It ain't (really) broke--should I try to fix it?

My BIL gave me a '95 Seca II that sat up for 3 years. I rode it a
couple hundred miles last year, then winter hit. I fired the thing up
for the first time the other day, and the #2 cylinder was missing when
cold, but a new set of plugs stopped that. The valve cover gasket is
leaking a teensy bit of oil--enough to notice a residue, but nothing
dripping or anything, so I decided to buy a valve adjustment tool and
do a valve adjustment while I've got the valve covers off. I have done
a bit of tinkering with cars, but never done any work on a motorcycle.


Here's the first question: With a cold engine, I get intermittent bits
of whitish smoke out of one tailpipe. I haven't noticed smoke with a
hot engine. I have a compression tester, but I need an adapter for the
plug holes in my cycle (where can I get one, BTW)? so I don't know if
the cylinders are holding pressure. The cycle has only 12K miles on
it, so I feel that is not likely the cause. The only other thing that
comes to my mind is a failed head gasket. The bike still runs well,
and the smoke is neither excessive nor constant--I notice it the most
when I gas the engine, but it quits completely as the engine idles back
down, and I only notice smoke at all before the engine is warmed up.
Is this problem something that needs immediate attention, or can I ride
awhile before I have to replace whatever it is that's malfunctioning?

Second question: Is there a field expedient test for lean/rich
mixture? The reason that I ask is that there is a little bit of
putting or popping noise when I close the throttle. I don't know if it
does it from relatively high RPMs, but the driveway test reveals noise
every time from 4-5K RPMs. Carburetors have always held some crazy
voodoo power in my mind, and the thought of removing, disassembling and
rebuilding even one (much less four) carb is a bit daunting. I suspect
that there is some goop somewhere in the...bowls or floats or jets or
valves or whatever, but I don't know if the carbs are even
synchronized, and I don't have a basis for comparison between how the
bike *actually* runs versus how it *should* be running.

If anyone could point me toward enlightenment, I'd appreciate it.

-Phil Crow

 

The valve guide oil seals are probably leaking a little oil into the
cylinders and this gets burned off by the time the engine warms up.
You might notice a ring of burnt oil on the metal part of the spark
spark plug from the cylinder that's leaking oil...

You can ride it, but over a period of time, a lot oil can burn onto the
intake valve's head and stop the valve from sealing. You'll hear the
engine spit back through the carburetor. The exhaust valves run hot
enough to burn oil off them, but the intakes run cooler. Nevertheless,
intake valves will still burn and pit if they can't seal properly
because of a lot of carbonized oil on them.
You might try a "shock treatment" of Chevron's Techron concentrate,
just a few ounces in a tank of gas to clean the intake valves.

Your idle jets are plugged up and the engine has to run on what it can
get through the idle bypass and the needle jet. It needs that last
little bit of mixture that comes past the idle mixture screw to run at
the precise fuel air mixture it needs...

I have described how to strip down and clean CV carburetors a few
hundred times in this forum. Google for "kaybearjr@aol +idle jet" and
you'll find a few megabytes of messages...

For an interim chemical fix, try adding 2 or 3 ounces of Berryman's
B-12 ChemTool to a tankful of gas and repeat this about three times.
You can get the B-12 at Walmart for about $2.50. It's mostly xylene and
acetone and it really does clean the inside of the carbs while you
ride...

Just google up those CV carb messages I mentioned...

The thought of digging into machinery always excited me. The first
thing I did with my first old car was pull off the rocker arm covers to
see the piston tops. They weren't there, I had to pull the cylinder
heads off. It took me about a year to go from totally naive to doing my
first valve job and swapping manifolds and carburetors with good advice
from most sidewalk observers and terrible advice from others...

Back in the late 1960's and early 1970's when we had slide valve
carburetors with four cables going into a cable splitter and one cable
went up to the twist grip, carbs would get "out of synch" often. An
engine would be running on three cylinders and sound strangely flat and
sick and a little twist of the throttle would start the fourth cylinder
firing and the engine would sound "right" as long as the throttle was
held open...

If the engine was only idling on *two* cylinders, it would sound really
flat, like some old Triumph vertical twin, and just as soon as the two
cylinders that were being dragged started firing the engine would pick
up a lot of RPM...

So, back during that era, a lot of mercury manometer banks called
"Carb Stix" were sold, and home mechanics all over America could be
seen hanging them from the rafters of their garages and synchronizing
their carbs. I just threw away my old carb stix last summer when I
cleaned the garage out...

Nowadays, the carburetors on most motorcycles are CV carbs and the four
throttle butterflies are all linked together by clamps and they just
*can't* get that far out of synch, unless the motorcycle has hundreds
of thousands of miles on it and the carbs are physically worn. But
$tealer$hip mechanic$ will $mile as they think of their cut of the $$$
that uneducated rider$ are willing to $pend, and they they the guy to
bring the bike in and they will $ynchronize the carb$...

With only 12K miles on your Seca, the carbs are probably not out of
synch, they just have "goop" in them, as you surmise. They probably
won't even have to be removed, if you do the Berryman's B-12 fuel
system cleaning I recommended. Get the liquid B-12 in the can, not the
aerosol, add about 2 or 3 ounces to a tank of gas and go for a long
ride. You don't want to ride fast and hard, just take it easy with that
stuff in the gas, the solvents can wash oil off the cylinder walls and
the piston might scuff or the rings might scratch the bore if you go
out redlining the engine and getting it really hot...

I had to physically disassemble my Yamaha's carbs last summer when the
bike sat in the summer heat so long all the gas evaporated in the carbs
and gummed up the idle jets. But, this spring, I just did the B-12
treatment and they cleaned up nice...

You can tell when the B-12 starts working, the idle RPM gets a little
faster and you have to adjust it lower...

 

[snip]

I must respectfully disagree here. My '94 VFR benefits substantially
from synchronizing carburetors. I can tell when it's out of synch
because of a slightly uneven idle and surging at steady throttle. 20
minutes with my CarbTune II and it idles dead even and the surging is
gone.

This may be something peculiar to the VFR750 (V4 config), or perhaps I'm
just covering up some carburetor problem by synchronizing. I really
don't know about the first, but I doubt the second.

No doubts here. Even though the carbtune is relatively expen$ive as a
synchronization tool (make in UK, no Mercury), It doesn't take many
sessions of use to make up that money at $45 an hour or whatever the
shop is charging now.

That sounds right. I've taken to treating my gas with a bottle of
Techron each spring when I get it out of the garage. It helped things
out when I first got the bike, and it shouldn't hurt if directions are
followed. Techron will also dissolve light gum, varnish, and deposits
left by fuel, though I suspect that it's not as aggressive as Berryman's.

 

Thanks, Krusty, searched up the info and it was very informative.

I owe you a cold beer (or a cup of coffee, if that's your thing).

-Phil Crow

 

Actually, its on both the #1 and 4 cylinders.

I read and re-read your really good help, and this particular bit makes
me want to ask, if the Techron doesn't help (can I put both it and B12
in the same tank of gas?), should I resign myself to a valve job? I
don't have tools for that, and I don't really have the money, but if it
means not causing serious damage, I'll do it. Also, if I pull the
head, why not drop the bottom end out too and replace rings, bearings,
etc? It would seem that the labor would be the major issue, although I
am quickly learning that parts for anything that says 'motorcycle' are
through the roof.

Thanks again,
-Phil Crow

 

No, I wouldn't recommend both B12 and Techron at the same time. I would
use up the B-12 to clean out the carbs, and then do the Techron
treatment...

I'm not saying that Techron will cure the leaking valve guide seals, or
stop the smoking from that source, if in fact that's what's happening.
The Techron will help keep oil from building up and carbonizing on the
valve heads and hopefully keep them from burning...

Techron treatments would be an on-going thing, repeated regularly to
keep deposits off the valve heads...

If you check the intake valve clearances and find there isn't any
clearance, or the clearance is over 1/1000th of an inch too tight,
chances are the valves may have already burned and pitted...

But the only way to be sure would be to do a compression check with the
engine warmed up and the throttle open so the rings will seal...

If the engine has less than about 140 pounds of compression and
squirting a small amount of oil into the cylinders doesn't help, the
valves probably are burned. But don't panic, take it a step at a time
and see what happens by using B-12 to clean the carbs and Techron to
clean the valves...

Techron will also help to free up piston rings that might be sticking.
Engines with stuck piston rings have a lot of blowby into the
crankcase, you can see a lot of smoke coming out of the breather hose
on top of the engine when the engine idles...

Doing a valve job on a motorcycle engine can be very educational and,
if you take your time it will work out OK. But, if the valves aren't
burned and you just can't stand to see the engine smoking because the
valve guide oil seals are worn out, there is a tricky way to replace
them without pulling the head off. You run many feet of string down the
spark plug hole of each cylinder, one at a time, while that piston is
at bottom dead center. Then you rotate the engine until the piston
pushes the string up into the combustion chamber and this stops the
valves from falling into the engine while you carefully remove the
valve spring keepers and the valve springs so you can reach in and pull
the old valve guide oil seal out and replace it with a new one. Then
you put the valve springs and the keepers back where they belong,
rotate the engine backwards, and pull the string out of the hole...

I wouldn't pull the head off unless the valves were burned. If I had
the head off, I would replace the rings, but I wouldn't go any deeper
into an engine than that. You can get into a world of unwanted trouble
if you have to split the cases, and that's what you'd have to do if you
wanted to replace bearings. Your motorcycle really doesn't sound like
it has enough mileage on it to need bearings...

 

krusty kritter wrote:

Snipperooski

Krusty, you are indeed the man. Thank you very much.

-Phil Crow

 

white smoke in normal for cold engine. a little bit of popping is
normal too.

.............................
Motorpsycho Jim

 

That's true, if the "smoke" you're seeing is condensed moisture coming
out the pipe on a cold morning. The "smoke" is white and it rises and
dissipates rapidly. But oil smoke is different. It's slightly bluish
white and it's more persistent...

With the EPA-mandated lean carburetion at idle, I would say that
popping on deceleration is *common*, especially in singles and twins,
and I'd even allow that it's *tolerated* by riders who don't know they
can sometimes fix the problem with a turn of a screwdriver on some
bikes...

 

I've always started my bikes up first time in the spring by adding a couple
of ounces of lacquer thinner to the tank. Ingredients are the same as the
more expensive brand name stuff (with maybe even a couple more
ingredients -- it's a real witch's brew of organic solvents) and it has
other uses around the garage. This technique has worked reliably for me even
in the absence of any gasoline stabilizer.