Is my Cyrano 970 faulty?

[hayaku`]

Hell everyone,

I got a Mares Cyrano 970 a few months ago, and I love it.
I think it might be defective though.

The pressure reduction switch is just about impossible to put into low pressure mode, you need 2 hands to do it. Compared to the similar switch on the Cressi SL55, which is smooth and light, this switch is extremely heavy and resistive.

Anyway, I recently de-gassed my gun for a flight to Melbourne, and had a better chance to see what was going on. It seems that the little piston that normally travels all the way horizontal to the gun, before clicking down vertically, his hitting resistance in the last 2-3mm of its horizontal travel, requiring quite a forceful push to make it 'click' all the way before it can slide down.

Does anyone with this gun know of this problem or if its serious enough to warrant a replacement? I have only had the gun for 2-3 months and it has always behaved like this, from day 1.

Cheers

 

[popgun pete]

I have just cured that problem on a "Stealth" (similar to the "Cyrano") which I have discussed in another post http://forums.deeperblue.com/pneumatic-spearguns/93603-deteriorating-finish-new-sporasub-mares-stealth.html. After the second reassembly of the gun the power regulator operation still seemed no better, although initially it worked until I established some high pressure air in the gun, so I investigated further by dismantling the gun yet again. The answer is the two locating pegs on the rear face of the white plastic power regulator block have a tiny amount of side play in the matching indents in the rear handle boss that they fit into so that when you assemble the gun (or the guy at the factory does) it is possible to have the alignment slightly out between the brass piston and the transfer port that it plugs for low power use. The amount of misalignment is very tiny, almost undetectable just looking at it. On the second reassembly I had put the gun on "low power", then tightened up the inlet valve body to keep the power regulator indexed in the rear handle, but never tightened the inlet valve body up completely (as in not being able to move the tube spanner at all). Then when I twisted the outer tank to align the external stickers, tightened the inlet valve body to the limit and then tightened the muzzle right up it must have moved the internal alignment out again. These screw threaded end pieces (inlet valve body and muzzle body) need to be really tight or you see excessive gaps around the tank ends which open up from nothing as the pressure builds up in the gun. You will always get some gaps there, but high preload on the inner barrel tube through tightening the screw ends fully keeps the gaps small (the inner barrel tube is the clamping bar that holds the gun together). I rely on experience to tell me how tight they have to be, but it is in the "barely able to move it" category using a short T-bar handle on the tube spanner and as a bar passed through the muzzle relief ports. Using a long T-bar handle risks busting something as you can exert torques that will test the strength of the alloy screw threads, so use something that allows the hands (you need both) to be kept close in to the object being tightened, say like that length used on an automotive spark plug spanner T-handle.

So the third time I put the rear handle and power regulator block assembly together with the port plugged and clamped it up with maximum twisting effort tightening the inlet valve body, to the point where the tube spanner would barely turn. This time the power regulator in the pressurized gun now works, but is still slightly tight as against being impossible to budge before. Maybe the factory guys don't check or have much stronger thumbs than you or I do, but the tolerances on the lugs should be tightened up to improve the indexing action. I guess the component moulds are getting a bit tired, although there will be more than one mould to create multiple parts each time the injection molding machine is cycled. The "Cyrano" has been around since 1994 from memory, first one I saw was at a Dive Expo, I remember wondering how long the fluoro-green sight would last before it bleached out in the sun, although it looked very cool.

You could have it fixed under warranty, or you can do it yourself, but you need to have some tools and mechanical aptitude for such tasks.

 

[hayaku`]

Thanks Pete. I will try my luck with warranty... your post was very helpful though and I'll be sure to stick it in the face of the mares rep should be give me any trouble hahaha

 

[popgun pete]

Be nice to him or he might tell you to get lost, especially as you have dismantled the gun (?). I would not mention that fact, just in case!

Here is a bit more info.

I just measured a "Cyrano" power regulator block's locating tab widths on the rear face and they are both 11.35 mm, or that is what repeat measurements with a digital vernier caliper averaged out at. Similar measurements of the width of the notches that those tabs fit into in the front face of the rear handle produced an average figure of 11.65 mm. That means at the outer circumference of the power regulator block there is a potential circumferential movement of 0.3 mm. It does not sound much, but that must be enough to stop the brass piston going into the transfer port as there are no other candidates for making the piston and its nose mounted "O" ring very hard to push into the port. I purchased this "Cyrano" back in 2000, so it must have been manufactured earlier (in Italy) as it sat in the dive shop for years gathering dust on the soft cover roll-up bag that they are supplied with.

I found that the gun's partitioning bulkhead to inner barrel "O" ring had a thin circumferential sliver of white plastic swarf trapped alongside it in the annular groove of the inner barrel which it shares with the white plastic circlip. The power regulator shaft "O" ring had a very tiny nick in its inner diameter which explains why it leaked air when the power regulator's control cursor was moved forwards in the selector gate. A near invisible fleck of aluminium had drifted in there on the "tide" of the lubricating oil and had eventually cut the "O" ring. I only caught sight of the cut with a jeweller's loupe when I saw the bright refection of the aluminium against the black rubber of the "O" ring and then saw the cut situated not that far away from it (in the highly magnified view that is). If I did not know it was leaking then I would have passed the "O" ring as OK as the cut was very difficult to see having already looked the "O" ring over twice before without finding it.

NB. Keep the new "O" rings and the removed old ones well separated on your work table as if you mix them up it is not always easy to find the faults that identify the damaged ones. I put all the old "O" rings in 35 mm film canisters that photographic film used to be supplied in then and write the name of the gun that they came from on the lid just in case I need them for future reference and as a way of remembering which rings I actually replaced as some rings can do another "turn of duty" if they look OK and never leaked before I dismantled the gun.

 

[popgun pete]

Here is a procedure which may improve the operation of the power regulator without dismantling the gun, provided that you can force the cursor or control knob to the "low power" position. Load the spear into the gun and push it nearly all the way down with the gun set on "low power", but stop just short of latching the mechanism and let the barrel sliding piston return to the muzzle before jerking the spear free from the gun. Then store the gun for a day or so with the muzzle pointed downwards and the cursor remaining on the "low power" setting. The pressure in the gun will now be much higher on the front face of the power regulator block's bulkhead than it will be on its rear face and this pressure increase should unload the front face from the restraining circlip on the inner barrel by pushing the entire assembly rearwards inside the gun. The sustained pressure imbalance acting internally over a day or so may be enough to twist the power regulator body around slightly on the inner barrel against the resistance of its inner and outer "O" rings. The brass piston plugging the transfer port will be acting as a locating dowel to help create the proper alignment. Success will be indicated by the cursor flying back as soon as the knob is lifted up in the selector gate and after that it should be much easier to select "low power" each time. This method will work better if the gun has plenty of air pressure in it, otherwise the cursor may tend to stick and not fly back when the knob is raised in the selector gate from the "low power" position. Then it is a full dismantling job to discover what else may be going on inside the gun, but not before trying the procedure a couple of times as it may not work the first time.