GSXR400 SP race bike info

[Quasievil]

Hi all a bit off a long shot but Im trying to find some information on how some other GSXR400 SP race bikes are set up , mostly interested in gearing and other mods done to the bike.
I have searched heaps on the net for some info but getting nought in return ,of interest anyway.
I raced Yesterday and had a few problems with speed, Im running a 47 tooth on the rear and a 13 tooth on the front (recently reduced from a 14 ) the bike was spluttering after about 11000-12000 rpms , I need the last 2500rpms to get the max speed out of the bike, My mates gsxr400 (not an SP) was whipping me on the straights. I should be getting more speed out of it.
Any advise or help or other will be appreciated.
Im thinking of getting the bike Dyno tuned soon to get it right as well

[bugjuice]

if it's spluttering at high revs, then that would point to a fuel starvation, wouldn't it..?? If you get the fuel flowing right, then you get the power sorted, then get the gearing sorted - would have thought.. Have the carbs had any work done on them? Compression in the cylinders good? and a good spark? May be get a compression test done

[Quasievil]

if it's spluttering at high revs, then that would point to a fuel starvation, wouldn't it..?? If you get the fuel flowing right, then you get the power sorted, then get the gearing sorted - would have thought.. Have the carbs had any work done on them? Compression in the cylinders good? and a good spark? May be get a compression test done

Yeah hear ya mate, fuel is likely. will be getting the Carbs soughted out at the shop soon.
I really have no idea about the condition of the engine and carbs as I have focused on other things clutch suspension etc, the engine does run sweet and I have had zero issues with it, but now I think yes its time to examine this further

[James Deuce]

Coil. 10 chars.

[FROSTY]

Hi all a bit off a long shot but Im trying to find some information on how some other GSXR400 SP race bikes are set up , mostly interested in gearing and other mods done to the bike.
I have searched heaps on the net for some info but getting nought in return ,of interest anyway.
I raced Yesterday and had a few problems with speed, Im running a 47 tooth on the rear and a 13 tooth on the front (recently reduced from a 14 ) the bike was spluttering after about 11000-12000 rpms , I need the last 2500rpms to get the max speed out of the bike, My mates gsxr400 (not an SP) was whipping me on the straights. I should be getting more speed out of it.
Any advise or help or other will be appreciated.
Im thinking of getting the bike Dyno tuned soon to get it right as well
Mate I told ya --you need to gear it up

[FROSTY]

actually mate I think ya need to talk to Mr slim (slims partner)
Theres a guy he bought his bike off of that really knows gixxers

[Quasievil]

Coil. 10 chars.

Explain Mr Jim for a retard ?

[Quasievil]

Mate I told ya --you need to gear it up

The gearing would have been perfect if I could rev it out.......... I think, Im going to put the 14 back on it anyway. this should give me more top end right, slower of the mark but better on the straights

[bugjuice]

Explain Mr Jim for a retard ?
if the coil is poked, it won't be able to fire a spark fast enough at high revs, which is also cause spluttering and misfiring. High voltage replacement coils (for your bike) could be an idea over stock ones if they do need replacing, since the bike is going to be spending more time at higher revs. Also check the leads too (no cracks, tight seals at the connections).. But as for the question, do they need replacing, that could/would be part of the elimination process of engine work. If they look knackered (and check for cracks in the unit), then the could be past their peak. But I'd get the carbs looked over and a compression check done too, to start with

Sorting out the clutch and suspension etc is obvisouly needed, but don't forget to look at the bike as a whole package! Brakes etc too!
Regular oil changes, checking plugs often, even take the head off the block (if you know what you're doing) and inspect the cylinders and fit a good compression gasket etc.. Depends on how far you (and your wallet) want to go. Looks like a sweet bike too, so it'd be a shame not to have the performance to go with the looks

[FROSTY]

Im beginning to be suspicious of that bike mate-- given our convo the other day.I just wonder if its soposed to have flat slides fitted to it.
Brett Please PLEASE -do yaself a favour and give it to Gary at GP trading.
Let him run it up on the dyno for ya and see if some jetting changes will let it rev out propperly.
The trouble with a race bike is the only way to tell how well its gonna go is on the track BUT a really good second place is the dyno.
You're going through the same shit I did with mella yella last year.As soon as it was rejetted and a couple of minor tweaks gary did it started to show its true potential.

[James Deuce]

Explain Mr Jim for a retard ?

I KNOW you're not one of them.

Are you running total loss? Check that your power supply is sufficient to generate spark at high RPM. Lack of electrical juice will manifest itself in a high RPM misfire, just when you don't want it. If your ignition coil is not generating enough energy for a decent spark it may also do the same thing.

[Artifice]

should top out about 190kph creates top power between 9.5 -10.5k rpm after 12k the power drops like a stone.

[bugjuice]

should top out about 190kph creates top power between 9.5 -10.5k rpm after 12k the power drops like a stone.
even an SP carb?

[Quasievil]

Its not a total loss its still a good bike !!!!



Nah kidding , it has a battery :whistle:

Thanks for the advice Buggy Frosty, I will get it over to GP trading for a dyno tune, whats the cost of that do ya know??

[Quasievil]

should top out about 190kph creates top power between 9.5 -10.5k rpm after 12k the power drops like a stone.

you sure dude ? whats yours a SP ?

Thanks

[Artifice]

http://www.400greybike.co.uk/
the guys here will have all the info you want in the forums.

mine is a 91 gsxr400 rr i think, frame is the gk76a.
it has an arrows exhaust and im only getting 13k/litre out of it on the hills.
cant seem to find my dyno chart for it.

[bugjuice]

http://www.400greybike.co.uk/
the guys here will have all the info you want in the forums.

mine is a 91 gsxr400 rr i think, frame is the gk76a.
it has an arrows exhaust and im only getting 13k/litre out of it on the hills.
cant seem to find my dyno chart for it.
the 'SP's have different carbs, designed to work better at higher rpm than 'regular' carbs, so the power band will be slightly different.. If yours isn't an SP, your bike might run out of steam quicker than Quasi's bike, but yours would be better at lower rpm and around town, sort of thing.. But the differences there would bearly be noticeable

[TwoSeven]

If you are running 13/47 tooth sprockets then I suspect you're way out of the ballpark.

I'm not familiar with the gsxr400 or what year bike you have but roughly plugging some numbers thru the calculator shows your only going to be getting about 150kph tops at 11k rpm with 13/47 final drive.

The bike was geared for roughly 180kph at 11k rpm (being a jap import they are all like that), so it would have to be geared stock 14/43 (or close to it). I suspect the SP model will probably be capabe of topping 220kph knowing the japanese.

They often design the bike with more power, then restrict it to 180kph, which is what its geared for stock, what this means is the torque which is minimum for its 220 top speed, becomes great for punching out of corners (what road bikes want).

My suggestion is go back to stock :)

If the bike is spitting at 11k rpm, whats the carb state of tune like - when was the last time it was stripped and cleaned. Do you have an aftermarket can on ?

[FROSTY]

Quazi --thinking about ya problem im a frigging eejut Im sorry --Unless your bike has the rev limiter bipassed ya aint ever gonna get full speed outa the SP
Sorry for not remembering
It costs about $50 and plugs into ya rev counter Otherwise when ya get to 180-190km/h or high revs in top gear the limiter cuts in and causes a misfire.
Your gearing is way out but ya already knew that. I think ya should have a 14 tooth front.
again talk to slims partner about the gearing thats about right.
Gary can sort that out for ya.
5746688 is GP's phone number

[Artifice]

well i found the old dyno chart.

[bugjuice]

well i found the old dyno chart.
does it redline at 12,500?

[Quasievil]

Thanks for all this guys fuck I love this site !!!!!!!!!!!!!!!!!!

[Artifice]

it redlines at 15000 :D

[Quasievil]

it redlines at 15000 :D

Mines reds out at 14500 rpm I think

[TwoSeven]

Quazi --thinking about ya problem im a frigging eejut Im sorry --Unless your bike has the rev limiter bipassed ya aint ever gonna get full speed outa the SP
Sorry for not remembering
It costs about $50 and plugs into ya rev counter Otherwise when ya get to 180-190km/h or high revs in top gear the limiter cuts in and causes a misfire.
Your gearing is way out but ya already knew that. I think ya should have a 14 tooth front.
again talk to slims partner about the gearing thats about right.
Gary can sort that out for ya.
5746688 is GP's phone number

Thats not a rev limiter, its a speed limiter (unless we are talking at cross purposes - then sorry in advance) - the rev limiter turns off spark to stop pistons/rods/cams moving faster they were designed for - eg. 12000 rpm, 15000 rpm etc. Often they'll turn off spark to reduce heat as well. That gives a shudder when it kicks in and you'll see the rev needle bounce back slighlty.

Speed limiter on most japanese bikes is 180km/hr - if its a mechanical speedo, likely you will find a contact in the back that needs a slight bend in it or you can just put a resistor across the wires at the cdi as some require (I cant remember which to wires, so you'll have to look at the wiring diagram).

On a 400, I probably wouldnt de-restrict it unless your going to re-jet and change the zorst, because the power it makes at top end, wont be enough to deliver the maximum speed in the distance you have available - the whole bike will have been designed to peak at 180kph. Often you'll find the dif. between an SP and normal bike is that the design has been moved 40kph up the scale. Its pointless extending the rev limiter unless you change the zorst design to move peak power and torque up the rev limiter further, if you change the zorst, your likely to require a re-jet to cover the impact on lower speed stuff (oh the joys of tuning).

The bike seems like it has incorrect gearing and bad fueling. I'd sort those first before tweaking anything else.

After that, i'd calculate your shift points and change properly. Is likely that you need to short shift a couple of gears if its using a road gearbox (proper race bikes use linear gears), As a rule, i've found that odd numbered gears are accelleration and even numbers are driving (they have big overlap), so you could probably short shift those, to enable you to get the drive required to get you up to speed (changing to a higher speed sprocket will counter this effect, hence its probably not worth de-restricting the bike unless you've increased power). You can check your shift points by doing an all-gear run on a dyno.

Not sure if any of that made sense, but what I am trying to say, is set it back to stock and fix the fueling - thats the optimum for that bike unless you do some engine work to increase power/torque. Remember, once its at optimum, the tradeoff will always be - gain speed on the straight at expense of corner exit capability. Thats why you often see bikes getting passed on the long bits, making it back on the short bits.

If you intend to ride at multiple tracks, then buy a few more rear sprockets, do the math and work out which combinations give the best results for each circuit and certainly consider a 520 chain - its worth a few ft-lbs of drive over a 425.

The last thing on changing sprockets is to remember that the angle of the chain/swingarm changes depending on the suspension compression - most bikes can only cope with 1-2 tooth difference before the chain loses drive or rubs against the swingarm (bad if the front sprocket is too small). So while the math might say 4 teeth difference on the rear, check the bike can actually take it :)

[FROSTY]

well aint it interesting -all the fancy theories flying around and ol frosty was right. --If he wants to I'll let quazi fill ya in on the exact details.
suffice it to say that quazi's bike will be a fair bit faster next time at pukie

[Quasievil]

well aint it interesting -all the fancy theories flying around and ol frosty was right. --If he wants to I'll let quazi fill ya in on the exact details.
suffice it to say that quazi's bike will be a fair bit faster next time at pukie

Okay good one ol frosty.

The Bike has been at GP Trading all week for a bit of attention, heres what they found
1/ Plugs needed to be replaced
2/ Needles needed to be adjusted as well as the jets
3/ They put in a Cam from a CBR600 ? I dont understand that one
4/ The bike had 3 speed restrictors in it, this would be why I was going so slow on the straights
5/ The engine was running lean down low and rich up top so theyve corrected it
6/ They gave it a good going over and tuned it on the dyno and got me another 3 HP and a engine which is running alot better

They did a bunch of other stuff as well to get it into race shape and have already suggested further mods and improvements for getting more grunt outta it.

Watch out Frost now I will be on youre Arse !!

[Artifice]

so, can you post your dyno chart? i think mine is just a little down on power.

[TwoSeven]

So they fixed the fueling - did they do the gearing as well ?. Also what year cibby cam(s) did they use - was it just inlet or exhaust as well ?

Not sure where the third restrictor was unless it was inlet (fuel) related, but I'd be interested in seeing if you beat 180 on the speed gun :)

[Quasievil]

so, can you post your dyno chart? i think mine is just a little down on power.

Yeah I will, the bike is still in Tauranga I pick it up On Tuesday so will post it then mate

[Hoon]

The Bike has been at GP Trading all week for a bit of attention, heres what they found

Haha you n00b!! But awesome dude....can I ask you how much it cost?? I'm thinking of getting my race bike tuned up just to get the most out of the package.

You should be flying now!! Sorry I wasn't much help but I under the impression that the problem you had was a new one that just appeared.

Yeah also your gearing sounds a bit short for Puke, would be alright for Taupo though. I"m running 14/45 (15/45 stock) at puke and I'm hitting the limiter just after the kink and also on the front straight in 5th (14500rpm) - I think I need to change to 15/46-47.

[Quasievil]

Haha you n00b!! But awesome dude....can I ask you how much it cost?? I'm thinking of getting my race bike tuned up just to get the most out of the package.

You should be flying now!! Sorry I wasn't much help but I under the impression that the problem you had was a new one that just appeared.

Yeah also your gearing sounds a bit short for Puke, would be alright for Taupo though. I"m running 14/45 (15/45 stock) at puke and I'm hitting the limiter just after the kink and also on the front straight in 5th (14500rpm) - I think I need to change to 15/46-47.

Errr yeah well okay Im a NooB

Im running 13/47 but wil change back to 14/47 and use 13/47 for taupo Im thinking. I need a trackday to sought it out a bit I reckon.
I havent had the Bill yet so dont know.... scary

[FROSTY]

Quazi
The cam was because it was easier than regrinding your cam. What you'll find is your midrange is going to feel a lot more punchy --Ie coming therough the esses after jennian your gonna have more oomph
I think you'll really notice it at Taupo when ya snap it on after the hairpin.
The jetting was all part of the dyno work -The reasion it needed it was it was still jetted to pass the jap emmission control laws and even worse it had that exhaust problem.
I'd try to work in another track day at pukie before the 21st and bring a range of sprockets. My gut still says you should be running at least 14/45
maybee even 15/45
Your starts on that bike arent ever gonna be super flash unless ya pluck 1st gear and bung in a stock gixxer400 first cog
Ohh and matey -given how fucken slow Im riding You'd best be aiming for someone elses ass unless ya wanna come dead last

[ggas250]

hey there Quasevil what cbr 600 cam did they put in your bike and did they put both in or just ex or inlet. What sort of difference did it make to the bike?
Cheers Wayne
Australia

[El Dopa]

hey there Quasevil what cbr 600 cam did they put in your bike and did they put both in or just ex or inlet. What sort of difference did it make to the bike?
Cheers Wayne
Australia

Wayne, Quasi sold his 400 months ago.

If you want tuning info on the gsxr400, I recommend hanging around on banditalley - http://forums.banditalley.net/index.php

There's a couple of guys on there who are really knowlegeable on all the 400 tuning stuff. Talk to gsxr400racer on that forum.

[Morcs]

They all go BANG pretty quickly anyway.

Sell it and get an nc30...