Cylinder crosshatching?

[supertiger]

Thanks Sir! As far as giving up trade secrets, my advice to anyone reading this and debating doing a self tune or sending it out.....with what I ve spent on tools, parts, and lubricants (not even counting time) trying to do a tune myself, .....wish I would have just sent it out.....probably cheaper and certainly a much better chance the gun will actually function when it's all done....hahahaha.......thanks for all the great advice!!   Just saw a post by MIke M on the same gun I'm doing (RS2), and his work is definitely much prettier than mine

[Jaymo]

Doing your own tunes is great fun if you hate sending your gun out for a tune, or you enjoy getting frustrated, or you have plenty of spare time to learn your gun intimately.
Otherwise, sending it out for a good pro tune is the way to go, because it's a lot less of a PITA. The money you pay a good tuner pays for their tooling, consumables, labor time, and mostly, their experience and expertise.

You can repair your own forklifts, if you want to spend a lot of time and money learning how, and acquiring all the necessary tools, technical info, and diagnostic equipment.
However, you'll come out a lot cheaper if you just call me out to fix it for you.
And, you will save yourself a lot of frustration and headache.
Just like if you send your springers out for a tune by a professional. They save you the headache of procuring the tools, supplies, and knowledge to do it right.

[CharlieDaTuna]

One thing for sure... if you do it yourself and it turns out decent, you will have good understanding of the mechanics and a great appreciation for your gun.

[Jaymo]

And a great appreciation for what pro tuners do.

[supertiger]

Well got the hone done. Did compression chamber with 400 grit brake hone and remainder of the tube with 1" 400 grit flex hones. Followed all the advice above and just a few quick passes with the flex hone. It definitely god rid of the sharp edges along the cocking slot and the holes for the trigger pins, which is what I think tore up my seal. Reversed the drill so I got it both directions. One more question.......barring a catastrophic failure in there, is the hone forever or does it have to be redone periodically like an engine? I assume if everything is working right, its only the seal making contact and should not wear out the cross hatch.

[airiscool]

Well got the hone done. Did compression chamber with 400 grit brake hone and remainder of the tube with 1" 400 grit flex hones. Followed all the advice above and just a few quick passes with the flex hone. It definitely god rid of the sharp edges along the cocking slot and the holes for the trigger pins, which is what I think tore up my seal. Reversed the drill so I got it both directions. One more question.......barring a catastrophic failure in there, is the hone forever or does it have to be redone periodically like an engine? I assume if everything is working right, its only the seal making contact and should not wear out the cross hatch.

 If the piston and ram, or coil spring, stay on a common center line, yes. But that rarely is the case.

It only takes a small amount of misalignment to have the rear end of the piston rubbing the inside of the compression tube walls. That's one reason why I ordered one of Gene's GRS kits to keep the ram centered in the piston. Hopefully, by keeping the ram centered, in turn it will help the piston stay centered.

Right now, the ram in my gun has the shaft at a slight angle to the ram body. It's been like that since day one. I tried straightening it, but stopped when it seemed anymore force would damage the insides of the ram. There is paint worn off the ram body and cooresponding wear inside the piston, so I'm sure it's causing the piston to rub the compression tube wall.  

Added to that, everytime the gun is cocked and fired, air moves in and out of the space behind the piston. Over time, that can draw some amount of dust particles into the compression tube which will eventually add some amount of wear. Shooting in a dusty area will just make that worse.

Paul.

 

[MichaelM]

It only takes a small amount of misalignment to have the rear end of the piston rubbing the inside of the compression tube walls.
Paul.

I agree with everything you said Paul but this....

the rear of the piston doesnt enter into the compression chamber at all.... now I am not saying the front of the piston even though it should technically be supported by the seal and kept centered AND it should be relieved enough that it DOESNT touch the walls still cant bump or rub the walls if there is some other problem (like you saying your ram is visably not streight(I would send that back and get a new one... cant be a good thing))  I am just pointing out the rear of the ram never enters the compression chamber at all

 

[airiscool]

It only takes a small amount of misalignment to have the rear end of the piston rubbing the inside of the compression tube walls.
Paul.

I agree with everything you said Paul but this....

the rear of the piston doesnt enter into the compression chamber at all.... now I am not saying the front of the piston even though it should technically be supported by the seal and kept centered AND it should be relieved enough that it DOESNT touch the walls still cant bump or rub the walls if there is some other problem (like you saying your ram is visably not streight(I would send that back and get a new one... cant be a good thing))  I am just pointing out the rear of the ram never enters the compression chamber at all

 

Good point Mike. I forgot how long the piston is compared to the stroke. That's what happens when you work with short skirted pistons in long stroke motors for a living.  

You would think even the factory seals (stiffer than Maccari's seals) would be stiff enough to keep the front end of the piston from touching the walls , but in the picture below (taken after only about 500 shots), you can see that the underside of my Trail XL piston was doing alot of rubbing on the compression chamber wall just to the rear of the seal.

The ram shaft was only off center line slightly, so slight in fact you can't see how much unless you roll the ram across a flat surface and watch the very tip of the ram shaft, but with the force of firing, it was enough to force the piston into contact with the compression chamber wall.

I've got a new ram here, plus Gene's GRS kit, but the gun is shooting so great now (slower, but great), that I'm waiting for the power to drop off more before I get back into it.

Paul.

[supertiger]

Gentlemen, can't tell you how much I appreciate all the great info. Pretty much decided on the Benji XL 1100 as my next gun, looks like thet're backordered everywhere. . Planning to get the GRS. Curious why it would slow down the gun.....drag?

[airiscool]

Gentlemen, can't tell you how much I appreciate all the great info. Pretty much decided on the Benji XL 1100 as my next gun, looks like thet're backordered everywhere. . Planning to get the GRS. Curious why it would slow down the gun.....drag?

Gentlemen, can't tell you how much I appreciate all the great info. Pretty much decided on the Benji XL 1100 as my next gun, looks like thet're backordered everywhere. . Planning to get the GRS. Curious why it would slow down the gun.....drag?

Sorry I wasn't more clear on that.

I haven't installed the new ram or the GRS yet, so don't think the GRS is what's slowing the gun down.

A few weeks ago, when I put a new scope on, I also chronied the gun. I discovered that the ram has lost about 70fps of power. It's shooting great otherwise. I'm waiting until it drops enough that it needs re-sighting, then I'll open the gun up again. I'll install the new ram and GRS kit, relube, etc.

Paul.

[MichaelM]

Actualy glad you posted that pic.... I forgot the the trails use that streight walled piston....... where alot of the pistons are smaller along its length except for the rear portion to ride in the action........ Honestly the best way to fix that along with Gene's kit is to turn the front and middle section down a bit...  doesnt take alot just enough to make some clearance......

have to admit I dont like those streight walled pistons much at all...  I dont think they are perfectly streight but they definatly are not relieved enough to make me feel comfortable