79 exciter help

WatertownBob · Post by **WatertownBob** » Mon Sep 10, 2007 1:09 pm

Hey guys I need help
I bought the sled with a no spark condition. The Yamaha mechanic said that the source coil is bad. The sled sat all summer and last week I pulled the rope and it fired right up! rode it around the yard and washed it up. Whent to start it for a friend later and no spark. I pulled the Flywheel off and all looked good but I replaced the source coil per the recomndation of the Mechanic at the Yamaha shop. Reassembled and pulled the rope started on the fist pull. Ran it around the house and back into the Garage. That night whent to start it to see if the instrument lights work and no start.

This afternoon I pulled the wires off of the key and tether switch also the wire going to the kill switch on the handel bars. And still no spark. Thought that mabey if I cut the ground to the externial coil that would make it a hot coil but still no spark! This is keeping me from haveing a near perfect 79 exciter 440.

Any ideas would be greatfully appreciated!

Thanks Bob

Mr. Deere · Post by **Mr. Deere** » Mon Sep 10, 2007 3:41 pm

Thats weird sounds like it only does it when the sled is warm or is wet. You could be shorting something out when moisture gets in the coil area. Try plugs and wires and caps also. BOB

WatertownBob · Post by **WatertownBob** » Tue Sep 11, 2007 7:37 am

more info
The sled has always sat over night or atleast more then 5 hours from the first time I start it until there is the no spark condition.
Also I started it shortly after I washed it still kind of wet and it ran and now it is completely dry and no spark. Also tried new plugs same condition.

Is there a way I can check the externail coil?

Thanks Bob

WatertownBob · Post by **WatertownBob** » Tue Sep 11, 2007 2:19 pm

Talked to the local Yamaha guy and he gave me all the resistance readings should be for the coils I hope I find a problem. Could be a bad connection I guess.

Bob

Mr. Deere · Post by **Mr. Deere** » Tue Sep 11, 2007 8:25 pm

Is it a separate coil cdi like the Deeres or is it combined. Also what about your wires and caps are they cracked at all you could be shorting out if they are cracked. The only thing that throws me off and im sure you as well is the intermittent spark. The only other thing could be that your flywheel is stopping in a dead spot. I just dont know. BOB

WatertownBob · Post by **WatertownBob** » Wed Sep 12, 2007 7:51 am

The spark plug wires and caps are in good shape. It is a seperate coil internal behind the flywheal and an external coil that has the wires going to the spark plugs. I took an ohm meter last night with my notes from the local Yamaha guy and tested the wires. The blue and black wire on the source coil is an open

I will need to pull off the flywheal and take a look.

bob

WatertownBob · Post by **WatertownBob** » Fri Sep 14, 2007 8:04 am

I took my stator assy in the the Yamaha shop and had them look at it. I replaced only one of the two internal source coils and the other is bad "open". This coil is no longer available and I am not sure that I could rewind it my self. Would need to rewind it verry tight as there is little room for the coil install. Part number for you Yamaha guys 8e7-85512-10-00. Mabey some one has old stock laying around I can always dream. HA HA

Thanks For all the help

Bob

Mr. Deere · Post by **Mr. Deere** » Fri Sep 14, 2007 5:51 pm

Well at least you figured it out. BOB

WatertownBob · Post by **WatertownBob** » Mon Sep 24, 2007 1:44 pm

Had the worng part number. The one I need is the smaller of the two part number 8E7-85541-10-00.
Just in case someone has one <_<

Thanks Bob

big danno 1970 · Post by **big danno 1970** » Mon Sep 24, 2007 2:38 pm

Watertownbob,you could try to get a coil from a different brand or other yamaha model sometimes if they fit in the hole it will work I would sure give that a try.Just take your bad coil in to a dealer and ask them to try and match the up size shape and the mounting holes.they will probably tell you theres wont work (wrong values) but trust me it will work as I have seen it done many times.
Good luck

Rodimus Prime · Post by **Rodimus Prime** » Mon Sep 24, 2007 9:44 pm

if you got a pic of the sled to give me an idea of which one it is it would help.

WatertownBob · Post by **WatertownBob** » Tue Sep 25, 2007 10:27 am

Item 330169140721 on Ebay is just like my sled. It says it is a 78 on ebay but it really is a 79.

I found that Mfgsupply has the coil available that I need but they did not have it in stock. They said that they would contact there parts warehouse and see of they could get it. There part number is 01-085-17. Looks like a parts unlimited part number wonder if they get some of there parts from the same provider.

Bob

WatertownBob · Post by **WatertownBob** » Tue Oct 30, 2007 9:07 am

I finally found the coil I need. Installed last nigh and it runs!

The sled is ready to go but I have not serviced the chain case oil yet. Is anyone familer with old yamahas how to I check the level of oil and what grade of oil should be used?
Thanks Bob

8ho · Post by **8ho** » Fri Nov 02, 2007 7:18 am

look throught the foot rest a small screw on the side of the chaincase the oil should run out if it has never been change then pull the pipe take the cover off and change it .I would check the bearing on the other side those go bad to yamaha still can get new ones