Valve Clearances

[darkember]

OK having fitted the front head back on last weekend I was unable to get the timing marks to line up perfectly. If the mark in the timing window is spot on then the cam sprocket marks are a shade off more prevalent on the inlet cam than the exhaust cam than the. The cycle has been tested & it rotates smoothly both cylinders sucking & blowing as they should. I have been informed that this is quite normal & the only way to get it spot on would be to dial the cams in.

With that said when I come to checking the lobe clearances to get a true reading do I need to set the cam sprocket marks bang on regardless to what the timing window is reporting which will be a couple of degrees further on??

Many thanks Wil

[VTRDark]

& the only way to get it spot on would be to dial the cams in.

And you can't do that because we don't have adjustable sprockets. in which case you could just slide the sprocket around slightly until things line up. Not quite degreeing cams as it's a bit more involved than that, but would be nice if we could get things spot on to Honda's marks.

Onto your question...how far off are you? I'm not sure if it would be better to have the crank/piston position spot on or the point of cams opening and closing valves. Either way you should still be within spec, Inlet 0.13 to 0.19mm (0.005 to 0.007 thou) Exhaust 0.28 to 0.34mm (0.011 to 0.013 thou)

If you adjust the crank, piston set to TDC so the the line on flywheel lines up with the line on the case (make sure your looking squarely on through the hole ) and the cams to wherever they end up. This would mean that the valves will either be slightly more open or closed at that point.

If you set the cams so they are lined up spot on and set the clearances this would mean that the piston will be either slightly more advanced or retarded at the point where the valves have maximum lift.

With regards to performance it's not going to make that much difference either way. Personally I would line the cams sprockets spot on to take the measurement as there is a good chance you will have less shims to change. Or as you say "more prevalent on the inlet cam" nudge the crank sightly so both cam sprockets align evenly with each other and take your measurement. This may require more messing with shims if you trying to get things spot on in the middle of spec ie Inlet 0.006 and Exhaust 0.012. So basically it comes down to whether your trying to get everything spot on which could be tricky or are happy to settle with being within spec.

Anther thing to consider is that valve clearances and accuracy comes down to feel hence the name feeler gauges, it comes down to experience and knowing what feels right. It's like the old argument with CCT's and doing them up my feel and backing off 1/4 turn. One person's feel is different to another. You don't wont the feeler gauge to slide in and out to easily and you don't want it so it's so tight that you bend the blade when pushing it in or have to give it to much of a tug to slide it back out, so don't force it. You want it in-between the two so you can just feel it nipping and with some slight resistance.

I think I have said this before, but the Honda timing marks are not all that accurate anyway and there is room for some error. It's not as if your valves are going to go crashing by being slightly out. Things become a bit more crucial with modified engines (aftermarket pistons, cams) in which case this is where degreeing becomes more crucial as there are less tolerances. Also the point at where the piston is when the plug fires at BTDC changes and you might have different valve clearances.

I think I covered most things there. Now lets see what others say.

(:-})

[8541Hawk]

My take on it is as long as you are on the base circle of the cam it really doesn't matter what the "exact" location the cam is set at.

So the couple of degrees difference between the crank makings and the cam marking will make no difference in the lash setting.

Also make sure you check the cam gear location with a straight edge set on the head. Otherwise it is very easy, on this bike, to be off a bit on your settings.

[darkember]

So from both the above replies it is better to have the crank & piston, in my case in a slightly advanced position on the downward stroke & the cam sprocket markings bang on on the head casing to take the measurements.

[lloydie]

So from both the above replies it is better to have the crank & piston, in my case in a slightly advanced position on the downward stroke & the cam sprocket markings bang on on the head casing to take the measurements.

Correct as long as the cams are at tdc you will be fine doing the clearances .

[darkember]

So from both the above replies it is better to have the crank & piston, in my case in a slightly advanced position on the downward stroke & the cam sprocket markings bang on on the head casing to take the measurements.

Correct as long as the cams are at tdc you will be fine doing the clearances .

Cool I like a straight answer like that

[lloydie]

So from both the above replies it is better to have the crank & piston, in my case in a slightly advanced position on the downward stroke & the cam sprocket markings bang on on the head casing to take the measurements.

Correct as long as the cams are at tdc you will be fine doing the clearances .

Cool I like a straight answer like that

I do try :-)

[VTRDark]

Yep line the cams up, that's what I would do. It also make it easier to take your measurement, remove cams add or remove shims and reposition cams to double check measurement and if necessary remove again etc etc.

Cool I like a straight answer like that

Right that's it I'm not going into so much detail anymore.

(:-})

[lloydie]

Yep line the cams up, that's what I would do. It also make it easier to take your measurement, remove cams add or remove shims and reposition cams to double check measurement and if necessary remove again etc etc.

Cool I like a straight answer like that

Right that's it I'm not going into so much detail anymore.

(:-})

yer but you like to woffle on and on and on

[VTRDark]

So do you if we joined all your short posts together. As the thread title is a good one, I like to try to think about others that may visit in the future and have questions. All we need now is some pictures to add to the thread.

(:-})

[lloydie]

So do you if we joined all your short posts together. As the thread title is a good one, I like to try to think about others that may visit in the future and have questions. All we need now is some pictures to add to the thread.

(:-})

if all my post were put together you might get a sentience or two
and it might be a little informative na itll be bollux lol
i do like the way you cover all angles in you thoughtout replys

[VTRDark]

My handwriting was terrible before I joined the forum, it's getting so much better with all the practice I'm getting. Seriously though, my English/Grammar is improving.

(:-})

[lloydie]

My handwriting was terrible before I joined the forum, it's getting so much better with all the practice I'm getting. Seriously though, my English/Grammar is improving.

(:-})

Mine ain't wonder why !!!

[darkember]

Today its called dyslexia. In my day you were just thought of as being dull & put to the back of the class

[8541Hawk]