Hot start problem Gen 3

[White-Busa]

Good day all

I saw some related topics to the hot start problem with Hayabusa gen 3.
I am facing the same issue with my Hayabusa 2023 and after visit the dealar he advised to replace the starter torque limiter part. I am wondering If any of Busa group try the same or If you guys have any other suggestion to solve this issue.

[Bumblebee]

Welcome,

Sorry to hear of your woes...

There is a thread on this subject in the Gen 3 section.

hard start | Gen 3 Busa Information

i experienced a hard start issue. its annoying and ive been able to recreate it. i first noticed it when i let someone ride it and they stalled it. then when they tried to restart it but hitting the start button (without cycling the key.) the engine is slow to crank and sounds as if the battery...

www.hayabusa.org

[Hayabusa Wannabe]

Welcome to the forum @White-Busa.

Do you get to ride year-round where you are?

[White-Busa]

Welcome to the forum @White-Busa.

Do you get to ride year-round where you are?

We only ride in winter for a couple months when the temperature around 15c to 23c

[Rocinante1966]

New to this forum. Got a 2 year old Gen 3 with 5700 miles on. Mine's just started the hot start problem. The first time it sounded like a battery issue when the starter was pressed. Every other time I get the sound of nothing at all. After 5 minutes or so it then starts no problem. Opening the throttle didn't work. Can't go touring with it like this. Any solutions please?

[Hayabusa Wannabe]

Welcome to the forum @Rocinante1966.

[Rocinante1966]

After speaking to my electrician I think I've found the solution to the Hot Start issue. He explained that cables have much greater resistance to electricity when exposed to high temperatures. Makes sense so far? As the cable cools, a greater flow is achieved. Therefore, the starter motor cable needs to be thicker in order to allow greater flow of current. This is why after a few minutes of having the problem, the cable cools and electricity can flow once again. Also if the bike battery is not 100%, this will also cause problems with power flow. Apparently this has also been an issue with certain Triumph motorcycles and replacing the starter motor cable has cured the problem.

[sixpack577]

After speaking to my electrician I think I've found the solution to the Hot Start issue. He explained that cables have much greater resistance to electricity when exposed to high temperatures. Makes sense so far? As the cable cools, a greater flow is achieved. Therefore, the starter motor cable needs to be thicker in order to allow greater flow of current. This is why after a few minutes of having the problem, the cable cools and electricity can flow once again. Also if the bike battery is not 100%, this will also cause problems with power flow. Apparently this has also been an issue with certain Triumph motorcycles and replacing the starter motor cable has cured the problem.

Sounds good in theory, and as no one has found a foolproof solution yet, I think you'll just have to try it and see.
A new starter cluch disc seems to have helped in some cases, but not completely fixed the issue.
Please let us know what you find out.

welcome to the org

[jellyrug]

After speaking to my electrician I think I've found the solution to the Hot Start issue. He explained that cables have much greater resistance to electricity when exposed to high temperatures. Makes sense so far? As the cable cools, a greater flow is achieved. Therefore, the starter motor cable needs to be thicker in order to allow greater flow of current. This is why after a few minutes of having the problem, the cable cools and electricity can flow once again. Also if the bike battery is not 100%, this will also cause problems with power flow. Apparently this has also been an issue with certain Triumph motorcycles and replacing the starter motor cable has cured the problem.

Unlikely, the voltage drop on such a short cable is totally negligible. What could affect it, is a bad connection somewhere, which is also unlikely.

[Peter1127]

Its a bit hard to diagnose with a "it doesnt start when hot". Does the engine go round smoothly and fast but just doesnt start, does go round very slowly, doesnt go round but it tries, or nothing at all? Can you find a workaround to start it, and what is it? Or do you have to wait for it to cool down? How do you try to start? On sidestand or not, in gear or not? Error codes or not?

Too much resistance in the high current cable is not the cause. If it worked before and stopped working, the cable didnt magically become smaller. It would also mean that all hayabusa's would have this problem, since they all have the same cable gauge.

As I see it, the following could be, although many should be the same cold or hot. I also stated unlikely causes.

Problem in the high current circuit

• Severe corroded connection.
• Loose connection.
• Failing starter relais. Measuring the voltage on the starter when trying to start would reveil that.
• Failing starter motor. If you push the bike back a bit when in gear, the starter moves a bit and carbon brushes are on a different position. When it starts then, replace carbon brushes or complete startermotor depending on the state of the copper contacts
• For the sake of being thorough: battery and/or charging system problem.

Problem in the wiring/sensors

• Measure the voltage towards the starter relais when trying to start. No voltage, of course no starting. Could be any gremlin of course, first check all connectors and use contact cleaner. Check for damaged wiring.
• Sidestand/neutral/clutch switch issue. Measure or bypass (when bypassing make sure bike is not in gear or wheel is off the floor)
• Crankshaft sensor. Does it throw codes?
• Cam sensor. Does it throw codes?

Problem in the ECU

• If I read the posts of the other problems, a power cycle solves it so imo that points to ECU related stuff. Does it throw codes?
• immobilizer gremlin
• aftermarket alarm

Problem with the ignition

• Coil(s) fail when hot
• Plug(s) fail when hot

Problem with the injection

• Bike is very hot: vapour lock so no fuel
• Pump problem: do you hear it priming or not? If it does, if you prime a couple of times does that help?
• Leaking injector causing hydrolock. The smoke after starting it again should give it away

Mechanical

• Hydrolock because of coolant in a cylinder from crack in head
• Clutch torque limiter was mentioned. I'm not sure how that would impact starting. When the bike is in neutral the whole clutch turns regardless of torque limiter, and when in gear with clutch lever in maybe a clutch problem causes this but you will notice the bike trying to go forward.
• When trying to start the bike in gear with a sticking clutch. You will notice the bike trying to go forward.
• Extremely low compression.

Hope this helps.

[Rocinante1966]

Good day all

I saw some related topics to the hot start problem with Hayabusa gen 3.
I am facing the same issue with my Hayabusa 2023 and after visit the dealar he advised to replace the starter torque limiter part. I am wondering If any of Busa group try the same or If you guys have any other suggestion to solve this issue.

Hi. Posted a solution on here earlier but can't find it. My electrician remembered some Triumphs have the same issue. Cables, when very hot, lose the ability to conduct electricity efficiently enough to turn the starter. This is perhaps why the bike will start again after only a few minutes. The solution is to replace the starter cable with a thicker one which can handle a greater electrical load. The problem can sometimes be made even worse if the battery is not quite 100%, which is why the starter will turn, but not enough to start the bike.

[mabupa]

Hi. Posted a solution on here earlier but can't find it. My electrician remembered some Triumphs have the same issue. Cables, when very hot, lose the ability to conduct electricity efficiently enough to turn the starter. This is perhaps why the bike will start again after only a few minutes. The solution is to replace the starter cable with a thicker one which can handle a greater electrical load. The problem can sometimes be made even worse if the battery is not quite 100%, which is why the starter will turn, but not enough to start the bike.

I think you are barking at the wrong tree. @pashnit found the part that eventually fails due to the engine struggling to turnover but, it can only be replaced with the same part and nobody has found why the engine provides so much resistance/compression when hot that it causes the clutch plates on the starter torque limiter to wear prematurely.

[pashnit]

I am facing the same issue with my Hayabusa 2023 and after visit the dealar he advised to replace the starter torque limiter part. I am wondering If any of Busa group try the same or If you guys have any other suggestion to solve this issue.

Here's your problem. Or... at least how I solved my hot start issue. After all, what do I know. You do you.

I replaced my Torque Limiter Assembly and it fixed my hot start issue completely.

I'm gonna miss this forum where we can't constantly argue over how to fix this and what's causing it.

All I can tell ya is my brand new 2022 wouldn't start once I reached 7000 miles on the clock when the motor was warm.
NONE of the 'throw darts at the wall' solutions listed above work, at least for me.

gas or varying the octane - nope
new battery - nope
cables - nope
Gremlins - yah, nope, not when it affects nearly every Gen3, that's not a gremlin, that's a bad part from the factory.
Re-programing the ECU - wait what, how does that make a slipping clutch work? That makes no logical sense.

I push-started my Gen3 for 5000 miles, until I replaced the Torque Limiter Assembly with a new stock Torque Limiter Assembly I got from Partzilla.
Nothing would make the bike start while this clutch is slipping & the motor is warm, push starting works, the bike fires right up with the slightest effort. Although I'm probably getting a little old to be push starting 550 lbs motorcycles.

Here's what's on the inside of the Torque Limiter Assembly. See the clutch plates? Again, it's a brand new bike, so none of this makes any sense. Worth mentioning I never had any hot start issue on my other three Hayabusas.

Now that the Torque Limiter Assembly has been replaced (with a stock part mind you), I've put another 30,000 miles on the Gen3 and zero issues starting.

However, I'm left with what the manual says when hot- I have to do this all day long when I'm touring, normal day for me is 300-500 mile days with lots of stopping and as long as I remember to twist the throttle 1/8 turn when starting, fueling up, stops for cookies - fires right up. I've put 35,000 miles on my Gen3 in the last 2 years. Fine, I can live with that.

Gonna miss you guys. Don't want to argue about this on Facebook.

If you try this above from the manual and it does not work, I'd start with the Torque Limiter Assembly.

[Peter1127]

Ah I was thinking the discussion was about the clutch back torque limiter...... That didnt make sense to me. Didnt take this apart (yet) and didnt know there is an actual clutch in there. Well you live you learn. I can see this causing a hot starting problem yes.