75 Twin

I have a 75 Twin, serial B75 2002156 that has been in the family since it was new. It was running when it was stored 15 years ago, but when I recently brought it out of storage and cleaned it up, I could not get it to start. After checking it out I found that it has no spark. Removed the flywheel and checked the magnets and everything looks good. The points looked good. I then disconnected the kill switch and still no spark. I am not sure how to check the coils. I really don't know how anything could go bad while it was stored. Any suggestions would be greatly appreciated. Thank You! Doug

Assuming it worked when put away and the timing is still correct...

The most obvious things that happen electrically to this motor when it is sitting are the points develop a film (corrosion or rust or whatever). You can try cleaning them. The other thing that happens over the years is the capacitor looses its capacitance. If it is bleeding, it probably is bad.

Coils could have a problem over time but if they looked ok (no cracks etc) they are probably ok.

You could at least check the continuity of each.

Without reinventing the wheel, there are a number of folks (who have spent more time on this model than me) on the site that have put together some nice troubleshooting ideas for this model. It has been a while since I have seen them, so it might be worth doing a search on the 7.5 hp.

Not knowing your knowledge or tools available (like ohm meter or volt meter), this could be difficult to convey without a manual in your hands.

It does sound like you know to disconnect the kill switch. That is a good start. I would try cleaning the points to start (pardon the pun..).

Mike

dougw181,

I should have asked in the last post...are you sure you do not have spark?

How did you test?

Do you know that both spark plug wires need to be connected to complete the circuit?

One tool I have used is a timing light on one of the spark plug wires. It is not perfect, but if you see no flashing light, there is no spark. Pay attention to the direction that the connector is put on the wire. I usually try both ways just to be sure. The only potential problem is...if the light does function, is the spark good enough?

I have found this to tell me all I need more than 95% of the time on these little motors.

Mike

Mike,

Thank You for all of the information. I'm sorry I did not reply sooner but a family crisis came up and I had to put the project on hold.

I was able to get the motor started after changing the plugs, cleaning the points and all of the electrical connections I could get to. I also replaced
the water pump impeller since it had been stored so long. The engine will only start and run in gear at half throttle or more. I can get it to hit at
lower throttle settings in neutral but it will not run. I am thinking that I need to remove the Carb and clean it out. Is there anything else I should
be checking?

Thanks again for all of the help. Doug

Disassembly and cleaning of the carb is probably the most likely next step for you.

I am assuming that compression and timing are ok....since I do not think you have a way to check them anyway.

Just be careful taking the carb apart. Some of the parts are no longer available.

Mike