Kickback

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blethermaskite
Posts: 133
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: Kickback

Postby blethermaskite » Mon May 25, 2020 4:24 pm

I would change your condenser......a dodgy condenser will give you a good spark when you are trying the plug out of the cylinder but it won't spark properly in the cylinder under compression.
Stay well,
Cheers,
George

frankfast
Posts: 140
Joined: Wed May 05, 2010 12:35 pm
Location: New York (upstate)

Re: Kickback

Postby frankfast » Mon May 25, 2020 6:25 pm

blethermaskite wrote:I would change your condenser......a dodgy condenser will give you a good spark when you are trying the plug out of the cylinder but it won't spark properly in the cylinder under compression.
Stay well,
Cheers,
George


Thought about that. I have to give it a try.

frankfast
Posts: 140
Joined: Wed May 05, 2010 12:35 pm
Location: New York (upstate)

Re: Kickback

Postby frankfast » Fri May 29, 2020 2:36 pm

I've followed the kickstart procedure offered by those in previous posts and am now getting the bike to fire. The problem is that I'm getting severe kickback. I've retarded the timing substantially with the same result. When the bike ran two years ago the timing was more advanced then it is now and timing it statically also calls for more advance. Is there any other reason the bike would kick back that has nothing to do with ignition timing? When a bike kicks back, does that mean the crank rotates backward?

DBDBrian
Posts: 87
Joined: Mon Mar 30, 2015 11:29 pm

Re: Kickback

Postby DBDBrian » Fri May 29, 2020 6:50 pm

(When a bike kicks back, does that mean the crank rotates backward?)
Yes, in so doing, reversing the drive train back to the kick start shaft, causing the sudden reversal of travel, of the lever.

Frank, I'm a bit confused by the symptoms, and it can be difficult at times to diagnose faults from a distance. Are you 100% certain, that you are actually retarding the ignition timing, and not advancing it ?
Brian
Made in England

frankfast
Posts: 140
Joined: Wed May 05, 2010 12:35 pm
Location: New York (upstate)

Re: Kickback

Postby frankfast » Fri May 29, 2020 8:00 pm

DBDBrian wrote:(When a bike kicks back, does that mean the crank rotates backward?)
Yes, in so doing, reversing the drive train back to the kick start shaft, causing the sudden reversal of travel, of the lever.

Frank, I'm a bit confused by the symptoms, and it can be difficult at times to diagnose faults from a distance. Are you 100% certain, that you are actually retarding the ignition timing, and not advancing it ?


Yes, rotating the points plate clockwise retards the spark.Points are set at .016. After not starting the bike for at least two years I'm not sure that I wouldn't expect a few kickbacks before it started. The problem is that my ankles and knees won't take it. Also I've heard that if the mixture is too lean, a kickback may result.
I haven't made any changes since it last ran except for a new (bigger) battery. I replaced the condenser but am not sure that the two that I have are good. Pretty much at wits end.

Jordan
Posts: 983
Joined: Fri Dec 24, 2010 11:29 am

Re: Kickback

Postby Jordan » Fri May 29, 2020 10:33 pm

Assuming you are doing the start procedure correctly on a well-tuned bike, if it's still difficult to start it's time to consider changing something more drastically.
Either to a smaller capacity 250, or a lower compression?
Compression lowering plates were available to put under the cylinder at one time, 2mm thick I think.
It won't do much for performance, but maybe that's not a priority?

frankfast
Posts: 140
Joined: Wed May 05, 2010 12:35 pm
Location: New York (upstate)

Re: Kickback

Postby frankfast » Fri May 29, 2020 11:23 pm

Jordan wrote:Assuming you are doing the start procedure correctly on a well-tuned bike, if it's still difficult to start it's time to consider changing something more drastically.
Either to a smaller capacity 250, or a lower compression?
Compression lowering plates were available to put under the cylinder at one time, 2mm thick I think.
It won't do much for performance, but maybe that's not a priority?


When I replaced piston and rings years ago, the replacement piston had a slightly higher crown on it than the one that was replaced. Not sure what compression the original was without looking it up in a book but am sure it's slightly higher now. Anyway, I have no problem kicking the bike to start. The problem is the kickback.

Jordan
Posts: 983
Joined: Fri Dec 24, 2010 11:29 am

Re: Kickback

Postby Jordan » Sat May 30, 2020 3:52 am

Please make a video of yourself, demonstrating the kickback.
I'm finding the English language is not quite enough.

Duccout
Posts: 261
Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Re: Kickback

Postby Duccout » Sat May 30, 2020 11:37 am

This all sounds not quite right to me. Whenever I have known a bike kick back more than just occasionally it has always been due to over advanced ignition timing, I don't think kicking technique on its own would make the engine kick back. There must be an ignition timing problem somewhere.

frankfast
Posts: 140
Joined: Wed May 05, 2010 12:35 pm
Location: New York (upstate)

Re: Kickback

Postby frankfast » Sat May 30, 2020 1:18 pm

I agree. I'm not sure how much advance would be needed to cause the kickback. I timed the bike statically at 8 degrees BTDC but not sure how accurate it was. I don't have a dial gauge and use a mechanism that screws into the plug thread with a rod that locates the piston. It is done by feeling when the rod is at the highest point. At 8 degrees static the points plate is near the end of its clockwise movement. Not having faith in locating TDC, I've made the mistake of moving it anti clockwise before to give the points plate more movement in both directions. That only increased the advance. I do have bit more retardation I can try which I intend to do but it seems odd that the points plate is almost out of travel in the clockwise direction. Would increasing the compression due to a new piston change the ignition advance? I know all the timing gears are in their proper place.


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