Project: Black Widow

cfh

Well-Known Member
#41
I would have not enlarged a stock dellorto! I run 16mm, 18mm, 19mm and 22mm dellortos on many of my bikes (all Tecumseh HS50 engines.) To be frank, i can not tell any performance difference. like none. as long as you have the jetting right, a 16mm and really no different than a 19mm. They look different, that's it. The 16mm and 18mm is upright, the 19mm is sideways. and the 22mm is just big. You get the performance gain when you switch from the crappy tecumseh carb to a slide carb. The size (16mm to 22mm), matters a whole lot less.
 

cfh

Well-Known Member
#42
Also the slide is different on these carbs. the 16mm slide is smaller than the 19mm. you can't just grind out the main air passage and call it a Ua19
 
#44
Thanks for the heads up. How is it working?
I ended up buying a different regulator/rectifier, in addition to the same one you bought.
Once I get my hand controls sorted, I want to try and start wiring it up.
The one you bought is adjustable. Did you end up having to adjust it?
Thanks
 
#45
Thanks for the heads up. How is it working?
I ended up buying a different regulator/rectifier, in addition to the same one you bought.
Once I get my hand controls sorted, I want to try and start wiring it up.
The one you bought is adjustable. Did you end up having to adjust it?
Thanks
Honestly, it sucks because it cuts out when you go above a certain RPM, and apparently the only way to get around that is to run a battery. And I did adjust the voltage down a bit. But if you need to run a battery, you might as well get a Kohler-style rectifier/regulator. Which is what I may end up doing.
 
#46
Thanks for the feedback, I greatly appreciate it
I may end up running a battery too
Think they make some small 12v batteries nowadays
I’m still looking into it
 
#49
So as you guys know I have an HS50 on my Black Widow. I abandoned the lighting coil idea when I decided to try and sell the bike, swapped the lighting coil/flywheel out for an original HS40 flywheel and magneto.

Anyway, this HS50 came with an untapped, not Rupp-style crank, and when I drilled/tapped it, I did not get the hole centered in the crank. So the torque converter driver is not supported well/is out of balance/wobbles.

I have a 1970 Rupp HS40 block that has a worn-out bore, but the crank is the correct one for the TC-1 torque converter, the side cover has a crank ball-bearing, and the cam has a mechanical compression release.

I want to swap in all these parts to the HS50 that has a good bore and billet rod already, plus the HS40 crank is lighter so the engine will rev faster.

I'll keep you folks updated with my progress, and with how the motor runs afterwards. I hope it doesn't vibrate too much, although with the torque converter in balance it may be smoother.

We shall see!
 

cfh

Well-Known Member
#50
you can't put a HS40 crank in an HS50 motor. i mean you can, it will fit, but the weighting is different. Mark sez it will come apart, so don't do that.

as for drilling the end of the crank for a 5.16-24 bolt... it doesn't have to be dead center. i mean it won't mess up balance. as to having enough wall thickness so you can tighten the bolt, that's another thing.
 
#51
swapping out the hs-40 stuff into a big bore hs-50 style block may not be a good thing to do. piston for a old style hs-50 is big and heavy. it may give you a bad balance and for making it rev quicker? it's not going to happen with your setup. you need a lot more things to happen to affect how it can rev much quicker.
I see you have a hs-40 block with a bad bore. what about having someone bore it out .010 or .020 over? or sleeve it and install a stock piston or look for a another block if your really cheap....lol
 
Last edited:
#52
what float size are you running in the UA16S? That top would use a different float style than an UA19S if I remember correctly.
Regards,
Joe51
 
#53
swapping out the hs-40 stuff into a big bore hs-50 style block may not be a good thing to do. piston for a old style hs-50 is big and heavy. it may give you a bad balance and for making it rev quicker? it's not going to happen with your setup. you need a lot more things to happen to affect how it can rev much quicker.
I see you have a hs-40 block with a bad bore. what about having someone bore it out .010 or .020 over? or sleeve it and install a stock piston or look for a another block if your really cheap....lol
If I could find an oversized piston, I would bore out the HS40. I looked into sleeving it, too expensive. If when I put the HS50 together it vibrates like crazy, I will take it back apart and consider the experiment a failure.
 
#54
If I could find an oversized piston, I would bore out the HS40. I looked into sleeving it, too expensive. If when I put the HS50 together it vibrates like crazy, I will take it back apart and consider the experiment a failure.
hopefully you didn't hurt anything....:scooter:
 

Top