i next get paid at the end of may I will be looking to upgrade! any advice would be helpful, cheers!

[RedexRobB]

hi there and welcome to the forum! Glad to hear you have joined the ZXR camp and not those sissy hondas again

Long as you keep the engine maintained it should last you for double that mileage. And any performance mods such as the full system, are setup correctly you shouldnt have any problems engine wise.

As for the 444 kit, ive no idea what effect that has on reliability, no one here has had one long enough to tell us really. I know the racers are running upto 80bhp with tuning (not big bore) and as far as i know they have no issues.

Personally id spend the money on getting the engine serviced with some light tuning and spend the rest on good cosmetics.

But sounds sounds like you will have an interesting project to play with so keep us informed!

[havnek]

hi dude thanks for ur reply

Yeh when i took the bike to the garage, I basically said that I would like the bike totally checked over so that anything that needs doing I will sort out now. The main issues were identified as the cam chain + chain/sprocket, which are being mended. Also the bike is being generally serviced (change oil etc.)Next on my agenda will be getting some iridium spark plugs as well as getting this alarm ive bought fitted.

The bike does need some work cosmetically, there are bits of a gaffa tape behind the speedo and other unnoticable areas. The bike still looks awesome from a distance. I figure these are inexpensive jobs to do, which I plan on doing myself over the next month or so.

Do you think I should do the exhaust system first before the ram air or big bore? I think the big bore kit will probably be the last thing I do. Although, I did make a phone call to AMS motorsport who supply the RAM air box and the guy on the phone said he really doesn't think I should get the full ram air system on a road going bike because it will shift power to the top end and make riding at low speed (through traffic etc) a pain. This makes me lean towards a big bore kit first hehe

I shall take some pictures when the bike is back from the garage so you can have some before and after pictures once ive finished supin it up

[jake]

howdee..
Im sure yr bike just needs a bit of a going over, new plugs, clean and balance them carbs, a new battery. It should not feel slower than the honda...i presume you are giving the kawasaki the full inch from death throttle that it needs?!
Ill agree with ams, and would'nt get the ramair setup on a roadbike..for one, it does'nt have provision for an air filter, the amount of crap you would suck up on a road would'nt be good for the engine. Just make sure your standard air filter is clean, if not buy another standard one.
After you get yr bike back with the new tensioner and cam chain, get stuck in to them carbs with some carb cleaner. new plugs and battery( check them plug leads). Then if you can afford it, get a beet system. Im sure someone on here got one direct from japan for around 500 quid. Then take the main jets up a tiny bit, around the 100 dynojet mark, with the air correctors blocked.
thats basically all i have on my racebike, and thats 63 bhp on a dynopro, which is probs pushing 70 on a dynojet. Its not a mega rocket, but it is quick
Im not sure how much the big bore kits give you...ive heard they put a bit of extra strain on your crank, dont really effect top end hp, but give you more mid umph. Likewise, im not sure how much they cost, but a rebore is probs gonna be 250+ surely.

good luck dude, and keep us informed!

[rover220]

rebore will be around £100 based on my car engine experience

[jake]

ahh, thats cheaper than i thought...but then add in head/base gaskets and labour charge, for engine out / strip/rebuild/in. all depends on how much Mr Havnek wants to do himself i guess..

[Jamz]

Over the next couple months I can either invest ~£1000 in getting a full exhaust system, big bore kit (to 444cc), RAM air system and some nice wavy discs + other various little mods

Are you sure you can get all that done for that price???

Just my rebore (ride-in service) cost £1500!!!

Having said that, it's a absolutely awesome mod - it gives it the same engine characteristics as the 750, and so it's much more useable (and faster) on the roads! It makes it feel like a whole different bike, and I'd love to rebore any and every bike I've ever had if i had the cash!

One thing I will say, is that if you're getting it re-bored, buy a whole new wiring loom and either fit it beforehand (so you can iron out minor problems) or let them do it.

Mine was a '94 model and once they disturbed the old loom I had no end of electrical faults simply because all the old wiring had been disturbed!

[havnek]

thanks for all your replies. Jake what you've posted makes a lot of sense. I think I need to get stuck in and restore this bike to what it can be before i start modding it. I spoke to my friend from Yamaha and he said to me that putting a ram air will improve the top speed but it wont be worth the cost at all. He did say that if I wanted faster acceleration I can get sprockets with more teeth on them. This drops the top speed but increases acceleration - which i think is brill. The only problem is I've just spent £70 on a new DID chain and sprocket kit and i really dont want to buy a new set already lol...

[Gemini]

there are bits of a gaffa tape behind the speedo and other unnoticable areas.

you didnt buy it off jamz did you?

gem

[Gemini]

i had an rvf400 so basically same engine as your vfr had

i then bought a zxr L1

you, as i did, will notice that the vfr/rvf will be quicker accelerating as the v4 engine gives greater low down torque, however the hondas will quickly run out of steam, whereas the zxr will go faster top end

gem

[Ballsout Racing]

The only problem is I've just spent £70 on a new DID chain and sprocket kit and i really dont want to buy a new set already lol...

Just get one tooth smaller front sprocket, that'll be the cheapest option. It has the same effect as increasing the rear sprocket by 3 teeth. No need to change anything else you've just bought