Valve clearance checks

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H2rider
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Valve clearance checks

Post by H2rider »

I'm doing a valve clearance on my h model . I just tried it and wrote down the gap sizes , I don't think iv done it correctly . I followed the manual but how can I tell when it's the #1 on tdc and when it's the #4 on tdc. One of my gaps I got was less than 0.05 which is completely off . Also do you have to change the shims if the gap is off? Is there any way of adjusting the lobs instead ? And what is the best gap size to have for a bike running stock . Inlets are 0.12 - 0.17 would it be best at 0.15 ?
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Miles
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Re: Valve clearance checks

Post by Miles »

#1 tdc will be when the lobes are pointing away from each other
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banner001
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Re: Valve clearance checks

Post by banner001 »

#1 and #4 will always be atdc simultaneously...whats needed is to make sure that #1 is atdc at the end of the compression stroke (i.e. the lobes are pointing away from each other), you then spin the engine 360 degrees so that now #4 is atdc at the end of the compression stroke.
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banner001
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Re: Valve clearance checks

Post by banner001 »

as for the gaps, the only way to change them is to change shims.

if your gap is too small then you need to fit smaller shims, and vice versa.

as for the gaps, its more important to make them consistent, a bike thats got all the inlets bang on 0.13mm will run better than one where half are 0.12 and the other half are 0.17.

remember that tighter is not always better, if you intend to rag your bike and always have it running hot then a bigger gap will be better for you.
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
H2rider
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Re: Valve clearance checks

Post by H2rider »

Thanks for that Im not planning on racing the bike, I'm getting it ready for road use . I'm in London so mostly slow moving , but of course I'd want to blow down the m roads . What size would you think is the best , at the moment I don't think any clearances are consistent.
There's two T marks on the cam , both opposite each other , is one for #1 and the other for #2 at tdc end of compression stroke ?
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Re: Valve clearance checks

Post by banner001 »

I can tell you, but I suggest you give the manual a damn good read before starting this, messing it up is a good way to detonate your engine.
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Valve clearance checks

Post by banner001 »

I only mention this as the T marks are on the timing plate that's attached to the crank, not the cams, I want to be sure that you know what you are doing and that you know all of the terminology.
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
H2rider
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Re: Valve clearance checks

Post by H2rider »

Hi sorry my mistake , is the manual wich is available on this forum , the full manual ? Iv read through that and understand which valves to check when each cylinder is at tdc . I was wondering if there was another manual which goes into more detail on how to do valve clearances . The one online is not very detailed ( for the h model )
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Re: Valve clearance checks

Post by banner001 »

UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Valve clearance checks

Post by H2rider »

Banner001 very very helpful . Especially the cam chain guide . I'll be checking if my sprockets are aligned using a mirror . One more thing viewtopic.php?f=117&t=13871 in this topic there's 2 pictures showing the cam chain tensioner . Mine is fully extended as shown in the first of the 2 pictures , is this an issue
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Re: Valve clearance checks

Post by banner001 »

if its extended to the point that its touching, or almost touching the metal engine casing then your cam chain is most likely knackered and needs replacing as this will affect the cam timing to a small degree

it could also be severely damaged/work chain guides as well, you will need to investigate more
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Valve clearance checks

Post by H2rider »

Banner001 , opened up the crank casing and did a quick check . There a plastic peice above the cam chain guide which was very loose . I removed the tensioner and done a check up and it seems ok . It's very tight and hard to press down ( even when pressing the taper part ). I put it back in according to the manual . The small plastic peice was much tighter when I put the tensioner back in but still moves a bit . ALeo is the cam chain supposed to be very tight on is there ment to be a very small amount of slack ?
I removed the top to check if the exhaust / inlet sprockets where aligned , they seem to be . I took a picture of the lobes of the first cylinder and that's how they look at tdc
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Re: Valve clearance checks

Post by banner001 »

How exactly did you replace the tensioner, you didn't just take it off and then put it back on did you?

Did you fully reset it or did you put it back in fully extended?
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Valve clearance checks

Post by H2rider »

I removed the bolt . Pushed the push rod down and put a pin in the spring to hold it down . I moved the rod holding the cam chain guide so the chair went loose . Then I put the tensioner back in and removed the pin . The manual states to remove the rod holding the cam guide but I only moved it down .
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Re: Valve clearance checks

Post by banner001 »

That's correct, I thought for a moment you had put the tensioner back in whilst fully extended.

Can you take a picture of the inside of your pulsar cover so I can see if you need a new cam chain, you need to take a picture of the rod that is pushed up by the tensioner
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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