Having some problems...

I have a Virago 250. I was performing my first valve clearance
adjustment. I unscrewed a tappet too far and dropped it down below the
cams. I took the cover off of the cam area and got the tappet out and
put it back into place. One of the cams came off and I may have changed
the cam timing but I am not sure. I put the tappet back into place and
started to move the crankshaft clockwise like the service manual
states. I encountered resistence and had the spark plugs out. I started
moving the crankshaft counter clockwise and there was no resistence.
Then I decided to go clockwise again because thats what the service
manual said to do. I pushed it through the resistance area to the TDC
and the intake rocker arm had no free play so I could not adjust the
valve clearance, the exhaust was fine. I put it all back together to
see if it would start. The bike starts very hard and dies as soon as I
let go of the starter button. I didn't realize until after I did that
that maybe the timing was messed up.

Could I have caused any damage to the valves?
I also read later on here about turning the crankshaft the wrong way
could damage something also could I have ruined anything by doing that?

Thanks for the replies,
Newbie who made an expensive mistake.

 

At least you have a manual!!! I would read it where it tell you how to
time the cam you untimed....just follow the directions as i am sure they are
accurate... then you will be able to readjust your valves....

good luck..

Fwed

 

So I don't have to worry about anything else being ruined i just
untimed it and need to retime it?

 

It would be nice if you mentioned the YEAR model. This is an
interesting problem. I suspect it involves the automatic cam chain
tensioner on that cylinder.

What do you mean "One of the cams came off"? The camshaft shouldn't
just
"come off" without unbolting the cam sprocket! Or are Yamaha V-twins
built so you can
remove the cams without disturbing the cam sprockets?

Anybody know for sure?

I looked at the CAMSHAFT CHAIN parts fiche for a 1999 XV250 Virago on
www.partsfish.com. You can use this site for free by registering.

# 7 is the bolt that apparently holds the # 6 timing sprocket onto the
end of the # 1 camshaft. Or does it just bolt the sprocket to the # 3
solid bush?

Did you actually have the # 1 camshaft out of the engine?

Did you remove the # 7 bolt? Before you ever do that, I would think
that you'd have to remove the # 14 automatic cam chain tensioner so it
doesn't take up all the slack in the chain. If you actually did remove
a camshaft and did not remove the spring-loaded tensioner in most
engines, you would play hell getting the sprocket back onto the cam
because you wouldn't have enough slack to work with!

(I had to spend an extra day working on a Nissan engine because the
Haynes manual wasn't clear about the NO slack problem that the
automatic cam chain tensioner would cause when it pushed the plunger
out.)

# 3 is a "solid bush" that the # 5 bolt and the # 4 plate somehow
attach to the camshaft to set the cam timing. From looking at the parts
fiche and my knowledge of how other motorcycles are built, the # 5 bolt
and # 4 plate would seem to have to come out of the engine before the
camshaft could be removed.

Looking at the VALVE parts fiche on www.partsfish.com, I see that # 9
is a screw, valve adjuster. I'm sure that's what you are calling a
"tappet".

# 11 is a rocker shaft, and # 8 is the rocker arm that pivots on the
shaft. Did you remove either of those?

That shouldn't change the cam timing, but disconnecting the cam
sprocket and removing a camshaft without removing the automatic cam
chain tensioner sure would change the timing. The automatic tensioner
will extend itself fully and you have to remove it and compress it
before reinstalling it. It has a little ratchet inside that keeps it
from backing out. You install the tensioner with the cap off the back
end of it after you set the cam timing and then push the plunger until
it stops moving and install the cap and you're done with that part.
Check the service manual for exact instructions.

I suspect that the automatic chain tensioner has probably extended and
that's what moved the cam timing.

Yes. You could have bent a valve. Been there, done that, on a Jaguar
engine. It sucked.

You can bend the rear cam chain guide turning the crankshaft backwards.

 

It is a 2005 Virago.

I didn't touch anything in the Camshaft Chain area, it fell right
through that down to the Crankcase. In the crankcase there were gears,
I thought these were cams. One of the gears came off and I replaced it
but it may not have been the same way as when it fell out.

The "tappets" are the screw adjuster. I didn't remove the rocker arms.
The only thing that was removed was the screw adjuster, by accident,
and a sprocket in the crankcase, again by accident.

How do I check to see if the rear cam chain guide was bent?

 

If I had to guess, I would say you bent the valves when you forced it past
the resistance. I could be wrong. If it is bent, it isn't the end of the
world and it is an excellent opportunity to learn about motorcycle engines.

It could be that it is just out of time but somehow I doubt it.

pierce

 

Why couldn't you just bring it to the dealer?? It seems to me that it
would still be under warrantee, and even if it weren't, a tappet adjustment
wouldn't have taken very long to do, so it wouldn't be a costly job ( i am
assuming anyway)

Fwed

 

OK, what I am guessing is that you were working on the forward cylinder
and you dropped the screw adjuster down the cam chain tunnel on the
left side of the engine
(as viewed when you're sitting on the motorbike).

So you removed the left hand cover and the starter idler gear fell out
when the cover came off.

Look at the STARTER CLUTCH parts fiche. It's item # 1. It doesn't
matter how you install that gear. It's the only gear I can think of
that you could easily have just "fall off"
when you're working on the engine. The idler gear turns on about a 10mm
shaft that just slides into the crankcase and is retained by the
starter clutch cover.

The other gear that might fall off is the oil pump drive gear, but I
think it's hidden behind the clutch, which is on the right hand side of
the engine.It has a little 1/8th inch dowel pin driving the gear.

Now the starter clutch is an interesting piece of engineering. Unlike
the Bendix on a car starter that engages with the flywheel of a car
when you try to start it, the starter clutch on a motorcycle
*automatically* engages every time the engine stops, and it disengages
when the engine turns above a certain RPM.

And, it's a one way clutch that *does not like to turn backwards*!!!!

So that might explain why the engine way hard to turn. The starter
clutch might have been binding from you trying to turn the crankshaft
the wrong way.

As to why the engine stalled after you released the starter button,
maybe you finally adjusted one of the valves wrong with the piston in
the wrong position. When you adjust valves, the piston is supposed to
be at top dead center and the sliding part of the rocker arms have to
on the heels of the cams, not on the acceleration ramps or the high
points of the lobes.

So, maybe you have one cylinder's valves adjusted correctly and one
cylinder's valves adjusted so you don't get any compression on that
cylinder, so the engine doesn't have enough power to idle on just one
cylinder. Recheck your valve clearances.

If you didn't mess with the cams, the cam chain guide probably isn't
bent. But if you did have to check it, you would have to remove the cam
chain tensioner and pull the tensioner out through the top of the
cylinder, after removing the cylinder head.

 

OK, as others have said, there is no way you've changed the cam timing
unless you actually removed the camchain, cam sprockets or crankshaft.

I doubt very much that you've damaged the satarter motor by turning the
engine the wrong way since (contrary to what Pale Fire says) very few
motorcycles actually have Bendix electric starters - they're rare on
bikes. My XS650 has one, andthe bigger XV vees have them but anyway,
just a little turning the wrong way won't be likely to do much damage.

Also, I doubt that you've altered the cam timing by having the tensioner
over-extend.

My guess is that the secret to the problem lies in this:

"I pushed it through the resistance area to the TDC and the intake
rocker arm had no free play so I could not adjust the valve clearance,
the exhaust was fine."

I think you may have adjusted the valve clearnace wrongly, and you've
got a tappet that's *woy* over-tight and is holding a valve open when it
shouldn't. As Pale Fire suggests.

Re-check the valve clearances. Do it with someone who has more of a clue
than you. Aso pay attention to the valve timing marks, just in case.

 

If you don't consistently turn the engine in the same (correct) direction,
you end up with improper valve clearances. (Changing direction when trying
to line up the timing mark for TDC leaves the camshaft in the wrong place
for valve adjustment.) Try re-setting the valve clearances again, turning
the engine only in one direction (the direction specified in the manual). If
you miss the mark, keep going around (twice) until it comes up again --
*don't* back up...

 

The problem isn't with turning the starter backwards. Starters don't
mind going backwards. It's the cylindrical rollersin the starter clutch
temporarily jamming between the ramps and the sleeve they ride on and
the *gear reduction* of the starter motor. It's about 10 to 1 ratio, so
you have to turn the starter several times to turn the crankshaft once
and you definitely do feel that resistance when you're trying to turn
the engine over with a wrench.

 

Yup, indeed.

 

Since we are now on the "finer" line of things in the ways of valve
adjustment.

For the optimal setting, always use the lowest part of the cam(Often
referred to as the heel), you will have to turn the engine the correct
way until you you get the most play, this is where you should set the
recommended gap, and not where the tdc mark is.

Of cause few or no manuals will ever tell you this..
To your surprise you might gain actual notable performance gains from this.

It relates to the overall geometry, you gain a little lift at the valve,
but also a tad more duration.

Some will argue the gains, but they are there, basic four stroke
operation..


P.J.

 

OK I went back to work on the bike today and found that the cam was not
timed properly. I took off the cam chain and aligned everything. Then I
readjusted the valves, with the timing set there was no resistance when
I turned the crankshaft by hand. I triple checked everything and
started it up no problem.

Thanks for the help.

 

Well done. I'm surprised you managed to upset the timing in the first
place, to be honest.

 

"Well done. I'm surprised you managed to upset the timing in the first
place, to be honest."

My dad had tried to help me get the screw adjuster out and unbeknownst
to me he took off the cam chain adjuster and turned the crankshaft, I'm
assuming the slack without the chain adjuster on may have allowed the
crankshaft to turn without the camshaft turning therefore untiming it.

 

I suppose if you removed the cam chain adjuster and didn't do anything
to stop the cam chain from sagging down toward the bottom of the
crankcase, the chain would fall off the lower sprocket as you described
because of the angle of the cylinders on a V-twin engine.

There are about 36 teeth on the cam sprocket and about 18 teeth on the
corresponding
crankshaft sprocket. So moving the cam chain one tooth on the lower
sprocket will change the timing by 360/18 = 20 degrees.

That's a lot of error in cam timing. You're very lucky you didn't bend
a valve.

 

Jesus Christ. As Pale Fire says, you're lucky not to have caused ayny
permanent damage.

When ignoramuses collide.... ;-))

 

Block of styrofoam or whatever between the lever and the bar.
Couple of wood shim wedges between the pads when the wheel's
out for a tire change. Not that it's OK to touch the bike, just that
it's better to be ready for them.

 

I *always* shove a spanner or something in there. SOP.