Re: Clean classes on a rebuild, a moped flex?!?

E3256C33-BCBC-412A-ABB5-6BC7E5A84F47.jpeg

Damn I did not notice it before but after looking at these picks......looking at the piston here but you can totally see how it is about 1mm off.

Re: Clean classes on a rebuild, a moped flex?!?

Yeah that hole needs to be centered most of the time. Also wtf is up with that shit stack on the headset?

Re: Clean classes on a rebuild, a moped flex?!?

> Daniel '' Wrote:

> -------------------------------------------------------

> Yeah that hole needs to be centered most of the time. Also wtf is up

> with that shit stack on the headset?

🤣🤣🤣. Spaced it out years ago with some spacers and a couple headset nuts. Idk always wanted to make a real spacer but it has worked for so long. Meh don’t even notice it all the time but when I do it is an eye sore.

Re: Clean classes on a rebuild, a moped flex?!?

I'm guessing the ring ends passing over a small booster port hasn't been a problem ?

Re: Clean classes on a rebuild, a moped flex?!?

Nope all of them do it.

BIgEsT problem I have seen has been the lack of oil on the bridge just past the intake hole. Hence the 3 oil holes. Did a couple pistons like this for some friends and all there are still running fine. (edited)

Re: Clean classes on a rebuild, a moped flex?!?

Polini kits have a number of known issues. The intake hardware threads are mm away from the bore. It can cause warping if you over tighten them, it is the main one that will toast your kit instantly. In my experience the ring usually snags on the down port and the ring smears around the ring pin. They get the sloppy piston sound before they let go typically. I have had better luck with them on za50, I think it’s because the rotation direction puts the combustion forces onto the exhaust side. There just isn’t enough meat on the intake side which is why it has oiling problems on that little strip. Naz had one running a ktm65 piston that was very rippy. I’ll try to ask him some question about it next time I see him.

Re: Clean classes on a rebuild, a moped flex?!?

That would be cool to hear what he did with that piston.

Ya they say to do 5ftlbs of torque on the intake bolts. I did 4. I was not messing around with overnighting.

It is crazy that some people just slap them in and they run forever. Don’t worry about torque specs or lining anything up.

Re: Clean classes on a rebuild, a moped flex?!?

Overpriced Parts /

> EH FCC of the QCB Wrote:

> -------------------------------------------------------

> That would be cool to hear what he did with that piston.

>

> Ya they say to do 5ftlbs of torque on the intake bolts. I did 4. I was

> not messing around with overnighting.

>

> It is crazy that some people just slap them in and they run forever.

> Don’t worry about torque specs or lining anything up.

I’ve had good luck Installing cylinder/topend first locking it in then install the intake cap screws for less cylinder warpage to piston

I don’t touch a dremel to the intake on the cylinder to open it up a little until the kit is broken in and when I kit other people bikes with polini kits no dremel at all, for the more metal holding the cylinder intake tongue the more heat sink and stronger it is all around.

Stock out the box those kits still rip so other than doing some cleanup and chamfer not much more is needed unless you go with a 4 petal intake large carburetor set up

Re: Clean classes on a rebuild, a moped flex?!?

I agree with ya on this one Ken 100% for sure. Best running ones I have seen have had a 15 Bing and just case matched or not at all. I honestly feel like the longest running ones have been on a Bing. Fasted one I ever saw was Calvin buzzards pinto with a 19 and a weekends pipe. But that was years ago. It was in the mid 60s crazy fast.

I feel like once you go overboard, these kits they don’t like it. Lower compression and timing is their happy place.

I just reshaped the exhaust and matched it to the pipe inlet. Mainly because mine was super square and rough. Last kit I had years ago out of the box I could put my thumb in it. This one I could not. Just because I don’t want to open this top end back up I mildly opened the intake, gaped and chamfered the ring and chamfered all the ports. It has a PHBG 21 and 4 pedal block. I don’t plan on opening the top again. But this all could change

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