bad kick back

andrsn

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Just got all wiring hooked up on my newly rebuilt engine, went to try and start it and it kicks back like crazy. My ankle hurts. I have a 78' motor, pamco elec. ignition, combo reg/rec, dual output mikes coil. The engine is fairly hard to kick over when not trying to start too, maybe the new rings/pistons?

What is the order of operation for diagnosing the problem. I don't wanna break my ankle this weekend. I've read that an advanced timing can cause kick back, I retarded the elec. ignition to the max (counter clockwise to the max). My advance springs could be worn, but wouldn't that just retard the timing even more?

thanks
 
Weak springs let the advancer advance sooner. Clip the loop off the spring and bend up the next turn for a loop. Do one spring it may be enough.
On www.yamahaxs650.com Pamcopete has a video on how the advancer should snap back. Check it out.
Retarding the timing that much might not work either. Set it as shown on the website, once you get it running you can set it with a light. I have mine set to the right hand f mark.
 
Weak springs let the advancer advance sooner. Clip the loop off the spring and bend up the next turn for a loop. Do one spring it may be enough.
On www.yamahaxs650.com Pamcopete has a video on how the advancer should snap back. Check it out.
Retarding the timing that much might not work either. Set it as shown on the website, once you get it running you can set it with a light. I have mine set to the right hand f mark.

I'm gonna assume from your response that the timing is the culprit causing the kick back. Is that the only thing it could be? I'll try the spring thing, they do feel a little loose. I just want the thing to start, I can tune it and get it running correctly later.
 
Are you confident that the engine was re-assembled with the correct timing relationship i.e. camshaft index marks/ crankshaft at TDC etc.?

When I put the engine back together I was pretty careful to follow the manual, I definitely triple checked that step. It's possible I got it wrong, but I'm 99% sure I did it correctly. After installing the cam chain, I turned it over multiple times to make sure the marks were lining up. If they were wrong, could that cause kick back? It seems like it would just make the engine not start or do anything, just turn over again and again.
 
I have found that most often when an engine kicks back the timimg is the thing. Back before electric starters became popular lots of riders had a "Sportster Limp". They would advance the timing so they made tons of power but would kick back when starting. Those old Sportsters could throw you over the bars and hurt your leg, Thus the "Sportster Limp".
The ignition and carbs often share the same symptoms. Making sure the carbs are clean and set close is a good idea.
On the carbs www.amckayltd.com/carbguide.pdf will help with the carbs.
 
Thanks for the help Leo. My carbs are pretty clean i bought them fully rebuilt off some one on the forum. When I put gas in the other day some poured out of the right pod filter, I think they need a cleaning after sitting in a box for 2 months. Maybe the needle wasn't closing properly or the floats are stuck. I'll check that out before trying to kick it again, run through that awesome pdf, and make sure my crankcase isn't full of gas.
 
That limp is not only given by Sportsters! My ol' '79 Super Glide gave me a limp now and again. Never threw me over my drag bars, thank goodness. Broke the lever at the pedal bolt once too. That scrape hurt! Moral of that story was no summer oil on a cold Fall morning
 
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I'd try by retarding the ignition about 10 degrees or so, the bike won't have much performance but you should be able to tell if it has an effect on this starting kick.

I.
 
I retarded the timing, it seemed to make the kick back start, but I still don't have the bike running reliably. When I get it going (gonna try again tomorrow) I'll let you know.
 
Just checking in to see you if you found any success.

sorry, totally forgot about this. yeah, i retarded the timing a bit and replaced the advance springs (used mikes springs for 10$ or so), problem solved. I haven't gotten around to setting the timing with a timing gun, but I'm sure it will be fine in regards to kick back. The new advance springs made the big difference, mine were 30yrs old and worn out. Engine fired right up, first time in 30yrs with two easy kicks and no kick back.
 
Weak springs let the advancer advance sooner. Clip the loop off the spring and bend up the next turn for a loop. Do one spring it may be enough.
On www.yamahaxs650.com Pamcopete has a video on how the advancer should snap back. Check it out.
Retarding the timing that much might not work either. Set it as shown on the website, once you get it running you can set it with a light. I have mine set to the right hand f mark.

Hi Leo - When you set your timing with the light did you need a dwell meter? Did you use a light with advance settings?
 
No need for a dwell meter or one off those fancy advance timing lights.
A dwell meter will help adjust the points gap.
Once the points are gapped right then adjust the timing.
I use used a basic Pamco but have sense upgraded to the E-advancer Pamco.
Once you install the Pamco you set the timing by hooking the timing light to a battery and around the plug wire. Some timing lights are polarity sensitive. To tell if yours is, with the plug wire clamp on one wire, you get a good flash, steady and bright. Flip the clamp over and the flash is inconsistent and dimmer.
Try the clamp on the wire both ways.
If the only light you have is one with the advance, set it to zero advance.
Now with the bike at idle point the light at the timing marks.
On the points bikes there are two marks on each side of an F.
The mark on the rotor should line up between this two marks.
On the TCI bikes there is just one line for the timing. The rotor mark should line up on the mark.
If not, loosen the sensor plate screws enough to turn the plate. Adjust the plate so the marks line up.
Once set snug the screws down.
Now with the timing light pointed at the marks, slowly rev the engine. The mark on the rotor should move smoothly to the left. At 3000-3200 rpms the mark should move over to the full advance mark, but NEVER go past at higher rpms.
On the points bikes there is a full advance mark over to the left.
On the TCI bikes there is a place that indicates full advance. Not a mark like the points bikes. In the bottom of the round hole there is a notch. The left side of this notch is the full advance indicator.
If it goes past the full advance mark note about how far past, return to idle. Now with the light on the marks adjust the idle timing to the right about the same amount as the timing went past the full mark.
Recheck the full advance timing. If still off a bit adjust the idle timing a bit more. It may take a few tries to get right but worth the effort.
Leo
 
thanks! That will be another project of mine down the road. I have a 75 and will probably just get the basic pamco when I go to upgrade my timing. Sounds like the 37k is fine for my needs since the OEM spart was only around 14k.

I will just get a plain jane timing light (no advance features) thanks!
 
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