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Stray

Cam reinstall - timing help needed

Need some help with my '98 5th gen can reinstall. 

 

I've done the clearances but made one big boo boo: took the cams out of BOTH front and rear cylinders so don't have a reference for reinstallation. 

 

In my defence the Haynes manual did not explain that only one side of the engine should be done at a time (or perhaps I missed it). 

 

Do I just turn the crank over to the right symbol and install one of the cams, then install the second one in reference to the first one? Or is there some other mark on the flywheel (or someplace else) that I need to alight the cams to? 

 

Does it matter where the cams get installed on the cogs if they are aligned properly to each other (and markings in the crank)? 

 

What confuses me is that with the correct mark showing in crank, sometimes the lobes are aligned correctly and sometimes you need to cycle the engine round one more time. So the mark is only correct 50% of the time. How do I know if I'm on the right or wrong cycle of the mark? 

 

How do mechanics reinstall the cams after a rebuild? 

 

I'd appreciate any advice you can offer. 

 

Thanks, 

 

Stray 

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The cams are mark FI FE & RI RR   (IIRC) for front intake, front exhaust, rear intake, rear exhaust  its cast into the body of the cam between the bearing faces.

 

For the timing, use the manual its available to download here. The front & rear banks have their own timing, it onlyt matters that the correct piston is at TDC when you install the cams. Use a soft rod like a wood dowl down the spark plug hole of the required.

 

Have fun.

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Drawing on 4th gen experience here, but pay attention to when they say timing arrows or timing marks. There are 2 distinct types of marks and are used for different alignments.

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Not to stray off topic but how many miles on your bike and which valves were out of spec and by how much? I am on my second 5th gen. Last one needed no adjustment until well over 100k miles.

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2 hours ago, Mohawk said:

Use a soft rod like a wood dowl down the spark plug hole of the required.

 

Have fun.

Dowel down the plug hole - that's genius! This answer really cheered me up. Big thank you Mohawk. 

2 hours ago, auggius said:

Drawing on 4th gen experience here, but pay attention to when they say timing arrows or timing marks. There are 2 distinct types of marks and are used for different alignments.

Thanks for this auggius - will keep an eye out. 

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1 hour ago, VFR Capt.Bob said:

Not to stray off topic but how many miles on your bike and which valves were out of spec and by how much? I am on my second 5th gen. Last one needed no adjustment until well over 100k miles.

My 5th gen has 60k miles in it and every single intake needed adjustment. Two of them were particularly bad. 

 

Hand drawn measurements attached. Sorry for the untidy pics. 

 

The intake ports arts are all in the middle (outside exhaust valves were spot on).

 

The big number is feeler gauge read. The F: figure is shim size printed on "face". Most don't have a number because they were so worn the figure had been rubbed off. The Mic: figure is shim size measured by "Micrometer". 

 

Particularly tight tolerances in cylinders 2 and 3. 

 

Stray

IMG_4283.JPG

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5 hours ago, Stray said:

Need some help with my '98 5th gen can reinstall. 

 

I've done the clearances but made one big boo boo: took the cams out of BOTH front and rear cylinders so don't have a reference for reinstallation. 

 

In my defence the Haynes manual did not explain that only one side of the engine should be done at a time (or perhaps I missed it). 

 

Do I just turn the crank over to the right symbol and install one of the cams, then install the second one in reference to the first one? Or is there some other mark on the flywheel (or someplace else) that I need to alight the cams to? 

 

Does it matter where the cams get installed on the cogs if they are aligned properly to each other (and markings in the crank)? 

 

What confuses me is that with the correct mark showing in crank, sometimes the lobes are aligned correctly and sometimes you need to cycle the engine round one more time. So the mark is only correct 50% of the time. How do I know if I'm on the right or wrong cycle of the mark? 

 

How do mechanics reinstall the cams after a rebuild? 

 

I'd appreciate any advice you can offer. 

 

Thanks, 

 

Stray 

Like people have already said, it's no big deal to re-establish the timing after removing both the camshafts from both the front and rear heads.  When you are careful and read the manual before-hand it is logical and straight forward...

 

Step #1.  Do as you have been told and download the manual.

Step #2.  Read through (carefully) the section that describes the procedure for re-establishing the timing.  Read it as many times as necessary for it to make perfect sense.

Step #3  As per the manual: re-establish the timing on the rear head.

Step #4  As per the manual: re-establish the timing on the front head.

Step #5  Pat yourself on the back for being such a good motorcycle mechanic.

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I'm not sure what causes tolerances to change. Is it spot or carbon build up? Could it be caused by hot running, poor fuel or wrong oil? What about short journeys in traffic vs long journeys on highway? 

 

Im not an expert but expect every bike will be different because they all endure different conditions. 

 

Clearly my my bike has led a different life from Capt.Bob's. 

 

On on the other hand perhaps your dealer couldn't be bothered with this awkward job and just told you everything was fine? Of course you may have checked tolerances yourself and found them within spec - I don't know. 

 

YMMV

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15 minutes ago, Stray said:

I'm not sure what causes tolerances to change. Is it spot or carbon build up? Could it be caused by hot running, poor fuel or wrong oil? What about short journeys in traffic vs long journeys on highway? 

 

Im not an expert but expect every bike will be different because they all endure different conditions. 

 

Clearly my my bike has led a different life from Capt.Bob's. 

 

On on the other hand perhaps your dealer couldn't be bothered with this awkward job and just told you everything was fine? Of course you may have checked tolerances yourself and found them within spec - I don't know. 

 

YMMV

I've wondered about this too...

 

Just like your post above, my exhaust valves were perfectly within spec (and I mean perfect, like the bike had just left the Honda factory), but on the other hand, almost every one of the intake valves were out-of-spec toward the too tight side  (just like your bike).  And this was on a bike that only had 19,000 miles on it.  

 

If the tolerance change was due to carbon build-up (on the back side of the valves or on the faces of the valve seats in the cylinder head) wouldn't they go out-of-spec toward the too loose side as the gap at the top of the valve stem was made wider by the carbon build-up?  So it has to be something that would induce a change that decreases the gap from the original factory-set specification.  Are the intake valves changing shape?  Are the valve stems stretching?  Or are the intake valves becoming more deeply seated into the cylinder head, meaning: are the valve seats becoming slightly deeper, is the aluminum structure becoming compacted?  Or are the valve faces beginning to "tulip" a bit?

 

I know that exhaust valves are normally build a bit more robust than intake valves because they have to deal with higher temperatures.  So maybe that explains the difference.

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11 minutes ago, GreginDenver said:

Step #5  Pat yourself on the back for being such a good motorcycle mechanic.

GreginDenver, thanks for your advice (and Mohawk and auggius). I will follow it. 

 

As for back patting, I am just your run-of-the mill home mechanic trying to keep his machines in good order despite work and family pressures. Not quite what I'd call a "good mechanic" but happy to have a crack at it. 

 

Also, like many others on this site, I get some pleasure out of it. 

 

Have rebuilt quite a few a few bikes using Haynes manuals but the VFR manual is not up to the same high standard as the others. Looks like the Workshop Manual available here is the way forward. 

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9 minutes ago, GreginDenver said:

I know that exhaust valves are normally build a bit more robust than intake valves because they have to deal with higher temperatures.  So maybe that explains the difference.

GreginDenver, if you're right about the exhaust valves being tougher then it probably has nothing to do with the aluminium head and everything to do with the valves themselves. After all, both In and Ex valves slap the head with the same speed/force - they are turned by the same mechanism. Why would only the In valves be suffering? 

 

In my my uneducated mind the Ex valves should be suffering most as the hot gasses, soot  and contaminants flowing through them are much worse than the clean fuel + air flowing through the In valves. Just goes to show how little I know. 

 

Does this his mean we can replace the intake valves with tougher exhaust valves and enjoy longer valve clearance service intervals? 

 

This is is just a lay stab-in-the-dark. I'm not a professional. 

 

Stray

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Interesting question here...

 

My understanding is that clearances decrease with time as the valve wears into the head. So maybe the carbon build up on the exhaust valve cushions them a little and preserves the clearance better than the clean valves on the intake? My experience on my three bikes (5G VFR, VTR1000 and ST1100, which all use the same cam/bucket/shim arrangement) is the same, intakes are the valves more likely to close up.

 

I do know that the exhaust clearance needs to be greater than the intake to allow for the greater thermal expansion of the hotter exhaust valve.

 

And to answer one of the original questions about crank and cam timing; always remember that on the four stroke, there are two crank revolutions per power stroke. That is why the cams run at half speed compared to the crank, so that each cam goes through a single revolution per power stroke. The piston is at TDC twice per power cycle, once with the valves open at the end of the exhaust cycle, and once with the valves closed at the top of the compression cycle. As the ignition fires at every crank revolution (the ignition pulse generator is off the crank) it does not matter whether you start the cam timing exercise on a "compression" or "exhaust cycle" but it is very important to get the four cams into the correct relationship to each other. As stated, read the service manual carefully and don't deviate from the procedure.

 

I know from the VTR1000 forum that it is possible to time the both cylinders correctly, or with one cylinder 360 crank degrees out of position; all the timing marks line up fine and the bike starts and runs OK but apparently loses its ability to run at high revs, which i would expect has something to do with intake or exhaust resonance. 

 

Because I doubt my own ability to get these things corrected easily, I only ever work on one cam at a time on my bikes. On my VTR (chain driven cams) I pull the cam off the sprocket, and leave the sprocket cable-tied to the chain so I can't lose timing.  This is a great idea until you refit the cam, and turn the crank without remembering to cut off the cable tie first....

 

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Pretty much agree with what has been said, deffo read the manual, especially section 8-28

If all cams have been removed pay particular attention to the rotation of the crank between rear and front installation.

450 degrees (1 and 1/4 turn) and ensure no. 4 cylinder is at TDC. Section 8-30

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On 09/08/2017 at 10:38 PM, Terry said:

And to answer one of the original questions about crank and cam timing; always remember that on the four stroke, there are two crank revolutions per power stroke. That is why the cams run at half speed compared to the crank, so that each cam goes through a single revolution per power stroke. The piston is at TDC twice per power cycle, once with the valves open at the end of the exhaust cycle, and once with the valves closed at the top of the compression cycle. As the ignition fires at every crank revolution (the ignition pulse generator is off the crank) it does not matter whether you start the cam timing exercise on a "compression" or "exhaust cycle" but it is very important to get the four cams into the correct relationship to each other. 

 

Terry, you've hit the bullseye!

 

If the ignition fires at every revolution of the cams then I just have to ensure piston is at TDC and  crank/cam markings line up as specified. Then I just have to ensure the second cam is installed in correct relation to the first. 

 

Thanks for the advice everyone. I've now read the Workshop manual which says to turn the crank until the correct mark lines up and "ensure piston is at Top Dead Centre". It doesn't explain how to check if piston is at TDC so Mohawk's dowel-down-the-spark-plug-hole suggestion is gold. Thanks again Mohawk. 

 

Finally does everyone replace the o-rings under the cam cover when they do a valve job or just reuse the old? Dealer wants silly money so I'd rather not buy if unnecessary. 

 

Thanks for your help - really appreciate it. 

 

Stray 

 

 

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No I have never replaced the o-rings on the cam cover. Just make sure you put some sealant on the half moons on the main gasket, the flat parts don't need it but the moons will weep without sealant. Don't over-tighten the cam cover bolts, have heard plenty of horror stories about snapping off the mounts in the head. 

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With your question about replacing rubber parts you've stumbled into one of the weirder areas of VFR800 myth and legend.  You may have already noticed that VFR owners are quick to crow about the longevity/durability of the engine (and maybe even the whole motorcycle too).

 

This "VFRs last forever" thing goes to different degrees with different people, some take it to extremes, like, "My VFR has 100,000 miles on it with nothing but gas, oil changes and air in the tires!"  The unwillingness to replace even normal consumables like rubber gaskets becomes a point of pride.

 

 

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I've replaced plenty of rubber parts on my 99, all the radiator hoses for example. But I've never noticed any weeping from the cam cover o-rings.


Sent from my iPhone using Tapatalk

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Thanks GregDenver and Terry. I'll follow your advice about o-rings and sealant. 

 

Every bike manual I've had says to replace just about everything you unbolt. If they had it their way you'd be rebuilding a brand new motorcycle every 5,000 miles. 

 

On the other hand I do like to replace "consumables" and keep on top of maintenance. Yes, a bike can run for ages on the original parts but a refresh can really enhance the joy of ownership. Changing wheel and swing arm bearings can make a tired old machine feel like new. Same with new spark plugs, filters and oil. 

 

But when o-rings cost more than premium bearings I feel a bit aggrieved and somewhat disobliging toward Mr Honda. 

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1 hour ago, Stray said:

Thanks GregDenver and Terry. I'll follow your advice about o-rings and sealant. 

 

Every bike manual I've had says to replace just about everything you unbolt. If they had it their way you'd be rebuilding a brand new motorcycle every 5,000 miles. 

 

On the other hand I do like to replace "consumables" and keep on top of maintenance. Yes, a bike can run for ages on the original parts but a refresh can really enhance the joy of ownership. Changing wheel and swing arm bearings can make a tired old machine feel like new. Same with new spark plugs, filters and oil. 

 

But when o-rings cost more than premium bearings I feel a bit aggrieved and somewhat disobliging toward Mr Honda. 

 

Actually I'm kinda new to VFR ownership.  I always admired the VFRs, especially the models with the gear-driven cams, but I was busy with life and work and by the time I got around to buying one (just this past December) the bike was 18+ years old.  

 

So I didn't hold back on the effort when it came to refurbishing it.  Now that I finally had a VFR I wanted to feel what the VFR800 felt like when it was new (what I missed out on back in 1999).

 

What I'm saying is: there are a lot of rubber gaskets and O-rings and such that have never been replaced on a lot of these 5th Generation VFRs.  And here we are, buying these 19 (going on 20) year old bikes and some of us want to act like they don't need a deeper level of care.

 

Here's what I did to my 5th Gen after I purchased it this past Devember: http://vfrworld.com/threads/refurbishing-my-99-5th-gen.52488/

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Neat write up on your rebuild. One thing I'd say, is that after that amount of strip down, cleaning & replacement. You didn't do the head bearings !? Which is a known area where the factory skimps on the grease, so even if you didn't replace the OEM bearings, they still have 20 year own hard grease in there !

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5 hours ago, Mohawk said:

Neat write up on your rebuild. One thing I'd say, is that after that amount of strip down, cleaning & replacement. You didn't do the head bearings !? Which is a known area where the factory skimps on the grease, so even if you didn't replace the OEM bearings, they still have 20 year own hard grease in there !

You're exactly right about the head bearings, my winter efforts ended short of a complete end-to-end refurbishment.  I ran out of time and that was the item that I decided to skip.  I've got another (much smaller) maintenance session tentatively scheduled for this fall.

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Wow Greg, that was one mother of a thread. Bike is virtually brand new now and I'd bet she runs beautifully. 

 

Difference between your refresh and mine is mileage. Yours had lowish miles and was cared for whereas mine has 65k on it and has clearly seen a lot of winter salt/abuse.  

 

As as such I'd be wasting my efforts and money going your route as my bike doesn't deserve it as much as yours. In England we say, "you can't polish a 7urd but you can roll it in glitter".

 

Of course I'll make her safe and refresh whatever I can but it will all be done on the cheap - can't justify throwing real money/time at her. 

 

So so far all I've spent is service parts (plugs/filters/oil), brake fuid, coolant, shims (Mr Honda screwed me on those) and tyres.  And a big dollop of elbow grease, of course. 

 

Still to come are bearings all round, seals and fork oil. 

 

Might throw in a few mods like PAIR plates, rear shock and possibly an USD front end off eBay (all as cheap as possible).

 

None of that will bring my bike anywhere near your high standards but it will run well and I will enjoy it. 

 

Your refurb is by far the gold standard - really well done. As a VFR owner I'm really grateful for the effort you put into that and am inspired to emulate (albeit at a lesser extent). I really hope you get maximum joy out of your lovely bike for many years to come. 

 

Stray

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Thanks for the help everyone. With the Manual and your advice I got it all buttoned up. 

 

A few notes for anyone doing this themselves: 

 

1. It is very hard to judge the if the timing marks are set flush if the engine is still in the bike. There's just not enough room even for a tiny mechanic's mirror. My solution was to use a popsicle stick along the top of the engine and contort myself to see if the marks line up correctly

 

IMG_4344.thumb.JPG.3973d574bd9a23ea38b65d6039ee9bc0.JPG

 

2. With the piston at TDC and timing marks facing outwards (as per manual) the cam lobes are partially engaged on one cylinder. I noticed this especially with the exhaust lobes on cylinder 2. Buttoning up the cam holders with valves slightly engaged forces the cam into its bearing races but the pressure is bad for the holder and could warp or break it. It also forces the crank over slightly messing up your alignment marks. The way arround this is to set the timing marks as instructed loosely and then rotate the engine SLIGHTLY off the mark so the valves are not engaged, before bolting the cam holder down.

 

When you button it up it will look wonky until you turn the crank back to its marking again - now your cam markings will lign up correctly. 

 

This is the crack turned slightly off its TDC

 

 

IMG_4360.thumb.JPG.93243121d0889924b210098ce140c6f8.JPG

 

This is how the markings looked after bolting up - slightly off. Red marks made by me on disassembly. 

 

 

IMG_4342.thumb.JPG.2c010c24c6af3a0c1582e829d28ef73c.JPG

 

When the crank is returned to TDC the markings line up perfectly (no pics, sorry). 

 

Truly a laborious process that took over 5 hours, most of it head scratching. 

 

Havent yet rechecked valve clearances in case in case one of them is out and I need to redo this. Can't face it just now.

 

 Stray

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