Seems like I never learn my lesson on these C G engines.
Always looking and hoping some one will finally make
A really decent motor. The Zeda is pretty good and my BT 80 has been the best so far. I like the one piece cylinder/head idea. There is a BT100 also but its pricy like the BT80. This one is not bad at $169 if it decent. The one review I saw on it was positive and indicated it was a torque monster for a CG type engine. That would be nice as you could run higher gearing. As recieved the piston was installed backwards, some things never change.
So watched the vid of Zeta Motorsports dyno run of a stock YD. It is as I hoped a torque engine. Makes its peak torque around 3k and max HP in the 4k range drops off after that peaking around 6500. As is its an ideal engine to make a powerful(relatively speaking) mellow rider. The 44t sprocket it comes with would be too low a ratio I feel. Will start with a 40. If geared to cruise in the thirties at a lower rpm say 5500 should be a right pleasant ride.
I know plenty of folks like to tweek the CG and do just that. More power to em(he he). For my tastes I prefer rideability and reliability. This engine is a good candidate. If I want to go fast I'll ride my motorcycle.
I've been trying to read more about these one pieces. As I noticed mine was just that. From what little I've found I think it's an nr80. I'm about 300 miles on the engine. It pulls great, I have no complaints yet. I did have to buy a new rear wheel as my coaster brake hub blew out. But I'm thinking about dropping down from the 44 tooth as it seems to want to go faster but I'm not willing to push the RPMs too high, I keep pace with cars on a 30 mph speed limit road so I figure I'm going about 35. I need a speedometer to know for sure.
Got the YD today. Full kit ,seems good quality have seen worse. Pulled the jug sure enough was piston backwards. If they are all like this maybe thats the correct way. Turned it around any way. Cleaned a small bit of flashing from the ports greased the gears, not a wisp of grease as received. Port matched the gaskets spiffed up the cylinder with a bit of black paint and called it done. Cylinder doesn't appear chrome but it is hardened. Rod has large oil reliefs. Mag appears better than most, sposed to be hi perf. Plate on motor is FBM came from Fast Bike Motors. Hope its not F in Bad Motors!
What I did find was the stud spacing on the jug is larger almost to the point the Stihl jug could be fitted, also the 12mm wrist pin may fit with a proper size bushing food for thought. May get a chance to try it tommorrow.
If the ring ends are on the outside of the exhaust port it may not make a difference, what I see looks good. Would be interesting to plasti-guage it to see what the squish is. That engine should have a lot of good power.
The ring ends were out side of the exhaust port but changed it anyway. Can't say on the piston skirt as I reassembled the engine before thinking about it, can't see down the intake and the gasket is glued, sorry.
The ports are rather small which means the engine is probably designed as a low end engine, something I was wanting. With porting and a better exhaust I'm sure there is power in there.
The engine in the link is another one still, I guess this is the trend. The pipe requires a lot of tuning. I have one on a zeda 66/80. In fact the YD is going on the zeda bike. I also have a 66cc engine with the single piece cylinder I have never used. The YD came along before I got to it. Will be swapping the engine this morning. If it quits raining may get a run soon.
Got everything swapped and got a few test rides in light rain, either dedicated or nuts.
Had to raise the needle one notch. That helped but the exhaust was way restrictive. Couldn't hardly hear it. Cut the tube flush with the cap and that woke it up. It makes great power down low on up til it revs out. A 44t as I suspected is a bit low.
I'm a founding member of the ride it like you stole it break in club so I ran it really hard. Its really fun to slam it open. Fat power til it flattens out I'd say around 30. Gonna try the pipe from the Zeda next. After It has a bit more "break in" and tuning will change to a 40t sprocket.