HS40 Rupp

delray

delray

Well-Known Member
#101
#101
after you get that motor running good and all you probably can get away and add less zinc. I would think 3oz's would be ok for a stock valve train. I tend to run more(5 ozs) because of the engines I have built. one has a #18 another #20 and my drag motor #42 pound springs. with a stock spring them, little motors are pretty forgiving when it comes to cams not getting damage. the only time I have seen a Tecumseh cam damage is when the oil is never change and the oil gets so dirty it just grinds them up. with the billet rod you should be able to set the governor at 4000+ rpm's.
I know with a 16 pound animal spring a stock cam will pull good up to 4700 rpm's, but with a stock old spring it might try to float or what they call valve bounce.
where are you buying the lucas zinc oil. I have found it on ebay for just under $16 ship to my door and at the local parts stores for 20+tax
next time I get some I think I will buy 3 for under $40 ship to my door. comes out to just over $13 only and I just use good old SAE 5w-30 no brand name for under $3 a quart. that only add's up to about $7 for quart of zinc oil for my engines and you only use 20oz's of that....
 
delray

delray

Well-Known Member
#102
#102
dalpan said:
The breather looked fine, I disassembled it, cleaned it and added a new filter element. Ok, just to clarify, if I add oil to the engine setting flat on the bench and oil line is midpoint to the threads, I should be good to go once I install the motor on the Rupp frame approx at a 20 degree angle? Do not add oil once the engine is mounted at that angle? Sorry for the confusion on my part...., just want to make sure.
Click to expand...
if you are using the rupp dipstick? it is set to be check at the angle mount...….
 
markus

markus

Well-Known Member
#103
#103
dalpan said:
The breather looked fine, I disassembled it, cleaned it and added a new filter element. Ok, just to clarify, if I add oil to the engine setting flat on the bench and oil line is midpoint to the threads, I should be good to go once I install the motor on the Rupp frame approx at a 20 degree angle? Do not add oil once the engine is mounted at that angle? Sorry for the confusion on my part...., just want to make sure.
Click to expand...
correct, the mark on the dipstick is the same amount of oil as what is in engine if it was sitting level, just the back of the engine is kicked up higher

So imagine the oil is the parts book I am holding sitting in the engine case "full" on a standard flat horizontal mount:
IMG_1313.JPG

Now take that same engine and mount it on a slanted engine plate bike, notice the dipstick line falls where the same amount of oil lays if the engine is tilted:

IMG_1314.JPG
 
C

cfh

Well-Known Member
#107
#107
I believe it has to do with the relationship between the driven and drive torque converter units, and what belts were available. Noticed the 20° motor set up is largely used on torque converter models (at least with rupp). With the engine tilted it increases the distance between the two torque converter units, and gives better clearances. Also the spacing inside the frame is easier with the motor tilted forward. This was probably the main reason. But also I think that it’s better for oil distribution inside the motor. It also looks kind of cool.
 
C

cfh

Well-Known Member
#108
#108
The 20° engine mount was almost a necessity when they went to 10 inch+ wheel bikes. They were converting Minibike frames to mini cycle frames, Sort of to look like mini motorcycles. And in order to accommodate the carburetor and air cleaner and torque converter the motor almost had to be mounted to 20°

Look at any of the Rupps, speedways or foxes and imagine them with a flat engine mount. See how the torque converter would be a problem? And the carburetor and air cleaner probably wouldn’t fit? That’s the main reasoning I believe. Also gives a much better and more balanced look
 
scrappybunch

scrappybunch

Active Member
#109
#109
Oh ok, so basically a packaging thing. I was thinking there was a performance increase with the intake a straighter shot at the valve, and less parasitic drag from the oil dipper.
 
dalpan

dalpan

#110
#110
markus said:
correct, the mark on the dipstick is the same amount of oil as what is in engine if it was sitting level, just the back of the engine is kicked up higher

So imagine the oil is the parts book I am holding sitting in the engine case "full" on a standard flat horizontal mount:
View attachment 248850

Now take that same engine and mount it on a slanted engine plate bike, notice the dipstick line falls where the same amount of oil lays if the engine is tilted:

View attachment 248851
Click to expand...
Well, I verified the oil level, fired the old rupp up and it still spews a little oil out the governor shaft. Not sure how to address the issue. But I did take it for a spin, it's been 45 year since i last rode the rupp.
Need to finish things up. Question on the wire harness, see attached pic, white wire comes from the point post and the black wire from the switch on the handle bars. I ground the black wire to the engine, where does the white go? With the black wire grounded the kill switch does not work. Of course when i touch the white wire to the black it kills the engine. What am i missing? I followed the wire schematic i got with switch. I'm sure it's a simple fix...just not seeing it....
20190902_080618.jpg
 
massacre

massacre

#111
#111
scrappybunch said:
Oh ok, so basically a packaging thing. I was thinking there was a performance increase with the intake a straighter shot at the valve, and less parasitic drag from the oil dipper.
Click to expand...
I know some of the junior dragsters use 30 degree mounts, when I asked my engine guy about it, he said it was to get a straighter shot at the back of the intake valve, and for oil control.
But those cars launch from a standing start so I figure their oil control would be different from a minibike.
My Blockzilla is mounted flat and runs like the dickens, but we only race short track 100ft
Or used to. Never ran into an oil control problem yet. I use the jr dragster oil in it which looks pretty thin
 
massacre

massacre

#112
#112
What kind of kill switch are you using for the handlebars?
From what I can see, looks like the white wire needs to go to one side of the kill switch, ground should go from the other side of the kill switch to engine ground. At least that is how I usually wire them up.
On my harness the kill wire is green, but it looks like yours may be white.

Or some switches are a push button that grounds out at the handlebars when you press the button in.
If you touch the white to the black and the engine dies, then the other end of that black wire is grounding somewhere, I would check out the other end of the black wire and see what is up with that.
 
dalpan

dalpan

#113
#113
I put on an oval shaped switch, 1541br, from Blackwidow sports. The lighted coil/stator are orig. I just put a new wire and connector on. According to the schematic the black wire goes to headlight. I did get the headlight and wire harness on ebay, it's not orig to bike. 20190902_183222.jpg
 
R

ruppking

Active Member
#114
#114
dalpan said:
I put on an oval shaped switch, 1541br, from Blackwidow sports. The lighted coil/stator are orig. I just put a new wire and connector on. According to the schematic the black wire goes to headlight. I did get the headlight and wire harness on ebay, it's not orig to bike. View attachment 248957
Click to expand...
The black wire with the ring terminal is the ground wire from the headlight to the engine block.
Your white wire from engine is not needed as the engine wiring with the plug should have a kill wire in it already.
It is the yellow wire in the Rupp wiring harness.
 
dalpan

dalpan

#115
#115
I had the black wire ring terminal grounded to the block and the white not connected, and pushed the kill button the engine continued to run.
I have the switch wired as the diagram shows in the top left corner.
 
massacre

massacre

#116
#116
ruppking said:
The black wire with the ring terminal is the ground wire from the headlight to the engine block.
Your white wire from engine is not needed as the engine wiring with the plug should have a kill wire in it already.
It is the yellow wire in the Rupp wiring harness.
Click to expand...
I forgot about that but now that you mention it you are totally right. My kill wire is green but you can clearly see the 3 wires and my harness is not a Rupp specific harness so the + wires are red and black instead of red and brown. And kill wire is green instead of yellow as you pointed out.
No additional kill wire needed.
I completely blew that one lol

My headlight grounds through the housing and frame though, no ground connection to the engine but now that I think of it, that’s actually a really good idea from a safety standpoint. Like if the headlight housing were to vibrate loose or something you wouldn’t lose headlight
 
massacre

massacre

#118
#118
Well obviously there is a break in the circuit somewhere.
I would unplug the harness and insert a length of wire with a spade terminal connected to it, from the yellow wire on the engine side of the harness with the engine running, and then ground the other end of the wire to the engine block.
If the motor dies, at least you know that the kill wire connection at the coil is working OK.
Then turn your attention to the chassis side of the harness.

When you installed the new kill wire, did you remove the original yellow wire at the coil?
 
dalpan

dalpan

#119
#119
I pulled up some pic I took when I started tearing the bike down. I don't think I need the white wire , dont' know what I was thinking.
But I would like to figure out my current situation. Tomorrows another day.... @Skipp still no slant manifold...fabricating my own. :)
 
massacre

massacre

#120
#120
If you need a slant manifold I have an extra one I am not using.
Never even been ran as I bought it for a spare motor and ended up using a Chikuni instead
It is from BWM
 
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