Hard starting randomly (redux)

[Buggy Nate]

Since I've started to have this problem again, and I've been in touch with my dealership about it, Yamaha is replacing my entire throttle body assembly under warranty.

That is such a lazy way of "fixing" the problem... So even if it does fix it, (which I doubt) they wont know what component was the cause. Be it the TPS, map sensor, Accelerator PS, Air temp sensor or the actual throttle bodies themselves. But please let us know how they get on with it.

[Guest dmizer]

Perhaps not, but I presume they aren't simply going to throw the thing in the trash. They will want it for testing.

[Buggy Nate]

Perhaps not, but I presume they aren't simply going to throw the thing in the trash. They will want it for testing.

 
Don't get me wrong, I hope it fixes your problems. I just get the shits with mechanics who don't know how to test and diagnose properly and are just parts swappers. It's these customers that we get the most of at work and already have a sour attitude (rightly so) after being dicked around for so long.
The components are much easier to test while they can be put back into service under operating conditions to ensure the problem is solved.

[britelitebob]

Perhaps not, but I presume they aren't simply going to throw the thing in the trash. They will want it for testing.

Don't get me wrong, I hope it fixes your problems. I just get the shets with mechanics who don't know how to test and diagnose properly and are just parts swappers. It's these customers that we get the most of at work and already have a sour attitude (rightly so) after being %$@#ed around for so long. The components are much easier to test while they can be put back into service under operating [span]    [/span]conditions to ensure the problem is solved.

 
 
You know things have really gotten bad when they cant even fix a Japanese bike in Japan.
 

[Guest dmizer]

I just get the shets with mechanics who don't know how to test and diagnose properly and are just parts swappers. It's these customers that we get the most of at work and already have a sour attitude (rightly so) after being %$@#ed around for so long. The components are much easier to test while they can be put back into service under operating conditions to ensure the problem is solved.

My mechanics are being told what to do by Yamaha corporate in Shizuoka Japan. Since this is a warranty issue, the local mechanics have no authority regarding claims against the bikes performance. And I, as a Yamaha owner, am very happy to donate my throttle body assembly to Yamaha directly with hopes that they may be able to solve the problem for many other riders. I do not feel as though I have been phucked around.

[Guest dmizer]

The mechanics allowed me to take a look at the throttle bodies before they were shipped off to Yamaha. After 35000 km, they had some pretty decent grime built up on the cylinder side:
 
This is the center one.

 
This is the right side (by far the worst).

 
The left one didn't have nearly as much build up, so I didn't take a picture.
 
I've only been on one ride since they were replaced, and the bike started up right away after a refueling. Obviously, this is just conjecture, but after having the problem corrected by unclogging the air filter, and now having the problem corrected by replacing these gunked up throttle bodies, I would say that this bike is very sensitive to intake issues.

[skipperT]

There is a product made by Yamaha called Ring Free plus which will clean up those deposits.
 
Much of it is due to deposit's left behind from our crappy fuel supplies. Ring free is amazing stuff, will clean off piston crowns and valve stems as well.
 
Not sure how good the fuel is in Japan compared to the US.
 
Skip

[ilanr1]

Hi , I have cleaned the throttle bodies of all the 3 intake with carburettor cleaning spray and now my issue is solved.
This action must be made at every service of 10k or less , it depends on your quality of your fuel in your area.
Thanks

[thruster8999]

Thats some crazy gunk. My zx6r has 27,000 miles on it and the throttle bodies look brand new. So why is the fj throttle bodies gunking up like that. It just cant be from the gas. It my also be the way it is tuned from the factory or aftermarket tuning being lean or rich. I dont know but I cant just believe it is gas or additives in the gas.

[wessie]

In the UK we have posh petrols that claim to clean up such deposits - Shell Vpower, Total Excellium, Tesco Momentum etc. I would hope the ordinary unleaded would not have that much crap dissolved in it. I wonder if there was an assembly problem that was letting unfiltered air through the intakes

[thruster8999]

I agree more with the unfiltered air idea. I really have to doudt its the gas. I occasionaly get the hard start but not that much and most of the time I fill up with non ethanol gas.
 
I wondering with those dirty throttle bodies was the airbox mod done and the ecu flashed or is this completely a stock bike?

[Guest dmizer]

The gunk was on the cylinder side, not the airbox side. The airbox side was very clean with a tiny hint of carbon.

[Buggy Nate]

Most of that looked fairly normal to be honest. I've seen Gsxr's and Busa's with so much carbon/oil residue on the back of the valves and butterflis that they barely idled. Seen a fair few trumpets that have taken a good long time to settle down into a normal idle after cleaning them too. (they have Idle air control valves too) But they didn't seem to exhibit this Yamaha trait of hard start. Will be interesting to hear what they find out.

[Guest dmizer]

Most of that looked fairly normal to be honest.

 
Neither I, nor my mechanic thought it was unreasonable build up, which is why I took pictures. However, my problem is solved and I'm actually getting way better fuel efficiency. I did notice that on start up, the fast idle is higher now than it was before and takes a little more time before it settles into the idling range. I will ask them if that was a setting they made in the computer.

[djbinchicago]

As I read this I would like to ask if anyone has noticed the check engine light being "on"?
 
I have had cold start issues only a couple of times in 2,000 miles. I performed the check list and the bike started / ran fine. Yesterday I had a different situation / sound. The bike was trotting like only one cylinder was trying to fire on a cold start. I got the bike started. About 1/4 mile down the road, I lost power and noticed the check engine light was on. I had that weird sound like a single cylinder was trying to fire and noticed the check engine light was on. When I managed to get it off the bike started and ran fine. But my confidence is now suffering that I might be trailering this bike someday to get it home.
 
Some of my thinking from working with control boards for the HVAC industry and the flaws they have in consistent product is this. We know the ECU is monitoring the side stand and other points where the ECU expecting certain values to be returned through those points. If all those point values were to be verified that they are sending the correct values, it could be possible the ECU is not consistantly processing the information correctly, is confused, and going into a safe mode? It would be interesting to know what my ECU saw when the check engine light was on and if that diagnostic was correct.