7/8th of a Rupp, how to proceed?
- Thread starter cfh
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Working on finishes for the gas tank. It's a hard thing to paint, so i tested my skills (or lack of them) on a Hustler tank. I gave up! instead i went with powder coating. Now powder coating a gas tank is tricky. Powder coat is burned in at 400 degrees F. Most solder melts at about 375 degrees. So i worked around this issue.
What i did was Tig weld the filler neck and the frame mount to the tank (these are soldered in place from the factory.) Don't need much, just enough of a weld to hold it in place (on the filler neck, just a small tack on two sides). Otherwise if the solder does melt, the tank pieces will fall off! so this keeps them in place during the process.
Next i bought some hi-temp 40/60 solder that melts at 460 degrees. It's only about 15% headroom, but if my powder coat guy's oven is accurate (and he insists it is), we should be safe. So i re-soldered the filler neck with the higher temp solder.
When powder coated, it was hung in the oven horizontally, so the solder (if it melts) has no where to go. It will just melt and stay in place, and them cool and solidify. After i got the tank, i did a quick pressure test and found the tank to be leak free.
Now i don't really recommend this process to people. I mean these are Rupp tanks, easy to get if things go badly. If you have some rare tank, where a replacement is impossible, you really don't want to do this.
Here's the result on the Hustler tank. I could never get this quality of a finish with paint! and certainly not get the durability of powder coat either. Will do the Black Widow tank next and see how that goes...
What i did was Tig weld the filler neck and the frame mount to the tank (these are soldered in place from the factory.) Don't need much, just enough of a weld to hold it in place (on the filler neck, just a small tack on two sides). Otherwise if the solder does melt, the tank pieces will fall off! so this keeps them in place during the process.
Next i bought some hi-temp 40/60 solder that melts at 460 degrees. It's only about 15% headroom, but if my powder coat guy's oven is accurate (and he insists it is), we should be safe. So i re-soldered the filler neck with the higher temp solder.
When powder coated, it was hung in the oven horizontally, so the solder (if it melts) has no where to go. It will just melt and stay in place, and them cool and solidify. After i got the tank, i did a quick pressure test and found the tank to be leak free.
Now i don't really recommend this process to people. I mean these are Rupp tanks, easy to get if things go badly. If you have some rare tank, where a replacement is impossible, you really don't want to do this.
Here's the result on the Hustler tank. I could never get this quality of a finish with paint! and certainly not get the durability of powder coat either. Will do the Black Widow tank next and see how that goes...
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So as a compromise to my black widow/roadster dilemma, i bought another trash pile of a Rupp, which in some sort of sad way is a 1971 Roadster, originally purple. Unfortunately it's such a hack job i'm not sure you could call it much more than a "steaming pile of junk". They left it outside for a year or two, which is never good here in michigan. I'm working on the original HS40 motor (with lighting coil), to see if that can be saved. But i'm going to powder coat this frame to black, and probably do a red roadster 1972 style tank/fenders. this is of course a slight distraction from the black widow project... If i can get the HS40 going i'll put a Dellorto Ua18s on it, which should be interesting.
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i'm still figure out motors... but in the meantime here's the work done on the rupp roadster so far. i know the front fender should be chrome, but it was in such bad shape, i decided to powdercoat it in the same color as the rear fender. i have to deal with the wheels next, getting the rust off them so they look decent. Then i'll be in the same position as the Black Widow, getting motors ready.
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All three frames are done and ready for the next step... engine work. So will get three black tecumseh 4 or 5hp motors ready for these bikes. The black widows will get HS50 motors, and the roadster will get a hs40 with a lighting coil. On the black widow motors, they will get Dellorto carbs for sure. Will probably also delete the governor, maybe an Arc rod, and perhaps a different cam.
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Time to deal with the motor(s). The original "7/8 rupp" came with a motor, and for some odd reason, i choose to make that my first strike option. Since it has the lighting coil, it seemed like a good choice to install on the red Roadster2... until i dug into the motor a bit.
First clue was the blower housing. It indicated the motor was a Tecumseh HS50. That didn't make any sense, since there was a lightning coil, a long Rupp PTO shaft, and a ball bearing side case. So my guess (which was later confirmed) was the blower housing was replaced. I removed the head and measured the width of the bore, and indeed it was 2 5/8", which means it is an HS40. No shocker there i guess - it was the original motor with a replaced housing.
So i took the removable metal off the motor, and sand blasted the motor, as it was a filthy mess. I drained the oil, and it was the thickest sludge i've ever seen come out of a motor (of any kind.) I knew this motor was going to be a problem. I removed the PTO seal and the "C" clip, and removed the side case. Man it was ugly inside, as that "oil" was just a gooey mess. Here's after i cleaned out the old oil.
But what really was revealed with the sand blasting (and why i do this type of thing), was this:
Looks like this motor threw a rod, and someone repaired a hole in the case with JB weld! The interior of the case showed this too. It was a decent job though. At this point, i'm still "in" with making this motor work again. But my hopes are knocked down a notch.
First clue was the blower housing. It indicated the motor was a Tecumseh HS50. That didn't make any sense, since there was a lightning coil, a long Rupp PTO shaft, and a ball bearing side case. So my guess (which was later confirmed) was the blower housing was replaced. I removed the head and measured the width of the bore, and indeed it was 2 5/8", which means it is an HS40. No shocker there i guess - it was the original motor with a replaced housing.
So i took the removable metal off the motor, and sand blasted the motor, as it was a filthy mess. I drained the oil, and it was the thickest sludge i've ever seen come out of a motor (of any kind.) I knew this motor was going to be a problem. I removed the PTO seal and the "C" clip, and removed the side case. Man it was ugly inside, as that "oil" was just a gooey mess. Here's after i cleaned out the old oil.
But what really was revealed with the sand blasting (and why i do this type of thing), was this:
Looks like this motor threw a rod, and someone repaired a hole in the case with JB weld! The interior of the case showed this too. It was a decent job though. At this point, i'm still "in" with making this motor work again. But my hopes are knocked down a notch.
As a distraction, i decide to remove the governor from the side case. I'm not sure why i do this now, but it's a solid distraction.
On the main case, i remove the governor mechanism. I'm using a slide carb, so that entire mech is not needed. Run a 8-32 tap through the case, and a 3/4" long hardened 8-32 bolt into the hole. That gets rid of the governor and all associated parts.
On the main case, i remove the governor mechanism. I'm using a slide carb, so that entire mech is not needed. Run a 8-32 tap through the case, and a 3/4" long hardened 8-32 bolt into the hole. That gets rid of the governor and all associated parts.
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Here's where things get worse though. I remove the connecting rod bolts (6 sided 1/4" socket), and check the bore closer. It's not "bad"... not great either, but workable. I think i can run a 3 stone hone through it and make it work. New rings obviously. The piston skirt shows some weirdness, but that doesn't really concern me much. The guys at the machine shop are like, "it's a freaking lawn mower engine. You're not riding it to Florida. How good does this really need to be?" Well i guess they do have a point. I'm not happy about it, but i'm trying to save this thing...
But here's where the trouble comes. Check out the rod journal on the crank! it's pretty scored. Again i show this to the machine shop guys, and get about the same response about lawn mowers and Florida. I mention that i could buy a new rod (which gets me a new rod bearing), and he's like, "why? Just smooth it out and hope there's no rod knock. Those grooves just allow more oil into the surface. As long as there's no rod knock, you're golden." Well OK then, what the hell. I'll work on smoothing it out, and bolt the rod to the crank and see what kind of play there is. They have some tricks to help remove the play, if needed...
There is one more option. Use a new (used) crank and new rod. Good chances it won't be a bearing crank. So replace the side cover too. that's an option i guess. But i'll try and work with what i have and see where it goes.
But here's where the trouble comes. Check out the rod journal on the crank! it's pretty scored. Again i show this to the machine shop guys, and get about the same response about lawn mowers and Florida. I mention that i could buy a new rod (which gets me a new rod bearing), and he's like, "why? Just smooth it out and hope there's no rod knock. Those grooves just allow more oil into the surface. As long as there's no rod knock, you're golden." Well OK then, what the hell. I'll work on smoothing it out, and bolt the rod to the crank and see what kind of play there is. They have some tricks to help remove the play, if needed...
There is one more option. Use a new (used) crank and new rod. Good chances it won't be a bearing crank. So replace the side cover too. that's an option i guess. But i'll try and work with what i have and see where it goes.
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I bolted the rod onto the suspect crank. Sure enough it’s way too loose. A little work with the sander and we got it to tighten up. As long as I’m not riding this to Florida, as the machine shop guys say, it may just work. It’s tightened up nicely. Got Hone the cylinder and lap the valves. I don’t know how this is going to turn out but it’s worth a shot