Loss of power and lots of sparks out of my exhaust. What did I break?
 

9000 rpm sustained on the highway in the fast lane. Plenty of oil. Coolant temperature nominal. Suddenly the bike loses power. I head check the lane on my right, and see a goddamn fireworks display coming out of my muffler. I keep the throttle pinned, but the engine is not firing. I make it over two lanes and then she roars back to life. She's running pretty shitty, but I slow way down, finally make it to the right hand lane, and figure if I pull in the clutch she will never start again... and I'm less than a mile from my exit. So I keep trucking. It has no power down low, so I have to downshift and keep the revs around 6000 in order to continue moving. She sputters again, and I move into the breakdown lane. I'm less than a quarter mile from my exit now. I get off the highway, down the ramp, and rev the bike in neutral to keep it from stalling. My house is just a couple miles from the exit, on 45mph and 25mph roads. By the time I pull into my neighborhood, my bike is running fine again. I pull into my driveway and it idles normally. I hit the kill switch, then try the ignition and it restarts fine.

There are no strange noises, and there is nothing obviously wrong with the bike. It revs freely, and makes no weird noises when I do.

Bike has 2800 miles on it. PO said he had done the 500 mile service and valve adjustment. I bought it with 1500 miles on it, so it wasn't due for 300 more miles.

What happened, and how bad was it?

Charles.

Update: Found the potential source of the sparks. The catalyst is mostly gone. There's a hole ripped right through the center of it. When I bought the bike the catalyst was fine. So, either that burned on its own (unlikely) or bits of hot metal took it out (more likely).

I'm going to do a compression test this weekend, and also rent an inspection probe and see if i can spot damage. My bets are that I lunched a valve.

Charles.

Oh man, I'm sorry to hear that. I never ran the bike that hard. When I adjusted the valves I triple checked everything to make sure it was right.
You say it still starts and runs fine with no weird noises? Will a bike do that if one of the valves is toast?

I've just had a crazy thought- I wonder if those mud daubers or yellow jackets built a nest inside the exhaust and over heated the catalyst?

Last summer I found a couple of good sized yellow jacket nests, one under the rear fender, and one behind one of the radiator shrouds? Both of them were about 3 inches in diameter. That's when I bought the cover.

Yup, just did a compression test. 80psi. I should have more like 180psi. I doubt she'll start cold.

So.... maybe this is the opportunity for me to put in the 300cc big bore kit right from the get-go.

Charles.

Another update: Exhaust valves have zero play. I can't fit my smallest .0015 (.038mm) feeler gauge in there. Also... access to the exhaust valves SUCKS.

How bad is removing the head? Can it be done with the engine in the frame?

Charles.

Did you adjust the vales and rechecked the compression? You may know this already but check the compression with the throttle open.

i would try readjsuting the valve and then testing compression again, before going whole hog on a tear down. if the valve is tight, it will cause a lean burn, which in turn WILL melt the cat... it may just be the tight valve and nothing else wrong....

That's my plan right now, I'm going to adjust the valves this evening. Got so much to do at work that I can't take any more time for farting around in the garage.


Charles.

Wow! They tightened up quick. I had them set tappy and happy at .08mm. Yea, access sucks. I had a hell of a time trying to get my fat fingers + a feeler gauge in there.

Well, so far so good. The exhaust valves had zero clearance but the intake valves were set properly. Warm engine last night, it made 80psi of compression. After adjusting the valves today it made 95psi of compression.

Since the bike has a built-in compression release, I'm hoping that the 95psi is simply where the compression release starts bleeding off pressure. Bike started easily. FAR more easily than it has ever started since the day I took it home, even though the battery was pretty run down from cranking the motor during the compression testing.

I have to take it out on a bunch of rides to see if I somehow avoided catastrophe. If it's reliable again... yay. If not... new head.

Charles.

Spoke too soon. It started earlier but now it won’t restart. No idea why. I’m frustrated and will work on it more tomorrow.

Charles.

Compression is at 100psi now. Plenty of hot fat spark. But I don’t smell fuel. I wonder if this was a fuel issue from the get go. I mean, power loss was like a light switch, and then it came back on just as sudden. If not for the hella sparks from my exhaust and my vaporized catalytic converters, I would honestly not have suspected a burned valve at all. I would have suspected fuel or spark.

Charles.

Can you hear the fuel pump when you turn the key on?

Did you do any electrical work before the the problems started? Maybe there is a bad connection somewhere.

No, no electrical work. I had never removed the tank before this. I always hear the fuel pump cycle.

Latest update:

Bike wouldn't start this morning. I loosened the side panels and slid the tank back, then propped it up vertically to check for kinked lines. No kinks. I pushed on all the connectors, and everything was properly seated. I tapped on the fuel filter. I sat the tank back down, turned the ignition on, and it started immediately.

So, I'm thinking this is a fueling issue. Either the injector or the fuel pump... but I'm leaning towards the fuel pump. I've read that the sock can deteriorate when a bike sits for a long time with the same fuel in it, and then it gets sucked into the pump and clogs it up. And this bike did sit a lot before I bought it from you. I'm betting that sloshing the fuel around and upending the tank is what allowed the bike to start. I'm going to get a siphon pump to drain the fuel out and then remove the tank and inspect the fuel pump to see if the sock is present and accounted for.

I'm not sure how a fueling issue can cause my catalyst to burn out, but if the whole problem is a faulty fuel pump I will be THRILLED. Easy and cheap to fix.

Charles.

Well, it did sit idle for a while but I'd start it once in a while to let it warm up. I noticed if I let it sit up for a few weeks then start it the pump would make a light squawking sound but after warming up it and starting it again it wouldn't make that noise. Sounds like you might have found the problem. As far as the catalyst, maybe a partially blocked fuel filter would create a very lean condition and possibly superheat the catalyst? FI systems are a little bit of my mechanical knowledge range. A clogged injector wouldn't be out of the question, those holes are tiny.

I already answered the question of how fueling can burn thru your cat...lean burn causes increased exhaust gas temps, overheats the catalyst material and melts it.

How restrictive should the fuel filter be? Should I be able to blow through it easily? Or should it be Somewhat difficult?

Charles

It should flow fuel pretty easy, air is a different story, especially if it is a paper element, and it is wet. If in doubt, replace it. Is the pump pumping fuel?

The pump does always make the pumping noise and obviously sometimes it flows fuel. I’m not sure if it’s making the noise but not pumping sometimes, or if that is even possible. It could also be an intermittently firing fuel injector, an intermittently clogged filter, or maybe electrical connection to injector.

Filter appears to be cellulose inside.

Charles.

Have you tried running a diagnostic test to see if any codes pop up (turn the key on, off, on, off, on) ?

I haven’t. I’ll do that in a hot minute, but I’m thinking I am closer to finding the problem.

What’s the trick to releasing the electrical connector on the fuel injector?

Charles.

I don't know.

Guys, I believe I solved the mystery!!

The bike sat a lot. I saw junk in the fuel filter. I blew it out in the direction of flow, and small chunks of varnish came out.

https://advrider.com/f/attachments/f...-jpeg.2654837/

There are still more chunks visible in the filter and I can reach in with a pick and manipulate them but can’t get them to come out.

Note that these chunks came out of the fuel injector side of the filter.

Charles.

Update. That’s not varnish. It’s glue. I cut the filter apart just to see the internals, and the glue that held it all together crumbled into a mess. So... we may want to consider finding an aftermarket filter, if the OEM is going to come apart like this.

Charles.

Ethanol Strikes Again
 

You appear to be the victim of ethanol gas. Filter media, as well as transmission clutch friction media, are glued with water based glue. This normally isn't a problem in an petroleum based environment, such as an engine or gas tank. The problems start when your vehicle gets flooded and water gets into the transmission, contacting the friction plates or, in the case of a fuel filter, the bike sits for an extended period and the ethanol in the gas absorbs water which ends up in the filter, compromising the water based adhesive. You will find similar, if not identical construction in other filters, so I don't know that switching to compatible different brand of filter would prevent a water exposure failure. It would be nice to have another option, though, that could be sourced locally when needed instead of having to get it from CSC.

The stock filter is also extremely restrictive. The end cap of the filter is almost an interference fit with the outer casing, vastly restricting fuel flow. That’s why it was so difficult to blow through. I’d post pictures but the forum is broken. Pics on advrider thread if you want to see.

Charles.

I'm thinking that perhaps the water in the fuel caused the filter media to swell up and expand the metal end cap enough to choke off your fuel flow at high RPM's, leaning out your fuel mixture and melting your catalyst honeycomb; alternatively you may have just got a poorly manufactured filter. It would be an interesting comparison to cut open a brand new, unused filter and contrast the internal condition to your used one, checking the fit of the metal end cap and its diameter versus your bad one, as well exposing it to some water and see how the adhesive behaves.

Hmmm, that filter could have been defective from the beginning and I never pushed it hard enough to cause any problems. I just rode the bike to work and back, a total of 15 miles.

Yeah I put 1300 miles on in two weeks. I ride a LOT. :)

I ordered a new filter and also some fittings so I can bypass the filter if need be. I’ve got a trip planned thanksgiving week and I need the bike to be fixed before this Friday.

Charles.

At any rate Russel, I don’t blame you at all. We’re good. This kind of stuff just happens. Fortunately it looks like it’s turning out to be a ten dollar fix.

Charles.

I appreciate that. If the bike had shown any signs of trouble I would've had it fixed before I sold it. I'm glad it will be cheap to fix.

I can easily blow through the filter (RX3 and RX4 have the same filter). Unless the element is plugged up the filter should pass the required fuel easily. We are not talking about moving a lot of liquid, only about 1 gallon per hour.

Glad to hear it's most likely a cheap fix. I would definitely recheck those valve adjustments though.

I've already checked and re-checked the valves. Will do a leakdown test just to be certain.

Charles.

Leak down test is worthless on a bike with aN automatic compression release. My filter still hadn’t arrived this morning, and I had the day off... but my fuel fittings from amazon did. So I made a bypass line and buttoned it all back up and went out for a two hour ride. I included all different terrain, including highway. I reached 87mph on the speedo (79mph actual) and that tells me the engine is perfectly fine!

Russel, you couldn’t have known the filter would start coming apart internally. It’s a bit of a design flaw, the filter is at the lowest point in the fuel system, and when a bike sits for a long time that’s where any water ends up.

I appear to be good to go. And low and behold my filter arrived. So now I can take the tank back apart and replace my bypass line.

Charles.

Glad it all turned out to the good. Now you can enjoy some riding. Run ethanol free fuel will save you a lot of headaches down the road.

That's good to hear.

Any CR design should be 'dynamic', cutting out when rpms get higher than xxx. With all the parts static, a leakdown test should be doable without any problem.
If you are at TDC, and have a CR leaking out the gases... it would be counter-productive at all rpms though less noticeable at high rpms. Most CR mechanisms use a bump on a cam lobe, or a movable interruptor, neither of which should be doing anything at static TDC.
Please explain how the CR works such that it would make a leakdown test unpossible? I have no mental picture that would explain.
Did you get an el-cheapo lipstick(?) camera to connect to a laptop PC and shove down a spark plug hole? They are less than $15 on DaRiver or DaBay. I have used one to inspect cylinder walls. I would be concerned that the lean condition did some damage to the piston crown. It MAY have eroded some of the metal around the perimeter. I have seen that happen on engines that got too hot. Most were air cooled, which seems to indicate they are more susceptible, but I wouldn't make any bets.
One last thought is that extra fuel that makes its way to a catalytic converter can cause the converter to glow cherry red. You would get a lot of sparkage if that occurred while turning 9k.

tom

This... leakdown is the answer to having a compression release, which skews a compression test. I do leakdown tests on ACR equipped motors every week...

Just wanted to add also that if you are using a low-cost compression test gauge, you may want to give a better gauge a chance. The low cost items don't seem to work too well on small displacement engines. Either the internal mechanism is too 'rough' and does not respond to small volumes, or the mechanism is too 'loose', and again doesn't respond properly. A larger piston/cylinder can flow a lot more air into the tubing and gauge than a smaller and still have a 'good' reading(at least for comparison to other cylinders), while a small displacement would be giving up a lot of its volume to the rubber tubing and gauge gizzards(relatively).
I bought one from -bay, and it read ~30psi, and when I used my old(~50) JC Whitney gauge, it read 75+ from memory. I got a refund for the low-cost unit.
tom