Maybe you guys can start my bike for me...

[ECP89]

Because I can't seem to get it going


Long story into a medium story: Bought the bike as non-running project. It had been sitting for a long time. I discovered it's a 79 engine in an early 82 frame (someone converted it to electronic ignition when they put the engine in, but used the wrong ignitor box).

So here's what I've done:
New NGK plugs
New AGM battery
Cleaned carbs (One size up on main for pod filters)
New used wiring harness to replace PO's hack job (completely stock now)
New used starter motor

So I figure it should run after I did all that... no such luck. I verified spark (great spark!) and I have fuel to the carbs. At first I had fuel coming out of the air filters, so I adjusted the float level and now it looks in spec.

The engine cranks fine, but doesn't want to turn over. A little backfiring/popping at first
but now it just cranks. Doesn't matter if I use choke or give it any throttle, it's the same always. I should mention that my starter/kill switch assembly was all broken and faded so I just hardwired the 2 red/white wires together and grounded the switch (I have painted bars). Is this ok? It's temporary; I have a switch in the mail. Just a regular dirtbike kill switch that I'll use for the starter and just use the key for shutoff.


Any input? I wanna ride this thing already!

 

[drewpy]

check the coil wires are not swapped round (grey and orange ones)

 

[ECP89]

Just went out and checked. Verified with the manual that they were on the correct sides, then swapped them just to try anyway... and still no go.

 

[jmd_forest]

If you have good spark and good compression (you have tested compression ... right) the problem is almost assuredly a carburation problem. Try using a little starter fluid sprayed on the pod filters to see if you can get it to kick over. If so, it is most likely the carbs need a better cleaning and adjustment than you have already done. Look around for a GOOD carb cleaning guide and follow it. The carbs for these bikes are very sensitive to dirt and corrosion.

 

[ECP89]

That's what I'm beginning to think as well. My old man's bringing his compression tester home for me tomorrow so I can check it, but it's looking like the carbs need to come off again.

Thanks

 

[bcware]

Is the timing right?

 

[ECP89]

Compression is 155 in #1 and ~150 in #2. So that's good.

We're gonna check the timing tomorrow hopefully. If that checks out fine, I'm sure it's a carb issue.

 

[ECP89]

So how can you check the timing if the engine isn't running? My manuals have very vague instructions.

Also, we squirted a bit of gas into each cylinder after we checked the compression... and it made one small pop from the left side but that was it.

 

[bcware]

Do you have points?

Static timing is employed for a non-running engine. If you search on here there are two videos for setting the timing. I'd recommend watching both. One was made by me. It's nice to get more than one perspective with different commentary.

You could also just search youtube for them.

 

[ECP89]

Okay, thanks... I'll look at those.

No points. It's a 79 engine that was converted (by a PO) to electronic ign.

 

[bcware]

If the conversion was successful you shouldn't need to touch the timing as it won't be adjustable.

 

[ThePsuedoMonkey]

If it's electronic you can't check it without it running (the magnet trips the pickup coil unpredictably early otherwise). I had an extra pair of hands/eyes watch the rotor with the timing light while I rotated the base plate of the pickup coil until I got it to fire directly on "LF" at idle while warm.

 

[jmd_forest]

When you say "converted to electronic ign", was that factory electronic ign from a later year bike or some after market product?

 

[DanMach]

Did you check valve clearances?? I've had my bike refuse to start due to tight valves but it rarely actually back fired.

 

[ECP89]

It's all factory components in the ignition system. No jumper wires or anything, completely stock harness and the correct TCI ignitor.

Dan, I haven't checked the valve clearances... but now you have me wanting to. I took the carbs off tonight to go through them again. Once they were off, I figured I'd try squirting a tiny bit of gas directly in each cylinder again. Nothing happened (except flames out the intake boots

So I'll go through the carbs once more... the float levels are off anyway. I'll look into the valves at the same time.

Thanks guys.

 

[ECP89]

Okay, after a much needed mental vacation from the bike... I dove back into it again. Both carbs were gone through again and cleaned all jets etc, float levels were brought back into spec.

Checked the valve clearances tonight; all but 1 (L intake side) were a smidge too tight. Not more than 1/8th of a turn though. Now they are all in spec.

Didn't change a thing... when I crank it over with no choke; it just cranks and cranks (no backfire). When I have full choke; it backfires out the mufflers AND the carbs start moving and smoke eventually comes out the air filters.

What's going on?

 

[bcware]

The timing may be off.

What did you set the floats to? How many turns out are your idle mixture screws? Try cracking open the throttle slightly when you're starting it.

 

[ECP89]

It must be a timing issue.... since I squirted gas directly in the cylinders and it still didn't take off. How can I remedy this or even check it if the bike doesn't run??

I set the floats to ~25mm from gasket surface to float arm. Not sure about the mixture screw. I did try starting with the throttle closed; then with it cracked a little; then cracked WFO; choke, then no choke, then half choke... and every combination possible and it never changes.

 

[bcware]

Did you up your pilot jet at all? Do you know where the idle mixture screws are?

My other question is, was this thing ever running? Have you ever seen it run or did you buy it without having seen it run?

 

[bcware]

I'm getting close to suggesting pulling the cam cover off so that you can check the cam timing. Smoke out of the air filters is a bit wonky.