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Timing / camshaft alignment on 2003 CB

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georgecb500
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Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Tue 03 Mar 2015, 12:39 am

I finally got round to checking the valve clearance on my 16k mi 2003 CB this weekend.  As it turns out they are all out of spec!  But all by similar amounts, so I'm taking that as even wear.  The odd thing was when positioning the camshafts prior measuring the clearances the /T mark on the alternator rotor didn't quite line up with the IN and EXH markings on the camshafts.  They were slightly out.





Turning the crank until the camshaft marks line up with the top of the cylinder head causes the /T mark to just about disappear out of the inspection window.




I checked the same with the /O marks, and they were out by the same amount.  So at least the /O and /T marks are in the right position relative to each other.

This was all done prior to removing the tensioner and camshafts.  As far as I know the timing has never been checked/altered since it came from the factory.  I bought it with decent history at 7k miles, so I don't think the valve cover should ever have been off before.

My main concern is how should I put it all back together?  It kind of looks like its one tooth out on the cams.  So should I try and "correct" it or leave it be!

Anyone got any ideas?
I did find this topic in a quick search but nothing conclusive.
link


Last edited by georgecb500 on Tue 03 Mar 2015, 12:46 am; edited 1 time in total (Reason for editing : added the photos properly this time!)
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Celt500
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Re: Timing / camshaft alignment on 2003 CB

Post by Celt500 on Tue 03 Mar 2015, 2:16 am

Mine did not line up perfectly either and the T mark ended up pretty much as it is in your first photo.
I'd imagine that if you try it one tooth out it will look 'more wrong', which would confirm things are ok to go back the way they were.

Proceed with caution anyway and turn it over gently by hand once you've got the cams torqued down.
Friendly tip; don't even try turning it over without the tensioner in!  Laughing
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jchesshyre
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Re: Timing / camshaft alignment on 2003 CB

Post by jchesshyre on Tue 03 Mar 2015, 10:18 am

My current '97 bike is like this and was at only 16000 miles, and my previous '94 one was as well throughout its 149,000-mile life. It annoys the hell out of my perfectionist side but I had to accept it. What I wasn't sure (and still am not) was whether to check the clearances with the T mark in line with the bump or with the IN and EX marks in line with the cylinder head - I'd have thought the latter since it's the camshaft position that's important - anyone know?
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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Tue 03 Mar 2015, 12:56 pm

Sounds like its nothing to worry about then.  Thanks for your help guys.

Any tips on making a key for the tensioner?  Does a screwdriver work like Haynes suggests?
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eternally_troubled
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Re: Timing / camshaft alignment on 2003 CB

Post by eternally_troubled on Tue 03 Mar 2015, 3:19 pm

Yes a screwdriver works. It just doesn't lock into the body of the tensioner the same way as the proper key does, so you have to hold it to stop the tensioner undoing itself.

Why do you want to remove the tensioner if the valve clearances seem OK?
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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Tue 03 Mar 2015, 10:17 pm

Thanks for tips.

The clearances are all out of spec by about 0.30 - 0.45mm.  I was just commenting that the fact they've all worn similarly is probably a good sign.
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eternally_troubled
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Re: Timing / camshaft alignment on 2003 CB

Post by eternally_troubled on Wed 04 Mar 2015, 1:16 pm

Oh I see... have fun buying those shims!
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Wed 04 Mar 2015, 1:17 pm

I was adjusting the valve clearance on two CBs after 16,000 and 20,000 kms. Although Honda recommends the check at 24,000 kms, almost every valve has been out of spec, too.

At both bikes, I had a slight misalignment as well and was worried about it. But remember that the marks should align on a brand new engine engine. The camshafts are mounted when the chain tensioner is NOT in place. When tensioning the chain at the engine's rear, the camshafts rotate clockwise and the crankshaft rotates counter-clockwise. For that reason, any wear of the chain that is eliminated by the cam chain tensioner causes the mentioned misalignment which increases when the cam chain is worn.
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Wed 04 Mar 2015, 2:10 pm

Regarding the tool, this is what I did:

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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Fri 06 Mar 2015, 3:04 pm

Great mod with the jubilee clip. I'm going to make use of that this afternoon!
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Llewelyn1965
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Re: Timing / camshaft alignment on 2003 CB

Post by Llewelyn1965 on Fri 06 Mar 2015, 3:15 pm

I'm sure we had a thread on here somewhere where someone made a key from some sheet metal. If there is, maybe the person could make a batch and sell them????
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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Fri 06 Mar 2015, 5:33 pm

So I made my tensioner key this aft.  Now it looks to me like access is pretty tricky without removing the airbox. Haynes doesn't mention if it needs to come out or not.  Anybody remember what they did?
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HomeBrew
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Re: Timing / camshaft alignment on 2003 CB

Post by HomeBrew on Fri 06 Mar 2015, 5:37 pm

You don't have to remove the airbox. It is a bit fiddly and tight but do-able.

sullivj
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Re: Timing / camshaft alignment on 2003 CB

Post by sullivj on Fri 06 Mar 2015, 6:03 pm

Llewelyn1965 wrote:I'm sure we had a thread on here somewhere where someone made a key from some sheet metal. If there is, maybe the person could make a batch and sell them????

Guilty!

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Celt500
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Re: Timing / camshaft alignment on 2003 CB

Post by Celt500 on Fri 06 Mar 2015, 10:10 pm

From what I remember, with a small enough screwdriver or key you could get it out without even removing the carbs, but you def don't need to take out the airbox.
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Sun 08 Mar 2015, 7:35 am

It is a little fiddly, but nothing has to be removed at all. Not the airbox, not the carbs, not even the fuel tank. But you'll need a tool that locks (!) the tensioner if you are going to do it all alone; a simple screwdriver has to be held in place all the time with one hand. So, spend five more minutes for the production of the mentioned "quick and dirty Flyingbrick special tool" and you'll be safe. Wink
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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Mon 09 Mar 2015, 12:12 am

In the end I removed the carbs and airbox, just looks like it will be easier to put the tensioner back that way.  I've measured the shims and found out I'm 3/8ths lucky. So only 5 to order at what are eye watering prices for something that really cost tit-all to make!  Checked David silver and it looks like one of the sizes I need are out of stock.  Anyone used Wemoto for shims? 

Also (and I think/hope my logic is correct!) I'm "aiming" to get the clearances towards the bottom limit of the tolerance band as using feeler gauges means really I'm measuring the "this is as small as the gap might be" distance.  

I find it kind of annoying that Honda set the clearance tolerance to 0.020mm but then only spec shims in 0.025mm increments.  Kind of limits your chances of getting near the nominal value!
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Mon 09 Mar 2015, 6:51 am

Not at all. The limit is +/- 0,02 which is 0,04 in summary. In most cases, you have 2 shims to choose from. For example, you measured 0,12 instead of 0,16 and the shim is a .210. A .205 shim would be 0,17 which is within the limit, and a .207 would be 0,145 which would be allowed as well.

I don't know which effort is needed to get your eyes wet, but EUR 2,50 per shim is not what I would call expensive. Very Happy

BTW: it takes me about five minutes to change the tensioner on a complete CB, using an 8mm wrench and the "special tool".
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stormbringer
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Re: Timing / camshaft alignment on 2003 CB

Post by stormbringer on Mon 09 Mar 2015, 7:59 am

I'll second Flyingbrick on the tensioner subject. It's really no biggie once you've got the tool.

Regarding shims: Sometime ago sullivj agreed to be the club's official 'Keeper of Shims'. If you know which sizes you need, try asking him if he's got them on stock. And if you end up having surplus shims once you're done, I'm sure he'll be happy to have them for someone else to use later on.
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jchesshyre
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Re: Timing / camshaft alignment on 2003 CB

Post by jchesshyre on Mon 09 Mar 2015, 8:53 am

If anything, you want to err on the larger end of the tolerance range, since the tendency is for the clearances to close up as the valve seats wear.

sullivj
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Re: Timing / camshaft alignment on 2003 CB

Post by sullivj on Mon 09 Mar 2015, 9:19 am

Well remembered SB. I'd already sent a PM.
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eternally_troubled
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Re: Timing / camshaft alignment on 2003 CB

Post by eternally_troubled on Mon 09 Mar 2015, 12:37 pm

It could be worse.

Lings sell them for 6.44GBP! David silvers are only 3.25GBP. I don't know where Flyingbrick gets them from for 2.50 euros.

My local mechanic/garage was doing them for 2.50GBP (I think) on an exchange basis.

Anyway, the amount that you have saved by doing the valve clearances yourself (rather than getting someone else to do it) has saved far more than you could possibly spend on shims to fix it up correctly.
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Mon 09 Mar 2015, 2:59 pm

I got them from Neubert Racing (http://www.ebay.de/itm/161412019028?_trksid=p2057872.m2749.l2649&var=460436148075&ssPageName=STRK%3AMEBIDX%3AIT)

Just go for shims with a diameter of 7.48 millimeters; they are used for a lot of different makes and models, including HoYaSuKa and even the 2V K75/K100 series.

By now, I needed shims between 2.00 and 2.12 millimeters at all serviced bikes (which are, regarding the valve clearance check, not so many). Honda offers them between 1.60 and 2.90 mm.
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georgecb500
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Re: Timing / camshaft alignment on 2003 CB

Post by georgecb500 on Mon 09 Mar 2015, 10:22 pm

Flying brick.  Where do you get your limits from?  The only one I have to go off is the Haynes manual which specifies Exh: 0.25 - 0.27 , In: 0.16 - 0.18mm.

Jchessyre. Reason I was heading for the lower end of the band was because the feeler gauge only gives you a bottom limit for the clearance.  Obviously its somewhere between the size that fits and the next one up, so I was trying to account for the clearance actually being slightly larger than I've "measured".  No doubt over thinking it as usual!
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Flyingbrick
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Re: Timing / camshaft alignment on 2003 CB

Post by Flyingbrick on Tue 10 Mar 2015, 8:46 am

This is an extract from the Workshop Manual:



The limits included in the Haynes Manual are wrong, indeed. I just checked my own copy and you're right, they are talking about 0.02 mm in total, not +/- 0.02 as it's meant to be.

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