Swapping flywheel covers Tecumseh

MrRustbucket

MrRustbucket

New Member
#1
#1
Can you take a newer tornado style Tecumseh engine pull start engine And swap the more vintage 4bolt pull cord fan shroud on it? Also what years 3.5 hp came with rear facing exhaust and not the side poper. Haven't seen a vintage mini bike come stock with a side poper engine. Or am I wrong. Sorry if this is asked a lot. Been wanting to try it but don't want to wast money on parts if its been tried and failed
 
massacre

massacre

#2
#2
Well the long answer is possibly, but it's not a direct swap. Lots of parts need to be swapped over from a points engine - flywheel, points, possibly crankshaft, points cam, condenser, flywheel cup, some of the newer engines can't be swapped over due to having no mount for the points.
The low-profile shrouds need a skinnier flywheel.
You could probably swap one of the wider shrouds with a 4-bolt starter without too much issue?
Others who are more knowledgeable will know for sure.
 
C

cfh

Well-Known Member
#3
#3
actually Mass that's not true. i use old style 4 bolt blower housing and pull start on 1990s HS50 motors a lot. like a ton. it's pretty much a direct swap. I can't remember if the starter cup is the same... but the blower housing fits, just it's snug on the two lower mount bolts. so gentle manipulation of those 2 bolts (i use a 1/4-20 tap and chase those 2 bolts through the blower housing, and it fits.) i t hink you will need a new starter cup too, just can't remember.

now some say that the pre-1987 blower housings with the 4 leg pull start cuts off circulation around the CDI unit. And tecumseh made a flat front 4 leg pull start blower for just this application in 1987/1988. But that said, again, i've used the older blower housings without issue on CDI engines. nothing rubs, and there does not seem to be any difference in engine temperature. But i'm not pushing these motors hard either...
 
C

cfh

Well-Known Member
#5
#5
the "cyclone" blower housings attach exactly the same as the older style blower housing. the pull start itself is completely different. so if you want to back date the motor you will need the older pre-1988ish blower housing and pull start. Maybe the starter cup too, can't remember...
 
markus

markus

Well-Known Member
#6
#6
MrRustbucket said:
Can you take a newer tornado style Tecumseh engine pull start engine And swap the more vintage 4bolt pull cord fan shroud on it? Also what years 3.5 hp came with rear facing exhaust and not the side poper. Haven't seen a vintage mini bike come stock with a side poper engine. Or am I wrong. Sorry if this is asked a lot. Been wanting to try it but don't want to wast money on parts if its been tried and failed
Click to expand...
This thread will give you some insight to doing the conversion, click and expand the quote on 2nd post as well: backdating shrouds

All years "small frame" H version engines were available in either side or rear exhaust, and there were actually a few mini bikes and karts that did in fact come with a side exhaust due to fitment from the early 1960's right up into the 1980's

you should take some time an properly Introduce yourself, what your working on, where your at in the world etc. We have been getting rashes of bad apples coming on here, and people have been a little less helpful due to time wasters and scammers. Good luck with your project.
 
C

cfh

Well-Known Member
#7
#7
On the blower housings the later model four leg blower housing does fit better than the pre-1988 style. It is designed for a CDI ignition. The CDI version is on the right in the picture below. And the older version obviously on the left. But you can make either work. I just can’t remember on the starter cup whether you will need it or not. But if you do the cup part number is 33662, I believe. It’s also nice to use the screen along with the starter cup, part number 590417.

i’ve done this conversion on a ton of 1990s hs50 engines. But to be honest, I am trying to stick to points and condenser motors now. In the early 1990s tecumseh changed the exhaust valve and it got smaller, for emission issues. I just find the larger valve motors better to modify and run a bit stronger.

1690721437044.jpeg
 
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