Help - 'simple' exchange of camshafts possible?

[mephiston]

Hi!

I have the low power 50hp german model and got 4 well conditioned camshafts of the 65hp Vision.

Tank, airbox and carb is removed, now I want to change the camshafts - my problem is that I have never done such a thing before.


1.   Is it possible to change the cams without removing the engine out of the frame?

2.   Can I carefully change each camshaft after another without destroying the correct timing, has someone done this before?


Thank you very much for any help!

[Rikugun]

Welcome to the site!  :) The short answer is yes the cams can be changed with the engine installed in the frame. There are several guys that have had the top end apart and are well versed in cam timing so I'll let them address that.

In addition to advice I'd recommend getting a repair manual. It will have fastener torque specs, cam journal service limits and everything else you'll need to know. It will also help with valve shim adjustment which you will absolutely need to check after swapping the cams. Removing the cams also reveals the head retaining fasteners. Checking cylinder head torque wouldn't be a bad idea since you'll have access.

[mephiston]

Thank you very much for your advice.

I was afraid of hearing some things like that (;

I have a repair manual out of the download section, there is pretty much stuff in there regarding the points you mentioned.
But I fear I´ve never done a valve shim adjustment before, so maybe I need professional help - damn (;

Thought I could change the cams and go for a run (;

[The Prophet of Doom]

There are parts lists for german 11V and European 11U.  Follow the link in my sig to find them - they are not on the downloads page.   The differences are not cams alone, but also jetting - with a fairly large difference, you can do all the jets just by buying replacements but to change the throttle valve means new carb bottoms for you.  Check out this thread from Guerrero who did the same thing.  http://ridersofvision.net/rovforum/index.php?topic=14699.0.

The cams can be done easily with the engine in place - easier if you remove the top engine clamp and drain the coolant (which should be done every 2-3 years anyway) and remove the large connecting hose.  If you go deeper, like a valve grind you will need to drop the engine.

The shim adjustment is easy if you are taking out the cams.  Just measure them all with a metric feeler gauge first, then follow the chart in the manual to determine the new shim size.  Once the cams are out, the shims are just sitting there and can be swapped around.  No need for the tool, just a 10mm spanner and a torque wrench.  Take care torquing the cams back in - there is not a lot of leeway before you have a snapped bolt in your head.

Also check out this post about re-aligning the cams after removal - if you get it wrong you can hit the piston with valves, so rotate slowly till you are sure everything clears.
http://ridersofvision.net/rovforum/index.php?topic=15014.msg138021#msg138021

[mephiston]

Hi!

Thank you very much for this worthful information.

I know about the different carb. I own actually three carbs now, one of them has the 120 throttle valves, which should be the high power version. Thats why I thought I can go for the change now...

Still unsure if I should risk the change.... but I think will try it.

[The Prophet of Doom]

The difference will be like going from a XZ400cc to a XZ550.  Having had both I can say it is a big change in performance - well worthwhile, and not that hard a job.

[b_racuda]

Hello, new in the forum and just purchased Vision. Just started with cleaning all the electrical connections, installing new battery, replacing the original fuse box with better one, cleaning the fuel tank with Evapo-rust (http://www.evaporust.com/), changing the motor oil and the oil filter. Then for the test drive and the lack of power is the first feeling. The VIN number for my bike is 11U-052... manufactured in the year 1983 or 1984 (in the papers it is 1984 model) and the bike is purchased from the Germany. I have also full power model cams waiting to be installed but I have wondered why you have to change the carbs also? German model has different throttle valves but they are slighly bigger ones, If I am understanding this right: http://www.xz550.de/tp3/fileadmin/xz-tipps/xz-50-oder-64ps-die%20unterschiede.pdf . I am also planning to change the exhaust from original to something else in the same time. Maybe there is used MAC- or Predator-system availeble with a reasonable price in the Ebay or somewhere else, any suggestions?

So if the jetting is adjusted with the new cams and exhaust (not the same jets as originally used with the full power model with different throttle valves) so maybe there is more power in the higher revs (bigger throttle valves)? Do you think this is going to work?

[Rikugun]

I'm a bit confused by that PDF and am unsure what they are showing. Understanding German and having a set of those carbs in my hand to compare to mine would help.

The red arrows seem show two things - 120 vs. 125 throttle valves and a thinned venturi outlet as a result of chamfering. The chamfer appears to end prior to influencing the venturi at the butterfly and therefore butterfly diameter. Again, without measurements I can only go by relative visual differences. Maybe the opening chamfer is to smooth the transition into a larger inlet port opening on the 50PS models?

What does the 120/125 value indicate? Venturi diameter is nominally 34 mm so I see no correlation there. Throttle valve thickness is larger than 12,5 mm. Could it reference the chamfer angle on the throttle plate edge? This may influence the transition holes' expression as the throttle plate opens. Since I assume air flow through the two carbs is different perhaps a different angle is in order?

If you do ahead with rejetting the existing carbs, please do post your results. I'd be very curious to learn your results.

[Rikugun]

Further to my last post, do the 64ps cams need to be used with the sprockets that came with them? In other words, is there a different part number for 50 and 64 ps cam sprockets?

Below are two GPz550 inlet cam sprockets - one from a 1983 and one from a 1984. You can see by the red marked teeth the slight difference in lobe centers the two sprockets provide. Slight as it seems a significant power delivery is achieved.

And no, the gears are not ginormous but rather held up by the worlds smallest functioning pliers.

[mephiston]

Hi!

If you need help translating parts of the german document it would be no problem, just ask me.

The red arrows show 2 things:
1. the number #120 for 64ps model or #125 for 50hp
2. the thickness. The document says, as the picture can proof, that the 50hp carb has thinner wanding.

Unfortunately, there are no hints about the model year used for this document. I did not find out yet what #125 and #120 really indicate.

For making it even more complicated, I can say that I own 3 carbs, two are clearly the 50hp models, one of em has the #120 throttle valves, so it should be the 64hp version. BUT my wand thickness of this model is exactly the same... so maybe there are even more different types of carbs out there, or I own a modified one, which I do not hope...

I did the camshaft change, put on the 64hp carb and the bike starts, but when I put in the first gear the engine nearly turns out. When I try to drive then, the engine turns out after 2 feet of driving ):

At the moment, I think the carb is not ok? Do you have a clue?

[Rikugun]

I think I got all the pertinent information provided in the document but am a little confused what you mean by "wand" thickness?  and "engine turns out"?

Since you have both 50 and 64 ps carbs you could shed some light on something. What are the butterfly diameters? If the PDF is accurate and both versions are BD34's, there should be no difference.  If you can't measure them directly, measuring the ID of the carb outlets (above the outlet chamfer)would tell me what I want to know.  Do not measure the outlet chamfer, measure above it as close to the butterfly as caliper jaws will reach. Thanks.

Do you know the origins of the PDF? I wonder if there are other differences like (e.g. compression ratio or valve size) the author was unaware of?

[QBS]

Rik, "engine turns out" probably means that the engine stops running on its' own accord.

[mephiston]

At the moment, the 64hp carb is installed. In order to eliminate my main problem, I changed the fuel pump. tomorrow I am going to do the next test. When it fails, so that I know the bad part it not the fuel pump, I´ll take the carb off again and try to take some measurements.

Regarding the "wand thickness": Sorry, I dont know how to call it else... look at the pic posted from the pdf showing some differences to the carbs. The pdf shows 3 arrows, the upper right one shows the number of the throttle valve. The other two show what I mean, the creator of the document says that the thickness of the metal between these two arrows vary between the 50/64 cab. But unfortunately on mine three carbs, the thickness is exactly the same.

And yes, QBS was right regarding "engine turns out". It sounds like it doesn´t get enough fuel. Thats why I changed the fuel pump now. Will report soon.

[Rikugun]

Thanks for replying and good luck with the diagnosis. I hope you figure out what's going on with it.

That's interesting how the two (presumably) 50HP carbs are different. The butterfly and outlet ID aren't necessarily the same as the venturi size but it would be good to document any measurements possible between the carbs. I know very little of the low power version and would welcome any insight you can provide.

If you get to take more measurements can you confirm the outlet outside diameter is the same between all the carbs' outlets? In other words, the dimension that fits in the rubber manifold.

EDIT: regarding the red arrows showing "wall thickness"...  the two red arrows on the 64 version clearly indicate outlet wall thickness - difference between ID and OD. On the 50 version, the arrows show a distance from the OD to the edge of a chamfer, not the ID of the bore like in the 64 version. It's difficult to tell from the picture's perspective, but the edge of the chamfer does not appear to go far enough back to affect throttle valve/outlet bore diameter. If so, the arrows on the 50 version aren't showing actual wall thickness like on the 64 version, but rather that the outlet has a chamfer. What the red arrows are showing is somewhat ambiguous as to the difference (if any) between the two versions butterfly valve diameter and outlet ID.

[b_racuda]

I can measure the 50hp carb dimension when they are apart from the bike. Unfortunately I think my the stator is also fried, the battery is empty after riding a while and trying to restart. So I have ordered new stator and R/R (Honda CBR 600 mosfet) and changing them at the same time. Because of buying the new stator and R/R I don't have money left to new exhaust so I am just changing the cams and the carb jettings.

[Amnesiace]

Perhaps can I help.
The difference between the two carbs, apart from the jets, is the diameter of the throttle valve. The 50 HP version has the larger diameter, because of that the housing is different.
Here in Germany the conversation is often made.
And there are many who does experiments with 50 HP and 64 HP carbs and different jetting, there conclusion was that nothing works really well expect the factory setting with the right carbs.
So 50HP cams with 50HP carbs and 64HP cams with 64HP carbs, all other will be rubbish.

[Rikugun]

Thank you for the response - now I know! So despite both sets of carbs being identified as "BD34's" in that PDF, throttle plate/outlet diameter are different diameter.

And there are many who does experiments with 50 HP and 64 HP carbs and different jetting, there conclusion was that nothing works really well expect the factory setting with the right carbs.

I guess I shouldn't be too surprised by this statement either.  :)

[b_racuda]

Thank you for the response - now I know! So despite both sets of carbs being identified as "BD34's" in that PDF, throttle plate/outlet diameter are different diameter.

And there are many who does experiments with 50 HP and 64 HP carbs and different jetting, there conclusion was that nothing works really well expect the factory setting with the right carbs.

I guess I shouldn't be too surprised by this statement either.  :)

Ok, thanks for the information. Amnesiace do you know how bad the 50hp carb is with the 64hp cams? What are the symptoms, is it really bad or just not exactly right? With limited budget going to the other parts I have to decide should I change the 64hp cams and drive it with 50hp carb or just leave 50hp cams and 50hp carbs and wait when I have money to buy real 64hp carb. 

[Amnesiace]

It will be some work to get this combination to run and then you will have Problems above 4000rpm.
50hp cams with 50hp carbs runs better than 64hp cams with 50hp carbs. So why would you change?
Change cams and carbs or leave it. You will have no fun with that.

[b_racuda]

I have now carburetors in my hand they seem to be full power versions. It says 120 in the butterfly valves. I have to take cams out and compare those to the full power versions. Perhaps they are still the original 50hp versions. Maybe somebody has started modifications in Germany but newer finished them ::)

Also found that my YICS is leaking internally. When blowing to the other tube the air is coming out from the another. I also destroyed the T-piece where is the sensor for the cooler system. The aluminium part cracked after I tied to loose the bolt on top of it. Luckily there was replacement part available in the Ebay. So there is a lot to do.