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General => Technical | How To => Topic started by: zombie on July 16, 2015, 10:50:39 PM
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I'm helping a member set up an engine. This is from a PM... Maybe some of this will help the rest of you understand what is happening inside these scoots (2t's).
I can help more if you need it...
"Yes the crank 1/2's can very easily twist on the con rod pin. You have to support only the side you are working on. Let the other side just hang in space.
On some of the better bearing sets there will be a thin band of Nylon on the outer race. The area that gets pressed into the case. That goes toward the inside IF you have it.
The nylon cage itself does not matter which side. Actually the Nylon cage is only quieter than the standard steel or the better bronze cage. Some people think they are better but in truth they are not. Bronze will outlast the engine cases. The problem with them is the hot/cool cycles. They get brittle, and fall apart. Just like plastic in the sun.
If you plan to keep the bike for 4-5 years then I would consider getting better bearings. If you want to sell it sooner... no issue.
I wouldn't use the toaster oven either. It will melt the cages. I would use a pot of boiling water or a pre heated oven.
The toaster oven goes full power untill it reaches temp. then it throttles down. You need at least an hour in a pre heated oven or same time in a pot of boiling water. Water hits 212* f, and no hotter. It's the safe bet
BUT you will only gain perhaps 0.0002-3" on expansion. Thats why I suggest to be ready with the press. You will need it.
Temp on the piston... Melting point is somewhere near 1200 - 1400* f depending on the alloy
Normal combustion temp is around 16-1800 * f. 400 is the magic number that many use for exterior head temp. I NEVER use this number because you can close the throttle on a long downhill, and see 5-600*f in heat soak, even tho the cylinder temp is cooling.
Here's a good article on this... http://www.contactmagazine.com/Issue54/EngineBasics.html (http://www.contactmagazine.com/Issue54/EngineBasics.html)
The Ignition timing on the Zuma begins around 15*BTDC just like all the other scooters, and slopes straight down to 0* at 12krpm. What this "curve does is gradually push the cylinders heat out into the pipe.
The ONLY chance of melting a piston is from Pre-Ignition (carbon/sharp edges, like a piston edge or spark plug hole, port edge, casting marks on the piston dome OR lean mixtures creating pre Ignition.
Detonation is controlled by the squish band. The band forces burning gasses into the center of the flame front to prevent runaway combustion. Listen close for crackling in the pipe. That crackle is detonation. You need more cool fuel mix to stop it and or a tighter squish depending on the head.
A relatively shallow or flat across head is more prone to detonation, and needs a tighter squish. A bell shaped head or high dome head needs less squish.
If you have or can find a large ball grinder or make one from sandpaper, and a golf ball, it pays to hollow the center of the head. You'll lose a few compression ratio points but lowering the jug to just a note paper gasket (if you can) will gain ax rpm, and reduce the chance of detonation.
It's a f***ing can of worms. One little thing messes with everything else. Even the wrong rollers can mess up a perfect cylinder... I hate scooters.
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Another exert:
Don't forget all the sharp edges on the piston... Circlip holes, wrist pin holes inside, and out. If your wrist pin does not have a taper or bevel on the ends... add one. I also cut off the circlip "tangs" The parts that make it easy to grab with needle nose pliers... The float of the wrist pin can push against them, and make the clip pop out. When you cut them off, an bevel the end of the pin, it will float OVER the clip, and actually lock it in place.
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Another exert:
Don't forget all the sharp edges on the piston... Circlip holes, wrist pin holes inside, and out. If your wrist pin does not have a taper or bevel on the ends... add one. I also cut off the circlip "tangs" The parts that make it easy to grab with needle nose pliers... The float of the wrist pin can push against them, and make the clip pop out. When you cut them off, an bevel the end of the pin, it will float OVER the clip, and actually lock it in place.
Hey zombie quick question. Where are you from. I live close to Dallas Texas and I want to meet up with some people who ride scooters like me but I have failed to find anyone close by. I was reading about the scooter meet you were planning back in 2012. And it sounded so dang awesome.
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I'm inCarrabelle Florida. Sort of 1/2 way between Pensacola, and Tallahassee. For the real world we are the RedNeck Rivera.
If I leave tonight I could meet up for a ride in September (if I ride the 4t bike) If I take the ZX, I'll be there before you get home w/ cold beer.
Too bad no one was able to make it down here in 2012. On the good side, it's my daily life. Look up "The Worlds Smallest Police Station". We have 2 lanes of Hwy. 98 that run for 75 miles in either direction on the coast, and not ONE traffic light or stop sign. Combine this, the worlds smallest police station, a mechanic that repairs ALL of the local cops boats, and a 90MPH 50cc scooter... How much fun do you think I have?
I just might know a fella or five that own stills too. Shhhhhh!
Maybe a few people might consider Labor Day as a good time to chill in a foreign land??????????? I have room for three or four, and I still have the connect at Timber Island. (RV park) They have one cabin that sleeps 8 that is always available for me.
Toss the idea around... My house is always open.
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That sounds awesome bro. I have the agility 50 and now I have a miu ht 150t-4. The 150 does around 50 mph right now but is suppose to do 70 mph from what the guy told me that I bought it from. I'm still tinkering with it though. Heck I wish y'all were closer to me I think it would be awesome to meet up and scoot around.
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It would be cool to ride with like minded people.
I have two types of riders here... The ones that buy a lawnmower, take off the fenders, and go get beer. Then there are the ones that buy the scooters I sell them. Broke ass bitches, that drink the beer the lawnmower guys bought.
Sigh...
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Lol I hear ya. Laughing my ass off at the pic. I'm a born bread and certified east Texan and that's a bad ass redneck hot tub. What kind of scooters do you have for sale and Price's. How much would it cost me for you to ship it here. Pics of the ones for sale would be awesome. Looking for one that will go 70 mph and for my size I'm only 5'2 150lbs. I'm really interested in something. I think I got the 150 I have sold today I hope
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I'm always selling the ZX-50... I could deliver 1/2 way.
There's around five grand in the bike, and I'll sell for 1,500.00
Right now it is a 93cc stroker that does 80?90? something... I have a new set of clutch pads to install, and finish tuning the carb/ignition.
I'm just soooooooooooooooo done with messing with this thing. There's an 80 dollar EGT gauge that I have not yet wired up, Around 250 dollars worth of custom LED lighting, not wired up, A new tach, not wired up.
I just have too many other projects to keep up with it. I am re doing it for the Speed Week event in October but even at this deadline, I might not get to it.
It's a race bike for sure, and it requires constant tweaking.
Other than the ZX I have a literal basket case 50cc 4t. It's some China made /Vespa looking pile of parts.
I have no time or desire to assemble it or order whatever parts it needs. 50 bucks can have that one...
If it sweetens the pot any, it belonged to a singer you can look up. Debbie Jordan. I figure just the seat could fetch a few bucks!
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Dang I wish I could but I can't swing that much dough right now. And on the other one it would probably cost too much for it to be shipped out to me I bet. Sure would be nice though
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Especially since my son sold our 2011 agility 50cc today to help a lady who needed transportation to and from her job to support her and her little girl. The lady didn't have a vehicle so my son said he would give up the scooter for her to have a way. Sold it for $650 which is enough to pay the rent this month. Awww... I'm pretty proud of him for doing that.
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Nice kid for sure.
Keep your eyes on Craigs List... Scooters are always on there, and many for less than a couple hundred. They all need the same things, Battery, carb, belt, rollers. A rattle can of paint, 200 on a scoot, and 100 on FleaBay... 400.00 dollar scooters all day. Ride em, till you find a buyer...
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Thanks and yea he's a pretty good kid. Makes me proud of him from time to time lol
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