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Post by 90GTVert on Jun 19, 2023 8:00:13 GMT -5
I attempted to cut a Malossi drive face that I replaced for being a little rough in the center. I wanted to cut it to 12.5* to match Polini’s PRE variator since they don’t seem to make one in a 14.8mm center version that would fit Piaggio/RC-One…. just a 16mm version. I don’t have that variator but ryan_ott does so maybe he could try it or send me the vari long enough to be the guinea pig. I used whatever this angle finder thingy is called. It’s not graduated in half degree increments, but I figured if I aimed for right between 12 and 13 it oughta be close enough.  I had to take the hand wheels off because they ran into each other at this angle.  I used a drill to move the dials. I thought it was going OK… not great… and then I decided to turn the speed up because I was getting a really rough surface. The face came loose. Then I wondered If that may have been why the finish was bad. It’s also not helpful that the little lathe only has so much travel and I’m trying to use a bit that gets right to the center so I’m sure the tool details are all wrong for a good finish. I took the time to get it straight again with a dial indicator and cut it slow. Still not great, but much better than what I had before. The problem is, I took off quite a bit of material in that process. I finished up and checked and it’s about 12* instead of 12.5 and it’s too thin in the center for me to think it’s safe.   What I’m thinking now is aim for 13* and see if I get 12.5. If I do, see if I can leave the lathe as-is till I can get a Polini or other large fixed half to cut. People are telling me the S6 vari is even larger BTW. If the angle still isn’t quite right, I’ve probably got some Minarelli drive faces to sacrifice for setup checks. I’m in no rush to get this done so it may be a bit before you see any updates. |
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Post by 90GTVert on Jun 19, 2023 11:34:16 GMT -5
I was looking at fixed halves. The Polini steel pulley has a ceramic coating that I'd ruin. The Stage6 appears to be aluminum, but I can't tell if it's very thick. They're both splined centers vs a hole in the Malossi. I guess as long as I machine an adapter that is a snug fit to the inward portions of splines it should still center just fine. Should be clamping force from the bolt/adapter doing the holding. The only negative about the Malossi is that it's smaller OD... but I'm not sure how much that matters. I could try to check with a mark, but my speed is nowhere near Ryan's so I still wouldn't know if others would have any issue. My guess is no, but if a belt comes off/apart at 90 and jams something up...
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Post by 90GTVert on Jun 19, 2023 19:21:36 GMT -5
I ordered the Stage 6 fixed half to see it for myself. I looked around a bit more but couldn't find anything stating 12.5 degree angle and fitting this setup. They generally like to say things like "optimized angles"... which I take to mean 14 degrees like everything else. Ryan is sending me his 12.5 variator to test and another Malossi fixed half in case it's of use.
Now it's just a matter of seeing if I can cut the right angle or not without thinning pulleys to the point that they make me nervous.
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Post by 90GTVert on Jun 21, 2023 12:39:12 GMT -5
I desperately needed a break from video editing (gets on my nerves quick after doing so much) so I went out to the mini lathe. An hour and a half of playing with gauges, an indicator and a mallet later; I had my 12.5 degree angle. Maybe. The gauge shown says 12.3 to 12.6, but settles on 12.5 often. Another says closer to 13. The iPhone says 12-13. Good enough.  Now if I could work out a better initial finish, I’d be ready to spend a bunch of time trying to chuck the next one straight and cut it. I’m sure I’m not using ideal angles here, but the travel of the lathe and need to cut close to center got me to what you see below. Working on the far side with the lathe in reverse. I turned any adjusters on parts not moving tighter to reduce play and I have my makeshift carriage lock on to remove that slop. I’ve tried changing part speed and feed speed and the best I have got so far is quite textured. Not grippy textured so much as belt wearing textured.  |
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Post by awines2326 on Jun 21, 2023 13:57:18 GMT -5
With your carb/float issues, are you running a fuel pump or just gravity fed? I haven't read every post to find it but I didn't see any lines to a pump on there. I run a TM28mm on a 70cc S6 R/T and I can't run WOT for more than 15 seconds without a fuel pump and that's with barely any angle on the carb. I'm building my S6 95cc R/T and realizing based on your troubles I will be in the same boat with the crazy angle on RC One intakes
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Post by 90GTVert on Jun 21, 2023 19:22:17 GMT -5
It's just gravity fed. A couple of people on YouTube commented about fuel pumps as well. The flow seems like it should be sufficient from my past flow tests. The system would move 900ml per minute. At that rate I could drain my whole 2.5 gallon tank in roughly 10 minutes.
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Post by awines2326 on Jun 21, 2023 20:36:19 GMT -5
It's just gravity fed. A couple of people on YouTube commented about fuel pumps as well. The flow seems like it should be sufficient from my past flow tests. The system would move 900ml per minute. At that rate I could drain my whole 2.5 gallon tank in roughly 10 minutes. On my 70 I used 1/4 line with no filter and it still wasn't sufficient only at WOT for any extended period, again with a completely full bowl of a 28mm carb. IDK if gravity feed is effected by your momentum or anything like that causing the speed of flow to change at higher speeds? But again for me, WOT regardless of the speed it started at always ended is fuel starvation. They sell cheap $10 electric pumps on amazon or the nicer vacuum pumps if you can tap into the case for like $30 but it might be worth testing. Having the carb on that short of an intake is an advantage so if you can keep from elongating and adding a bend its worth it. |
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Post by 190mech on Jun 22, 2023 4:21:37 GMT -5
When I worked at an automotive machine shop as a young man, we would turn a lot of brake rotors, they would get a harmonic buzz going during cutting and make a rough surface cut..Had a thick rubber belt that would stretch around the OD and dampen out the chatter,it was designed to pop off when the tool bit contacted it at the end of the cut. It worked well...  |
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Post by oldgeek on Jun 22, 2023 5:30:15 GMT -5
I wonder if a cutter that is wider at the tip would help the finish? Also a wide scraping type tool could be held to the pulley as it turns to work on the finish. Or possibly set up the foredom with a buffing wheel in the tool holder and go for that mirror finish.  |
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Post by 90GTVert on Jun 22, 2023 7:25:40 GMT -5
When I worked at an automotive machine shop as a young man, we would turn a lot of brake rotors, they would get a harmonic buzz going during cutting and make a rough surface cut..Had a thick rubber belt that would stretch around the OD and dampen out the chatter,it was designed to pop off when the tool bit contacted it at the end of the cut. It worked well... Interesting. I wouldn't even think of that working. I think the closest thing I'd have around would be a bungee strap and that doesn't sound terribly safe. I wonder if a cutter that is wider at the tip would help the finish? That's what I was thinking. A rounder nose tool would probably be better for finishing passes. I do have to cut some of the center away that's left where the face is clamped down anyhow, so if it's still close to center it's probably fine. |
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Post by rollingbender on Jun 22, 2023 13:49:23 GMT -5
When I worked at an automotive machine shop as a young man, we would turn a lot of brake rotors, they would get a harmonic buzz going during cutting and make a rough surface cut..Had a thick rubber belt that would stretch around the OD and dampen out the chatter,it was designed to pop off when the tool bit contacted it at the end of the cut. It worked well... Another trick to reduce chatter is to set something heavy-ish on the tool post to deaden the vibrations. I lay a dead blow hammer on the tool and it helps a lot. |
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Post by 90GTVert on Jun 22, 2023 17:42:39 GMT -5
I ground a more rounded tool this morning to see if that may help the finish. Looks kinda pointy here, but I think something was on it. I actually noticed when I took the pic and then honed it.  I chucked up the Malossi fixed half that I’ve been practicing on… but it broke when tightening from getting so thin.  I wound up using another fixed half that I had around and got a better finish. Not great, but not terrible. Then I tried to turn the speed up and it was really bad again, so slow feed and speed seems to be as good as I’ll get. I was also gonna put an indicator on the carriage so I know what I’m moving. I’ve been just moving up and bumping against the piece and locking down and sometimes I’ve cut way more than intended that way. UPS showed up and I didn’t get that far. Here’s the Stage6 fixed half… and I picked up more shims.   I measured it at 100mm even, so maybe the vari is the biggest but the fixed half is not. It’s just slightly smaller than the Malossi. I checked the angle and it looks like I don’t need to fire up the lathe. It shows 12.7-12.8 degrees!  A package from Mr. Ott arrived shortly after. He’s just rubbing it in now.  Ryan sent the 12.5 degree Polini variator to test. It measures 12.7 or 12.8 for me too. That’ll work!  That’s as far as I got. Lots of rain in the forecast anyway and 2 friends wanting help with different tasks over the weekend. |
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Post by aeroxbud on Jun 22, 2023 17:51:13 GMT -5
That made me laugh.
Only the second fastest though? Not according to the YouTube comments. 😂
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Post by 90GTVert on Jun 22, 2023 18:14:40 GMT -5
That made me laugh. Only the second fastest though? Not according to the YouTube comments. 😂 Since we were the only 2 scooters and 2 strokes that showed up for the Small Bore Rally drags, I told Ryan we should declare ourselves the 1st and 2nd fastest 2Ts in the US. Somehow when you put them both on paper together, it feels like a dig though. LOL I'm actually the slowest scooter on YouTube. How I manage to be both the 2nd fastest AND the slowest has baffled the great thinkers of the world. On a more serious note, I have had multiple people comment about how the Malossi Trophy RC-Ones have done over 105MPH on some tracks. I'd love to know myself. My best answer is that fine tuning to the nth degree and people that really know how to port can make much more than most of us. It's definitely not coming out of the box like that though, and I'm curious exactly how much they can modify them. We won't get answers on any specifics I'm sure. Because racing. |
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Post by awines2326 on Jun 22, 2023 22:00:03 GMT -5
That made me laugh. Only the second fastest though? Not according to the YouTube comments. 😂 Since we were the only 2 scooters and 2 strokes that showed up for the Small Bore Rally drags, I told Ryan we should declare ourselves the 1st and 2nd fastest 2Ts in the US. Somehow when you put them both on paper together, it feels like a dig though. LOL I'm actually the slowest scooter on YouTube. How I manage to be both the 2nd fastest AND the slowest has baffled the great thinkers of the world. On a more serious note, I have had multiple people comment about how the Malossi Trophy RC-Ones have done over 105MPH on some tracks. I'd love to know myself. My best answer is that fine tuning to the nth degree and people that really know how to port can make much more than most of us. It's definitely not coming out of the box like that though, and I'm curious exactly how much they can modify them. We won't get answers on any specifics I'm sure. Because racing. This right here is the beauty of the affliction we have as small bore 2T enthusiasts. How every MPH or 100RPM we gain by .001mm of Porting via trial and error is a win. Somebody always finds a better way and you've got to decipher how to move the needle past them! |
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