"tweak the Teke" and other vintage hop up articles

markus

markus

Well-Known Member
#1
#1
this was brought up in the classifieds that someone was looking for the "tweak the Teke" 3 part series that was done in Mini Bike Guide magazine in 1971. While a better scan of part one (may 1971) would really be appreciated, this rough copy can actually be found on another great site to get mini bike information from...minidoodle.com . Not sure the fate of that site since the owner Jay had passed away, but his legacy lives on for now and its thankfully still up and running. As for parts 2 and 3, I had those in my collection so I have scanned them to complete the article :thumbsup:


PART 1 (thanks to Minidoodle.com and someone named Rich :shrug:)




 
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markus

markus

Well-Known Member
#4
#4
OldMiniBikes Member AJF had also posted another article on Ron Stewarts "yellowjacket" engine mods to a Tecumseh from another Minibike magazine. I took the liberty to adjust the photos he had taken so its a little easier to read, but these are From AJF (thank you :thumbsup:)





 
ole4

ole4

#8
#8
Markus thanks for posting! I love this old stuff. The marketing BS is amazing, they give the torque and rpm but say the calculations for HP require a genius calculation and imply it took a lot of time (rpm x tq / 5252 = hp) that is the real formula and if you plug in the numbers it is 28HP!! No way a tec makes north of 13 FT lbs of torque and certainly not at 6000 rpm. Reminds me of when I drank the cool aid building a 302 powered mustang in 1980 and bought a holley street dominator single plane manifold based on a manifold comparison which was just marketing BS it sucked and in addition made no induction noise as the open plenum cuts velocity thru it in half. Still a interesting article knowing what we know now but it was certainly not known by many people back then.
 
O

oldcarcbx

#9
#9
Thanks for posting up all three installments. Again I remember the first two but not the third. Anyways, thanks again to all who kept the ball rolling.
 
markus

markus

Well-Known Member
#11
#11
I'll try to scan in the article from Mini Bike World concerning performance parts of the time when I get a chance. It was published at the same time. It shows some briggs and even Hodaka hop up parts too but goes along with these articles pretty good.


Ok, who is milling heads and where can I get a billet rod, and where's my dremel?
Click to expand...
Getting some heads milled is something I have been wanting to get done as well. I dunno if machine setup is an issue but if someone was going to gear up to do them maybe it's easier to do them that way :shrug:
 
markus

markus

Well-Known Member
#13
#13
Aaron emailed me some Better scans of the article he was nice enough to post up. cant go back and edit that original post so sorry for the confusion, but its worth it as these came out really good! Thank you again Aaron (AJF)

markus said:
OldMiniBikes Member AJF had also posted another article on Ron Stewarts "yellowjacket" engine mods to a Tecumseh from another Minibike magazine. I took the liberty to adjust the photos he had taken so its a little easier to read, but these are From AJF (thank you :thumbsup:)
Click to expand...




 
joshua. c.

joshua. c.

Well-Known Member
#14
#14
did anyone else get dumfounded about that fuel injection? it claims gains over the dellorto 22mm carb. honestly it sounds better than any small engine carb on the market and it was made way back then, why haven't we herd of this before!!! and where can I get a dozen?
 
Sixpac440

Sixpac440

#16
#16
Hopping up my H50 ...

Does anyone have a performance cam for a 1970 H50?
In the absence of a replacement cam what about welding .020, .030 (?) to the cam lobes for a bit more lift?
Will grinding the valve tops smooth make a difference?

I have 2 identical Hilltoppers (70 & 71) with original Tec H50 motors on them.
I put in new rings and milled the head (minimum cleanup, about .010 to .015) and there is a very noticeable difference between the 2 bikes now.
This year I will be updating the other H50 and after reading the hop up articles I think I am going to do a bit more to it but still keep the stock appearance.
The series 30 TAV is only recommended up to 8hp so we don't need to go crazy, just a little more oompf!!

A cam would be nice.
Mill the head.
Smooth grind the intake and exhaust passages.
Lap the valves.
Hard weld the valve stems to make up slack.
Safety wire the rod bolts.
Etc ...
 
ole4

ole4

#18
#18
is it a internal or external magneto? If external you can get the motorsports hi perf coil.
tecumseh ignition 36605k | eBay
Isky can weld and grind your cam but its pricy. There is a H50 motorsports shortblock on ebay very reasonable but the shipping is expensive. Those motors came with billet rod, stainless valves and a large basecircle cam that is grindable and also made from a better material for welding according to Clements. Has good valvesprings and alloy split keeper retainers.
Tecumseh 5.0HP shortblock (994k) | eBay
 
buckeye

buckeye

Well-Known Member
#19
#19
He has a bunch of tec parts.
Thanks for sharing Marcus.
If I could adjust a dang carb, I've be in business. Geezz, I hate these things.
 
ole4

ole4

#20
#20
One thing I noticed is that in all this modding no mention of the flywheel or a modded version added to these motors . "
David good question, The flywheel on my motorsports H50 looks just like a regular cast iron H50 external magnet flywheel and those motors ran 6 to7K the way they came. I wonder if they had a K suffix like the motorsports race parts or if they were just stock flywheels. I know back in the day they did have billet H50 wheels but they were for modded motors don't know much about issues with the stock flywheels or if maybe they were made with better materials or quality control. Don't know if there ever was a billet wheel for a regular Tec. Also the early HSmotors ones had a smaller taper than the later ones.
 
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