This (81 special) has been my daily rider for about 4 years now. Never had any issues with reliability, or smoke coming from the exhaust before. Only reason I did the rebuild was the plastic pieces from the front cam chain guide getting into the bottom of the engine. Had to replace that, so I replaced the rings even though they were still within spec, replaced the valve guide seals and lapped the valves, new cam chain, and new gaskets. I put yamabond on top and bottom of the head gasket, and torqued everything to specs. After starting for the first time I am getting white smoke from the exhaust on both sides, but more on the left and especially when you rev it. Thought maybe it would go away after it warmed up, but no. Cam chain and valves clearances are all right on. I didn't do anything different with the carbs because they were working great before. I retorqued the 8 big ones on top from 25 to 30 thinking that may help, but to no avail. I am willing to take it apart again and replace the valves, guides, and seals again if I have to, but I don't want to just start replacing things if they don't need to be. They seemed fine before. If something is not right with the valve guide seals,even though they are brand new, would I be ok just replacing the ones on the exhaust side and leave the intake ones alone?
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Maybe the new rings haven't seated yet? But they usually do seat quite quickly with a proper hone. Maybe not fully immediately, but enough so it's not smoking. Full seating may take a few hundred miles or so. If it is the guide seals, it could be any of them, not just necessarily the exhaust ones. Oil getting past the intake seals would mix with the incoming air/fuel mix. You'd get an oil and gas mix in the cylinder, like a 2 stroke, and we all know how they smoke.
I did not hone the cylinders. I'm not an expert, and maybe that was foolish, but they seemed to be perfectly smooth to me. I was just going to clean up the pistons and reuse the rings because they were still within spec, but I snapped one taking them off. Is there a way to know if it is the rings, or the valve seals causing the smoke? Will the rings I put in seat without a honing? The way it is smoking now I don't even want to ride it down the street.
Hi pahako,
it takes a long long time for new rings to seat in polished bores, you shoulda honed them.
Will they seat? Eventually, yes.
Are you prepared to smoke up the neighborhood until they wear in, rather than do another teardown?
That's up to you.
You could always take a 1,000 mile trip someplace to spread the worst of the oil smoke amongst strangers.
it takes a long long time for new rings to seat in polished bores, you shoulda honed them.
Will they seat? Eventually, yes.
Are you prepared to smoke up the neighborhood until they wear in, rather than do another teardown?
That's up to you.
You could always take a 1,000 mile trip someplace to spread the worst of the oil smoke amongst strangers.
Hi pahako,
this guy from Harbor Freight will work:-
http://www.harborfreight.com/4-inch-engine-cylinder-hone-97164.html
Slowest speed in a drill press or even a variable speed hand drill if it'll run slow enough.
Up and down motion, sluice with cutting oil, you should see figure 8 shaped swirl marks in the bore.
But first! The dimension checks!
Piston rings to ring grooves up and down clearance.
Piston rings in bores end gaps.
Piston to bore clearance.
You'll find all the numbers by using the search function.
So after taking my engine apart again to get the cylinders deglazed, I started looking at the rings again. They are DNJ PR211 (honda civic) and I wasn't 100% sure of which way the groove was supposed to go on the 2nd ring, and the inside bevel on the first ring, because there are no markings on either one. After looking around on the web I found this which helps explain the correct way to install them. https://www.hastingsmfg.com/ServiceTips/compression_ring_installation.htm
I had the 2nd ring with the groove facing up, so instead of scraping oil down, it was pushing it up, and likely adding to the amount of smoke coming out of the exhaust.
Hopefully with deglazed cyliders and the rings in right side up, things will work out. New head gasket should be here tomorrow. I'll post the results.
I had the 2nd ring with the groove facing up, so instead of scraping oil down, it was pushing it up, and likely adding to the amount of smoke coming out of the exhaust.
Hopefully with deglazed cyliders and the rings in right side up, things will work out. New head gasket should be here tomorrow. I'll post the results.
scabber
XS650 Guru
I would invest in motorcycle rings at this point. What the rings are made of plays a part on how well they work. I think Yamaha used a chrome top compression ring for its wear factor.
Just a follow up. I went ahead and purchased the correct rings, and honed the cylinders. It's a good thing I had to take it apart again because I did not notice the first time that the cam bearings on the left side had a lot of play in them. Replaced them too and all is well in my xs world again. The top end is far less noisy now with new bearings. If you are getting a lot of top end noise, check those bearings.
beto jimenez
XS650 Member
Hello there pahako, are those rings standard size, or are they oversize? cause i think i need new rings but its real hard and expensive for me to get'em from mikes xs. Can you give me some help on what car can i get the rings and pistons from?
Many of us are getting our pistons and rings from this eBay seller now. Nice stuff at a good price .....
http://www.ebay.com/itm/76-82-YAMAH...04444852?vxp=mtr&hash=item20e070d6b4#shpCntId
http://www.ebay.com/itm/76-82-YAMAH...04444852?vxp=mtr&hash=item20e070d6b4#shpCntId
I did not need to boar the cylinder so I used standard size rings for my rebuild.
beto jimenez
XS650 Member
thanks a lot guys!
