[Hareton]

Originally Posted by DeBurca

Well as you say that the paper did not move then all is grand there
The cylinder is perfect for your barrel, so that just leaves the gearbox

A non liner spring will not effect the FPS, its just makes life easier for the motor to get up to speed
It would seem the you have an air leak within the gearbox

I would first check the piston head O-ring by doing a compression test without the air-nozzle
If all is good then repeat the test with the air-nozzle attached so as to check if air is escaping between air-nozzle and the cylinder head brass pipe
Do the air-nozzle test with the air-nozzle in both the retracted and extended position

Done all that before assembly. Cylinder head is Teflon taped o ring air nozzle. Compression is spot on a lot of effort need to move the piston when it passes the port. Really only leaves the spring then doesn't it??

[$kilkenny]

the gun fluctuates by 2fps, around 240-242 in the chrono witch is amazing so its deffinatly not an air leak.

[sci-ops]

Hi Hareton,

I'm going to ask a stupid but obvious question, what weight bb are you using and is the chrono configured for it?

[Hareton]

Originally Posted by sci-ops

Hi Hareton,

I'm going to ask a stupid but obvious question, what weight bb are you using and is the chrono configured for it?

Ha .2g and the chrono was set for it.

[DeBurca]

If the compression is all good then it must be the SPRING as has been mentioned several times already

Why fit a new M90 spring ?????? was the old spring broken/damaged in any way
Can you refit it and do a comparsion test to see by how much the FPS changes

[Hareton]

Originally Posted by DeBurca

If the compression is all good then it must be the SPRING as has been mentioned several times already

Why fit a new M90 spring ?????? was the old spring broken/damaged in any way
Can you refit it and do a comparsion test to see by how much the FPS changes

Put in a different spring. Not sure what strength. Can see a power increase. Haven't chronod yet. Now the motor and battery get really hot when firing. Checked the wiring then checked again. No shorts or splits in the wire. Any ideas? Tried firing with the previous spring again and no over heating

[Stercus Accidit]

Ported cylinders deliver lower fps in my experience than non-ported in mp5 length barrels, combined with an m90 which is a weak spring and that's your problem. I've used m90's in long AK barrels with full cylinders and gotten low fps, you dont sound like you have an air leak.

For a 363mm Barrel (m4?) I don't think you need a ported cylinder, so either lose the m90 or the ported cylinder.

Originally Posted by Hareton

Put in a different spring. Not sure what strength. Can see a power increase. Haven't chronod yet. Now the motor and battery get really hot when firing. Checked the wiring then checked again. No shorts or splits in the wire. Any ideas? Tried firing with the previous spring again and no over heating

Typical if the motor is under heavier strain, I get that on many of my guns too, maybe get higher guage wiring or a higher torque motor.

[DeBurca]

Originally Posted by Hareton

Put in a different spring. Not sure what strength. Can see a power increase. Haven't chronod yet. Now the motor and battery get really hot when firing. Checked the wiring then checked again. No shorts or splits in the wire. Any ideas? Tried firing with the previous spring again and no over heating

Your motor is getting hot due to the extra load being placed on it by a stronger spring
If the motor has to work harder to compress a stronger spring then it will draw a greater current from the battery which will in turn get hotter

So if a different spring is giving a power increase it looks like your problem has always been the spring

[Hareton]

Originally Posted by DeBurca

Your motor is getting hot due to the extra load being placed on it by a stronger spring
If the motor has to work harder to compress a stronger spring then it will draw a greater current from the battery which will in turn get hotter

So if a different spring is giving a power increase it looks like your problem has always been the spring

Ah rite. Thanks for the help guys