YY250T running (updated) By damin69 (Read 1,571 times)

[damin69]

Ok So back last october I had to have the crank and Piston for my scooter since the crank bearing was shot.

Ok so I did not get a new head just piston and crank for my scooter.

So I get it running and I am it seams to be burning Oil. I figure this is because I did not get a new sleave just the piston and rings. Do you think that this will stop once this piston wears into the old sleave? or is this going to be a major problem?

[damin69]

So I am kinda thinking the line of a full top end rebuild so it would have a new piston and sleeve. Any other way that that much oil would end up in the cylinder? I started it warmed up and in matter of less than 10 min about 4 oz oil out of the motor.

[Cruiser]

One problem when just replacing the piston is that the cylinder is broken in from the previous piston/ring set and has a nice smooth finish on it. The new piston rings do not have the cross hatch grinding markings found on a new cylinder to seat them selves and they will not wear in properly and oil burning and possibly low compression results. Deglazing the old cylinder, which is nothing more then running a cylinder hone to get rid on the smooth surface on the wall of the cylinder, is recommended so that the parts can wear into each other.

[damin69]

No did not hone cylinder. Heck I am new to this motor rebuilding stuff. just kinda sucks that I even have this issue to begin with. Now I just need to figure out how to take care of it.

Just knowing that I had the motor tore all the way apart and put it back together and it actually ran is one huge step. The fact that it is burning so much oil that is not good.

SO I guess I just need to know what the easyest fix is? I do not have honing equipment.

[Cruiser]

If the oil burning doesn't improve very fast, then it looks like you will have to tear it down again. While apart, check the condition of the rings. It could be a broken oil ring, but you could also have a broken compression ring especially if there was a ridge at the top of the cylinder from the previous cylinder.

If the rings all look good, then cleaning up the cylinder (ridge removal and honing) can be done by any automotive machine shop. Remember when installing the piston to stagger the ring gaps evenly around the cylinder (a gap every 120 degrees if you have 3 rings). If the gaps are all in line, you will burn a lot of oil regardless of how you prepare the cylinder.

[damin69]

Ok sounds good. So if I tear this thing down do I have to replace the Head gasket everytime I tear it down?

[bhinch]

Yes....everytime you use a head gasket ...it has to be replaced....whether it is a scooter or car...a good honing will cross hatch the cylinder (up and down movement will give you the required pattern) to promote the rings to seat....your are not trying to remove material ...just give the rings a chance to seat...I would replace the rings also...while your there....

[damin69]

Thanks, You all have pretty much made up my mind. We just ordered a complete top end rebuild kit for it from Scrappy. No one locally does honing. I figure it will take us a few hours to rebuild the top end and then we should be good to go from there.

[damin69]

Ok so Top end is on the way. So if all goes well the Pissed off Bumble Bee will be back on the road this next weekend with NO SMOKE. I sure would hate to start another Indian war sending all wrong smoke signals from the back end of scooter.

[bobf]

Going to all that expense I would think you could find a hone somewhere. Maybe a tool rental shop, or maybe a company like Sears or auto stores. It would not take you long and if you have a good drill you can drive a hone. I have done that myself on a lawn mower engine. I had the kind of hone that had three grinding stones on a spring assembly. You need to compress it and insert it into the cylinder then run the drill to rotate the grinding assembly. A few times down and up will do the job of removing glaze and preparing the cylinder for startup with new rings.

Are there no auto mechanics around where you live. If rural how about a tractor mechanic.

Here is a Sears link. I don't know if it will fit your engine but worth a look. Not too expensive either.

www.sears.com/shc/s/p_10153_12605_00960635000P?prdNo=1&blockNo=1&blockType=G1
.

[Jeff]

Napa stores often have machine shops too.
www.napaonline.com/wi/platteville has one.

[damin69]

for what it cost for gas and time as well as gasket. for a should work out fine. the $124 for the Piston head and gaskets is not that bad a price. I can always send the old head to get done and have a backup top end. All is good.

[damin69]

Ok got the top end rebuilt. All is running all is good. It actually runs better now I think than it did when I got it.

I did find out the reason for the Oil blow by. It seems the A$$ holes at EVOsales sent me the new Piston but did not install all the rings. it seems that after I had did some investigation on line about installing the rings before rebuilding top end that there are two thin rings that go on each side of what I believe is the oil ring they were NOT on the piston that they sent me with the new parts to rebuild my motor.

So it is running good and almost no smoke anymore. Still a bit of oil left that is still burning out of the Muffler. The muffler had a quite a bit of oil that had blown by in it.

[damin69]

Now one more thing I have noticed since the complete motor rebuild. My charging is way better. I think getting all the metal shavings completely cleaned out of the motor has helped TONS. It is 95 degrees here today and running around town fan running charging is up around 15 volts with fan running... SWEET....

[Cruiser]

Congratulations, Todd. Interesting result on your charging system which was a result of cleaning out the insides of the engine. I have heard that the metal filings from normal engine wear will degrade the output of the charging system. Other things can happen too. Read this description of the magnetic drain plug that I installed on my scoot:

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