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Bike Troubles

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So I went out to Autoclub Speedway in Fontana for my first track day there today, and sadly it was cut short due to some mechanical issues. The bike was running fine during the first two sessions and then the bike lost some power, like 20mph off my straight speed and 10 sec off my lap worth of power, and the exhaust started burning the paint off my belly pan, I've ridden out at streets in much hotter weather than this and never had a issue, the engine temp on my gauge wasn't any hotter than I normally see it, but it was definitely hot enough to make the paint smoke and blister after I pulled into the garage


Any advice on where to start looking ?





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if you're losing power like that - you might not like the answer. I'd get it checked out. Definitely sounds lean and if its lost of power and running rough, could be pistons. Hopefully its something simpler like filters, etc.

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Did you do anything different before this track day? Did you run the first 2 sessions on gas that was in the tank and then topped her up with gas from a jug? If so was the gas fresh or old? Stored inside or outside....? Gas from a different store or anything that could affect the operation of the motor. Is your bike carbed or injected? Did you continue to push the motor or did you back off/shut down after the 3rd session?

If you got gas from a different station then it could be as simple as bad gas. But depending on how you treated the bike after she started complaining could have a lot to do with repair cost and time.


If the exhaust is glowing then you are running lean, very lean. You mentioned that the temp gauge was showing normal. Unless it is bad then the cooling system is working just fine. Did you hear any funky noises coming from the engine? Blah blah blah......


I always look at the cheap stuff first. I have learned that more times than not it is the cheap stuff that caused the problem in the first place.


I would recommend draining the gas from the tank and trying fresh/different gas first. You can always use the drained gas to smoke out an ant bed.


Let's hope that it is nothing major, unless you were looking for an excuse to upgrade :)


Good luck and let us know what you find.



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Let's see,


It's a 07 R6 so its fuel injected, the only thing I did different for sunday that I don't normally do is wash some of the dust and grime off the bodywork


I was last out at Streets mid April so the little bit of gas in the tank sat for less than 30 days, fuel'd it up the day prior at the same gas station i've bought all my gas from for the past 2 years, and I run a fuel treatment enzyme to reduce fuel breakdown and ethanol issues, which I've run without issues for about a year or so. I think its unlikely it was a fuel issue, but not impossible.


At the track I never managed more than 4 laps due to nonstop red flag conditions, partway through session 2 it was acting a little funny and had a bit of I guess hesitation and a touch of smoke coming off the belly pan when I pulled into the garage, session 3 it was obviously down on power and I noticed the 20mph drop in my speed down the straight, after session 3 I had lots of smoke coming off the belly pan and removed it in the garage to find a massive black mark and the clear coat and paint blistering and bubbling up, Session 4 I went out did one lap to confirm it was still acting up, pulled in, handed in my transponder and loaded it up in the van. I would say the note of the engine was a little different, it sounded like it had more of a growl than a whine like it normally does, but it didn't sound rough to me.


So far I've checked the ignition coils, all good, pulled out the spark plugs also look fine, airway and air filter both fine, battery voltage both off and running are within spec, Fuel pump pumps gas just fine, though I lack the adapter to check the pressure in the injector rails. removed the throttle bodies and inspected the intake valves, which are a bit dirty but not broken or seized up or anything of the like.


The one thing I've found that was amis was a small piece of plastic that has broken off inside the airbox and is no longer there, hope to take a peak inside the cylinder's with a inspection scope later this week, hopefully I'll get the oil and coolant drained tomorrow so I can inspect those as well.

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After reading all of this I would suspect the fuel pump first. You need to install a fuel pressure gauge and go out and ride it. Im sure you will see the pressure drop off as demand goes up. it could be a screen filter before the pump too. I had this problem before I changed painters, the old one would spray inside the fuel neck instead of taping it off before the seal and the gas would eat it off and the remains would end up in the screen. hardly noticable at first just a slow drop in power.

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  • 2 weeks later...

l, I wouldn't say I've actually nailed down the cause of my problem just yet. Thus far I removed the throttle bodies and inspecting the tops of the intake valves, they had some crud on them and were a tad dirty, Next I removed the exhaust headers and the header for cylinder #2 looked a bit different from the other 3, and the exhaust port for #2 looked just a bit wet with oil, so I decided it was worth pulling the head off and taking a look at the cylinders and heads, and again the #2 head had some additional buildup and didn't match the other 3 so I just decided it was worth it to just send the head off for a valve job. Hope to hear back from the machine shop by the end of this week. I'm not entirely convince that whatever is going on with cylinder #2 is the actual cause of my issue, my gut tells me its a fuel pressure issue but I won't really be able to test that till I have the engine back together and splice a pressure gauge into the fuel system



# 1 & 2




# 3 @ 4



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Interesting pictures. I would have thought that all of the combustion chambers would have been identical. I'm not talking about the carbon buildup. Looking at the areas between the exhaust valves in particular cyl's 1 & 2 have divots or casting irregularities compared to cyl's 3 & 4. And something looks a touch odd about the exhaust valves on cyl 1, but it could be the angle of the picture too.

It is neat that they included a small recess in the casting to enhance flame propagation.

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If #2 managed to eat some plastic that melted, it could have caused valves to burn (severely reducing compression and hence power) and, if the chunk was big enough, coat the inside of the header, both reducing flow but also causing the header to run very hot as the plastic continued to burn/melt away.

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  • 4 weeks later...

Just a little update,


I finally got my Head back from the machine shop today and it looks fantastic




unfortunately they said all 8 exhaust valves were pretty damaged and unusable, and it turns out titanium valves are not cheap parts to replace :angry:




and while cleaning the engine up getting ready to reassemble it I happened across this leftover present from the previous owner




So the engine is now at a welding shop to have that patched up before I reassemble it all, In the meantime I have managed to test the fuel pressure coming from the fuel pump, although not with the bike running at WO, I also checked the thermostat and coolant temp sensor which were both good. Hopefully I will have the engine back together next weekend

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Too bad on the exhaust valves, T.

From the picture, it looks like there at least two screw receptors (what do you actually call those in English?) that need patching.



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