Managed to get bike running, WAHOO still need advice please

[400_Rider]

Right ... so close :)

I couldn't sleep much last night thinking about the 400RR and I was going through in my mind all possibilities, see most of what I have read online says you need 20mm when setting the float height and my factory pro stage 3 instructions says I need 15mm, I did set them to 15mm and thats at its absolute max and 20mm is not possible.

I did read that the carbs on the SP2 model were different to other GSX-R 400's and I think thats where the confusion is.

So today I decided to do the opposite of what I have been reading online and I LOWERED the float heights to 12mm each.

Once I did this I tried to start the bike, no joy, then I tried to bump it, still no joy but it sounded better like there was more chance of it starting.

I had all but given up when I thought I will give it one last go but try something different and this is what I did.

Ignition off, choke on full, I then pulled the throttle right back and held it there, put ignition on and hit the starter button, the engine began to crank and crank and about 4 seconds later the think started YAYYYYYYYY.

I took some videos to better demonstrate whats going on with the bike as follows :

This video shows the bike about 1 min after it started, I quickly got the camera out and started to record.

As you can see, plenty of white smoke which soon stopped, and you can also see bits of oil that have been spat out the exhaust against the back door, this was before I did a carb overhaul so I am not sure if it still does this.

You can then see me revving the bike and adjusting the idle to try and get it as low as poss, the bike rev counter STARTS at 3,000rpm and it doesn't want to go much lower than this.

http://www.youtube.com/watch?v=s1KOVss_tCk

Listen to this video around the 14 second mark, this is typical of what happens, idle is ok, ya rev it or do owt and the revs drop and the bike dies :

http://www.youtube.com/watch?v=xa4cv4SQpCA

Finally .... I sat on the bike, pulled off slightly then pulled the clutch back in and put the bike in neutral and this action stalled the bike, again no good if am at a set of lights, so why is this happening ?

http://www.youtube.com/watch?v=9MxAq5F-qKE

The main thing is, I can get it started :D so I can now test compression when the engine has been run to get an accurate reading and I can also set idle screws correctly with me coloutune.

But before I do any of that this is my question that I do not have the answer to .....

How come the bike started with the throttle back to the stopper ? whats happening and the relation in the carbs when I do this ? and does this suggest that the needles need to be lowered or raised in order to compensate for this ? or is it all idle ? I just don't know.

ANY input would be much apprecaited.

Matt - Soon to be (with any luck) super fast 400RR Road Racer :D

[timoth123]

it doesnt sound like its running on all 4 to me. but then that could be video quality

[400_Rider]

Any easy way for me to tell Tim ?

[Variablevalves suck]

Hi,
Easy way to tell is the exhaust down pipes get very hot very quick, so if one aint workin it will stay cool. You'll have to take abit of time settin up the carbs if you want to run no air box, theres no quick fix.
You should always start with correct float hights then the main jet and main air jet, main jets to give the corret mixture at the bottom end and then change the main air jet to corret the mixture at the top, on lots of production carbs the main air jet aint adjustable so problemo, then set the idle with the pilot air jet and pilot screw, then the midrange is needle jet which will be fix, part of the emulsion tube, and the needle, but remember they all overlap. From the video youve got a big hole just as you open the throttle which wil be helped by richenin up the idle system, but could cause the tickover to be lumpy, a bigger needle jet may help but you carnt change this so poss lifting the needle up may help, this could give too much fuel in the midrange but worth a go, if youve the money, the quickest way will be to dyno the bike!
Chris.

[400_Rider]

Thanks for that Chris :D I'll give it me best shot and if I can't get it right, dyno shop here we come then

[Variablevalves suck]

Ive tried to keep it as simple as i can, they all overlap but try and look at them as seperate parts. Remember just running with and without the plastics can make a difference. If you race you never got the carbs shut so can put up with bottom end issues, but on the road they can be a pain. Dont run it weak and remember they usually feel crisper when weak but go pop!

[gsxr400 racer]

turn the idle down...counter clockwise...please adjust the valves noisy as hell...if it wont idle when you turn it down you have carb issues figure out why the one cylinder isnt working

[Variablevalves suck]

If you want to stick at it yourself get either Motorcycle Service and Set-Up Data by John robinson or Motorcycle tuning 4-stroke by the same guy, d'nt know how much for the first title but the second is expensive as not printed anymore, they were wrote about the sametime as the gxsr was made and wot he dont know aint worth knowin, possibly buy them second hand. They are not to deep a read and will tell you everything you need to know about carbs.

[400_Rider]

Thanks for the info guys, I've been out to it twice tonight, both times it fired up straight away, problem is, it will only do this if I ALWAYS leave choke off and give it FULL throttle before I press the start button, when I do this it fires instantly.

I'll get the idles set tomorrow, of float bowls was set at 15mm, wouldnt run for love or money, I set em back to 12mm and after a bit of fiddlin it started.

Bikes .. who'd have em eh

I'll know more tomorrow :)

[Variablevalves suck]

it should be ok at 15mm, sounds like youer gettin to much air due to the open carbs.