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MP7 Problem, Gear Timing

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Old April 21st, 2006, 18:50   #1
nic_s
 
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Arrow MP7 Problem, Gear Timing

I got my MP7 when they first came out, and I bought it new. Since day one though, it's had some troubles. When firing on full-auto, the BBs would usually just drop out of the barrel and fly about ten feet. Semi-auto was better but it would often have the same problem. Not all the time though, which is strange. Now, when it does this, the gun sounds like it's dry firing. This makes me think that the nozzle is retracted when the piston moves forward to push the air out of the cylinder.

So, I took the gun apart, and upon inspection of the gearbox I have found that the gear timing apears to be off from the factory, since the nozzle was about half way back at 'zero'.

After opening the mechbox, I also found that the damping foam on the cylinder head was partially torn, and there was a chunk that was about to break free. I removed all the damping foam, since the asymetric nature of the torn foam would probably affect accuracy. That's a minor detail though. The main issue here is ger timing.

So: Has anyone here had similar issues? How did you fix it? Any thoughts or theories?
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Old April 21st, 2006, 19:39   #2
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So, how did you fix the "timing problem"?
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Old April 21st, 2006, 20:25   #3
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It only did that to me when the battery was weak.
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Old April 21st, 2006, 20:34   #4
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In my experience, there is no such thing as "gear timing". The gears reset to "zero" after the completing one cycle.
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Old April 21st, 2006, 21:18   #5
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I dont know how many times people have to say it, but, THERE IS NO SUCH THING AS GEAR TIMING. If you have any mechanical sense whatsoever, this should be very evident the first time you take a mech box apart. Your problems are coming from somewhere else.
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Old April 21st, 2006, 22:39   #6
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LOL

Anyhow yeah I had the same problem with mine. till I lubed up the mags and fires great now
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Old April 22nd, 2006, 15:15   #7
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No such thing as gear timing? Maybe I'm not explaining this right... Sorry if my terminology is off here.

I'll put it together again with the loading nozzle/tappet plate all the way forward, i.e. the sector gear is not actuating the tappet plate at all.
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Old April 23rd, 2006, 04:38   #8
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OK, re-assembled the mechbox today, did a test run, and for some reason the piston got completely chewed. The entire first tooth is cracked off. No idea why, although I have heard of other people chewing up MP7 pistons.

This is really getting frustrating...
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Old April 23rd, 2006, 04:53   #9
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Just to add another .2 cents - when i first got mine, I had issues with BB's just plopping out or firing wildly. Same as Blastyman mentions, I tried a little silicone spray in the loading rod before filling it with BB's, which in turn lubed up the mag, its been 100% ever since. Hope it helps! (after you get a new piston...)
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Old May 3rd, 2006, 05:46   #10
nic_s
 
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[bump]More input anybody?[/bump]
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Old May 3rd, 2006, 20:14   #11
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Quote:
Originally Posted by Ghost Snake
I dont know how many times people have to say it, but, THERE IS NO SUCH THING AS GEAR TIMING. If you have any mechanical sense whatsoever, this should be very evident the first time you take a mech box apart. Your problems are coming from somewhere else.
Sorry for the thread jack but you've gotta love it when people regurgitate what others have said yet don't offer any solution other than, "the problems are coming from something else". Sorry for the rant.
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Old February 5th, 2007, 21:25   #12
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Nic,

Did you ever get this fixed? I seem to have the same issue.

EDIT*** Hummm, I cleaned out the berrel and lubed it up some more. Seem to be working better now.

Man this gun is worse than a woman.
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Old July 18th, 2007, 07:45   #13
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All aep's suffer from the same problem.

When ever the, not feeding / bb's dopping / no distance or power thing comes up...

Just fill a mag with bb's, put a few drops of light weight silicone oil on the top bb in the mag.

Presto, problem solved.

As for the chewed piston.... that sux. Sorry.
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Old July 18th, 2007, 10:25   #14
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your piston problem is quite obvious...

you removed the foam on the face of the piston head.... so your piston was always too far foward when the sector gear catch the first tooth, so it is slipping every cycle..

get a new piston head
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Old July 18th, 2007, 11:13   #15
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yeah, you should be able to push the piston all the way foward in the cylidner till it stops(including cylidner head), then you should check to see if the sector gear grabs the first tooth.

Yeah if your ripping stuff off teh piston head, things are gonna hit the fan man
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