From: ericm@microunity.com (Eric Murray)
Subject: Re: misc.
Organization: MicroUnity Systems Engineering Inc.
Date: Wed, 29 Jul 1992 21:57:55 GMT

In article <1992Jul29.183321.10576@ohrd.uucp> ohrd!jlevine@cs.toronto.edu (Jody Levine) writes:
[...]
>
>the meaty stuff first
>
>Yamaha Power Valve System problems (RZ350)
>------------------------------------------
>The bike is an 89, we bought it from an idiot (who had to put a new clutch
>in it) in October of 89 when it had 7500 km on it. Soon afterward, the 
>power valve cylcle at turn on added a chkchkchkchkchkchkchkchkchkchk...
>at the end of its usual bzzzzbzzzz. Being an ignoramus myself, I ignored it
>hoping that there was nothing wrong. The bike now has 28 000 km and
>tends to choke on the highway. I'd be going along just fine when it would
>decide that it does not want to get abouve 5-6000 rpm. If I have any gears
>left I can gear up to maintain the speed at lower rpm, but this is just
>a demonstration that the bike can still provide power, not a good way to ride
>a sick bike. We tried hooking up the Radian's brand-new battery to it, but
>the turn-on YPVS cycling is still too slow and still continues with the
>chkchkchkchkchkchkchkchkchk... at the end. So the power valves are probably
>gummed up. This morning they didn't even get through their cycle, they just
>went  Bzz...zz..bz..bzzz.zzz..chkchkchkchkchkbzzz....bzz....  bad news.
>
>HELP!

Oh oh.  My RZ500 did the same thing.  I then adjusted the YVPS
cables to spec (they wern't pulling the valves fully open)
and promptly destroyed the cheapo plastic gears inside the servo.
$219 cdn., and no you can't buy the gears seperately, just the whole unit.
It sounds like you just lunched it; that's exactly the sound my 500 made.

So I pulled the engine, thinking that the valves were gummed up (they
wouldn't turn quite all the way open).  It turned out that a nut
had been kicked up off the road (it didn't look like anything off
the bike) and had jammed itself in the lower cylinder's mechanisim
(the 500s have the valves opened by a lever that's between the cylinders).
I took the engine apart anyhow, since I already had it out of the frame.


>Do the valves usually develop problems at this age?

Yes, they do.

> How can I fix them, fast?


Pull the cylinders and take the valves out and lube them with moly grease.
I'd bet that you can pull the cylinders with the engine in the bike
instead of taking it out like the 500.

>(I hate my car) One bike shop suggested that I pull the headers off, spray
>contact cleaner on the valves and work them until they're loose, then spray
>Pam on them for lubrication. Is this a really bad idea?

Probably.  I haven't done it, so I can't say for sure that it's a bad
idea.  But PAM doesn't sound like a good lube.

> Is there a better way?

Pull the cylinders and do it right.  It isn't hard, really.

>Are the power valves really the problem? I really don't want to take the
>engine apart to clean the power valves, I was going to make a trip to a 
>friend's cottage on the upcoming long weekend.


The powervalves are definately the problem, (unless you have a bolt stuck
in your linkage, a near-impossibility with the 350's design).
Skip the cottage, and fix the bike.


Once I had my cylinders off, it took a couple hours per cylinder
to lube the valves.  I took all the carbon off them, and polished 'em up
real shiny to reduce the build-up, so that took some extra time.
If you just scraped out the carbon (with a soft scraper, don't scratch
the aluminum!) and hit it with carb cleaner, it'd take way less time.

Taking off the cylinder head should be a 2-hour job, if you're doing it
the first time.  Pulling the cylinders, maybe an hour.  With 28000kms
you should also get new rings, wrist pins, and small-end bearings.
You'll be needing them soon anyhow.  If you do all that, you've
just done a top-end re-build of your engine, and it should go
another 20k miles!


--
Eric Murray   ericm@microunity.com   Ride fast, die young, wear black leather.
Newsgroups: rec.motorcycles