2 Simplex projects

[Ricks]

That is an original wheel sheave.  They used the bolt on sheave for most years and only went to the clip on style late in production.   I don't know what Wayne has for sale, but they are interchangeable. 

HINT:  when installing a bolt on style, one of the holes is offset, to clear the valve stem.  Make sure you line it up properly, or you will create an extra hour of work for yourself!

[Mike Sal]

My seat has a rough textured molded rubber/plastic cover that must have been stretched over the pan when it was new & plyable.  I'm glad it's in good condition, as I don't think it could come off now unless I cut it.
Mike Sal

[kartjockey]

Rick, just reviewing all the pics here. I must tell you I am quite jealous of that NOS spark coil! My bike runs great but only fires on one plug. And I hate knowing that. Being a machinist my whole life, attention to detail and perfection is a must for me!

[Ricks]

Rick, just reviewing all the pics here. I must tell you I am quite jealous of that NOS spark coil! My bike runs great but only fires on one plug. And I hate knowing that. Being a machinist my whole life, attention to detail and perfection is a must for me!

Truth be told, that coil is sitting back in it's box.  I had one of Wayne's single output coils for a cushman that I wanted to try, and I put it in.  They both run the same.  As I understand it, the last of the simplex automatics have a 1 spark plug head with the plug centered.  Simplex must have decided that the second plug wasn't really a help.

[Ricks]

A couple of weeks ago I decided to put a new cylinder on the bike.  The one I got with the bike had a large brass insert for the spark plug put in it at some point in it's life.  I could never get it to stop leaking.  Wayne told me he could weld an aluminum plug in the hole and drill and tap it back to new.  I got another cylinder, had it bored .090 and fitted a new oversize piston. While at it, I put in a .030 longer rod that helps raise the compression.  What a difference!  I think I picked up about 5 miles an hour.  Look out for me at Portland next year.  lol

The old cylinder is going to Wayne for the repair and will be ready for another project in the future.

[simplex1957]

More comp. It will be interesting to see how long it last. I just saw the inside of a simplex motor today, and it was a lot different than what I am youst to seeing. I don't think it would take much comp  , but hay, like I said I am new to this
motor. Hope it works out well, I may do it to mine.

[Ricks]

More comp. It will be interesting to see how long it last. I just saw the inside of a simplex motor today, and it was a lot different than what I am youst to seeing. I don't think it would take much comp  , but hay, like I said I am new to this
motor. Hope it works out well, I may do it to mine.

The weak link in a simplex motor is the rod.  The rod I put in is a billet aluminum rod. 

The next time I do a motor, I think I will try to get a rod from Bob Kerr, which has needle bearings in the big end.  Here is a picture of his ord.

[simplex1957]

That is a nice looking rod. But it looks to me that the weak link is just one main bearing to support the flywheel assembly.
But, I am just learning about these motors.

[admin]

All the old timers have told me it is the rod that dooms these motors.  I have not seen a problem with the bearings in any of the motors I have disassembled, nor have I heard of any.

[Bruce]

Those rods expensive?

[simplex1957]

That is good to know. I was surprised to see a roller bearing on the lower rod.

[Ricks]

Those rods expensive?

I think Bob gets about $100 for one. 

[Bruce]

Nice upgrade for sure

[pd]

Another option :

IF your connecting rod is in good condition and you think you want to increase compression , deck the case cylinder mating surface by .030" , along with the bottom edge of the cylinder sleeve . Then chamfer the inside lower edge of the sleeve about the same amount .

[Ricks]

Another option :

IF your connecting rod is in good condition and you think you want to increase compression , deck the case cylinder mating surface by .030" , along with the bottom edge of the cylinder sleeve . Then chamfer the inside lower edge of the sleeve about the same amount .

IMHO, this is not a good idea.  If you deck the case, you take strength out of the mating flange; same thing if you deck the cylinder.  I am dealing with this on a motor now.  The guy that built the motor for my sportsman did this, with catastrophic results.  The flange on the cylinder broke, leaving it useless.  The case was cut so much that the piston head had to be cut to regain clearance!


The stock rod is the weak link, get rid of it.  This is easier and cheaper than decking the case or cylinder.