'83 VF750f - camshaft installation problems

Hi,

First post here so hello, my name is Quinn and I like motorcycles. There, I said it out loud but I refuse to recover!

I was given a '83 VF750f by a very good friend of mine. The stipulation was that I finish putting it back together and he would send me the title. So in between raising an 18 month old and getting ready for another to soon be born I'm finally getting some work done on the top end.

Unfortunately the only manual I have is a Clymer and it's confusing as hell. Not what I'm used to at all. over the weekend I started installing the camshafts per the manuals instruction, I think. I installed the rear cylinder cams first without too much trouble.

Began working on the front cams and low and behold there is not enough slack in the chain to install them. The manual is fairly useless and I don't see any external cam chain tensioner adjustments to make things easy. I'm sure it's not as difficult as I'm making it so I'm seeking the expertise of those who've got some experience with these old beauties.

Thanks much,

Quinn

 

Welcome Quinn,

You have come to the right place for help.
Try here its a microfische to see if you can find what your "looking for"

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Alright...I'll bite. You have to back the cam chain tensioner off for sure. Easy to demonstrate but hard to describe.

It's a wedge type tensioner...Notice the two little blocks on the top of it. Take a large screwdriver and push on one of the blocks (don't remember if it's top or bottem) while your pushing back on the tensioner guide. When you get it backed of completely, you'll notice there's two small holes that line up near the top of it. Lock it in position by installing a bent nail or something that fits. Make sure the cam chain is on the bottem sprocket. Now you should be ready to install.

You don't have to, but it's easier to back the tensioner off if you remove it from the head. Remove the small cotter and pin holding the tensioner guide and the four six mm hex bolts...simply pull it out the top.

 

Not to thow a wrench in this , but how did you get the rear cams in without resetting the tensioner? You may want to inspect it to be sure it is not damaged as they are prone to failure.Good job on the description Dizzy.

 

I was wondering that too but was afraid to ask. Oh...and I forgot to mention...take the 'bent' nail out when you're done.

 

Your replies were sent to my junk folder so I'm just now reading them.

When I installed the rear Intake cam there was just enough room to pull it into place without doing any damage. I found it odd also but figured I was just missing some way to adjust the chain. After closer inspection I found nothing similar to what I've dealt with on some other bikes. Thanks to your responses I'll take another look and see if I can release that chain tension. As far as damage on the tensioner itself, I didn't see anything obvious but considering the large difference in tension between heads should I remove the rear tensioner and inspect further or is that difference normal? I also noticed that when I was adjusting the valves on the rear head I had to slightly nudge the crank in order to get my gauge under two of the four rocker arms. In other words there was no point at TDCC where all valves were closed. I also noticed that when placing both rear cams in there correct "timed" position one lobe on each cam was not completely at rest if you know what I mean.

The only experience I've had with Honda was during my time at MMI and I was in the Harley program so I really didn't get to tear into any big Japanese bikes. Before that I was wrenching old British bikes, some old Harleys, an old Guzzi and BMW. I really was chalking this stuff up to my ignorance which is why I posted here and it sounds like I really need to get my hands on a better manual. Any suggestions?

 

The cams should be at a 10 and 2 position roughly on the hole that is at TDC. The lock on the tensioner tends to crack where the rod goes through the lock.

 

It's been five years or so since I've had cams out of one of these...so I'm working from a memory gap. But I can tell you a few things...

The tensioners are automatic...from my experience you need to back them off or you won't get the cams into their journals. Once you allow them to tension, they should lock...as more slack is taken in the chain, they should take it up auto. So you may want to remove both tensioners, compare, etc. It was fairly common 'back in the day' to have to replace them. They'd tend to back off, causing an intermittent nasty sounding rattle. Often you weren't able to visually see anything wrong with them.

Any four stroke engine I've seen there's always a TDC compression stroke every 720 degrees of engine rotation where both valves must be closed, including this model. These older V4's are not the easiest ones to figure out. First off, they don't fire symmetrically...they fire 90 - 270 - 90 - 270. Plus...when you get one cylinder bank timed you HAVE to time the other to it...as well as it's own set of pistons. Because of the wierd firing pulses...the cam lobes aren't always in the same spot at TDC compression stroke on every cylinder...but...the valves on that cylinder are ALWAYS closed at that point.

You should try to get your hands on an original equipment shop manual for a resource.

 

Thank you all for the feedback. I'm searching now for a factory manual and then I'll make attempt number two.