Early 1972 Simplex Spitfire restoration

Mini Bike & Go-Kart Parts

#28
Took the H50 apart. Not looking very good for this little engine. It looks to have had a rough life in the past. Hope it is going to clean up with a .020 overbore but i think it is a dream. 20201019_211231.jpg 20201019_211300.jpg 20201019_211240.jpg
 

mustangfrank

Well-Known Member
#31
Yes it is the origanal motor to the bike
I took another 1971 H50 off the shelf and will be the donor block for the bike View attachment 270364 View attachment 270365
Just another H50 with a 30755 alloy flywheel and an alternator...nice, I'm impressed. Every time I try saving an original engine with that much bore wear I end up regretting the time spent, the valve guides, bushings and every wear surface is well worn too...not the kind of job satisfaction I need.
 

markus

Well-Known Member
#33
There is a nice NOS H70 short block available right now if your OK with starter lugs on the front of the block (would have the extended exhaust cooling fins on the side as well) It's a mid 1980's built replacement so it has the later block but the old taper "Long life" standard output crank shaft. Only swap you would want to do is use one of your ball bearing sidecovers along with a Briggs and scrap heap bearing since it bushing sidecover. Shows as having the Mechanical compression release cam in it too (I think that was standard on the H70's) PM me and I'll send you a link to it if you have to go that route. There are a few H50's short blocks floating around as well right now at an OK price as well. Bike is looking great!
 
#34
I have a fresh 1971 h50...cast iron block, lighted.....been on the shelf for a while....has a mikuni and straight pipe in it now....or a fresh h60 if you need either.... D8D16D7B-5DCF-423A-B295-8B8623D3C5AC.jpeg
Pic of the 50....it was going on a suspended frame but can’t find any you’re welcome to it...
 
#35
There is a nice NOS H70 short block available right now if your OK with starter lugs on the front of the block (would have the extended exhaust cooling fins on the side as well) It's a mid 1980's built replacement so it has the later block but the old taper "Long life" standard output crank shaft. Only swap you would want to do is use one of your ball bearing sidecovers along with a Briggs and scrap heap bearing since it bushing sidecover. Shows as having the Mechanical compression release cam in it too (I think that was standard on the H70's) PM me and I'll send you a link to it if you have to go that route. There are a few H50's short blocks floating around as well right now at an OK price as well. Bike is looking great!
I have another good H50 i am using
I foumd a second one on the shelf if i need too. Want to stay correct on the motor size. I thought about bigger motor but then it would not be correct restoration. Thanks for thinking of it for me Markus.
 

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