Big bore
Tourer
Joined: Mar 2010
Posts: 428
Likes: 35
From: Calgary Alberta Canada
Still sounds like fuel to me. If you have a way to spray a bit of gas into the intake (be careful) then just as it sounds laboured spray a bit of fuel into the intake . If it speeds up / keeps running then i'm going with a fuel problem. Does it do this multiple times or was it once and now it won't start? The little O ring in the fuel quick disconnect can cut off all the fuel when it decides to crap out. Once thing you can check is. Turn on the key and then wait for fuel pump to stop. Shut off key. Remove quick disconnect. Carefully with a rag and a small screw drive push in the poppet valve on the fuel line. Do you see fuel running out into your rag? If so then there is fuel (and pressure) in the fuel rail which feeds the injectors. If that checks out , make sure that the fuel injector wiring is connected good to the rear injector. Give those items a try.
Seasoned HDF Member
Joined: Apr 2015
Posts: 6,861
Likes: 3,725
From: St. Charles, MO
Still sounds like fuel to me. If you have a way to spray a bit of gas into the intake (be careful) then just as it sounds laboured spray a bit of fuel into the intake . If it speeds up / keeps running then i'm going with a fuel problem. Does it do this multiple times or was it once and now it won't start? The little O ring in the fuel quick disconnect can cut off all the fuel when it decides to crap out. Once thing you can check is. Turn on the key and then wait for fuel pump to stop. Shut off key. Remove quick disconnect. Carefully with a rag and a small screw drive push in the poppet valve on the fuel line. Do you see fuel running out into your rag? If so then there is fuel (and pressure) in the fuel rail which feeds the injectors. If that checks out , make sure that the fuel injector wiring is connected good to the rear injector. Give those items a try.
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Novice
Joined: Jun 2017
Posts: 24
Likes: 0
From: northern alberta
Well guys. It's really looking like its a piston/cylinder clearance issue. I checked, rechecked and tried checked all my connections. Fuel pump is working, not dropping the fuel pump relay. I reset my valves, and started my bike. Once again it fires up, runs, labor's and stalls. Restarted it a couple times and each time it restarts it runs less time and stalls and each restart the starter has a harder time turning the engine over. So I let it cool for approximately 10 minutes, got my wrench ready, fired up my bike and waited...when it stalled, I yanked out the plugs and immediately hit the starter button...the starter is laboring to turn over the engine with no spark plugs in the engine...pretty well zero compression. Which tells me the piston is expanded in the bore to the point there is some serious drag between piston and cylinder. I pulled the case oil sump plug and strained out the small amount of oil and sure enough...bits of aluminum piston material. Put the borescope back in the rear cylinder spark plug hole and I am starting to see faint vertical lines in the bore, around the bore in a few different spots.
Road Master
Joined: Sep 2011
Posts: 1,033
Likes: 41
From: Mount Airy, North Carolina
take the plugs out, jack up the rear wheel. Put it in 6th gear and see if you can rotate the wheel and turn the motor over several times with ease and nothing sounds like its in a bind. If you can turn the motor over by hand, then I bet its sumping. Crank case is filling with oil because the o-ring on the cam plate for the scavenging side of the pump didn't seal. If the crank case is filling with oil, it will cause exactly what you describe. runs fine for a little while until the crank case fills wit oil. The flywheels and crank pin are dragging through a bath of oil if the scavenging side of the oil pump cant push oil back to the oil tank.
Nevermind. posted before I read your last post. Seems its not sumping, metal = no good.
Nevermind. posted before I read your last post. Seems its not sumping, metal = no good.
Last edited by liquidr1; Sep 16, 2017 at 03:20 PM.
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Thread Starter
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Novice
Joined: Jun 2017
Posts: 24
Likes: 0
From: northern alberta
Got the rear cylinder removed, and yes it is a clearance issue. Piston is not looking too bad but the cylinder has some nice blue tracks starting to form around the circumference of the bore spaced out just beautifully...and the oil wafer ring was starting to make its own trails about half way down the cylinder. So not only does it appear to be a clearance issue, I may also have a taper machined into this bore. None too happy. Will measure it when I get back to work on Monday. And the machine shop will be getting a call for sure.
Outstanding HDF Member
Joined: Dec 2008
Posts: 2,007
Likes: 353
From: Ohio
Clearance/taper problem? Were the cylinders bored with torque plates? Ones for your cylinders? I know plates can be expensive and a few machine shops make compromises when it comes to using the right ones.
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