An Introduction to myself and an emerging Build.
Greetings all, I am Jim aka RiverCity, in Rocklin Ca by way of Mason City IA. I’m a coder by trade and a midnight mechanic with an impressive portfolio of unfinished projects.
Got a basically identical pair of 77 pug 103s recently. But one of them turned out to be considerably slower than the other, So I says to myself: “hey you’re the shit, why don’t you speed it up?” and there my friends is the story. Jump cut through several dozen youtube vids, hours of mopedarmy lurkage, hundreds of images perused, and I start feeling like Neo: “Hey I know moped kungfu”!
But after the story laid out below, I’m now into the “don’t try to hit me, Hit me!” phase and my collar’s starting to get a little tight because what I thought were some very attainable goals are receding from my grasp like one of them “Hitchcock Zooms”.
When I got it, it would run up right around 31 on the level. Under certain conditions it would take a pause and then run up a little higher. Then it got a bit hard to start.
Installed partie cdi, with trailtek regulator,1.5 mm advance.. Deleted the decomp.Removed the stock muffler baffle. definitely ran stronger and at that point I could roll up into the the 36mph range and hold onto it for a while.
I Noticed that the belt was far under 13mm wide, and the marker test showed that the outer range of the variator cheeks were unused, so changed to a gates A32 which I realize now was a significant change.. Went from 4 balls to 3, added a star spring: bike clearly slower and that “second wind” of rpm range unavailable. Back to 31mph dead tops.
Cylinder out, cleaned it all up.
- Rings and piston were loaded up and seating (in my view) badly with some score marks that didn’t seem to correspond with the condition of the cylinder.
- Piston slightly loose in the bore. Ran through CheetahChrome’s drop test a bit quick.
‘D’ Cylinder in fact looked pretty good. Although can see a ghost of wear underneath the ports. (wish I nkew how to distinguish chrome and nikasill)
- Noticed what I think is the groove for an o-ring in the head with no o-ring in sight. The head chamber is also considerably wider than the bore. (I failed to measure that.. If memory serves it was about 41mm. I’ll get that measured shortly). And I see carbon inside that “ring groove” which is pretty suspicious to me, but no evidence of leaking to the outside.
-Removed what I thought was last bit of exhaust port lip and smoothed it out a bit.
-Also radiused/smoothed the inside lip of the exhaust header where it meets the head, since there's a gigantic step there.
- Opened up the airbox holes just a bit with a step drill
Back together. Cranks right up. Zero effect. Now I got a 31mph pug, I ton of suspicions, and the certainty that I haven’t succeeded in baselining this little motor.
Now it's back on the table, motor out, carb off , reed box out..
My goals: a satisfying cafe-ride that I can take into the foothills of Placer county, capable of reaching atleast 40 in short order and tractable and torquey enough to climb long 5% grades in our heat without burning up.
I took into my head that I could do a “single pass” resto-mod on this thing, but clearly I just don’t have the experience to do that, so I’m faced with the “what first” problem. I don’t want to just indiscriminately throw parts at mr. pug as I’m not trying to pimp it per se, although I know I'm going to need some new hardware..
Well, that’s my story. All input welcome. I'll try to keep a log here on this build... I got a fair range of skills and tools, and I’ve enjoyed riding this thing so much….
Not looking for a parts list, but for diagnostic traction…and clarity. After all, it is the question that drives us: What does it do, this ped you seek?
I think the first thing this ped does, is to run without a gurtner…