1941 Simplex in the works

mexlas

New Member
Apr 15, 2010
28
6
3
California
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
 

indian22

Well-Known Member
Dec 31, 2014
3,823
4,550
113
Oklahoma
The Old guy likes your Simplex and heartily concurs with your decision to match up a Preddy 212....grrrr! Rick C.
 

MotoMagz

Well-Known Member
Aug 2, 2010
1,746
929
113
Michigan
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.
 

mexlas

New Member
Apr 15, 2010
28
6
3
California
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.
 

indian22

Well-Known Member
Dec 31, 2014
3,823
4,550
113
Oklahoma
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

Well-Known Member
Aug 2, 2010
1,746
929
113
Michigan
A lot of the Simlex guys and gals at Portland put V twins Vanguards. Harbor Frieght carries a v twin now. Pm sent
 

Velodrome

Well-Known Member
May 27, 2011
2,387
216
63
Phoenix-ish
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

New Member
Apr 15, 2010
28
6
3
California
Anyone now anything about MRE Miller Racing Engine? I found one local complete with exhaust and clutch for 100. It run too