Camshaft lifter tool?

Side note - as a fan of phrases - where does 'breaking a bowling ball in a sandbox' come from - haven't heard this one before but I like it!

 

That first part you said puzzled me! But let my try and explain....

From Wikipedia, Newtons Third Law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and −F the "reaction.

What this means is when the lobe of the cam comes around, it hits the rocker arm, and tries to open the valve. Since the valve is at rest and has the resistance of the pressure of the valve spring holding it shut, there is significant force ( in the opposite direction of opening the valve ) exerted back into the face of the cam lobe ( via the rocker arm ). On most designs this force would be virtually all absorbed by secure mounting of the cam itself, transferring that force exerted into the cam straight into the oil film/ cam bearings/cam bearing journals( caps ) and the head.

On 84-85 VF's the cam mounting is so lacking that in operation the cam itself moves significantly enough to induce "virtual" clearance in the valve train. Instead of the valve moving while the cam remains in position, the valve moves some, but the cam also moves away from the rocker due to the resistance of the valve opening. It would be the same effect as leaving the cam caps loose and running the engine----clackety clack.

When adjusting with the lifter tool, its goal is to replicate the movement of the cam by actually pulling it up in the cam cap ( and away from the rocker arm , increasing valve clearance measured by conventional means ). I should also note that not all of this movement if from cam-cap deflection, and a lot of it is from the cam-to-journal clearances caused by Honda's non-traditional method of manufacturing the heads.....

EXCERPT from MCN "..... Instead of line boring the cam journals with the caps attached to the head (so the caps were accurately matched), Honda milled them in two separate operations (for neatness, they said). This led to play in the cam bearing, which meant that when setting valve clearances, valve spring and camchain tension tilted the camshaft. This artificially reduced clearance between cam lobes and rocker arms so that what looked right during a service could double when the motor was running. Result: the lobes hammered the rockers, knackering both..."

Now, it seems from whats been said here and from techs I've talked to over the years, that adjusting the valves with the tool actually leaves little to no clearance ( and in fact may tend to "preload" the valve.. IE-negative clearance!! ) when its removed and the lash is checked in the "normal" manner. If thats the case, then it would be impossible to adjust lash without the tool ( you can't measure less than nothing ) if the engine in question has a lot of cam movement and really needs the tool.

You can also see why it freaks guys out. Of loose or tight valves, tight ones are far more likely to cause problems, and it seems that when using this tool, Honda is counting on valve spring pressure to overcome the pressure needed to deflect the cam caps just slightly and/or take up slack, and keep the valve on its seat. This undoubtedly leads to excessive wear on the rocker arm and cam lobes even if the valve manages to remain on its seat and keep from burning or causing driveability/starting problems.

As you can ( hopefully ) see, it is a very mickey-mouse solution to a poor design.

Did that make sense? I don't know if it makes sense to me.....

 

Great post! Thank you DG.

Given all you know, would you forgo using the tool?

 

I really don't know where it came from. I heard it once and it stuck.

DG Thanks for your explanation of how the caps where made and mated. Sounds like the only real fix w/stock parts would be to sand the cap mating surface, reinstall and line hone to factory clearance spec.

May be the best way is to check it first. It seems possible that you could get pieces parts that do line up and are in spec. I would install and torque caps without cam in place and measure to see what you have first. Then decide from there. You could use a set of snap gauges to do that if you don't have a bore gauge.

I just looked up the cam specs for the 750 and cam run out is a whopping .004" and the clearance for bearing surfaces are: center=.008" and ends-.004" I also looked in my on line 700/750 manual released in 1/84 and the valve clearance is .006. Where as my 83 750 manual released 1/83 the valve clearance is .005. So they did make a change. Both books show the same bearing surface clearances. I now know why the cams can "flex" some. With the timing chain in the center and what ever pressure it puts on the cam they need a larger clearance to keep from contact. Mmm interesting.

I think whether you use the tool or not is a crap shoot without checking bearing clearances first.

 

If I could ask, what issue is this from? I'd like to see if I can locate a copy for my V-Four file. Thx!

Side note - the '86 had line bored cam journals but still had valve train issues - at least from what I've read. Do you know what the cause of this was - i.e. manufacturing limitations of the valve springs back in the day?

 

For reference here are the VF500F cam runout and camshaft journal service limit spec's from the '84 FSM.

On a side note - do the journal caps wear in a specific pattern and as such should they be kept in order? Is it okay to interchange them and/or substitute for a spare set in better condition?

Thx!

 

NO! Do not change the caps around. One reason is they may be scuffed in or seated differently from compression of bolting down. Scuffing is bad to begin with but you could compound the problem. Unless may be you measure them after changing. I wouldn't do it if I could stay away from it.

If you read pg 9-7 at the bottom that you posted. It says if the oil clearance w/caps is out of spec (to large) to replace the head and cam shaft holders (caps) with new. This is telling me they are a matched set. The more I look at the photos, you may not be able to line hone because of the side of the head case is higher than the bearing surfaces. A good machinist should be able to define that.

Now here's an interesting note. I went back to the beginning of this topic and read #4 reply in which you reference an article about the tool. If you read column #3, bottom half. They mention that if the cam chain has tension on it, it will pull the cam to the bottom bearing surfaces. You make your adjustment. Then when you start the motor the clearances become larger. Bingo! I've always turned the motor over past the point I need then back it up to where the adjustment marks are on the alt case. This would relieve the tension on the cams. So they would not be pulled down. This is just dumb luck on my part. So if you relieved the tension from the cam chain BEFORE you adjust your valves, you may just have a fighting chance of not getting them to loose once running. So no need for the tool. Which I would think you need two of them. One for each end of the cam. Otherwise I would think the cam could be out of plane. One side higher than the other and would throw the adjustment off a tad. This is just speculation on my part having not checked it.

 

Thanks for the post Grey. Interesting note on 'backing-off' the pressure on the cam...

In part I was asking about the caps as a little while ago I purchased a set of used inner and outer valve springs (all are inside the service limits) to have in my back pocket as these are NLA. The seller sent a bunch of other head parts including the camshaft journal caps. He was really fastidious about cleaning all the parts before sending and these caps look to be in fine shape - no scoring. I guess though that my hunch was correct? They aren't really of use as they should be mated...

On this note - it makes sense then to purchase a used set of heads that are complete or at the very least have the caps if not the cams.

Any thoughts on why the line bored '86 heads still suffer dropped valves - valve springs perhaps?

 

you may be able to use the cam holders. Bolt them on and take measurements of both the old first then the new and see what you have. Problem is you don't know where the increased clearance is. Is it in the holders or the head or both? Something you'd have to play with. Getting other heads may not solve your problem for they may be out of tolerance too. Unless you can measure them before buying.

"Any thoughts on why the line bored '86 heads still suffer dropped valves - valve springs perhaps? "

That sounds like a different problem. If the valve locks (keepers) come off and the valve drops. The first thing I would suspect weak springs. This will cause valve bounce and possibly loosening of the keepers enough to fall out. Here's a video of a Spintron machine which photo's the spring and valve action when the motor is running. Notice how the springs dance around and the valve bounces off the seat.

YouTube - Valve Float

There are other videos of the Spintron if you want to look at what's good and what's bad. Just do a search.

 

Thanks Grey. I'll check out the video.

 

You flatter me...
I've had only one of these bikes. I just did a lot of research on why things were the way they were. I think Jamie is a far better source of "Guru" information, and he has made his feelings clear.

If it were mine id check the clearances without and just see how the bike sounds. If there's too much clearance, it will let you know with noise. If its loud, then i don't see any way but to use it.

I would be curious to see what the settings are without the tool after its used. If there's any clearance, id be much more inclined to use it...but as Grey said, i think its really a crap shoot either way.

So the real solution is to swap to 86 heads and be rid of the floppy cam problem ( and just deal with the crappy valve problem...lol). The 86 heads are easily distinguished by little half-moons in the cam-cover gasket surface area. This is because they were align-bored and the "hole" was necessary for the hone to go in from the side. They also have an extra bolt in the corner of the cam cap...if you notice on you posted FSM pages, the caps have only 3 bolts. The 86 has a fourth bolt between the rocker area and the outside of the head ( making a "square pattern" to help illustrate ), and if i recall this necessitated juggling of the head bolts in some way ( maybe went form a bolt to a stud? I'm sure the manual illustrates ).

I got the MCN quote from a site i found a few years ago....

More Cam Perspectives -- Performance Bikes magazine
This is a great source of info about the problems and their causes...

There was also a post of what looks like the actual page in the "valves" page linked to near the beginning of the topic.

Guys, i think we've managed to make a very informative thread here!

 

Thank you for the post.

I really appreciate you taking the time to write down your thoughts on this topic.

The '86's camshafts, being align bored, are definitely and upgrade in terms of setting the valve lash - though there is a secondary part to a head swap - whether it is best to use a set of '86 carburetors in conjunction with an '86 head.

I have read that using the larger 32mm bore '84/'85 carburetors on the '86 gains a few HP but...you would think Honda dialed in the correct cam/valve/carburetor combination and that the '86 carb's would be the best choice on the '86 head (for a stock bike).

 

Most likely for a stock machine. You could always use the 84/85 carbs and see how they work. One thing to remember is even though the theory of something working sounds good. It may be different in the real world once put to the test. Besides pulling your hair out you just might learn somemore about your motor. The down side would be you become a guru on the VF500 motors and everybody comes to you for advice!:faint:

good luck

 

For reference a cam cap comparison (photos originally posted by 'sirepair' on the Yahoo Groups VF500F website)

'84/85



'86

 

Hi Tink!

True enough,,,though there isn't a gear driven cam 500cc Second Gen option.

I've been looking into an NC30 or NC35 but they are grey market and as you know a bit salty.

The 500 is really its own animal. If I wanted a larger displacement bike I would be tempted to purchase a Second Gen but I like 400cc and 500cc bikes so here I am hoarding gaskets and valve springs ;-)

 

Noise when rotating engine

So thanks to Toe, for the replacement bolts. I was able to finish the top end( I had broken one cam cap bolt) Now as I have rotated the engine for the valve adjust I have a big noise in the engine(motor out on bench ) As the engine is rotated I think the starter sprag is dragging I sure hope so as I don't want to take it apart now . This is a long term bike build so the motor will be sealed after the valve set. I have ordered the valve tool from England.
Thanks to you guy's here for the info. So any help with the noise . I'm going to do a recheck on the cams and running gear today . Thanks again, Mike R. in Calgary..:VFR1200F:

 

Good deal. Hope everything works out.

Please keep us posted on your thoughts after having a chance to use the Factory tool.

 

Sadly...your probably right.

Truth is i like the 500 and 1000 in the first gen, and then the 86 ( i think ) 750 that was the first fully faired ( but those seem highly prized ). Besides that, i don't really have any desire for a VF/VFRs up until maybe the 5th gen. The 6th gen seems like a step back wards or sideways despite its techno wizardry, and the CBR1000RR i used to own pretty much killed my admiration of underseat exhaust.

The new 1200 seems bad-ass for sure but...( maybe i am just getting old ).....all the new bikes these days just seem butt ugly! I seem stuck in the late 80's and 90's from what i think looks good.
I still think the original 900RR is one of the best looking bikes ever. Still love the looks of the Hurricane, F2,F3 and F4 (which i also owned ), but find the new 600RR a bit...adolescent, i guess is the word.

The truth is nobody makes a sport(y) bike at the moment that i truly want. The top of my wish-list? An updated Super hawk, preferably the "Naked" one rumored to be in the pipe several years ago. Or an updated SV that doesn't look like that new Gladyouass thing ( make it comfy this time, if you please ).