81 FXS Timing Question
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Tourer
Joined: Oct 2016
Posts: 256
Likes: 36
From: Hartford, CT
81 FXS Timing Question
Hey all.
Happy spring.
I'm re-installing an Ultima ignition. The bike hasn't run since the fall. I have timing plug and plugs out. I followed the supplied instructions and the bike will start but backfires largely out of the front cylinder and runs rough. My bike has single lower dot and vertical line for timing marks. I've been using the vertical line as my mark since the instructions call for TDC on the front cylinder.
I believe I'm on the front compression stroke. I can see the rear piston is down and the intake valve open. Is this correct? Thinking maybe I have 2 problems - carb and timing, but need to get the ignition installed correctly before moving on.
Thanks
Nick
Happy spring.
I'm re-installing an Ultima ignition. The bike hasn't run since the fall. I have timing plug and plugs out. I followed the supplied instructions and the bike will start but backfires largely out of the front cylinder and runs rough. My bike has single lower dot and vertical line for timing marks. I've been using the vertical line as my mark since the instructions call for TDC on the front cylinder.
I believe I'm on the front compression stroke. I can see the rear piston is down and the intake valve open. Is this correct? Thinking maybe I have 2 problems - carb and timing, but need to get the ignition installed correctly before moving on.
Thanks
Nick
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
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From: la la land jerzey
Use a drinking straw and rotate the engine till the straw stops moving up look in the window - take a 3/8 piece of rubber hose stick it on the plug hole and blow if it has resistance your firing on the front and what’s ever is in the window is TDC
Thread Starter
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Tourer
Joined: Oct 2016
Posts: 256
Likes: 36
From: Hartford, CT
I did what you suggested and turns out I had it right. The vertical line is TDC. That being said, I followed the instructions to set the static timing again, and tried getting it running. It starts but will not stay running and backfires from the front cylinder. I drained the fuel in the tanks and put fresh fuel in. I also quickly cleaned out the carb and jets. I finally ended up running the battery down.
If the module is almost all the way to the left, does that mean the timing is retarded? Not sure where to go from here. This is supposed to be the easy shiz..
Thanks
Stellar HDF Member
Joined: Apr 2016
Posts: 3,323
Likes: 2,114
From: Masshole
How can that be? You said you have line and low dot fly wheels. If that is the case then low dot right side is TDC. The picture I posted above is from the fsm, yours is the left 2 pictures. #1 lower left picture.
Thread Starter
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Tourer
Joined: Oct 2016
Posts: 256
Likes: 36
From: Hartford, CT
John, plugs aren't fouled. I'll try another set for good measure.
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Tourer
Joined: Oct 2016
Posts: 256
Likes: 36
From: Hartford, CT
I have the FSM and asked the same question. When moving the crankshaft by turning the rear wheel CCW, I see the low dot first, then line. I even watched the piston move with a bore camera - when it got to TDC, the line was dead center in the inspection hole.
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Road Master
Joined: May 2012
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From: Potter County, PA
Are you single fire or dual fire? If Single Fire do you have the coil wired properly?
Also are you rotating the engine with the rear tire or kicker. If using the rear tire you should be rotating the tire the way the bike drives; the marks in the timing window should be going from the rear of the bike to the front.
Also are you rotating the engine with the rear tire or kicker. If using the rear tire you should be rotating the tire the way the bike drives; the marks in the timing window should be going from the rear of the bike to the front.