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HOW TO - Valve Adjustment

 
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HOW TO - Valve Adjustment
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cowboyrob



Joined: 26 Mar 2007
Posts: 831
Location: Fayetteville, AR

Post HOW TO - Valve Adjustment Reply with quote
I am at 300 miles on the odometer and will have to do the maintenance/adjustments myself. I am fairly handy with a wrench and have some mechanical experience. I have not adjusted the valves on anything in my life. I saw a walk through on how to do it on the yahoo forums from AL and thought I would follow that. I am asking anyone with experience doing this to their own scooter to give me any tips if they have them. Also if there are any recomendations in addition to the things in the manual to do at this 300 mile point.
Thank you all,
Robby

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Mon Apr 09, 2007 9:19 pm View user's profile Send private message
monza



Joined: 26 Mar 2007
Posts: 343
Location: Kansas City

Post Reply with quote
Just for reference on this subject, here is the post from Al:

Quote:

Message: 1614 From: Albert Kolvites Received: Tue Sep 17, 2002 10:44 AM
Subject: Re: Valve Adjustment on Bajaj

Make sure the TDC you are using for valve adjustment is on the
compression stroke, NOT the exhaust stroke.

remove the spark plug, put your finger over the hole, rotate the engine.
When you feel the pressure building, you know you are on the compression
stroke, not the exhaust stroke.

The pencil, or straw, or wooden stick is perfectly OK for finding TDC.
(no screwdrivers please) I admire Phil's stress on accuracy, but in
this case +/- 5 degrees is just fine.

If you adjust valve clearance with the piston TDC on the exhaust stroke
the clearances will not be correct because the rockers are partially
resting on the cams.

Valve adjustment is something that you should be very careful about. A
wrong move and you can easily damage the engine. I would recommend to
those that have never done it to learn the technique from experienced
mechanic

regards,

Al Kolvites


and also

Quote:

Message: 27878 From: Al Received: Sun Jan 22, 2006 5:20 PM
Subject: A suggestiion or two on valve adjustments

Remember the piston is at top-dead-center twice. Both at the end of
the compression stroke and at the end of the exhaust stroke. The
valves are adjusted at the end of the compression stroke when both
valves are closed, the cam is off the lifter, and of course the lash
is greatest. You must be careful to perform the adjustment at the
end of the compression stroke.

Identifying the compression stroke tdc is not awfully difficult.
However, be aware the the "pressure against the thumb" method must
be used with some caution as some pressure can also be felt at the
tdc that occurs at the end of the exhuast stroke. Confusion can be
avoided by checking the existing lash; lash will exist for both
valves ONLY at compression tdc and of course this is the tdc at
which the lash is adjusted.

A special tool is used by cycle mechanics to identify the precise
point at which the piston is at tdc. It is devise that consists of a
barrel through which a plunger passes. The barrel is threaded into
the sparkplug hole and the plunger makes contact with top of the
piston. Tdc is sensed by the plunger rising to its greatest exposed
length.A stiff wire can be used with some success if the special
tool is not available. The wire is passed into the sparkplug hole
and hand-held while the engine is slowly turned. Never drop anything
into the sparkplug hole and so be careful that the wire is long
enough so that it does not disappear into the engine!

The engine must be slowly turned to arrive at tdc. There are
several ways that this can be done: 1. Place the scoot in top gear
and with the rear wheel of the ground that wheel can now be turned
to position the piston. 2. An assistant can gently use the kick-
start lever to position the piston. 3. The most precise method is to
place a wrench on the nut that secures the blower or alternater to
the crankshaft. The last two of these methods are of course done
with machine in neutral.

I hope all of this is of some help!





I plan to do mine here in the next few days, so I will post some info when I get it done.

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-Paul O.

75 Vespa Primavera "Parmakit 130", P200E,
Mon Apr 09, 2007 9:42 pm View user's profile Send private message Visit poster's website
markd



Joined: 27 Mar 2007
Posts: 223
Location: Milwaukee, WI

Post Reply with quote
Did either of you tackle this yet? We need to mc's some time soon but would like to learn from other newbies first Cool

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-mark
Mon Apr 16, 2007 10:16 am View user's profile Send private message AIM Address Yahoo Messenger
cowboyrob



Joined: 26 Mar 2007
Posts: 831
Location: Fayetteville, AR

Post Reply with quote
I haven't done it yet, I am looking for someone with experience to help me through it. I met this guy who rides alot of the old, small cc, japanese 4 strokes and he is realy into wrenching so I hope to run into him in a couple of weeks and ask for his help. It would be nice to see a pictorial guide on the forum, If I had that I would probably go ahead by myself. If I am the first to get to it I will be sure to take pics and post it. Smile
Rob

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It was just an innocent gas pump fight...who would know it could be dangerous?

Last edited by cowboyrob on Mon Apr 16, 2007 8:26 pm; edited 1 time in total
Mon Apr 16, 2007 11:06 am View user's profile Send private message
mc



Joined: 27 Mar 2007
Posts: 152
Location: Milwaukee, WI

Post Reply with quote
monza wrote:
...post from Al:


This is from the great and mighty Al Kolvites as well.
Same info, lots of detail:

Quote:

Message #8994 From: Al Received: Sat Jul 19, 2003 10:53 am
Subject: Adjusting valve clearance

OK Mark et al, here is the proper and detailed procedure for adjusting
the valves on the Chetak or Legend. As I write this, I hear a voice
in my head telling me that "no good deed goes unpunished"

Valve clearance adjustments are made with the engine at room
temperature.

Remove the spark plug.

Remove the screws holding the plastic fan shroud and remove the fan
shroud. This exposes the flywheel and you will more easily be able to
remove and replace the valve adjust covers. The 2003 Legend and
Chetaks have a wrench in the tool kit for removing the valve adjust
covers, if you don't have the tool, a large adjustable will do, but
please! no pipe wrenches, pliers or other barbarian tools.

Put your finger over the spark plug hole and rotate the flywheel
clockwise. When you feel pressure building in the cylinder you will
know that the piston is coming up to it's compression stroke. This is
important because there are TWO Top Dead Centers. One is TDC on the
compression stroke and one is TDC on the exhaust stroke. If you pick
the wrong TDC, disaster will result. On the compression TDC both
valves are off of the cam. On the exhaust TDC, the exhaust valve is
being lifted by the cam.
Now you can use a soft probe to determine TDC (like a plastic straw)
or, since you have the shroud off, you can now see the lines on the
flywheel through a rectangular slot in the engine housing. There are
3 lines in the flywheel. The leftmost line is TDC the two to the
right indicate the two stages of spark advance used by the TRICS
system. This is more than you need to know. As long as you are
somewhere around TDC on the compression stroke, you will be able to
accurately adjust the valves. Even if the piston is half way up on
the compression stroke or halfway down on the power stroke, your
valves are still off of the cam and can be adjusted properly.

The first thing you want to do is check to see if your valves actually
need to have the clearance adjusted. The proper clearance between the
rocker arm and top of the valve stem is between .08 to .12mm. If you
have American size feeler gauges then it's .003 to .004". .003" is
about the thickness of 20 lb. bond copy paper. I tell you this, not
to suggest you use paper as a feeler gauge, but to give you an idea of
how fussy this clearance is. If you make the clearance too small, as
the engine heats up the valve will not seat fully causing leakage,
cause low compression and eventually burnt valves. If the clearance
is too much, the smooth engagement and release of the rocker to the
cam is defeated and the clatter you will hear is the rocker arms
trying to destroy themselves and the valve stems.

When checking valve clearance there are two measurements you must make
with the feeler gauges. The .003 must GO, the .004 must NOT GO. If
the .004 fits but is snug with a little drag that's OK, if the .003
fits but is snug, that's OK. The difference between a snug fit and
not going is around .0002" difference. (Take that .003" copy paper,
peel it apart into 3 separate .001" sheets. Now take one of those
sheets and peel it apart into 10 separate sheets, each sheet is now
.0001" thick, take just 2 of those sheets, that's the difference
between slip and snug.)

If the valves require adjustment, use a 9 mm box wrench (never an open
end wrench) and a small adjustable wrench (or better yet Valve
Adjusting Screw Holder P/N 37103153)
Loosen the 9mm nut just enough to be able to turn the adjuster screw
(while feeling a little drag on the adjuster). Hold the 9mm wrench
steady and turn the adjuster screw clockwise to reduce clearance and
counterclockwise to increase clearance. The adjust screw has a very
fine pitch, non the less, a 1/10 of a turn on the adjuster screw could
make the difference between GO and NO GO. Make very small
adjustments, re-tighten the 9mm nut and check the clearance. This
procedure requires a fine touch and patience, it may take several
tries before you get it right. When tighenting the 9mm nut, be sure
to prevent the adjuster screw from turning. Need I remind you that
this is a small nut and requires less torque than larger nuts?
Specifically, torque for this nut should be .9 to 1.0 kgm.

Make sure the "O" rings under the valve covers are in good condition
and seated properly. Since these covers are made of aluminum and have
fine threads, carefully thread it into the cylinder head by hand...
it's easy to cross the threads. Then tighten .5 to .9 kgm

Replace fan shroud. Tighten screws .6 to .8 kgm.

Put some anti-seize compound on the spark plug thread and install.
Tighten 2.5 to 3.0 kgm
--------------------------------------------------------------------

Any glaring errors? Comments? Suggestions? If I can get this
explanation sufficiently refined, we'll put it on the Bajaj Wiki

If you do not completely understand this explanation or don't have the
tools to do it properly, leave the job to a qualified mechanic. You
can do a lot of damage to the engine if you do not adjust the valves
corectly.

Regards,
Al Kolvites
www.BajajUSA.com


I've got about 2700 miles on my scooter, and have yet to get the valves adjusted. Hopefully Mark can do this for me next weekend. We'll compare notes. Cool

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Monica
Mon Apr 16, 2007 7:35 pm View user's profile Send private message
scootermike



Joined: 25 Mar 2007
Posts: 525
Location: portland,oregon

Post Reply with quote
do the job first thing in the morning the engine must be cold if not let the bike sit for 3 hours. also remove the plastic engine cover trying to get the valve covers off are 100% easier with the cover off I learned this from experience I could get it off but putting it back on I had to cut the plastic around it just to get it back on. I bought a cheap set of deep sockets from harbor freight to do the job it was like 12.00 makes the job way easier also one of the sockets fits the oil filter cover. might as well change the oil and clean the filter while you have it all off.
Tue Apr 17, 2007 2:36 am View user's profile Send private message Visit poster's website
danman1178
Site Admin


Joined: 25 Mar 2007
Posts: 336

Post Reply with quote
What does this do? Why does it need to be done? I am at 600 miles...should I have already done this...I have changed the oil already but need to change back to summer weight..


Hey Monza - when you do this....lets see some pics and we should start a new thred and make it a sticky..
Tue Apr 17, 2007 2:50 am View user's profile Send private message
scootermike



Joined: 25 Mar 2007
Posts: 525
Location: portland,oregon

Post Reply with quote
it should be done in the first service after that its every 3 thousand miles. in the 5 times mine have been done they have very rarely been off at all I think twice they were off a tiny bit, from my understanding of it there are 2 valves intake and exhaust the adjustments determine how far the valves open. if yours were off you would probably know it your engine would run like crap I learned that from doing it wrong the first time.
Mike
Tue Apr 17, 2007 3:09 am View user's profile Send private message Visit poster's website
monza



Joined: 26 Mar 2007
Posts: 343
Location: Kansas City

Post Reply with quote
It has to be done because these engines have the rockers follow the cam directly without a hydraulic lifter inbetween (like on most cars). When the engine is new, everything is nice and tight, but when it gets broken in, the cam wears a little, the rocker wears a little, etc...and you get some extra "valve lash". What ends up happening is if you dont adjust the rockers, the lash will continue to get bigger and bigger and it will get louder and louder (clicking sounds). Eventually the rockers and/or cam will be shot, and possibly the valve seats. The adjustment simply sets the lash back to tolerances.

You have to do it cold (not cold cold, but the engine has to not have been run for a few hours). This is because you are setting the clearance such that when the engine gets hot, the clearance is nearly zero (since the parts expand as they get hot, the clearance goes from what you set it at towards zero). If you were to do this procedure while the engine is hot, then what would happen is when it is cold it would click loudly and could damage something. The engineers came up with a 'sweet spot' when they determined the proper clearance, and that is what we want to shoot for.

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-Paul O.

75 Vespa Primavera "Parmakit 130", P200E,
Tue Apr 17, 2007 12:44 pm View user's profile Send private message Visit poster's website
danman1178
Site Admin


Joined: 25 Mar 2007
Posts: 336

Post Reply with quote
Ok, Great thanks - I cant wait for the detailed HOW TO!!!
Tue Apr 17, 2007 11:21 pm View user's profile Send private message
mc



Joined: 27 Mar 2007
Posts: 152
Location: Milwaukee, WI

Post Reply with quote
danman1178 wrote:
Ok, Great thanks - I cant wait for the detailed HOW TO!!!


I'll try to take pictures as Mark does the work. We were doing this when he cleaned the carburetor, but our retired neighbor came over to chat ("I heard your air compressor!") and I got sidetracked. Wink

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Monica
Tue Apr 17, 2007 11:35 pm View user's profile Send private message
danman1178
Site Admin


Joined: 25 Mar 2007
Posts: 336

Post Reply with quote
OOOH - picture of the carbarator cleaning would great too!!!

Please anyone who does any mods or maint...please take good pics....this will help to make this site a great help to visitors....


I will make a section for HOW TO'S in the future...so any effort would be SUPER!
Wed Apr 18, 2007 2:55 am View user's profile Send private message
munkeyjump



Joined: 26 Mar 2007
Posts: 79
Location: Seattle, WA

Post reasons for valve adjustment Reply with quote
FYI the biggest reason for valve adjustment is because the valves actually stretch in a new engine, not shrink. As they are heated they can get longer making the lash less and less. If this happens you can get a situation where the valves never really close and you have constant blow by. This will over heat the head and the valve and will eventually cause you to "drop" a valve into the cylinder, then you're really in trouble. You are much better off having a little too much valve lash than not enough. Having way too much will make the engine clatter allot and eventually can cause the valve stem to mushroom, you always need some lash on a cold engine though, because as the engine warms up the valve stems extend and lash decreases. If you want a good tutorial on adjusting valves look up air-cooled VW valve adjust, there are lots of great tutorials available and the process is identical, except you only have one cylinder to adjust of course.
David
Wed Apr 18, 2007 8:40 pm View user's profile Send private message
monza



Joined: 26 Mar 2007
Posts: 343
Location: Kansas City

Post Reply with quote
Ok, so I checked my valve lash this morning. I did it according to the Al K. provided procedure listed above. Here are some pics.

Note- I didnt have to adjust my valves. I have 500 miles on it so far and they were within the .003 to .004 spec. When I actually have to adjust them, I will post some pics. Also note, that if you do this, make sure your feeler guages have the .003 and .004 sizes. I have two sets of feelers, one had them that small, the other didnt.

1) remove valve cap. There are two of these, one top (intake valve) and one bottom (exh valve)


2)The two feelers you will need. .003" and .004".


2.5) (not pictured). Follow the procedure above for getting TDC on the compression stroke. I did it by putting my finger in the hole and feeling for the pressure. Then I watched looked at the cam (which I couldnt get a good picture of) to make sure it was inbetween the intake and exhaust stroke. I used a pencil to stick in the spark plug hole to feel for the pistons position. I made small adjustments to the crank position using the flywheel until I could tell the piston was @ TDC. According to Al K. it is not critical that you be dead on TDC.

3)Fit the feeler inbetween the adjuster on the rocker and the valve stem. The .003 should slip in, and the .004 should either not fit, or fit snugly.


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-Paul O.

75 Vespa Primavera "Parmakit 130", P200E,
Sat Apr 21, 2007 8:13 pm View user's profile Send private message Visit poster's website
cowboyrob



Joined: 26 Mar 2007
Posts: 831
Location: Fayetteville, AR

Post Thanks Monza! Reply with quote
Pictures make things so much easier to understand, thanks for taking the time to document what you did.
Rob

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It was just an innocent gas pump fight...who would know it could be dangerous?
Sat Apr 21, 2007 9:20 pm View user's profile Send private message
monza



Joined: 26 Mar 2007
Posts: 343
Location: Kansas City

Post Reply with quote
no problem. It only takes a few extra minutes to do stuff like this...and also could we have ever done anything like this on Yahoo? Heck no. This thread consists of what would have been 16 messages on Yahoo all mixed in with messages of other stuff....

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-Paul O.

75 Vespa Primavera "Parmakit 130", P200E,
Sat Apr 21, 2007 10:51 pm View user's profile Send private message Visit poster's website
dirkhunt
Guest





Post Reply with quote
I just did mine,

When you do the exhaust valve put a rag or paper towels over the exhaust pipes, a small amount of oil will come out of the hole as well as the plug will have about a tablespoon of oil in it.

I found using a big socket (27mm?) to remove the valve covers is really easy and you don't have to cut down the plastic to remove it (as in the pics above).

If you do need to adjust, holding the square end of the screw with needle nose pliers while tightening the nut made it easier as well (didn't have to go back and redo it several times, just once).

Have fun
Tue Oct 07, 2008 6:48 pm
cane_prevost



Joined: 23 Mar 2010
Posts: 215
Location: Portland Oregon

Post Reply with quote
Hey Monza, your pictures aren't showing up. Any chance you could repost them? Thanks much!
Tue Mar 30, 2010 4:17 pm View user's profile Send private message
rufusswan



Joined: 29 Sep 2007
Posts: 1786
Location: Taneyville, Missouri

Post Reply with quote
Monza hasn't been here in quite a while AND it appears that the Totos have moved their site to a different server. Apparently the photos/links are no longer valid. He may respond though.

If you want to learn how to do this, then the above directions are correct. Before you ever change the current gap settings though, you should be comfortable with the process .. setup, finding TDC, and verifying the current gap setting. Learn how to check settings before you attempt to change them.

Do remove the outer shroud, then you can see the timing marks on the flywheel.

Check both valves and you will begin to get a "feel" for how tight or loose the gauge feels inside the gap. DO NOT wipe the oil off the feeler gauge nor in between the tappet and the valve. Oil belongs in there and does take up some gap space in normal operation.

Learn how to check valve clearance before you attempt to change it.

Unless the valve gap is way too tight, at TDC the valve should be loose and you should be able to move it up and down and feel it click. This is normal.

When you tighten the nut on the adjuster it can (and will sometimes will) turn the adjuster, making the gap too small. This is where beginners get frustrated. Just do it again, until you get it right.

When you think you are finished, you are not. Rotate the motor thru a couple of cycles and recheck you work. Then button things up and ride.

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Tue Mar 30, 2010 5:32 pm View user's profile Send private message Send e-mail MSN Messenger
cane_prevost



Joined: 23 Mar 2010
Posts: 215
Location: Portland Oregon

Post Reply with quote
Thanks much! I'll open it up and get comfortable just checking the gap and finding TDC a few times before I attempt to adjust...
Tue Mar 30, 2010 5:58 pm View user's profile Send private message
cane_prevost



Joined: 23 Mar 2010
Posts: 215
Location: Portland Oregon

Post Reply with quote
Well, I went in to do a valve adjustment and snapped a few pictures. Thought I'd share in case someone else is trying this for the first time. let me know if you see any errors.

Step 1- Remove the engine cowl and set aside. You'll need a phillips screwdriver to remove the plastic engine shroud. Before you start go ahead and remove the spark plug cap.

Step 2- I believe there are 5 phillips screws holding the shroud on. They are all the same size. Remove them and it should slip right off.



Step 3- Remove the valve covers. One is on top and one is on the bottom.

Step 4- Remove the spark plug. This is a good time to replace with a new one.

Step 5- You should practice finding top dead center a few times before you check your clearance. Here are a couple of ways you can do this. The straw method- Find a straw. Don't have one? Go get a milkshake. You'll deserve one when you get this finished. Put a straw down in the spark plug hole and rotate the flywheel clockwise. You'll see the straw come out of the hole and sink back in. When it is pushed out to its farthest point out of the hole you are at top dead center. (somebody confirm this for me). Do this a few times. You can see I used a socket wrench to turn the flywheel. You can just turn it by hand or use the kick start.

Straw in the spark plug hole below

Next, take the straw out and put your finger over the hole and block it off. Rotate the flywheel clockwise and you'll feel either the engine sucking against your finger or pushing against it. When you feel the pushing against your finger you are in the compression stroke which is where you want to adjust the valves. Do this a number of times so you can see how it works.


Next, when you feel the pressure building against your finger take your finger off and insert the straw. Rotate until the straw is at it's highest point. This should be top dead center. Do this a few times until you are pretty sure you are finding top dead center. After 3 or 4 times you are ready to check the clearance.
Step 6- Get your feeler gauge and test the gap. The .003 should fit and the .004 should not fit. Check both top and bottom valves. Repeat finding top dead center and checking the valves until you get the same reading 4 or 5 times.

Step7- If they are out of adjustment use a 9mm wrench to loosen the lock nut. I used a small vice grip on the adjuster to move it. Set the gap and tighten down the lock nut.
Step8- Check the clearances. If they look good rotate the engine and find top dead center again and check. Try this a few times to be sure. If all looks good button it all up and give it a test. If it sounds funny or runs crappy you got the gap wrong. Drink the milkshake and wait until the next day for the valves to cool and try again.[img][/img]
Wed Aug 15, 2012 9:28 pm View user's profile Send private message
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