How to replace rings on Linhai 257cc By jenningsjosh (Read 3,752 times)

[Alleyoop]

If it pumps out around 200PSI that is a lot more power, so it should pull the weight really good. You are also getting a new belt so it should be a good runner.
Alleyoop

[jenningsjosh]

Ok.. so I found a lil money.. anyways.. I got the impact wrench...

I need to know a couple things... do I have the 70mm piston? I think so...

Also.. the belt they sell for thos engine on scrappy dogs is an 871 23... which is what I measure at.. I know the belt size has been said to me many times.. but I have found a lot of contradicting information from various websites... most do point towards the 871

So I want to make for 110% that my belt for some reason is supposed to be shorter...

Any info that can point me to correct piston size and correct belt is helpful. .. not doubting what has previously been said.. I just want to dot all my I's and cross my t's before I order... thanks

[jenningsjosh]

Nothing? I would like to get the rings and the belt ordered before riding season is over lol... thanks agn for help

[Alleyoop]

Unfortunately the rings can be any of 3 sizes, 68,70,72 and you will have to measure the piston or the inside wall of the jug before you order the rings. But it should be 70 or 72.

As for the belt that is the size it calls for SO measure the belt on there and see how much it stretched or if its the wrong one.
Alleyoop

[jenningsjosh]

I have already posted the pic of the measured belt.... but here it is again.. guess it was diff thread... anyways... yes the engine calls for the 871 23.. but you all keep telling me that it should be a shorter belt....




as you can see..if this was a 871 belt... <----- what engine calls for......it has maybe stretched a mm or two.... but you all told me to get a 856-23-30..... <---- what you told me it should be

[Alleyoop]

Oh yea forgot all about it, but as you can see that belt is almost 3/4 of an inch to big.
So bite the bullet and get the 856-23-30 and be done with it.
Alleyoop

[jenningsjosh]

But alley.. other sites are telling me that 871 23 is the correct length.. not the 856 23 as you suggest... I just want to be sure.. I mean I trust your word.. but you gotta understand where I am comin from

[jenningsjosh]

www.roketapartsonline.com/linhai-260cc-engine-parts-cvt-drive-belt-871-230-for-linhai-260cc-p-13652.html

www.scrappydogscooters.com/site/mobile?url=http%3A%2F%2Fwww.scrappydogscooters.com%2FLH170MN_Linhai_257___275.html#2853


Here are two examples that show the 871 belt.... there are many more

item.mobileweb.ebay.com/viewitem?itemId=271082044970&cmd=VIDESC

And here is one on ebay that shows your suggestion

[Alleyoop]

Not a problem get whichever one you feel is the right one. We said to get the 856 due to your current belt flopping all over the place.

Do this take the Variator off and see how the belt fits OVER THE BOSS, It should fit a little tight and a little hard to get it over the BOSS. If it has a lot of slack over the BOSS then you know it is to long. That's about all I can recommend and then you decide which one to get.
Alleyoop

[jenningsjosh]

ok... now i have got down to the rings... it looks FANTASTIC inside... I mean i dont really know exactly what to look for... but it does all feel smooth...

Upon taking this all apart i have found 1... just 1 piece that is worn.... here it is



and here is where it came from

[jenningsjosh]

The question is this... when my bike is on the stand.. the motor does not push down on the exhaust... but while down, the motor does push down... I know my engine and exhaust move together as 1... BUT

Could an exhaust leak cause all of these issues? maybe make my compression low? due to the face that the leak is right at the exhaust valve?

Anything HELPS.... throw it at me

[jenningsjosh]

Here are some random pics... If you see something that looks "off" damaged.. or whatever just shout it out... THANKS

I do realize there is a little bit of buildup on the top of the piston.... and i will clean that all off before i put back together



The valves



timing chain off



Crank shaft



piston on shaft still


closeup of rings-- off shaft

[Alleyoop]

A leak at the exhaust valve will not cause low compression it would be backfiring if it where leaking and it was not backfireing first of all.

The Rings do not look good LOOK AT THE GAPS on the rings looks like someone put on 68mm rings or part of the rings ends broke off. There should be only a small gap. I mean what are you arguing about anyhow you proved that the rings where leaking when you put some oil in the there and re-checked the compression and it went up, Most likely due to the WIDE GAPS ON THEM. I would bet that scoot never ran good since you bought it unless you yourself changed the rings earlier and you put in the wrong rings.

But now that you have it apart measure the piston across and the inside of the cylinder so you can get the right size rings and be done with it.
Alleyoop

[Alleyoop]

Look at the middle ring it looks like at least 1/2 gap BRO, part of it either broke off or wrong size rings where put on.
Alleyoop

[jenningsjosh]

I am not arguing anything... NOTHING.. just trying to get help man... NOBODY has ever done anything to the rings... NOBODY has ever worked on this bike before me.. NOBODY! The bike ran DAMN good for about 500 miles... it only has 1200 miles on it... those are the FACTORY rings... I will be happy to change the rings... but they dont look worn at all... the gap disappears quite a bite when the rings are squeezed... i have NO PROBLEM replacing them and all the gaskets.. and i will... but that ring where the exhaust comes out is JUNK... all bent and pressed and it does leak air significantly there