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-   -   HELP! Messed up my valve clearances! (https://www.horizonsunlimited.com/hubb/yamaha-tech/help-messed-up-my-valve-49102)

elv73 19 Mar 2010 20:41

HELP! Messed up my valve clearances!
 
Thought id do my valve clearances today and was feeling all pleased with myself when id finished.....until I fired it up!
It now sounds like someone has thrown a bag of bolts into the top of the engine:helpsmilie:

Im pretty sure i set them correctly but my bike is a 4PT with a 3TB engine and Im now thinking that the clearances may be different as im using a 4PT manual?? Can any one tell me the correct clearances for a 3TB.

I set it to TDC by removing the spark plug and putting a drinking straw down the hole so its rested on top of the piston. I then turned the engine over (manually of course) until the straw started to rise which I assumed meant that it was on the compression stroke and then lined up the TDC mark as it came around.

Can someone please clarify if this is the correct way to set TDC before adjusting the valves because if it is then I can only assume that ive set the gaps incorrectly!!

Would the fact that it now sounds like a bag of spanners indicate that the valve clearances are too small or too big?? im thinking the former:frown:

Any help would be appreciated as I really dont want to knacker my engine, really wish id just left it alone now!!!

bikerz 19 Mar 2010 21:02

so were the gaps quite tight when you set them?

i'm thinking you set them on the rocking stroke and now they are way too big!

you need to make sure it is the firing stroke and not rocking.if its noisy they are loose, not tight i would say.

elv73 19 Mar 2010 21:10

that sounds like you may well be right as before I set them I couldnt get the feeler gauge in there at all so assumed they were too tight.
I then set them to the gaps as stated in the manual but it definatly sounds like ive set them on the wrong stroke and theyre now too big :(

How to I make sure im on the right stroke before re setting them:confused1:

Jens Eskildsen 19 Mar 2010 22:32

Take all valvecovers of an turn the engine. The pistoen doesn't nescesarily need top be at TDC, just spin it so you can see the intake valves arent in "operation" then adjust them, and do the same for the exhaust.

Otherwise you need to do as per the manual. and look for timing mark on the flywheel

Pigford 19 Mar 2010 22:36

You Just Need To Make Sure The Cam Lobe Is Pointing Away From The Valve You Are Checking.
When They Are Right, The Max Clearance Will Be So You Can Only Just Wiggle The Rocker - Slight Movement Only !

kentbiker 19 Mar 2010 23:24

Tdc
 
To get TDC, take all the valve caps off and rotate the engine until you can see the inlet valves open and close again. Then look at your straw and you should see it rise. When it is at the top, adjust the clearances. If you use the 1st gear/rotate rear wheel method, you will be able to rock the wheel back and forth to get the precise point of TDC. The problem is that the piston movement doesn't equate to very much wheel movement, so you will need to practice a bit. Just keep trying until it feels right. All valve clearances ought to be slack at this point but if you've ballsed up the adjustment previously that may not be the case.
I will be very, very surprised if the figures for the two engines are any different. In fact, it's probable that all Jap big singles are the same!
Anyway, take your time and enjoy the learning process and the feel good factor you will get when you've succeeded.
I'll be doing mine tomorrow as well, so I'll post again if I come across anything tricky.

Geoff

wolfzero 20 Mar 2010 02:25

tdc screw is on the magneto cover take the screw out an you will see the tdc mark set the valves off that and it should be fine.
at least your cock up is the right side, tight valves cause damage loose does f*ck all :cool4:

kentbiker 20 Mar 2010 19:02

Quote:

Originally Posted by wolfzero (Post 281560)
tdc screw is on the magneto cover take the screw out an you will see the tdc mark set the valves off that and it should be fine.
at least your cock up is the right side, tight valves cause damage loose does f*ck all :cool4:

Yes of course, I'd forgotten about the access screws. Good point Wolfzero. Don't forget the engine turns anti clockwise. When I did mine this morning I also removed the coil, horn and throttle cables for easier access.

Geoff

elv73 20 Mar 2010 20:11

Thanks for all the help guys, clearances now readjusted properly and no more clattering!:thumbup1:
On another note I hadnt realised I was supposed to turn the engine anticlockwise until I read it this morning so when I did them the first time I was turning it clockwise:(
Will this have caused any damage? Bike seems to be running fine now.

Pigford 20 Mar 2010 20:21

Direction won't harm the bike, its just to ensure you've taken up the cam chain slack if doing anything real complicated, like cam or ignition timing .


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