1969-1970 7.5 Thunderbolt

[bob1340]

I haven't torn this apart yet for this issue.

Last year I got this motor and re-built the carb, fuel pump, new water pump ETC. Motor ran fairly well, but the compression is low and power down. It starts right up though and I can live with it.

Here's the problem.

After my "shake down" run last year I noticed the motor area full of junk. Well the junk is the insulation off the ignition wires up under the stator. LOL, I sure am glad nothing shorted out? I have had no time to mess with this in a year. Now I am getting ready to pull the flywheel ETC and look what all I can fix.

Am I going to be able to just solder in new wires? If I need to replace a bunch of stuff I'll just junk it.

Any advice?

 

[MercMan82]

Re: 1969-1970 7.5 Thunderbolt

http://www.maxrules.com/CDITSHOOTING.html
Here are some specs for you to troubleshoot your ignition.

 

[cr2k]

Re: 1969-1970 7.5 Thunderbolt

Get some liquid tape and coat everything. Back then they used rubber insulation and it gets baked hard. If you move any wire you will have the same problem. Best fix is a new stator.

 

[bob1340]

Re: 1969-1970 7.5 Thunderbolt

http://www.maxrules.com/CDITSHOOTING.html
Here are some specs for you to troubleshoot your ignition.

I have that. The ignition has good spark, no issues. I just ain't torn it apart to see if I can actually just replace the bad wires or not.

Get some liquid tape and coat everything. Back then they used rubber insulation and it gets baked hard. If you move any wire you will have the same problem. Best fix is a new stator.

Yup. Good old rubber insulation. Crumbled to zilch! I am hoping to replace the leads which in my minds eye are all that have insulation on them. A stator costs like a huge down payment on a new motor.

 

[Mi duckdown]

Re: 1969-1970 7.5 Thunderbolt

First. What is your compression? I would check that first before going further.

 

[MercMan82]

Re: 1969-1970 7.5 Thunderbolt

First. What is your compression? I would check that first before going further.

Yes, check it first. I rewired one a bit similar to yours before. Not too difficult. Just make sure you use same gauge wire and liquid electrical tape can be extremely handy when rewiring. That's like the best stuff since crunchy peanut butter! Ingenious stuff.

 

[bob1340]

Re: 1969-1970 7.5 Thunderbolt

First. What is your compression? I would check that first before going further.

Compression is terrible, IIRC is was about 65 lbs, but the same on both cylinders. But that has nothing to do with my question or issue. The compression has no effect on wire insulation.

Yes, check it first. I rewired one a bit similar to yours before. Not too difficult. Just make sure you use same gauge wire and liquid electrical tape can be extremely handy when rewiring. That's like the best stuff since crunchy peanut butter! Ingenious stuff.

Being I haven't pulled this apart yet I am guessing from your experience I can indeed solder new wires in then? That would be too cool. I haven't used the liquid tape much, but I can see where it may come in handy here. Thanks.
Creamy for me.

 

[etracer68]

Re: 1969-1970 7.5 Thunderbolt

If your talking about the white and green wires, yes they can be replaced. They run through the insulator blocks to the points, and are soldered on little studs, The problem may be getting the studs out of the insulators without cracking them, most times there cracked alreadly.

 

[MercMan82]

Re: 1969-1970 7.5 Thunderbolt

Compression is terrible, IIRC is was about 65 lbs, but the same on both cylinders. But that has nothing to do with my question or issue. The compression has no effect on wire insulation.

well, you wouldn't want to replace the wires without fixing that compression problem. Those are two separate and equally important things that need to be resolved before you can run it.

 

[bob1340]

Re: 1969-1970 7.5 Thunderbolt

If your talking about the white and green wires, yes they can be replaced. They run through the insulator blocks to the points, and are soldered on little studs, The problem may be getting the studs out of the insulators without cracking them, most times there cracked alreadly.

I am thinking these wires were brown, but being they are now basically bare I'll need to mark everything good. But it does appear they are the wires that go to the points.

 

[bob1340]

Re: 1969-1970 7.5 Thunderbolt

well, you wouldn't want to replace the wires without fixing that compression problem. Those are two separate and equally important things that need to be resolved before you can run it.

The motor runs with the low compression if you look at the original post. Not as well as it possibly could, but fine for me.
Once one of these bare wires shorts out and blows the stator the whole motor goes for parts as it ain't worth buying a stator for this old motor. This is a $75.00 to me. I don't want to pump huge volumes of cash into it.

BTW I will maybe pull the head apart someday and fix the compression issue. But more than likely I'll sell it and buy a 4 stroke as more places around here are not allowing these old 2 strokes in the water.