1941 Simplex in the works

[mexlas]

Hello all,

I recently picket up a resto mod 1941 Simplex Servi-Cycle. It has few original parts on it but not much. It has an old Briggs flathead 3.5 hp engine. I finally got it going but not happy with the speed and performance of the engine. I am going to attempt to install a Predator 212cc with an torque converter. I will post pics along the way and also ask tons of questions.

Mark

 

[mexlas]

 

[indian22]

The Old guy likes your Simplex and heartily concurs with your decision to match up a Preddy 212....grrrr! Rick C.

 

[curtisfox]

NICE BIKE! 3 hp should do about 30 mph, depending on the gearing.............Curt

 

[MotoMagz]

Cool bike,definitely keep the sheave coming of your new torque converter with the 212cc. Off the torque go with a 2-3” pulley and a Ax belt. You will be happy.

 

[culvercityclassic]

Nice bike, I would replace it with a 5hp raptor flat head to keep the look. Add a cam, flywheel, carb and pipe and you will be happy...

 

[curtisfox]

Yes that would be so much KOOLER old school look.........Curt

 

[mexlas]

Thanks all,

Where can I find a new 5ph flathead? I really wanted to go that route to keep this cool looking primary cover.. I looked around and couldn't find any 5hp flatheads used... I started off with a basic Briggs and replace the flo-jet carb with a 19mm and a valve job. It's runs about 25mph with current gearing.

 

[mexlas]

I can easily switch to a 5hp flathead build before I get too far into this build..

 

[ZipTie]

The lines of that bike are very beautiful, I would love to make a find like that, congrats.

 

[indian22]

The 4 cycle flat head would also be a good looking performer on the Simplex.
The original 2 cycle Simplex engines are small, the earliest 79 cc & later 115 cc; with 125 cc & eventually a 150 cc displacement. Power was intentionally limited by the factory for safety on these engines, to under 5 hp, but 45 mph speeds were still reached on the later Automatics.
A couple of the guys I rode with back in 1961 & '62, rode Simplex 150cc Automatics and they kept up pretty good with the 5 hp Cushman's and looked so cool doing it!! Both the Cushman's & Simplex bikes had the mandatory factory "under 5 hp" engine sticker required in Oklahoma for 14 yr. scooter license.
Check out the Simplex forum for in depth info with good photos as well.
I'll look forward to seeing more photos as you swap motors, regardless of which engine you select. Rick C.

 

[MotoMagz]

A lot of the Simlex guys and gals at Portland put V twins Vanguards. Harbor Frieght carries a v twin now. Pm sent

 

[culvercityclassic]

https://www.ebay.com/i/263246056817...3D711-117182-37290-0%26rvr_id%3D1336958626669

 

[culvercityclassic]

Remove the sheet metal and it become a beauty queen

 

[Mr.B.]

Great project!

Here’s a fellow who put a Gravely Model L engine on one...
I’m not suggesting this as it’s not exactly a practical option- Never the less it’s well executed, inspirational and an example that anything is possible!

 

[culvercityclassic]

I like that Gravely in the bike, sounds great too.

 

[Velodrome]

Im in love with that Gravley but Wolf's suggestion in post #14 would be a much more doable and meet your speed / torque goals. Hey CCC where you get those Raptors? Can you get em pre built or do you have to piece and part them togather on your own?

 

[mexlas]

View attachment 96286 Remove the sheet metal and it become a beauty queen

Wow! What a Beauty!!! Now that what I'm talking about... Okay it's settled, direction for my build is now 5hp flathead. Thanks all for your input.

Mark

 

[mexlas]

Anyone now anything about MRE Miller Racing Engine? I found one local complete with exhaust and clutch for 100. It run too

 

[mexlas]

Anyone now anything about MRE Miller Racing Engine? I found one local complete with exhaust and clutch for 100. It run too

Briggs 5hp model 135232