weak spark

[yamamunn]

I picked up an 81 special. got it running it sat for a few years. only getting good spark to the right side. switched coil leads to opposite sides and now sparks weak on other side. so my ? is either one of the wires that connect to back of coils directly lead to each plug side or is my problem in my coil? I thought that since its a single coil that both plug leads would get power from same source

 

[gggGary]

5K plug caps are known to fail, check that strands of wire are in good contact with the prong in the cap. often cut a 1/4 of insulation fan out the wires replace cap helps, Ohm the cap separately, should show 5K ohms.

 

[yamamunn]

gggGary sure enough one cap 5.3K other cap was hard to even get a reading but when I could was 11.9K thanks! Now to get it running smoothly. It’s wont throttle up, stumbles bad. ? Order of next step carbs have been thoroughly cleaned new needles and seats, set cam chain tension then adjust valves? Then sync carbs. They were bench synchronized

 

[yamamunn]

5K plug caps are known to fail check that strands of wire are in good contact with the prong in the cap. often cut a 1/4 of insulation fan out the wires replace cap helps, Ohm the cap separately, should show 5K ohms.

Thanks Gary

 

[XSLeo]

On the TCI bikes the TCI box doesn't like low voltage. If it drops much below 12 volts the TCI can't function as it should. Resulting in running issues you describe. It can also be a weak magnet in the rotor.
You can do an easy check for both of these issues by fully charging the battery then unplugging the reg/rec. This stops the power flow trough the rotor. Allowing full battery voltage to the TCI as well as letting the pick ups read the magnet better.
If it runs well with the reg/rec unplugged then you need to check out the charging system to ensure the TCI gets the voltage it needs.
Once you get the charging system working right that may take care of your running issues.
If not then you can check the strength of the rotor magnet. Try sticking something steel on it and see how hard it comes off. If it's easy to pull off the magnet may be weak.
On your carbs, did you buy a kit with jets and such in it? Most kits don't come with the right jets and such with them.
Myself and others don't recommend kits fort his reason. Follow the carb guide to tear down, clean, inspect your carbs. Once you determine what needs replacement just buy what you need. Most of the internal parts and if careful even gaskets can be reused.
When cleaning pay particular attention to the idle circuits. They have small passages and tiny ports that plug easily. and are hard to get clean.
Leo

 

[yamamunn]

Thanks for your reply, ordered new plug caps, most everything in carb cleaned up well. I am going to go through them again after reading how to clean through the fuel screw. I did remove the brass cap and cleaned just not sure I got the 3 holes by the throttle plate completely cleaned. They should be reset at 3-3.5 turns out correct?

 

[5twins]

You removed the caps over the mix screws but did you pull the screws and all their little parts out and inspect them?

There is a tiny o-ring on the mix screw and it needs to be in good shape for the screw to adjust up properly. Also, the screw needs to be removed to do a proper cleaning of the idle circuit. Yes, 3 to 3.5 turns out is the usual setting range on these BS34s.

 

[yamamunn]

Yes I got it all out. It looked good, I just wasn’t aware of the 3 holes near the throttle plate

 

[yamamunn]

Yes I got it all out. It looked good, I just wasn’t aware of the 3 holes near the throttle plate

So I need to clean them

 

[yamamunn]

Thanks for your reply, ordered new plug caps, most everything in carb cleaned up well. I am going to go through them again after reading how to clean through the fuel screw. I did remove the brass cap and cleaned just not sure I got the 3 holes by the throttle plate completely cleaned. They should be reset at 3-3.5 turns out correct?

The battery is brand new

 

[yamamunn]

On the TCI bikes the TCI box doesn't like low voltage. If it drops much below 12 volts the TCI can't function as it should. Resulting in running issues you describe. It can also be a weak magnet in the rotor.
You can do an easy check for both of these issues by fully charging the battery then unplugging the reg/rec. This stops the power flow trough the rotor. Allowing full battery voltage to the TCI as well as letting the pick ups read the magnet better.
If it runs well with the reg/rec unplugged then you need to check out the charging system to ensure the TCI gets the voltage it needs.
Once you get the charging system working right that may take care of your running issues.
If not then you can check the strength of the rotor magnet. Try sticking something steel on it and see how hard it comes off. If it's easy to pull off the magnet may be weak.
On your carbs, did you buy a kit with jets and such in it? Most kits don't come with the right jets and such with them.
Myself and others don't recommend kits fort his reason. Follow the carb guide to tear down, clean, inspect your carbs. Once you determine what needs replacement just buy what you need. Most of the internal parts and if careful even gaskets can be reused.
When cleaning pay particular attention to the idle circuits. They have small passages and tiny ports that plug easily. and are hard to get clean.
Leo

Ok I disconnected the reg/rec runs the same checked rotor for magnet nothing with key off and not much with key on. Shouldn’t this be magnetized all the time?