Age old debate on valves........1/6th......1/5th??

upshegoes · Dec 1, 2010

Hello, back after a really long time and re building 02 650.

I have been looking through the doc and at one point it says 1/8 th turn on the clearance?
I also seem to
remember an old thread saying 1/6th on inlet and 1/5th on exhaust........
The problem i'm finding on the adjustment is the exhaust valves i can lightly turn to stop then set them. Then its like they are real loose compared to the inlets and of i mess with the decomp arm on the head they them need re adjusting. I'm out of time now but i have flicked through a thread about 2002 650's and the timing mark is an imaginary line in front of the two actual lines.............tut tut mr husaberg you are absolutely doing my napper in!!!!
Thanks in advance of any comments!!

Bayside Burg · Dec 2, 2010

0.10th of a mm. Messured by feeler gauges. Why trust anything else?

ned37 · Dec 2, 2010

Why trust anything else

because the rocker pads tend to wear concave over time and give you a false reading. i've always used 1/6 turn and if i measure afterwards, i get 0.1 mm.

plumbbob · Dec 2, 2010

Now then Upshegoes,

first off get your manual de-comp adjusted right so that when you get to TDC its not interfering with the Exh. follower. It should have free play in it at TDC.
TDC should be just in front of the two marks on the flywheel at about the same distance, hope that makes sense!

On my old 02 650 i aim for 1/5th on both and check em regularly, so bloody hard to get spot on but that works for me.

Hope that helps,

Carl

upshegoes · Dec 3, 2010

Hey Plumbbob, long time no speak!!
Hows things pal......good i hope?
Any way me old mucka, its been ages since i stripped the bike and undid all the cables and spring etc to the decomp, i have since then just started to rebuild it all and i'm not sure if i adjusted the cables to get them off?????
Do the cables need adjusting so that the arm is not touching either side of the flat side onto the rocker arm. Then once it is parallel to the rocker surface do you adjust the clearance? Hope this makes sense...............
The setting of the timing mark is an imaginary line approx 5mm in front of the two other lines i have read on here. Is that just on 2002 650's or all 650's or just OEM stators or am i just worrying about nothing????
This bike was re built by DCR in the past so surely they would have set the timing properly as the bike ran good before the valve spring broke on me :angry:
Luckily it just failed and no more :mrgreen:
Exciting news though is that i have a 39mm fcr with a taff sm kit for it :bounce3: :cheers:

Bayside Burg · Dec 3, 2010

I may be missing something here so correct me if I am wrong please, but the thread pitch being what it is gives you a certain adjustment depending on how far you turn it. So if when you did your valves and simply adjust the nut (especially to a dedicated 1/5 or 1/6 of a turn) would you not just be continually over tightening your valves :?

upshegoes · Dec 3, 2010

Hey Bayside,
No you are not turning the nut, you simply use the nut to lock the thread after adjusting the tappet screw. After you wind the screw to a gentle stop you then wind it back off by the affore mentioned 1/6th of a turn (which equates to .10 feeler gauge), which is the required gap for the tappet face. Then hold the screw head in place and re lock the nut up. The debate seems to be in the distance to wind back....I.e 1/6th or 1/5th. Feeler guages are meant to be difficult to get in and can give an incorrect reading of the gap........
Its all a little fiddly for my chunky fingers either way :roll:

BoneGraft · Dec 5, 2010

Bayside Burg said:
I may be missing something here so correct me if I am wrong please, but the thread pitch being what it is gives you a certain adjustment depending on how far you turn it. So if when you did your valves and simply adjust the nut (especially to a dedicated 1/5 or 1/6 of a turn) would you not just be continually over tightening your valves :?

John, next time your valves are due for a check come over and I'll show you how to do it this way. I no longer trust the feeler gauge method now my engine has some hours up. Trust me, once you see it done (and hear it run) it beats the hell out of the feeler gauge method.

Bayside Burg · Dec 5, 2010

Matt that would be tops, give me a bell when you do yours next.

John

Taffy · Dec 6, 2010

I tend to go for 1/6th of a turn on the inlets and on the exhausts I'll still do a 1/6th but if i can pick an imaginary line just past that I do on the exhausts. because I'm having two or three pinches at it I can pick a place I choose.

one thing I have learnt is that if you go much more than 1/6th on the exhausts - you wreck the auto decomp device. I once lost all the ADC simply by trying a larger gap and the bike became like a gold star to kick over.

so there are good reasons for sticking to 1/6th.

regards

Taffy

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Age old debate on valves........1/6th......1/5th??

upshegoes

Bayside Burg

ned37

plumbbob

upshegoes

Bayside Burg

upshegoes

BoneGraft

Bayside Burg

Taffy

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