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77 XL125 won't start

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I just spent the past little while rebuilding my 1977 Honda XL 125 motor from the bottom up. New gaskets, new cylinder and piston. Finally got it mounted in the frame and for the past week, I cannot get this thing started no matter how much I try. Here's what I've done.

- Adjusted cam timing and tension several times
- Checked and adjusted points and timing numerous times
- Readjusted valves twice (they were also previously adjusted on the wrong stroke)
- Checked resistances through the stator up to the ignition coil to confirm good spark
- Kicked spark plug over cylinder to also confirm good spark ^^ (spark is a nice sharp blue)
 

The first night I put the engine in the frame I was able to get one backfire, but since then I haven't been able to recreate it. Whenever I put my thumb over the spark plug hole, it constantly blows dry, so a fuel problem is evident. Spark plug is always dry and clean and only smells of gas. I even added starting fluid (both in the intake and directly into the cylinder) and got nothing. I am out of ideas.

Edited by CrazyQuickDraw

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That one backfire is a clue that something is still out of time; the cam or when the points are opening. 

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No mention of your carburetor.  Take it apart and clean it with carb cleaner and try again.  Eliminate that possibility and reset your ignition.  The good thing about engines is that they cannot refuse to run if you get everything set right.  

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Forgot to mention I did a compression test. Got 60-90 PSI... well below what it should be (min. 153 PSI). I'm suspecting valve issues, so I have disassembled the top end again.

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Low compression cld mean valves are out of synch and you're losing pressure.  Fire some WD-40 in the plug hole and see if compression improves.  If it makes no difference, your valve timing/seating is suspect.  Could be a piston ring stuck too.  Pop the top end off and have a look-see.

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Cant expect high compression till your rings are bedded in a bit, especially if you've used starting fluid and washed any assembly oil off.

    use a little oil down the plughole and see if comp comes up a bit. If it does, it may also give more suck to pull fuel through the carb, which sounds more like your problem than anything if plug is dry......

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Tore the top end off again and figured I'd get some new chain guides and cam chain cause they were pretty worn. New cam chain is really tight, no slack what so ever. Barely got it on and the tension adjuster is completely backed off. Is this normal for these bikes?

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I believe when the tensioner screw is "backed off" (counterclockwise turning), the tensioner tightens. Turning the screw clockwise loosens the tensioner. 

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I know how the tensioner works.... was just wondering if these new cam chains are suppose to be really tight.

Edited by CrazyQuickDraw

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If you didn't find the problem already , no, they shouldn't be that tight, even if new. If it's an aftermarket chain, that may be a factor. There are Chinese knock-off parts out there. You could compare the number of links with the original. Also make sure it's not binding at the crankshaft sprocket. It's been a while since I worked on one of these, but I think the tensioner bar could get out of position during cylinder assembly, causing the tightness. 

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Reassembled the top end. Cam chain is still tight but I'm capable of wiggling it pretty good. But the bike still won't fire or even give me one pop. I even rebuilt the carb because the jets looked pretty bad. At least I'm getting a "whooshing" sound when I kick with the choke off. I'm assuming my compression is good. Spark seams okay but I'm going to confirm with a spark tester and go over the timing again... Fuel seams to be my main problem. Plug is constantly dry (even after carb rebuild). 

Edited by CrazyQuickDraw

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