CDHPOWER80cc/66cc Windowed Piston Set - 66cc/80cc Gas Motorized Bicycle

Please make sure to properly break-in your engine when installing a new PISTON & CYLINDER...6-8 oz of oil for the first gallon of gas. I use 6oz as to me 8oz seems a bit too much.....Then what you want to do is let the engine idle for 15 to 10min then let the engine cooll down for 30min. Due this process 4 times in a row. The 5 time you do it let engine idle for about 5 min and then drive the bike no more then 15mph max is 20mph anything above that would result in a ENGINE FAILURE....Trust me i blew out 4 engines before i knew this information

Perfect

The windowed piston fit perfectly, installed easily, with little "clean up" to the machined edges of the piston, before final installation. The Piston by itself, installed in the engine, would not run! Only after I added the Reed valve assembly, did the motor Roar to life with more power! The the windowed piston AND the Reed valve assembly, are a notable upgrade! If done right, you WILL notice more power, improved performance, cooler running, and longer life.

So what I disliked about this product was when I put when I ordered it it did not tell me if it was a high or low centered piston so after I bought it and tried to install it I found out that it was a high center and I needed a low center it would be nice if the product would tell you what it was for because now I can't return it and I'm out the money. Although if it would have been the right one it looked nice and it probably would have worked great

Part looked good, I ordered this and paying a little more than other brands to get a quality product, the opening windows In the piston aren’t cut properly and by glancing at how it was made, it was ready to blow up my motor. I didn’t install due to that. I plan on refunding and having a replace of the product.

This is my second one and they work very well if you check and set your port timing your engine will run very well and have plenty of power..I see some reviews where they give a bad review because they ordered the wrong one and waited to late to try and send back... that's your fault on both cases not the pistons .....it's a very good product...

When I first got this product I was looking forward to installing it. Until I saw that the ports are very roughly cut. If you put this in your engine before chamfering the edges you WILL DESTROY THE CYLINDER. The edges were sharp and would have destroyed my cylinder. Just take some sandpaper or a sharp steel knife and you can chamfer down the edges for a smoother transition into the cylinder. I have had ZERO issues and ZERO scarring with a chamfer on the piston. This is also NOT FOR 49CC. Only 80. You also MUST HAVE SOME KIND OF REED VALVE. So many people complain about it not working but forget to pair it with the other piece of the puzzle. This is not a swap it and be done. You must put the appropriate parts on it as well. I have also taken this piston on long endurance rides and have not seized my engine with it as well. Recommended for tinkerers, not for the average user.

It is what it is

I'm super happy with it, just worked amazing with my reed valve. Noticable in the whole power band. Did not expect the combination to make such a big difference but it did.

Three stars due to the clean up around the windows and skirt, very rough and uneven,But for the price and a bit of time to polish the roughness out they seem ok,,Only time will tell if they last, just installed and waiting for warmer weather to test, will update the review as I get time on the piston

This is the high hole model and is used with a long rod Only! Works as intended. Needed a little clean up but overall pretty good quality. Purchased it to take measurements to replicate my own. No complaints.