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Post by oldgeek on Jul 4, 2019 23:16:01 GMT -5
I meant to ask, does anyone have a clue what the "tab" on one side of the piston wrist pin bearing journal is for?  |
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Post by ryan_ott on Jul 4, 2019 23:21:35 GMT -5
Maybe just the casting method?? I’ve got a few Polini pistons that are similar.
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Post by oldgeek on Sept 6, 2019 22:34:44 GMT -5
It's been a busy summer at work. I have not done much with this rebuild except lots of thinking about ways I could move forward with it. I ordered a few parts and another 52.4 stroke crank a while back. I want to see how a crank from a different manufacturer works with this setup. The parts came, but the crank was missing, I got it straightened out ok, but it may be awhile before the crankshaft gets here.
The crankcase spacer I made allows me to fit standard width bearings on my existing crank instead of the special thin bearings usually needed for it. However using the spacer introduces another problem. It throws the cylinder stud spacing off just enough that the cylinder will not seat in the cases. I was playing with a couple ways to overcome the problem, by using 2 6mm standard cylinder studs and 2 4mm cylinder studs, but I think it's just not worth the effort and I should just go with the thin bearings.
I really need to get this 103 build going so I can move on to the other motor builds I would like to do.
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Post by 190mech on Sept 6, 2019 22:52:47 GMT -5
Is there enough meat in the cylinder to open the stud holes to 8mm(5/16")?Most Mina motors have an 8mm hole with a 7mm stud..
PS,I'd whack that little pee pee lump off the piston to even up the transfer flow...
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Post by oldgeek on Sept 6, 2019 23:03:30 GMT -5
Is there enough meat in the cylinder to open the stud holes to 8mm(5/16")?Most Mina motors have an 8mm hole with a 7mm stud.. I will have to check on that. Sounds like a good idea ........PS,I'd whack that little pee pee lump off the piston to even up the transfer flow... That piston is for the aluminium kit I was just showing off, but yeah when it come time to build that one, that lump is coming off! |
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Post by oldgeek on Sept 7, 2019 23:04:17 GMT -5
Is there enough meat in the cylinder to open the stud holes to 8mm(5/16")?Most Mina motors have an 8mm hole with a 7mm stud. I was able to check tonight and there is not enough meat left to enlarge 2 of the studs because someone enlarged the transfers so much the studs will barely seal as it.  So I came up with another way to get the clearance I need. I am working on deepening or widening the crank bearing pockets on each side of the cases by about .5mm I am using some self stick 80 grit sandpaper on the side of an old bearing. I just need to come up with a way to reliably spin it till it removes the material I want it to. I should have an old crank laying around that I can cut the flywheel stub off of, then add a tack weld or two and I should be good. |
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Post by oldgeek on Sept 11, 2019 20:47:07 GMT -5
This is the setup I came up with to deepen the crank bearing pockets on both case halves. It took a while turning it by hand but I went slow and measured it carefully.  After removing the center race from a couple of old crank bearings, I tacked welded them together. Then I cut an 80 grit adhesive backed disc the same size as the bearing. A piece of 2" PVC pipe was a perfect press fit for the bearings.  I press fit a large socket in the other end of the PVC pipe to get a better grip and to make it easier to turn by hand.  The area marked with a black sharpie is where I want to remove just under .5mm from.  Finished both case halves. The oddball wide crank now works with standard width crank bearings.  This time around I am going to use shimstock to install the crank bearings into the cases. Then as 190mech suggested use the TUSK crank tool to pull the crank into the bearings and pull the cases together. |
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Post by 190mech on Sept 11, 2019 20:52:39 GMT -5
Awesome work as always!You'd be a wizard if a lathe was residing at Scootopia!!!  |
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Post by oldgeek on Sept 22, 2019 0:23:59 GMT -5
Spent all day on this rebuild. Everything got a bath, all new bearings even in the gearbox. And yeah I already put the gear oil in the gearbox Using the hot cold method I installed the crank bearings in the cases along with some .001 shim stock to hold them in place. I also added some loctite 680 to hopefully assist in holding the bearings in place. I was going to pull the crank into the case halves using the puller, but I just went with the hot cold again to first, install the crank into the small case half and second, to put the small case half with crank into the big case. It went together pretty easily and the crank turns freely so I am happy how that turned out. Getting the cases sealed up is a bit tricky so I spent considerable time getting it right, I hope.... I usually dont bother leak testing motors, I dont even have a pressure rig setup ATM. I was going to head home around 10PM, but I ended up staying till midnight. I honed the cylinder and cleaned it up real good, then I checked the new ring end gaps. According to Brents ring gap calculator, a 50mm cylinder should have ring end gaps of .0085. My new rings had gaps at .013 Oh well that's the way it goes! Around 3 this afternoon, My buddy that has a Harley came by Scootopia. I ended up going for a ride with him to get some food. I rode my Blue Kymco, he rode his Harley. It was still fun. I plan to try and finish up the rebuild tomorrow, and hopefully get it installed in the Naked Kymco. I have really missed riding that scoot.  |
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Post by oldgeek on Sept 22, 2019 23:02:04 GMT -5
I spent most of the day finishing motor assembly, and fixing some problems that popped up. I finally got the motor in the scoot and everything hooked up.
It fired up in about 5 kicks, and sounded pretty good. I rode it just a bit and it pulled well but sorta felt like it was being held back. It turns out the gearbox was getting tight. It was slightly tight after I put it all together and I was hoping it would free up as I rode it a bit, but instead it was getting tighter. I put the scoot back on the lift and pulled everything that needed to go in order to split the gearbox open. Inside I found the bushing repair I made was jacked up, likely because of the set screw I recently added to it in an effort to prevent the bushing from turning in the case. I think all the set screw did was push the bushing out of alignment and that caused it to heat up and fail quickly. I got the old bushing out, and cleaned up the pocket good. I cut some shim stock and played around with different thicknesses as I test fit a new bushing. After I get the bushing cut down, I will install it using the shim stock and some retaining compound. I am NOT going to be putting the stupid set screw back in.
The motor felt plenty strong, so I gotta get this gearbox sorted out if I wanna find out what it can do.
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Post by oldgeek on Sept 29, 2019 20:13:08 GMT -5
Well I got the new bushing installed in the gearbox, It went well and should have lasted forever! But due to extenuating circumstances and my stupidity I forgot to put gear oil in, again. It was a short ride, about 3 miles before it locked up briefly, but unlocked again. I coasted to a stop and called for my brother to come and get me and the scoot. I can fix the bushing again, but finding a set of stock gears again is likely not gonna happen. So I have a set of primary Malossi up gears I am going to try. They are very tall, and had to be modified a bit to fit properly. I hope to be able to get the bushing repaired this week and get it all back together to see how the gears work. I think I need to order some "Remove Before Flight" to tag the gearbox with. Me forgetting gear oil 2 times now is getting ridiculous! |
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Post by Jwhood on Sept 29, 2019 22:29:47 GMT -5
Well I got the new bushing installed in the gearbox, It went well and should have lasted forever! But due to extenuating circumstances and my stupidity I forgot to put gear oil in, again. It was a short ride, about 3 miles before it locked up briefly, but unlocked again. I coasted to a stop and called for my brother to come and get me and the scoot. I can fix the bushing again, but finding a set of stock gears again is likely not gonna happen. So I have a set of primary Malossi up gears I am going to try. They are very tall, and had to be modified a bit to fit properly. I hope to be able to get the bushing repaired this week and get it all back together to see how the gears work. I think I need to order some "Remove Before Flight" to tag the gearbox with. Me forgetting gear oil 2 times now is getting ridiculous! That's crazy bro I'd be flipping out |
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Post by oldgeek on Sept 30, 2019 6:14:58 GMT -5
Well I got the new bushing installed in the gearbox, It went well and should have lasted forever! But due to extenuating circumstances and my stupidity I forgot to put gear oil in, again. It was a short ride, about 3 miles before it locked up briefly, but unlocked again. I coasted to a stop and called for my brother to come and get me and the scoot. I can fix the bushing again, but finding a set of stock gears again is likely not gonna happen. So I have a set of primary Malossi up gears I am going to try. They are very tall, and had to be modified a bit to fit properly. I hope to be able to get the bushing repaired this week and get it all back together to see how the gears work. I think I need to order some "Remove Before Flight" to tag the gearbox with. Me forgetting gear oil 2 times now is getting ridiculous! That's crazy bro I'd be flipping out The first time I did it a couple years ago I was devastated, it took quite a while for me to get over it. This time, I just laughed at myself! Like I said, there were extenuating circumstances working against me. With the Malossi primaries, it comes out to 6.92:1 IIRC. If this 103cc setup wont pull them, Ill modify the cases to accept the 54mm cylinder and see how 120cc pulls them. I got nothing to lose. |
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Post by pinkscoot on Sept 30, 2019 9:35:35 GMT -5
Sorry to hear it happened again.
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Post by pitobread on Sept 30, 2019 15:00:02 GMT -5
Lots of the trofei malossi scoots lock wire the dipstick tube to the drain nut. In theory this would be the last step after filling it, and also a visual reminder that this important step was done... maybe start doing that!
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