Hello from Minnesota

[BrewerB]

Hello all,

I have been lurking these forums for several months now and this is my first post. I have found heaps of helpful knowledge here, and I figured I should chime in to say hi!

I completed my first build over this past summer. It is a 66cc bone-stock 2 stroke that I put on an older Bridgestone bike, and I have about 100 miles on it. Another tank of 16:1 and I will call it broken in and switch to 24:1 or so.

When spring arrives I plan to make a few upgrades to the engine, namely replacing the cylinder and carb with a ported jug, 21mm OKO carb, windowed piston a DIO reed setup and a Zeda 66 pipe. I am kind of a big guy (6' 5", 240 lbs), and I am looking for mostly low to mid-range power, I really don't care about how fast I can get the bike going as I live in Minneapolis and the speed limit is 30 mph pretty much anywhere you go in the city.

Do you all think that those would be good upgrades for good off-the-line power, or should I simply port/polish the stock cylinder and trim the piston skirt?

Thanks in advance for any responses!

 

[BrewerB]

Here is a photo of the bike:

 

[crassius]

quickest, cheapest way to low end power (when top speed is not a problem) is to get a larger rear sprocket

 

[BrewerB]

Currently running a 44t rear sprocket. I am very handy, so I am going to go the engine modification (fixing China's crappy castings) route to create more power.

 

[FurryOnTheInside]

I think those bolt-on are way over the top for your purposes.
Besides I would only feel safe once I upgraded the centre pull (cantilever) brakes with linear pull (V) brakes or better!

Then in preparation for the extra power I would change the head for one with better cooling, better compression and no tendency to warp. MZ "R" head is working well on my no-name 66cc, with the twisted Teflon tape gasket.
I'd fit a reed valve but only the little RSE (I just got one) but first I would balance the crank, lighten the con rod and piston, widen ports "the right way", knife and redirect transfers, extend the intake, upgrade the filter, open the exhaust flange, upgrade the plug, boot and wire, retard the timing at the magnet key and narrow the sprockets to fit lighter chain..
In fact I'm just going to end up describing my first build here lol! Take any route you like to more power; but wear your helmet, stay safe and have fun.

 

[BrewerB]

Yeah, the brakes are pretty crap. I intend to replace my front fork to add a rotor brake before I go too hog-wild on speed/acceleration. I also forgot to mention a head, I was planning on a genuine Fred Head at 6cc. The crank seems to be relatively well balanced, as I get very little vibration over a wide range of RPM. @FurryOnTheInside , have you installed the reed yet, and what carb are you running?

 

[FurryOnTheInside]

Yeah, the brakes are pretty crap. I intend to replace my front fork to add a rotor brake before I go too hog-wild on speed/acceleration. I also forgot to mention a head, I was planning on a genuine Fred Head at 6cc. The crank seems to be relatively well balanced, as I get very little vibration over a wide range of RPM. @FurryOnTheInside , have you installed the reed yet, and what carb are you running?

Some newer engines are balanced better, all I can get in Europe is the old style generic so yours may well be better.
No not yet, I have been planning to port another cylinder specifically for the reed valve, and use my current cylinder to the second build (shifter). The porting for reed doesn't require me to start again from stock, but this P.P. cylinder is working very nicely so I may as well keep it.
No piston notch btw, just lowered intake a little bit (0.5mm so far) and widened the usual way.
Running the stock 14mm NT carb and will keep that when I switch to the reed set up. Want to keep the airflow velocity over the Venturi. Might try the 16mm NT Speed but only on the P.P. build.

 

[curtisfox]

Welcome aboard! I am from Brainerd, not a 2 stroker but love the motor bikes.

Make sure you change all the fasteners, to better grade bolts & nuts. As far as 30 mph you go with the flow, so you would need to go a little faster LOL............Curt

 

[BrewerB]

Well, it has been very cold here in MN as of late, but I have been collecting parts for springtime when I can rip into the bike and make some major improvements. I have some Shimano V pull brakes on the way, a full gasket set for the engine, and yesterday I pulled the trigger on the Zeda 88 pipe from bicycle-engines.com (It was only $39.99 USD!). I plan to pull the jug and do some porting/polishing, replace all of the gaskets and hardware, and then add the pipe. Once I have that put back together I will fiddle with carb jets. Getting excited!

 

[BrewerB]

Getting close to being where I want to be! I recently got a new engine (Zeda 80) to replace the last one (bikeberry - wish I would have known then what I know now...) and put a CNC head on with a NGK plug, the Zeda 88 pipe and a muffler from ebay (found the link here). New tubes/tires, repacked and greased all bearings. Holy hell this thing rips and its not even broken in yet. With a 44t sprocket I found myself accelerating up pretty good inclines, and I weigh 240 lbs! I have new handlebars coming and when they get here I will install new v brakes. Looking forward to finally completing this and logging some serious miles this summer.

As you may see in the picture, I had to bend the exhaust out so the expansion chamber portion would clear the cylinder head, so the mounting strap is pulled away from the clutch cover. I need to find a long M6 1.0 bolt to secure the exhaust and come up with a spacer to add rigidity, and then finally devise a strap to hold the muffler so all the weight is not hanging on the stinger of the exhaust.