depends on the era of the crankshaft. Pre-1981 will fit the crankshaft, but does not mesh with the shroud, as it is a smaller flywheel so you want to use the 1969-1974 HS40 or H25-35 curved shroud and corresponding backplate as well in order allow the flywheel to move the air through and over and around the clyinder.
just figured out how to navigate. and you are right. the hole reason for the flywheel swap is to get rid of my giant steel lighted flywheel. i wan't the look of the h-35 minibikes when i was a kid around 1970. do you have a part number for the correct backing plate. if i can't find the parts separately i know of a complete hs-40 for sale. it needs to be rebuilt so i will just take what i need off it as my hs-50 is a fresh rebuild.
#30658 Tecumseh called them baffles, they are NLA though so most likely your only going to find them used or on donor engines. You do want to try and get the mid/late 1969-74 style shroud. that is when they upgraded the HS40 to the wider head (that is shared with the later made HS50 engines) as they modified the small frame shrouds at that time to better fit both style small and large bolt pattern heads.
my donor engine is a 1970 rupp hs-40 with the correct lighted aluminum flywheel. so i am lucking out. it will also have the baffle and shroud you recommend. i would like to send you a picture of the bike bu i don't know how. it is a bad dog frame. i cut the fender and seat tabs of made nicer ones and welded them on. extended the foot pegs out 2 inches per side. found new old stock headlight on eBay made tabes for that welded them on. all wiring is inside the frame. i built it with all the care i give full size bikes iv built. you are a wealth of knowledge with the tecumseh. thanks for the info. anthony.
look at the background shot. my ducati 1198-s. before i moved hear to spring hill fl. i had a big house i nj. i sold it when my job shut down. i had bought seven tecumseh engines. i gave them to the moving company guy. had no room in the new downsized house.
Nice clean build! Since your already setup, and looks like its rideable I would love to hear what you think of the HS50's driveablilty before and after the conversion. That size bike you have with the large rear tire would be a pretty good test on how much, if any, loss you get on the low end with the lighter flywheel. I've have converted a few but when I did it they were either on bikes I never rode with anything else on them or just built and sold the engines. I would also keep an eye out for an actual HS50 exhaust pipe. They dont choke down at the flange like that HS40 one on there does. The earlier ones actually match the port really well and seal up good. Not a big deal but every little bit helps!
yes iv noticed the port mismatch. i also have an identical looking one with an even smaller port hole. it must be for a h-35. when i started this bike it was 2010. i did no research witch was silly. i had money to burn back then. it was all impulse buy's on eBay. anyway i had the bike all mocked up. no paint yet but nearly ready. the my boss died at 58 years old. i had a cushy welding and metal fab job for 17 years and then it was gone. anyway i moved 4 times in 5 years. the bike did not go together until 2015. the last time i messed with a tecumseh i was 16. it was a 7 hp. h-70. my friend tommy had the same motor. we both had go carts. i had a stella he had a muller. his brother and a guy named john were drag racers. john gave us a magazine on how to port tecumseh and brigs motors and fire slot the block. we put cams and straight pipe exhaust on them. we were amazed. the were stupid fast. tommy had really big sprocket. it was about 1/4 inch from touching the ground. he would pour bleach on the street and do bleach burnouts. fun times. i was going to port this engine put a cam and billet rod in. i am glad i did not. with the small wheel base it is a scary ride.it pushes the front wheel around every turn. scary. I'm sure il be giving up a bit of torque. but it should rev a bit quicker. i can't wait to get the new parts. I'm like a child with this stuff. i will keep you posted. hear is a picture of a triumph i built for my nephew in 2004. its the very last real bike i built. twenty grand in parts. who knows how many hours. it came out better than i could have imagined. i will keep you posted. anthony.
that is the fourth one i built. it was also the best one i built all had joe hun't mags. back in the 70s i paid $175.00 for a brand new one at frank marmoes triumph in patterson nj. in 2004 i paid $1200.00 for the same mag.
finally got a lighted aluminum flywheel and round style blower cover for my 1972 tecumseh hs50 on eBay. had to buy a lighted rupp hs40 to get it. $505.00 must loosing my mined. hears some pictures of the donor motor.
i can put my square blower cover and steel flywheel on it. it will still be a lighted rupp hs40. that should bring some good money. i really don't feel that bad spending the money. i love the look of the early h35. brings me back to the early 70s. all my friends had the h35. i had dinky briggs 2-1/2 hp. couldn't keep up with none of them. really pissed me off.