The General is pretty close to being done. I gotta say, after spending time in and out of this bike its not too bad, for a top tank that is.
During:
I never knew these were Taiwaneese, and very late for mopeds, mine is 1985... pretty surprising that these aren't still being made, even with a crummy honda lifan clone this would be a pretty sweet small motorcycle. It really is a small motorcycle, big hydraulic forks, partial DC electrical system, even the fork lock doubles as a kill switch! The brakes are huge drums that stop you like woah, and the controls are all motorcycle. Personally, I kinda like it for a motorcycle but I dont like it for a moped. After putting some miles on it, It really resembles a very light vintage enduro/dirt bike. The soft suspension and light weight make it very skittish like an old enduro type bike, but it turns in sluggish and resists being thrown around
Its actually lighter than my Peugeot, I think, but feels top heavy and mushy. Personally I like the exposed, tossable moped feeling better, but Caitlin wants something substantial between her legs and will appreciate the hydraulic forks, good brakes, and comfy seat, so its probably going to stay in the family for awhile.
The previous owner, Brandon from Minneapolis, was a high school kid and apparently a pretty good mechanic. I gotta say, I didn't do nearly this nice of work when I was in high school, i was an idiot. He had a lot of the minor stuff done, the rims were cleaned up (pretty well considering the chrome is worse than a lot of spray paint i've seen) the chain was about the right length, the spark plug wire and boot was replaced, he had my favorite kind of 'Window air conditioner filter foam' air filter on the SHA which doesn't leak too bad.
The list goes on, brand new gazelles with the ticklers still on them, new petcock, etc etc. Pretty nice bike all around, for $400 it was an awesome smokin' deal (even though it is the most expensive moped i've bought since my first maxi which i overpaid for).
There were only a few issues, but since this is a bike for Caitlin and it has to be perfectly reliable and safe, I had to take care of those right away. The pipe was at one point an EV Racing, it was all messed up. The header was cut and spliced... cant imagine why.. maybe it had been hack and welded then got hack and welded back? There was even a small bolt welded through the header for some completely inconceivable reason.
I could tell right away that this pipe had some design flaws from the factory. The header was way too small for the chamber, and it had a big ugly shim and over lap where the header goes into the divergent cone. I have developed a theory about this, because it is the same thing you see in the Proma GP, and to a lesser extent with the Boss. Aside from the obvious that it is much easier to weld a lap weld than a butt weld, there is something going on with these pipes that gives them better bottom end than pipes that dont have the step. I think when the header is kept small the exhaust pulse signal from a 50cc cylinder is much stronger... well any cylinder that is, but a small header is more critical on a small cylinder. So with limited porting and a short blow-down you maintain the strength of that exhaust pulse. The big step going into the chamber creates a pipe-within-a-pipe where that pulse hitting the end of that header tube creates its own return pulse before the return pulse from the chamber itself... I'm not sure if there is any validity to that theory but it would explain why pipes with that step in them work well on 50cc cylinders and why they seem to have a mystery power band way up high that you can hit with a high revving small displacement setup.
Either way, the header was too gnarled up to re-use and maybe my theory is just some crazy stuff i came up with in a dream and not real and its always good to go with tried and true stuff when you have 5000 variables and need something that will work without a lot of screwing around. With a long header this should keep plenty of grunt, and opening up like that, hopefully it will be able to stretch its legs on top.
To fix it I used my favorite trick of splicing in a piece of large diameter tube to give the header a slight overall taper. I bent up some 1" EMT conduit and combined it with the stock header to get the compound bend needed to clear everything. This is great for the top end of a pipe and doesn't really hurt the lows or mids. A lot of smart pipe makers use this trick to make a cheap tapered header without having to roll long tight cones, which are a pain in the butt and almost impossible with the tools i have access to. Plus it gives you a joint that you can put a little misalignment in to make things line up better.
The silencer was also a major problem. I rode the bike once and was amazed how quiet it was, i could tell the silencer was pretty badly plugged or something, and I was right. The perf tube was capped off inside, causing the gasses to go around the tube, through the glass, and out the back. It was homemade by the PO, who did a pretty good job of creatively making it re-packable and laid down some decent welds on it, but the design was flawed. Greasy fuzz was all jammed up at the back where exhaust should come out. The exhaust was all leaking out around the edges of the silencer and completely plugged off from coming out the back. Thats not good. Its really not much of a loss because the stock EV silencer is a completely worthless hunk of crap which usually breaks instantly anyhow, and even when it is intact, doesn't decrease noise much if any.
I set to work on version 2 of my Lymo silencer and came up with a nifty new way of packaging it that will give me some additional tuneability while only moderately restricting flow. There will be more details to come soon regarding this new silencer technology, but i'm pretty excited for the possibility of ninja-quiet mopeds. Even the higher performance version 1 that i built is quieter than a glass pack and has no flow restriction whatsoever. The new one is more restricted but easily as quiet as a stock pipe. The new packaging technique also allows the possibility for a relief valve to be incorporated that could open when you are WOT blasting and let more air out. It could actually lower the power band of your pipe so as you reach the top of the pipe's power band a valve opens and you get your power band back... awesome huh? Maybe? Who knows! The possibilities are endless! :Like a million people have experimented with this kinda stuff and made it work but until now nobody has really made the push to make it something everyone can have on their bike, so it hasn't reached that critical mass of a lot of people having them and developing a community of tuning knowledge. I'm going to get to a good jumping off point where everyone can have one of these and then start tweaking them and figure out what works for each pipe, engine, kit etc setup.
Its all under wraps for now until I get a production prototype fabricated, and there is still a lot of design engineering and testing to be done to get the design perfecto and quiet as possible, but for now i'm really happy at how well this is going to work on this bike. The older I get the more I like stock-ish bikes that do what a moped is supposed to do, get you where you are going as fun as possible. For Caitlin, riding a moped that isn't deafening and obnoxious is more fun than one that is, so for now Lymo2 is a success.
Any Minarelli fans should be excited reading this because the addition to a Minarelli to my fleet will be sure to precipitate the development of plenty of new goodies for the Minarelli crowd. I've already used my test buddies all over the country to help me design some great new Minarelli heads, but stuff like the engine stand holding this engine, didn't get designed and built until I had some personal motivation. I hate to plug my MF parts too much on my personal blog, but I gotta say these dumb little engine stands make working on engines on the bench so much easier. Its always a pain holding onto moped engines and with this little guy you have both hands free to wrench on stuff, plus it keeps everything tipped up vertical so working on the top end is a lot easier. Removing wrist pin circlips with the engine bolted down is night and day easier than trying to do it tipped on its side. Sorry for the plug but its true, i wouldn't make this stuff if I didn't need it myself, y'know.
Minarelli engine stands should be in stock at the major moped retaileirs in the next week or two. Dont worry tomos/sachs guys those will be out soon too. The rest of you guys will just have to wait, sorry. If you really want me to make some goofy engine stand for ya send me an email and i'll see what i can do.
Before going anywhere with the engine, I planned out some basic stock upgrades. Since I always buy basket cases, I always pull the cylinder off right away to make sure the engine is in good shape, no rusted out con rod bearings, that kinda thing, and this one was a beauty. The rings were perfect, no blow by whatsoever. These late model V1's are just really nice engines, the machining and casting on them is top notch, the roller bearing rod, etc. I haven't worked on many of these, but I believe people who do when they say they can take a ton of power and are rock solid reliable. If the 3500 miles on the odometer is to be believed, there is a lot of life left in this engine.
At first glance the porting is pretty aggressive for a stock engine. Should be in the 35mph + club no problem with the pipe. I left that alone for now. In the future it will get opened up a fair bit, but its always best to get a bike running 100% perfecto stock before screwing around with that sort of thing. (The 3rd rule of mopeds) The deck clearance was about 1.5 mm so I took the head down scosch and gave it a nice squish band for a bit more torque. As the engine gets tuned up, this head should maintain torque and keep things cool with bigger porting, for now it wont make much difference.
The intake on these is usually a huge restriction, coming from the factory at like 12 mm, there is a lot to be gained by port matching. Lucky for me the previous owner did a real nice job of this, opening up the whole intake manifold to 14mm... looks like i'll have to drill out the carb to match soon. Maybe i'll go to a much bigger and more tuneable Bing with a custom forward facing intake, to provide a nice smooth airflow into the engine. Ed says these like big carbs, and given the fact that it is a piston port i would agree, but for now that might be too much compromise of low end for a heavy bike that is supposed to be tame and predictable. I have a bad habit of over-tuning bikes that I want Caitlin to ride.. whoops. Maybe we'll end up with one of those 17mm bings on there or something wacky, for now the SHA should be good for her to get the hang of riding and feel more comfortable behind the handlebars.
Well that was about it, I bolted everything back up, tensioned the chain. The rear wheel is sitting a little screwy so the adjusters are at two different settings and the fender is much closer on one side than the other, but all in all its looking pretty good. I'm pretty sure the rear fender support (which is part of the tail light bracket) is misaligned or the tail light is a little tweaked. No big deal, but at full compression the tire will rub.
I rode it in to work yesterday and it was cruising along nicely at 35. The speedo -in motorcycle fashion- seems to be somewhat accurate matching up to a mounted speed camera on my ride to work. I'm almost positive the timing is too far advanced based on my visual looking at the points and seeing them too far open, the sluggishness on the top end, a possible pinging rattle, and that crusty whiteness on the piston crown. Dialing that in should get me a better idea of the true top speed and from there what performance mods are needed to get it hanging out with the big dudes.
I better hurry up and get either my sachs or polini on the road quick so i'm not slower than my girl; that would be embarassing!
