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Old 04-21-2012, 03:05 PM
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DaveC DaveC is offline
Motorized Bicycle Elite Member
Join Date: Jul 2010
Location: Boise, ID
Posts: 967
Default Re: Best Upgrades for $600 and Tips for Performance?

Mid-west means fairly flat land so really the right gear ratio for a top speed of maybe 35 MPH. Most state laws say no more than 30 MPH but like a car it's nice to have a power reserve. The Chinee motors have problem's with construction that can cause them to fail for many reasons.

One of the first things I'd do is get a better ignition system. Buy a spare magneto coil. The after market coils are better made that the stock unit. That holds true for almost every part on the motor. Some here would advise a complete rebuild with the better bearings and seals that member's here have found. The new reed valve setup shows promise. Better clutch parts can be made or found. Treatland for a Puch 70cc Hi Compression head for $30 + shipping. Of course a sick bike parts expansion chamber. Boy Go Fast on eBay for a CNS version 1 carburator. Properly adjusted it's the best carb without spending a bunch for a Dellorto or Mukuni carb. The right carb has low and hi speed adjustment and a choke cable that goes up to the handle bar so you don't have to bend over to adjust it. The right carb has a tapered fabric filter.

Better bolts from sick bike parts, too. Case bolts set and head bolt set. You need the head bolt set to use the Puch head anyway. There are reasons for that. Even without the head the stud set is a good idea. The stock capnuts are trash. Even if all you do is replace then on the stock studs it needs to be done. When torqueing them down they can give false readings and usually that causes a head gasket leak and the black oily goo that leaks all over a motor. Plus if left it can cause torching, that's where hot gassesd actually burn a tunnel, ruining a head or cylinder top.

I'm skimming the surface here. In reality I ditched the HT motors infavor of Morini's. It takes more fabricating skills to build with them but all that money you just spent on the China motor brought you close to the lowest powered Morini, like I have. 3.5 HP S5 N for around 1990. Air cooled to 9.5 or water cooled to over 11 HP. A mid-ranged good used motor can be found fairly cheap. Thing about a used Morini is they are made to be rebuilt, iron bores means oversized pistons are avalible. Another good thing about Morini is durability. Many mopeds with Morini motors go 10,000 miles and more with no more problems than any 4 stroke. I'm not sure what's avalible right now, a damn good replacement motor is the new Dax motor. At 9 HP it smokes anything you can do to a HT for any price

With these small motors a two stroke makes more sense if you worry about the power to move you around. 50cc is about 2 cubic inches, not much to work with. There are chainsaws and weedeaters with bigger displacememt
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