been a minute, back on busa, need help please

[busa matt]

ok guys, after a long while of riding 1k's, im back on an 07 busa. I love this thing, but its seriously pissing me off lately! im going to try to explain this as best I can, without making it tooo long. first off its an 07 with zero motor mods, save for two brothers slippers, flashed ecu, air filter,tre, that's it. it runs excellent. I have done an 08 1k front end swap, and im running 1k wheels. other than that shes pretty much stock.

the problem I am having is when its warmed up and I stop the bike most of the time it takes a while to fire back up when I try to restart. sometimes it will start right away, and others it will just crank and crank till it finally goes. sometimes to near the point of the battery dying. its very intermittent, no pattern, just random. it starts right away when cold. this is only when hot.

things ive tried with no change whatsoever:
compression check and checked valve lash
new battery
checked grounds
swapped ecus with known good one
swapped gas tanks with known good
swapped cam position sensor
checked crank position sensor and charging system
changed plugs
checked codes and set tps

im really at a loss here. I know my way around bikes very well. I build engines, im an industrial electrician with a strong controls background. and im ready to put bullet holes in this thing. please someone point me in the right direction with this....any help is greatly appreciated.

 

[c10]

Coils have you had a look at them ? I have seen many go on Kawasaki models causing similar starting issues .

 

[busa matt]

I have swapped coils, no change.

 

[c10]

Had a first Gen FJR1300 that would start easy , and sometimes not start at all . It turned out to be a Ignition switch wire broken . With bars in a certain location it would start fine , but in other positions no start . Found the bike had been taken apart in front end for service I guess in past , and the wires were not routed correctly , and the tie strap that keeps a load of the wire harness was not present .

Fix was split loom solder broken pwr wire , and heat shrink it .

Good luck .

 

[VIPER]

first dump the tre. that maybe your problem. if the ecu is flashed it and the tre will fight each other. keep us posted.

 

[Lycan6]

first dump the tre. that maybe your problem. if the ecu is flashed it and the tre will fight each other. keep us posted.

agreed. If you have the ecu flashed there really is no need for a tre.

 

[busa matt]

I did do that, I thought the same way. It too didn't make any changes tho. I went through yesterday with the manual and tested the majority of the sensors on the bike. All came out good. This is really baffling me. I'm going to try to upgrade the size of wires to ground and to starter relay and starter. I shad this similar issue in a big bore 06 that had troubles starting and that fixed it.

 

[VIPER]

yours is almost acting like the fuel pump isnt building pressure to the fuel injectors

 

[TallTom]

Keep us posted. I sometimes suffer with this. It has no rhyme nor reason. I have often wondered WTH sometimes.

 

[RedBusarider]

Something to try, as you didn't say you did, is try some fuel additive. Techron, or Seafoam are 2 worth trying.

Doubt it could/would make it any worse - and it just might surprise you and make things better - like easier to start etc.

 

[Aruba_Busa]

i Had this issue on my 2006 , and it turned out to be the clutch lever switch , it drove me crazy
:tantrum::tantrum::tantrum:

 

[busa matt]

I swapped complete tanks with my brothers 05 which runs fine, no change

 

[Busarider007]

have you checked for spark when cranking? injectors? is it overheating?

 

[Kennith Fultz]

Are you absolutely certain that it has not been bored to 1397?

 

[busa matt]

have you checked for spark when cranking? injectors? is it overheating?

Yes checked spark, not overheating.

 

[busa matt]

Are you absolutely certain that it has not been bored to 1397?

I wish,haha!

 

[Busarider007]

Seems that you tried the most common symptoms, have you tried to jump the side stand & clutch switch? any codes again, sometimes the TPS could give a false reading, try swapping it as well.

 

[busa matt]

Seems that you tried the most common symptoms, have you tried to jump the side stand & clutch switch? any codes again, sometimes the TPS could give a false reading, try swapping it as well.

I found a decent set of throttle bodies, I'm going to try swapping out, but I did set tps properly and triple checked readings

 

[sixpack577]

I went through the same thing with a 94 zx7.
It turned out ot be a short in the main wiring harness.
I sold it to the guy I bought my parts from then, as I had given up(and had bought a 1k)...took him 4 months to find it.
As the break in the wire would only seperate or short when pulled, twisted(or vibrated from the running engine which after wouldn't restart).

 

[busa matt]

Ok, so I swapped out the throttle bodies, set the tps, and found a quite noticeable difference. Starts better, idles much better, nice throttle response, and no more high idle when warm. Not totally sure this was the whole problem, but it is better. I'm going to up wire size to battery, and starter/relay and see if this helps out.