RCU Forums - MVVS26cc PISTON help

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aandreas

11-18-2008 02:33 PM

MVVS26cc PISTON help

Hello everyone i need some advise ..i strip down my mvvs 26 to change a bearing and i didnt mark the way that the piston goes ...the piston has a big opening at the botom off the one side and a smaler opening at the other side ..which side is the front??

RC Extreme power

11-18-2008 02:34 PM

RE: MVVS26cc PISTON help

Is there a mark on the top of piston

aandreas

11-18-2008 02:48 PM

RE: MVVS26cc PISTON help

no i saw no mark

Charley

11-18-2008 02:48 PM

RE: MVVS26cc PISTON help

Quote:

ORIGINAL: aandreas

Hello everyone i need some advise ..i strip down my mvvs 26 to change a bearing and i didnt mark the way that the piston goes ...the piston has a big opening at the botom off the one side and a smaler opening at the other side ..which side is the front??

This is from memory: If you mean that the piston skirt has a big cutout on one side and a small cutout on the other, match the big cutout to the rear crank bearing. The small one should be to clear the back plate. Ck and see.

CR

aandreas

11-18-2008 02:58 PM

RE: MVVS26cc PISTON help

thanks....... thats what i mean ....sorry for my spelink[:o]

RC Extreme power

11-18-2008 02:59 PM

RE: MVVS26cc PISTON help

The other thing you have to look out for is when the piston is put into the cylinder just make sure the the opening in the rings do not hit any of the ports, If they do it could cause them to break while running. The rings should have a locking pin to hold them in one place.

Milton

arobatx

11-18-2008 03:36 PM

RE: MVVS26cc PISTON help

....edited due to incorrect information.

Pe will probably speak up soon and put this all to rest for sure though :)

Charley

11-18-2008 07:39 PM

RE: MVVS26cc PISTON help

Quote:

ORIGINAL: arobatx

....and typically, if the ring groove is pinned, I've found the pin location will usually be opposite the exhaust port. Pe will probably speak up soon and put this all to rest for sure though :)

It's not pinned on my older MVVS piston. How do I know? I bought one of the original MVVS 26s. I bought a later teflon-coated piston/sleeve from Pe and installed them.. So I have the older piston/sleeve out to look at. ;)

CR

pe reivers

11-19-2008 11:11 AM

RE: MVVS26cc PISTON help

the piston has a date code, that should be on the same side as the large radius cutout. That points to the front of the engine, so the cutout clears the bearing.
The antirotation pin is on the exhaust port side.

arobatx

11-19-2008 11:33 AM

RE: MVVS26cc PISTON help

Thanks for clarifying that PE....I think my head was in ZDZ80 land, where the pin is opposite the exhaust port. Interesting Charley notes that his older piston ring groove is not pinned...

pe reivers

11-19-2008 11:36 AM

RE: MVVS26cc PISTON help

So far, all engines I saw were pinned, even the very first back in 2001.

Charley

11-19-2008 12:05 PM

RE: MVVS26cc PISTON help

Quote:

ORIGINAL: pe reivers

the piston has a date code, that should be on the same side as the large radius cutout. That points to the front of the engine, so the cutout clears the bearing.
The antirotation pin is on the exhaust port side.

Huh, the original piston from my 26, bought in December, '03, has a B stamped on the top but it's opposite the oval cutout for bearing clearance. the opposite side of the piston skirt has no oval cutout; just the rectangular one that is in both sides. Is that B a date code?

As you say, it does have a pin in it. Guess I misremembered about that detail.

CR

Charley

11-19-2008 12:17 PM

RE: MVVS26cc PISTON help

Quote:

ORIGINAL: arobatx

Thanks for clarifying that PE....I think my head was in ZDZ80 land, where the pin is opposite the exhaust port. Interesting Charley notes that his older piston ring groove is not pinned...

Argh! I blew it on that one! Sorry. When I saw Pe's post I looked at the piston again and rotated the ring whilst looking in the groove. Sure enough, there's a pin.

On your piston, where does the ring gap fall in the sleeve?

CR

pe reivers

11-19-2008 02:16 PM

RE: MVVS26cc PISTON help

Quote:

ORIGINAL: Charley

Quote:

The older pistons did not yet have the date stamp. I think it was first introduced on evolution engines, and then carried over to all mvvs production.

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