• Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

Mares Cyrano - Muzzle leak

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.

johnnydwood

New Member
Feb 27, 2011
2
0
0
I have a Mares Cyrano 1100 with a intermittent leak in the muzzle. Air escapes only when the butt of the spear shaft is seated in the piston and the wiggled around. Also when i pull the spear out of the muzzle, a little bit of pressure escapes. After reading the exhaustive information on disassembly i am ready to attemp a repair. However i don't know what exactly i should replace. The piston? All the o-rings? the shock absorber? I dont really want to take it apart any more that i have to. Has anyone ever had this issue? What is most likely the problem?
 
Hi Jonny.
Welcome to db.
If you've read through the modification/disassembly threads, then you'll know we have some serious pneumatic gun experts on db.
I'm pretty sure they'll be along to help you out, in the meantime, how much use has the gun had?
Has the gun been taken apart before?
Has it been used in sandy or gritty conditions?

My own advice would be to give the gun a service, check the O-rings and replace any that look worn or defective.
Pay special attention to the flat ring on the piston (forget the name), but it keeps sand etc out of the barrel.

Like I said, someone with much more knowledge will help you out, if you answer the questions they will be able to give you a more detailed answer.
 
The history of the gun is a complete mystery. I bought it used.
So I don't know if there is sand or abrasion damage. It does hold a seal when loaded&cocked. Only when the spear butt first makes contact with the piston, is there a leak.
Posted via Mobile Device
 
the piston oring or piston could be damaged. Remove air completely, unscrew muzzle, remove piston, remove oil, check piston and oring. Add new fork oil 10w about 25mm to 35mm depending on size of gun.

Go to youtube for complete dismantling.
 
I have had a "Sten" with those symptoms. The air leak was through a small tear in the rear skirt of the rubber cone seal on the back of the piston. While the piston sat straight in the inner barrel there was no air leak, but as soon as it tilted some air came out. During muzzle loading a small amount of air also came out, but I never noticed it initially as the leak was very small at first, plus the leak occurring depended on which way the piston was tilted. As the piston revolves in the inner barrel during loading the orientation in the gun always changes. Once cocked the gun never leaked and once discharged the gun never leaked. It was easier to buy a new piston assembly rather than find a replacement cone seal.
 
if its any consolation a few of my guns do the same thing when they are first loaded. and they are all brand new. i just always attributed it to poor loading form or just something that i had to accept. it has always only been a few tiny bubbles and nothing more. i have used my cyrano 700 and 550 quite extensively with no problems due to this occuring. the medisten does it too. might just be the o rings getting compacted for just a second to one side. however- i am a complete amateur regarding these amazing guns so i could be horribly wrong about all of the above just being ''a fact of life'' good luck to you.
 
I should add that I used the gun for a long time with the leak that I described before deciding to fix it, and that was only because it eventually began to lose too much air and I needed to find the cause. A pneumatic gun should be pressure tight, but very tiny leaks can be ignored until you do the next oil change where you have to remove the muzzle and piston anyway.
 
The cyrano has a piston with some space to carry oil or grease between the two seals, according to Mares this helps in reducing friction. So I would check that second seal and if it is good I wouldn't worry much about some small bubbles because the seal on the front of the piston is just to keep it balanced. Or you could just replace the piston body for a straight 13mm one with no space for oil or grease, or take the piston out and fill the space with some marine grease. A new gun shouldn't have seals busted.
 
Cyrano has an 11 mm piston. You can readily order one from dive Inn store for about 8 USD. However, just like in my Cyrano 90, methink that the front end portion of the barrel has some corrosion thus leaking air during shooting. I tried replacing the piston but still the same. so what I did was asked a machinist friend to machine a 10.5 mm hard plastic for me, groove at the mid portion for the O-ring and attach it to the existing piston by a threaded M5 stud screw, just long enough so that the O-ring of the piston never reaches the corroded portion of the barrel. And Presto! No leaks.
 
Sand particles can scratch inner barrel bores and one way it gets in is if you plonk your gun down on the beach with the muzzle hitting the sand. Although it washes out when the gun is in the water the best thing to do is to swish the gun muzzle around forcing water through the muzzle via the relief ports. Do that a couple of times before you attempt to put the spear tail in the muzzle. Over the life of a gun you can get tiny hairline marks in the running surface, but these only show up when the barrel is illuminated by looking through it with the inner barrel out of the gun and these don't cause leaks because the rubber seal edges can squirm down into them.
 
DeeperBlue.com - The Worlds Largest Community Dedicated To Freediving, Scuba Diving and Spearfishing

ABOUT US

ISSN 1469-865X | Copyright © 1996 - 2024 deeperblue.net limited.

DeeperBlue.com is the World's Largest Community dedicated to Freediving, Scuba Diving, Ocean Advocacy and Diving Travel.

We've been dedicated to bringing you the freshest news, features and discussions from around the underwater world since 1996.

ADVERT