tecumseh-ohh build

delray

delray

Well-Known Member
#41
#41
here is something i did over the summer. i took a complete stock ohh-engine and milled the head .040 on my lathe.



i also gave it the same treatment as my built motor got. use the aftermarket style retainers and keepers with a set of factory 15+ pound animal springs. thats what the guys at dyno cam rate them at. then installed a steel camshaft out of a newer flathead hs-50. something i notes about the newer flathead camshafts. they are lighter because they are machine out like the plastic camshafts with the valve relist built into them. i just remove that part before installing it. sorry no pictures of it. like i said before it looks just like the plastic camshaft,but steel. also i mic it and they have about .010 higher lift lobe then the older flathead cams do. timing on the engine was advance to 30+ degrees
something else i notes, the intake did not match the head,so i went ahead and port match that and clean up the intake side too.



now we are really talking about budget build here. took the stock rod and polish the rod beam up....:doah:

engine was built to run in a stock drag class. 10hp and under with stock cast iron flywheel and no aftermaket racing cams or carb's for example a mikuni carb. only a aftermarket air cleaner and you can rejet your stock carb. this class was really setup for the clone guys so they could put a new motion tube and jets. for me all i could do is install adjustable hs-40-50
carb.


kept the engine and bike kind of crusty looking so it would not stand out.......:laugh:
unfortunately the first race the throttle unit broke internally. causing it to fail. funny thing was the throttle caught enough cable to open the carb,but at this point the guy next to him(clone engine) got a head start by a bike or so. the bike ran him down and almost beat him......:doah: that guy end up running his bike all the way to the finals and he got beat by a kid that might of weigh 80 pounds on a clone engine. so i was still very impressed on how much power this ohh-motor has. if the cable just didn't break.......:doah: it has a thumb throttle on it now.....:thumbsup:eek:nly way to go...:scooter:
 
delray

delray

Well-Known Member
#43
#43
also made this later in the summer for the bike. a poor mans K&N filter.....:laugh:
first i cut the steel air cleaner housing off and only save the retainer part.


and then slip over a outerwear cover keep the dirt from getting in the filter.
 
delray

delray

Well-Known Member
#46
#46
hey guys, just little up date i thought i would post with this thread. i found the correct part number for the side cover with bearing..:thumbsup: tecumseh#36731
also be cautious when looking this number up on ebay. sometimes a person will list a cover with that number and it will be a bushing cover..:doah:long as they have good pictures you will be able to tell......:thumbsup:
also note the pictures i posted have the correct part number right on the box...:thumbsup:

 
Last edited:
owend

owend

#47
#47
I couldn't believe how well your Tec OHV ran, awesome power and sounded great:thumbsup: You pulled away from me at the start of the parade and I was way behind!
 
Dr. Shop Teacher

Dr. Shop Teacher

#49
#49
The engine really is a strong motor with the right carb and a few tweaks. Brian's work shows how to really open it up. Gangsta CAT's OHH was governed but had the HS40-50 carb, port matching and a Torque-tube--it "roared" and pulled that bike and a 200lb rider easily. This is an engine that deserves a closer look.
 
joshua. c.

joshua. c.

Well-Known Member
#50
#50
I have another mod I've done to my motor that I haven't herd hear yet. the stock intake tubes internal diameter is smaller at the bottom than the top, which means its quite restrictive. if you open it up to the same diameter all the way down it make quite a difference in power. also one side of the intake at the very bottom is indented in a little to clear the screws so when I did mine that spot wasn't opened as much to not brake threw that side. an aftermarket custom intake and bigger carb would be better for power but this mod is cheaper and maintains a stock appearance.
 
delray

delray

Well-Known Member
#51
#51
yes joshua. c. , something i notes right away too on my mild built engine when i use the factory intake. the block and the intake manifold did not match. so i went ahead and port match them and also notes how restricted the carb end was and that too got open up little. just so the air would flow better. with only using a new hs-50 adjustable carb and a stock newer style steel cam i didn't think there was much more improvement. if anything it might of just work perfect for what i was using it for. 10hp and under minibike drag class that must use stock parts and no aftermarket performance parts. only header,air cleaner and jetting.
like you said early if you start to get into cams and aftermarket carbs...etc. then a custom manifold would need to be done...:thumbsup:
 
delray

delray

Well-Known Member
#56
#56
been a very busy summer for me trying to build another ohh-motor for one race that was this weekend and it came down to the wire with this one. just so many things i wanted to try and that have never been done on a ohh-motor and i did get it done. place i had it bored was what brought me down to the wire. boring and cylinder work took extra 2+ weeks to get it done. try to make a story real short. i fired the bike up last weds and by friday i had it running good. also at the same time i was trying to get the jackshaft set correct. running a 22mm carb and had to jet it up to a 137.5 jet and the plug was still coming out white,but i new was getting close. at 6:00pm friday night i had to call it. run 137.5 jet. i didn't have any larger jets and also didn't have any large enough number drill bits to open it up and if i did wasn't sure i still wanted to do it..:doah:
i got the bike there on saturday and by 11:00 saturday morning it was crazy. they had 82 bikes that sign up. my class was big(modified rope start only) and the other two below me where too.
bike was so fast. it was just eliminating one bike after other. most of them where built honda's and clones and couple briggs(might have been animals)
came down to first place and got second. i just f---up on the starting line. i was trying to set the bike and i was just not quite ready and the girl drop the flag....:doah:
still was very happy how it ran and had so much fun riding it and was so impressed on how will it performed.
another thing i notes about the engine was how well it pulled at midway on the track.
track was only 125 ft on clay and it felt like it wanted to keep pulling more beyond 125ft.
so i will work on the gearing and jetting and also the stall in the torque converter and maybe get back my 130 pound driver next year? he got deployed to korea couple weeks ago...:doah:
also cam i had made for it was design to pull good up to 8500 rpm's and my engine was only pulling 7930rpm's at 125ft and still felt like it wanted to keep pulling at that point. so i will need to work on the drive train......:thumbsup:

kept the bike low key looking and nothing special. just made it so it would hook and go. kind of the rat rod drag bike...:rolleyes:


just wanted to say a BIG THANKS to evil ed for hooking me up with tim isky and grinding me this cam for a ohh-motor. thanks tim it gave me the valve clearance i was looking for and with out a doubt the power range i was looking for too....:thumbsup:
and millennium technologies advanced engine solutions for doing there part.......:thumbsup:
and a guy at work (gary) for letting me use his mill....:thumbsup:
and david wolf...:thumbsup: we are always going back a fourth on ideals that work and sometimes don't work....:thumbsup: alot of pre-testing this summer ....:scooter:
 
delray

delray

Well-Known Member
#58
#58
it was alot fun fistfullabar. i just got word it was total of 85 bikes that race this year. i got whole year to really get it dialed in. sorry i didn't do a thread on this engine build. i just didn't have time for it. head i built for it was just supposed to be a test head and wasn't meant to be use for racing. it just became crunch time and had to go on. that head will come off this winter and now i will build a head to race and will out perform this one...:thumbsup: lots of things still to do this winter...:thumbsup:
 
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