Accessing Coils

How does one access the coils in an 84 Maxim 400 such that the plug wires can be successfully swapped out? I see the bolts holding them in, but I cannot see the way to get them out and back in. Do they just drop down? Maybe I should ask the more pertinent question, how do you put the coils back???

New picture of the bike, we did about 80 km today, great ride:

MaximAl

 

You have to remove the seat then gas tank. The coil is mouted under the gas tank. Like all other yamaha ignition coils the plug wires are not replaceable. They can be replaced if you get to work with a Dremel tool and cut away the molded plastic. Most folks find replacement coils. The wire can be cut and a new section spliced on, that is a good temporary fix.

 

Actually the coil wires on the 400's ARE replaceable. To get to them, you have to remove the gas tank, AND the engine support plates (the chrome plates that bolt to the frame and the top of the engine). You'll see the coil attached inside the frame by two nuts per side.

You have to remove the little support plate that the main wire harness and spark cables run through (it's one large headed philips screw on each side.

After you've removed the engine supports, and harness support you have access to the two nuts for the coils, do ONE AT A TIME to make your life easier.

The bolt part is part of the coil itself, and they will drop out of the frame cavity with some fiddling.

The spark plug wires are the screw on type connectors, they just unscrew from the coil and pull right out. You'll see the primary leads soldered to the top of the coil as well, if those need to be serviced/taken off at all as well.

Ask away if i'm not clear on anything.

This may help as well:

http://www.bikebandit.com/houseofmotorc ... 8sch218690

You can see how the coils are attached and oriented in the frame.

 

Thanks for the info, I'll practice on my parts bike some more. So far, I've got it to the point where I had the nuts off the first coil (the rearmost one) and can't get it to drop, although I didn't try that hard. Question I have is you suggest to do these one at a time, but I can't see how to get the second coil (frontmost, and a bit higher up in there) out with the first one re-attached again. Nor do I see any amount of fiddling getting it back up there, might need some assistance with that.

Al

 

You get some more room if you can take off the leads from the TCI, but they're REALLY hard to get off up in the frame, just be patient, don't get frustrated and they'll drop.

They should be the same height inside the frame from what i remember.

 

Well I must say there's nothing like a parts bike to practice with. I managed to drop both coils and put 'em back too. You'll see in the pictures that they are in different locations, the right hand one being the most challenging.

To get them out I removed the nuts on the left one, let it drop somewhat then detached the TCI lead, wiggled it about and out it came. Good hint: keep those nuts nearby.

Did the same with the right one, now time to try to put them back. Another good hint is to understand the feel of the primary leads so you know how the coil is oriented (the leads being opposite the bolts). Get it back up in there and hook up the TCI lead again. It is fingertip work so be patient, feel for those primary leads to get it turned the right way and within about 5 minutes I had a couple of threads for the bottom bolt through. This is why you want to keep those nuts close by (I didn't...grrr). Grab one and spin it on. Then you need to sort of pivot it til you see the top bolt in there and now get it through, just a few threads, grab that other nut and it's done (don't forget the washers...). Once you've done that one the other one seems like changing a spark plug. Easy. And the plug wires do come off as described so now all I gotta do is find some good ones.

Thanks for the help,

Al