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View Full Version : Valve clearances. What is it?



mattian
12th December 2010, 16:37
Ok so, I'm a dummy when it comes to mechanics.

Bikes coming up to 30,000 ks and needs a full service. I've been told I should get my valve clearances done.... and I just nod my head and agree like I know what it means. :blink:

I am sure its essential, but somebody please tell me what it is and why?

hehehe.... thanks.

Ocean1
12th December 2010, 16:45
You've seen valves? those mushroom shaped things that open and close ports in your head?

Well they're opened by your cam, a shaft with a lump on it. That's driven, (usually) by a chain from your crankshaft. When the lump turns it pushes on the flat surface of a follower which, (in your case) is a cylinder sliding up and down in a hole. The follower sits against the valve stem and when the lump pushes on the follower it in turn pushes the valve open. It's closed by a spring.

There's a slight gap between the follower and the valve. The gap is reasonably critical, too much and it'll rattle like fuck and cause damage, too little and it'll close up when it gets warm and hold the valve open a tad, causing it to burn out.

So yes, you do need to get it done. And yes, on your bike it's a bit of a mission. Suck it up and pay the man.

mattian
12th December 2010, 16:47
You've seen valves? those mushroom shaped things that open and close ports in your head?

Well they're opened by your cam, a shaft with a lump on it. That's driven, (usually) by a chain from your crankshaft. When the lump turns it pushes on the flat surface of a follower which, (in your case) is a cylinder sliding up and down in a hole. The follower sits against the valve stem and when the lump pushes on the follower it in turn pushes the valve open. It's closed by a spring.

There's a slight gap between the follower and the valve. The gap is reasonably critical, too much and it'll rattle like fuck and cause damage, too little and it'll close up when it gets warm and hold the valve open a tad, causing it to burn out.

So yes, you do need to get it done. And yes, on your bike it's a bit of a mission. Suck it up and pay the man.

Sweet! I usually have trouble following alot of information at once.... but, you've explained it very well! Thanks for that. Time to check the bank funds.

Ocean1
12th December 2010, 16:56
Time to check the bank funds.

Not defense budget stuff, good man orta be able to do it in a couple hrs. Not sure what's due at those miles on an SV but if anyone offers to lighten your wallet by more than a couple of hundred just for the valves, filters and oil you might ask them to break it down...

BASS-TREBLE
12th December 2010, 17:02
If you know someone that knows what they're doing then they can show you which means that next time you don't have to get someone to do it for you. It's never to late to learn.

Here is what Ocean1 described in a pic
http://www.international-auto.com/images/originals/AR_4cyl_valve_train.gif

racefactory
14th December 2010, 09:15
Probably just open it up and check it yourself mate, you don't have to adjust anything but it'll probably all be within spec and won't need adjustment.

imdying
14th December 2010, 14:35
Just let your dealer follow the maintenance schedule like the manufacturer intended, and it'll get seen to at the appropriate intervals.

The alternative is to dismantle a quantity of the bike yourself and check them. It's not an impossible mission, but you'll need sufficient confidence in your abilities to put it back together.

Get yourself a workshop manual for it, it'll describe the process and you can make a judgement call on what to do. Personally, I wouldn't pick it for my first maintenance task!

White trash
14th December 2010, 14:42
Personally, I wouldn't pick it for my first maintenance task!

+1 Especially considering your bike more than likely has a bucket and shim type arangement as opposed to a nice, easy to adjust, rocker arm.

If you get really worried, just chuck a new PowerPand in there and the valves will most likely self adjust to meet the new requirements.

You're welcome.

Ronin
14th December 2010, 15:19
+1 Especially considering your bike more than likely has a bucket and shim type arangement as opposed to a nice, easy to adjust, rocker arm.

If you get really worried, just chuck a new PowerPand in there and the valves will most likely self adjust to meet the new requirements.

You're welcome.

Could he try 2 stroke valves?

White trash
14th December 2010, 15:24
Could he try 2 stroke valves?

Rotary valves from an RG500 would be the go, don't need to adjust the clearances on them......

Ronin
14th December 2010, 15:30
Rotary valves from an RG500 would be the go, don't need to adjust the clearances on them......

Do they work with the red power bands?

White trash
14th December 2010, 15:32
Do they work with the red power bands?

Are you mental?! Only guy I know that tried rotary valves with red powerbands went hooning past Dukie like he was standing still, that's how much power the thing had. Be careful what you wish for.......

Ronin
14th December 2010, 15:35
Are you mental?! Only guy I know that tried rotary valves with red powerbands went hooning past Dukie like he was standing still, that's how much power the thing had. Be careful what you wish for.......

Blue it is then... Can't beat a good Dukie.