turbo on a 400?

[TUG]

i been reading about tuning my fzr, and in 4 stroke tuning it says that air boxes on bikes are basicaly aload of shit, so i was wondering if anyone knows what mm my carbs are and where can i get some K&N stacks to fit? cotton ones.
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Haz ER-5, innit!

[Big Pete]

If you're reading the book by Bell, the airboxes hes talking about are from the likes of GS1000s, which were indeed shiite. However, on more modern tackle the airboxes are pretty good, and a set of K&N filters are likely to make matters worse rather than better.
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Trust me, I`m an engineer
GarageOfPower.co.uk

[TUG]

thats the very book, when people do the tank swap on my bike they cut the airbox up and it works better, so its either mod the box or use stacks. what would you recomoned?
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Haz ER-5, innit!

[Kickstart]

Hi

Airbox is there to provide a large calm reservior of air. Think the rule of thumb is that they need to be at least 10 times the capacity of the engine (ie, your bike needs an airbox of at least 4L volume).

Next important bit is the length of the pipes from the carbs into the airbox. The lengths on these is tailored to the revs the bike is designed to produce best power at (just like exhausts), so if you loose these when you fit single filters you will likely have a mismatch between the engine tuning and the intake tuning.

Then there is the issue of single filters getting wet when it rains.

Not sure on the FZR400 but I know people have major issues getting the 1000 to run acceptably when they dump the airbox. Far easier with the airbox in place if you want to avoid flat spots all over the place.

I would suspect that if you are changing the tank for one from another FZR then the best thing to do would be to get the complete airbox from that bike as well. You might be able to unscrew the top of the airbox and put it onto the existing bottom of the airbox from your bike.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[TUG]

i dunno then, everything seems to have a set back. maybe drill a few holes in the box or cut the nozzle down, some one cut down there box on the GB400 forum and used a car filter and it worked really well. dunno i suspect that i'll have to do most of this stuff after an engine rebuild and carb refurb then dyno then tailor everything to suit when i start the tuning process.
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Haz ER-5, innit!

[Kickstart]

Hi

Cutting holes in the airbox would not be a good idea (and would also bypass the air filter which would definatly not be a good idea on the road).

Cutting down the airbox would be much the same as removing it, except you would keep the stock "ram tubes".

I would doubt the air filter on the 400 is restrictive, so changing it (or fitting a K&N) will probably do next to nothing (although you can clean the K&N).

Everything has a down side because the people who designed the bike did a pretty good job, within the bounds of keeping it legal and selling it for a reasonable price (and new it cost would have been equivalent to, say, an R6 or CBR600RR). You might well be able to get some more power with a decent exhaust system and spending a bit of time setting it up on a dyno. But on a 15+ year old grey import bike you will struggle to find a decent exhaust system.

To be honest, start out and work out what your budget is and what you really want. If you have, say, £1k to spend then just budget to pay someone for a rebuild (eg, replace rings, replace valves, camchain, main and big end shells, clutch basket, clutch plates, maybe a gear or 2). £2k then the same rebuild but with a big bore and some stronger rods, and with a bit more money a bit spent on gas flowing the head. And on like that.

If you are concerned about cost (and given your comments on going overdrawn to buy the fairings I suspect you are) then just pick up an FZR600 engine and lob that in. Simply put, for the cost of paying someone for a full rebuild of the 400 engine you could probably buy half a dozen 600 engines and lob them in until you find one that is perfect.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[TUG]

if i was to have it rebuilt i'd buy parts to save labour, and i'm not selling the bike, if i was to sell the 20 yr old bike in mint condition i would be lucky to get £1200, and i've already spent that so i would lose. we'll see what happends, might just overhaul the engine and carbs and leave it be, with refreshed engine and carbs it will pump out 50-60bhp i cant remember how much it pumps out stock.
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Haz ER-5, innit!

[bladerunner]

Here is a dyno from a iffy 400

https://www.29dreamsracing.com/images/Dyno.jpg[/url]

And here is a dyno from an FZR 600

https://heath.agdog.com/fzr/specifications/dyno-values.jpg

Now why spend the ££ on a 400??
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[TUG]

because i'm original?
i'll end up buying an NSR250 before a 600 anyway.
loikes how they looks and sound. if a good 600 comes along then will buy one, but atm i'm thinking of just refurbing the bike as a true restoration project.
all the info in this thread was amazing thanks guys.
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Haz ER-5, innit!

[NSR Mick]

[TUG]

i guess its more than likey to happen anyway mick, i like old bikes, an 2 strokes have been cool for my for ages, i like the NSRs and TZRs most, and the RGVs and really really nice. it must be the the fact of rareety that appeals to me.
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Haz ER-5, innit!

[NSR Mick]

You'll need to decide pretty soon. People are starting to ask silly money for NSR's if that's what your after.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[TUG]

i kno, thinking of getting one next year, buying one from a dealer on terms, looking at about £4000 if i find a better one cheaper then that will be the buy, but who knows, its all about luck at the end of the day.

my girlfriend really likes them so i guess the push to buy one is also very very great, been told i can keep the 125 version in on corner of the living room and the 250 version in the other
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Haz ER-5, innit!

[bladerunner]

I race a couple of RGV's. Any info you want on them..pop over to RGV250.co.uk you'll also find links to the NSR forum there as well.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[TUG]

i've got to say the only 250 i dont like is the kwak Kr1 i dont know why, mye its just nice looking enough. but if i get a decent job a bike like the nsr will be bought.
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Haz ER-5, innit!