Rings

I have to remove the barrels to fix a small leak in the base gasket. Is it worth replacing the piston rings as a matter of course? The speedo shows 28,000 miles but as I am not the original owner I cannot guarentee the acuracy of this. Thanks in advance. #Nobby

 

What was the compression before you pulled the top end off?...

If you don't know, the rings are probably OK as long as it ran well and didn't have any oil consumption problems.

FWIW- rings are not cheap, might be hard to find, and you'll need to take a trip to the machine shop to have the cylinders honed before putting in the new rings.

28K miles is not really all that much, and if you want to freshen things up, a valve job would be a better investment.

 

I have over 56,000 miles on my 86 maxim and no prblems of any sort so far. Oil changes and plugs, carbs sync'd keep her in line.

 

Depends on the price you have to pay for rings IF reasonable then 'just do it'
Bob Traceys World of motorcycles (google) sells OEM Yama rings for approx
$24 a piston.. And frankly for a hundred ..well worth doing if you plan on keeping the bike for a few more summers. When you have it apart DO measure the rings' end gap according to a Manual even a Haynes will do... that should help you decide.

 

The answer depends on the wear of your cylinders. The existing rings are already broken-in or "worn in" if you will. If there is significant wear, for example there is a noticeable "edge" at the highest point that is reached by rings, I would not put the new rings without at least honing the cylinders. Sometimes new rings make thing worse - the engine may start to smoke, but because the cylinder is already worn, the rings won't break in correctly. After smoking for a while the rings get "smoked in" or stuck and compression goes down. In the most severe cases the rings will break and ruin the cylider in process.

If the cylinder looks (and measures) "mint" I'd replace the rings though, as it is a perfectly appropriate thing to do.

 

There's "Two School's of Thought" when you ask about doing that Piston and Ring work.

1. "If it ain't broke ... don't fix it."

2. "Your crazy not to go the extra mile."

My very own personal opinion is: --> #2.

While the head is off; I'd clean off all the carbon. Clean the Valve Faces of carbon and each combustion chamber. I'd have shining aluminum or Polished Aluminum combustion chambers. A two-hour job, by hand ... Cake with air or a Dremel.

LAP the valves and pop-on some NEW Valve seals. I'd look at the Exhaust Ports and get-in to remove any carbon deposits. I'd clean-out the Exhaust Ports and sand them as smooth as humanly possible.

I'd mirror finish the tops of each Piston.
New set of Standard Rings after cleaning the Ring grooves and Oil Control Passages.

A nice light touch of Honing a new Cross-hatch pattern in the holes.

You should have nothing to do, now, until around 60K when you do the timing chain!

 

Re piston rings...everything that Rick said and more.

My 900 had "53000kms" on the clock when I got it a few years ago. I read that as 153,000kms. Why, because it was drinking oil like you wouldn't believe, blackening the spark plugs, and smoking out the neighbourhood when I started it up on a cool morning.

So, off with its head! I did the valve lapping thing (a bugger of a job taking off and replacing the valve springs etc.) and it made a huge difference getting rid of all that carbon buildup. Polished the pistons and honed the cylinders myself with a low cost honing tool from the local auto store - a bit of trial and error but it did a good job. applied new rings (Yamaha ones might be a bit expensive but in the States there might be aftermarket ones available at a lower cost).

If you're doing the rings you might as well put in a new camchain at the same time while you have eberything off.

Do the job slowly and with loving attention and when you have the bike back together you'll be rewarded with a much better running engine. Mine no longer has an (oil) drinking problem as a result. Any hints or tips along the way Rick or myself will be able to assist. Been there, done that, made a couple of silly mistakes but it all worked out in the end.

Karl

 

Run a compression test....less thah 30 psi. Added oil..120 psi. Looks like new rings and maybe a rebore. Might be cheaper looking for a used set of barrels and pistons. With my luck, maybe I am not really meant to ride
:cry: :cry:

 

Yes .. start looking for a decent used cyl and piston assembly, Buying rings and gaskets is bad enough, but add in pistons and it's cheaper to buy another Bike.. lots less work too.
Do Not buy any bits until you've taken a good hard look at the innards.
These Yama models can do high mileages but when they are worn out..
it's all over.
You will have to open it up.
Easy (well a bit way is to leave the motor in the bike.to pull head and cyl block.. assuming it comes off, many cyl blocks simply don't cooperate.. .to satisfy your curiosity.. You may be pleasantly surprised or you may not.
g'luck

 

When I see a reading like that ... I'll ask this:

Did you take the readings with the Throttle Wide Open?

 

I did not have the throttle wide open, I only opened it up to about 1/4 and I must confess that I had not fully warmed up the engine. The reading did not change from tick over to 1/4 open. Maybe I should retest after a ride? ( Can you feel the hope in this reply?) I was not going to order any parts before looking inside just in case it had already had a rebore.

 

No.
You can try it ... but, as long as the Fly's weren't actually closed ... the reading will probably be about the same.

You could probably shop a few Breaker's and find a whole engine to exchange
for yours. UK got more of these XJ Bikes than did USA; I think!

 

OK, I'll confess...... I did the whole compression test wrong. I will try again at the weekend.