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[Admin]

Unfortunately, MSD designed the flywheel and hogged out the material between the permannet magnet and the hub. The cross section looks exactly like the sketch in the post directly above.

The magnet is in the perfect position but MSD removed too much material.

In the first concept drawing, I thought I could save the flywheel hub and make my own disc. I think either design is workable but there are pros and cons to both.

Here is a sketch of the bracket I need to make if the flywheel is above the triggers.

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[Admin]

I had a horrible feeling that would be the case. So back to the Pros and Cons.

For the modified stock set up, how would the stator plate mount up? Does it need the same adapter plate but fitted to shortened standoffs that the alternator used?

If it needs an adapter plate, do you still have enough height on the flywheel?

For the triggers outside design, you could probably make elongated slots in the adapter plate to make timing adjustment simpler/quicker. If that appeals to you, you might want to look at making it fit the recess that the alternator sits in, though that will not be easy with teh standoff placement.

It should also be possible to make the ring for the flywheel as a press fit and not bother welding it to the machined down flywheel.

These are exactly the issues that Suzukidave and I have been working through with trying to adapt Polaris ignitions. Fortunately for dave, the ignition he chose is small enough to fit. I, on the other hand, went with a more recent ignition with TPS and other connections and of course, it's larger and won't fit.

What was wrong with those Suzuki engineers? Didn't they realize that we would be trying to adapt 21st century technology to these motors almost 40 years after the bike was designed!

[Admin]

Yes...for the flywheel above the trigger concept, you can't fit an adapter bracket underneath the trigger plate so I designed one to mount on top of it. It's shown in the post above. That bracket would avoid the triggers. The triggers that I have have a "pemnut" permanently attached on the upper side so a socket head bolt comes through the back of the trigger plate and into the pemnut. That's the way the Actic Cat is setup. The socket head location is countersunk so it won't interfere with the crankshaft seal. To thin down the trigger plate, you would have to remove material from the upper surface rather than the underside.

The adapter bracket would be secured with the three existing standoffs for the stator and would have to be cut down. It would be easy to mark them and cut with a disc dremel. I'm just concerned about thread engagement and breaking through the case.

For the "Triggers-Above-" concept, I also thought about using the machined landing from the alternator but it seemed that the "triangle" shape of the adapter bracket mounted to the standoffs would allow a lot of access. In this case, the standoffs are used as-is and height is controlled by stack-up. The MSD triggers all come with shims too.

From an engineering perspective, the "Triggers-Above" concept seems more sound since there is tons of room to work outward. The flywheel is light but it never hurts to have a rotating mass as close to the main bearing as possible. By opening up the hole in the MSD trigger plate, not only can we adjust the triggers indidually, but we can adjust the trigger plate as an assembly as well as have access to the flywheel to ahdjust timing there too.

I keep telling myself, this is the fun part....and I have no idea what the Japanese were thinking....

[Admin]

Agreed. Triggers above, looks better in some ways. And way more "trick" looking to boot.

My preference for rotating masses, is keep 'em close, and even though teh modified flywheel should be light, there will be less crank whip effect if it's nice and close.

BTW, if you don't have much to do this weekend, maybe you could zip over to my place and design an adapter for me to mount a GSXR alternator rotor on my GT750 crank end

[Admin]

TZ, I would be happy to do it....

[Admin]

Here is the layout drawn a bit more to scale. Left side shows triggers below and right side shows triggers above. In either case, the adapter bracket that attaches the MSD trigger plate to the 3 alternator standoffs must mount on the face of the trigger plate. It seems clearer now, which option needs to be taken.

Triggers above allow better access all around for adjusting and there are few dimensional constraints. It eliminates any risk associated with cutting the standoffs down and possibly breaking through into the crankcase and eliminates any machining modification to the MSD trigger plate. There is a registered diameter on the adapter plate that will keep the trigger plate relatively concentric to the shaft.

We'll just fabricate the adapter bracket (shown in the post above) and modify the flywheel with a new disc then install the permanent magnet.

I bought 6061 alumimum .25" stock for the adapter bracket and 7075-T6 x .375 for the flywheel disc. I added a groove in the flywheel hub for a removal tool. Should be done soon. I will post the completed pictures.

[Admin]

kevin, sounds like a plan.

[Admin]

Just wanted to post some additional progress on the MSD ignition installation. Here is the Trigger Plate Adapter almost complete. The outermost clearance holes will use the existing engine case standoffs where the alternator stator used to be mounted. The recess fits the MSD Trigger Plate perfectly so I can easily rotate the entire trigger plate several degrees in each direction without touching the flywheel.

I still have to cut along the straight lines so that the triggers can be installed. This will allow each trigger to be set individually for each cylinder and locked down easily...

Dave helped me out when the flywheel hub was being machined and we needed a taper tool to cut down the MSD flywheel. The new flywheel will be balanced and ready tomorrow for install on the bike.

[img][img]http://i305.photobucket.com/albums/nn22 ... G_0882.jpg[/img][/img]


[img][img]http://i305.photobucket.com/albums/nn22 ... G_0890.jpg[/img][/img]

[Admin]

I guess the tapered piece i sent you worked out OK ? .. Dave

[Admin]

Dave,

I think it worked out ok. The taper tool was just slightly larger than the hub but we managed to get it cut. I'll get to see it tomorrow. Can't thank you enough for helping me out on this one. It will be on its way back to you tomorrow.

[Admin]

Here is the new GT750 flywheel to complete the MSD Ignition system upgrade. The hub, is a cut-down flywheel from the MSD Actic Cat triple. We kept it since the hub matched the GT750 crank. It was machined as shown in the previously posted sketches with a notch for a flywheel puller. The flywheel itself is 7075-T6 plate to match the hub and was heated and pressed on to the hub this morning. The permanent magnet was weighed at 1.9 grams v. 0.3 grams for same dimensions of aluminum removed....so holes were added on the backside near the permanent magnet to balance the flywheel. A new magnet was pressed in place.

I'll try to post images once I get over to the shop and assemble it on the bike.

[Admin]

I wish I had a machine shop, I wish I had a machine shop, I wish I had a machine shop.......

Nice work.


Lane

[Admin]

Well, tonight I was able to fit up the new assembly on the bike....the first pic is the flywheel fitup...no problems dimensionally.



These two shows the MSD trigger plate mounted to the adapter with spacers in place....I found an issue with one of the triggers and ordered a new one. Stock Suzuki cover fits over the assembly. With this configuration, I can get at each trigger individually to set timing and I can rotate the trigger plate as an assembly.

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[Admin]

Wow! That is dead sexy!
Very nice work.

[Admin]

Thats cool Kevin , that setup came out extra nice , adjustable too .. very nice