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#1
07-26-2012, 06:28 PM
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starting trouble...
so i just finished putting a replacement head on my bike, and she turns over but doesn't start. start button wasn't working so i hooked the bike up to a car battery(car wasn't running) and the start button worked and the bike cranks vigorusly. has fuel, pulled the plugs out and all of them have a good spark. any suggestions, i'm going to do a compression test, but any and all input would be helpful. as this is my first motorcycle build i'm not the most eduacted with bikes, but am very mechanically inclined as i do all my auto repairs, and have rebuilt engines so i'm not clueless. thanks in advance.
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80 MNS; 81 Venturer 
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#2
07-26-2012, 06:48 PM
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Nick, if your sure you've got fuel and spark the only other thing required is compression.
Are you sure you have the cam timing right? Don't mess up that good head. 
__________________
Greg Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.” ― Albert Einstein 80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks. The list changes. 
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#3
07-26-2012, 06:52 PM
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yeah greg the timing is dead nuts. i rotated the cam about ten or fifteen rotations (clockwise) and the timing marks hadn't changed. i am wondering if perhaps valve shimming may be the culprate. would this give a no-start condition
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80 MNS; 81 Venturer
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#4
07-26-2012, 06:56 PM
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How were your clearances when you checked them? Did you set the valves before you installed?
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Greg Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.” ― Albert Einstein 80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks. The list changes.
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#6
07-26-2012, 07:00 PM
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I would do the compression test first as you have just replaced the head. It takes only a small mistake to get valve timing wrong and bend up some valves.
As you have fuel and spark the only things missing are air, compression and timing. Did you by any chance have any of the ignition system apart. On occasion members have hooked the coils up backwards and while they have spark it is at the wrong time for the motor. 2 and 3 fire when 1 and 4 are supposed to be sort of thing. That is just a thought. Is it firing at all or even backfiring or any other associated noises? Is there any chance that an electrical issue may be happening like an emergency kill switch still on or a tipover switch installed upside down kind of thing. Just some thoughts to get us going here. As BA80 says make sure about the cam timing and chain tension and all that good stuff.
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2-79 XS1100 SF 2-78 XS1100 E Best bike Ever 80 XS 1100 SG Big bore kit but not fully running yet. Couple of more parts bikes of which 2 more will live!
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#7
07-26-2012, 07:03 PM
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Quote:
__________________
Greg Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.” ― Albert Einstein 80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks. The list changes.
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#8
07-26-2012, 07:10 PM
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you need to define "doesn't start..."
does it mean that it does not fire up? is it coughing and sneezing ? did you pull the plugs and are they went from fuel?
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Nick 1979 XS11 F,Yamaha fairings w/hard bags, TC's fuse box, K&N air filter 1982 Virago 750 (it's alive!) 1979 XS 11 F, Windjammer IV, Samsonite luggage cases(another rescue)
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#9
07-27-2012, 03:30 AM
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If you replaced the head, did you also remove the coils for clearance? Did you perhaps swap the wires from the coils? Did you make sure you put the plug wires on the correct plugs? Yeah I know your not stupid, I just have found its typically the simple stuff that causes these problems.
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Life is what happens while your planning everything else! When your work speaks for itself, don't interrupt. 81 XS1100 Special - Humpty Dumpty 80 XS1100 Special - Project Resurrection Previously owned 93 GSX600F 80 XS1100 Special - Ruby 81 XS1100 Special 81 CB750 C 80 CB750 C 78 XS750
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#10
07-31-2012, 02:34 PM
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Update
well i went back through the cams, and re-shimmed everything so numbers are without a doubt in tolerance... and i did a compression test, but beings how it is not starting(does crank over) not sure the results are the best. here they ar:
Cyl. 1= 100 Cyl 2= 100 Cyl 3= less than 10 cyl 4= 100
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80 MNS; 81 Venturer
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#12
07-31-2012, 03:08 PM
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Put a table spoon or so of oil in the bad cylinder and redo the test on that one. If the compression comes up then its the rings that are not seating or a hole in the piston. If it doesn't come up then it is in the valves, and I am betting on a valve being f'ed up or not shimmed right.
how did you do the shims? What size shims do you have in there?
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Nathan KD9ARL μολὼν λαβέ 1978 XS1100E K&N Filter #45 pilot Jet, #137.5 Main Jet OEM Exhaust ATK Fork Brace LED Dash lights Ammeter, Oil Pressure, Oil Temp, and Volt Meters Green Monster Coils SS Brake Lines Vision 550 Auto Tensioner In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing. Theodore Roosevelt
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#13
07-31-2012, 03:15 PM
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yeah i am heading out to do a wet test now, valves are all shimmed up coreectly, they were a little out of spec initaially, but i can't imagine enough to bend them ill re-post in a few
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80 MNS; 81 Venturer
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#14
07-31-2012, 03:20 PM
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Did you have any compression numbers on that cylinder before the rebuild?
When I first got my SG, I didn't know it, but #3 had a ever so slightly bent exhaust valve. You wouldn't have known it except the compression number was way low, so then I pulled the head and saw a half moon shaft of light thru the exhaust port.  Got a new valve for $26 and everything is good now. Edit: just re-read the initial post. It's a replacement head. Before you put it on, did it look like all the valves seated good?
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Hi, my name is George & I'm a twisty addict! 80G (Green paint(PO idea)) The Green Monster K&N A/F, TC's fuse block, '81 oil cooler, TC's homemade 4-2 w/Mac Mufflers, Raptor 660 ACCT Got him in '04. bald tire & borrowing parts 80SG (Black w/red emblems & calipers) Scarlet K&N A/F, TC's fuse block, WJ5, Shoei bags, Raptor 660 ACCT. Got her in '11 Ready for the twisties! 81H (previously CPMaynard's) Hugo Full Venturer, Indigo Blue with B/W painted tank. Cold weather ride
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