spark plug wire question 84 Yamaha, 115 HP

[mike101650]

New to me 84 115 hp Yamaha. I bought a service manual but I think it assumes some knowledge that I don't have. It pretty much says to use some special test equip on the spark plugs and wires but doesn't address actually changing or repairing the wires. After cleaning the gas tank and carbs, the thing finally runs and runs great. However, it doesn't run great for ever. Three of the 4 spark plug wires are backing off the spark plugs. I tried to squish the spring that goes over the spark plug tip to make them tighter but had no luck doing that. Since this is 30yrs old and probably has the original wires, I think I will replace them. Now does the wire pull out of the coil?? I pulled on it a little bit but did not want to ruin a coil. So please tell me how it works. What is the secret of getting the wire out of the coil? Also, the only replacement wire I have found is a roll of wire and a bunch of connectors without boots. Can I buy a wire set already made up to just plug in?

 

[99yam40]

Re: spark plug wire question 84 Yamaha, 115 HP

I think the wires come as part of coils and are not replaceable unless you get new coils.
Not sure about that old motor but some of the plug caps were replaceable.

Does your manual give specs for the resistance of cap separate from secondary of coil?

 

[mike101650]

Re: spark plug wire question 84 Yamaha, 115 HP

I think the wires come as part of coils and are not replaceable unless you get new coils.
Not sure about that old motor but some of the plug caps were replaceable.

Does your manual give specs for the resistance of cap separate from secondary of coil?

Yes. The manual talks about removing the plug wire caps. It also talks about removing the caps when performing the secondary coil resistance measurement. I guess you have to read between the lines to see that the coil and wire are a unit and not separable. This seems kinda weird that the little springs inside the caps no longer fit. The caps slide on and off the plugs on cylinders 1,3,4 with little effort. I have successfully removed one of the caps but I am not sure I am doing any good until I can buy another cap/wire/spring or whatever it is called. I hope I don't have to buy new coils. They sound expensive and I am in a boat on a low budget situation.

I was reading some other threads to try and glean some info on this problem and found one tip recommending putting a plastic tie around the boot to hold it on. While the caps come on and off easily, they do make contact. Do you have any thoughts on this solution?

Thanks for your input on this.
Mike

 

[mike101650]

Re: spark plug wire question 84 Yamaha, 115 HP

I just checked Iboats parts for these coils and they list one for 1985 to 1991 but nothing for 1984. I may not be able to find coils anyway.