What piston do i want for high rof in an AK?

[badas]

Hi all,

Just wondered what piston people would recomend i use in a Cyma AK for a higher ROF?

Would removing one tooth from the piston and gear / two teeth off each result in a massive loss of FPS and range also?

Thanks

[HuntR]

Re: What piston do i want for high rof in an AK?

Element Duracon or TM is always a wise choice. But you will definately have to shave some teeth to prevent premature engagement.

Short stroking will significantly reduce FPS yes. But this is easily combated by a higher rated spring.

[badas]

Re: What piston do i want for high rof in an AK?

Thought i would have to have a more powerful spring, but then surely part of the short stroking process would be deemed as being pointless?

More powerful springs mean lower ROF from my experience.

Do you know what version gearbox a Cyma AK is?

Thanks

[HuntR]

Re: What piston do i want for high rof in an AK?

Not really mate. A high torque motor will be roughly the same on an M130 as it would with an M90. And the Cyma comes stock with a high torque. It uses a V3 gearbox.

I'd avoid using a high speed motor while short stroking especially the G&P M120. It will wear out too quickly. Your best bang for buck would be the following:

SHS high torque motor
Element duracon piston
Element duracon piston head
7mm solid bushings
Bearing spring guide

Depending on battery you may want to add a sector gear chip. How fast do you want it. With those parts and a decent 7.4 lipo you'll be looking at low to mid 20's area.

[badas]

Re: What piston do i want for high rof in an AK?

mid 20's would be nice and it's using a 9.6V 1500mah stick battery

removing 1 / 2 teeth from the piston would allow me to lower the metal teeth down yes?

would there not be and free play in the metal teeth sliding plate after a short time though?

thanks again appreciate the help

[HuntR]

Re: What piston do i want for high rof in an AK?

You wouldn't need to short stroke it on that setup mate. The teeth to remove of the ones from the back end of the piston. Not the pickup tooth but the 2 after that. The teeth on the front of the piston don't ever get touched unless your short stroking. But unless you wanted to use a huge 11.1v the need to short stroke isn't really prominent.
I would however use a stick lipo. Using a 9.6v nimh i'd rather go for the SHS high speed motor. And use an M100 spring.

[badas]

Re: What piston do i want for high rof in an AK?

Ok thanks, just need to find where to buy the parts from in stock

[North West Outpost]

Re: What piston do i want for high rof in an AK?

Mid 20's will be easily availible with either the torque or speed motor with a 9.6. Probably with standard ratio gear set too.

I usually short stroke if I want over 30 a sec, but you can run up to 40 a sec without it...Aparently...I wouldn't myself.

With the neo high torque motors you should be able to run bigger springs than that without loosing rof, they just become much more dependant on the battery being able to give the required output. Output should remain the same but demand on the battery rises. Considerably!

Erm...Make sure you correct AOE, I'm sure that's what Hunter is getting at but I can't see it any where...lol. Which is why you need to remove the second and third teeth as they clash instead of mesh as the sector gear is rotated anti clockwise to correct aoe.

[sj_asc]

Re: What piston do i want for high rof in an AK?

Thought i would have to have a more powerful spring, but then surely part of the short stroking process would be deemed as being pointless?

More powerful springs mean lower ROF from my experience.

To clairfiy, Higher rated springs are required to keep the Piston in time with the higher cycle rates - what it does is allow you to push the ROF even higher. It will increase the load theoretically dropping the cycle rate, but you compensate by using a higher output battery pack and or motor with stronger magnets. You can also use different gear ratio gear sets.

Do you know what version gearbox a Cyma AK is?

Thanks

V3, Short shaft motor.

[badas]

Re: What piston do i want for high rof in an AK?

Got all the kit, short stroked the piston and gear by 3 teeth and fitted an m130 spring....

Problem is though that the metal slide with teeth on it on the piston that i cut short (took 3 teeth off) is now moving on the piston when its inside the gearbox it seems

After 3 or 4 shots it just locks up the gearbox, i take it all apart to see this metal sliding plating with the chopped off teeth has moved position so i am guessing this is the fault?

Thanks

[JOE90]

Re: What piston do i want for high rof in an AK?

where exactly did you remove the teeth from, did you short stroke it or did you correct the aoe?, you should of left the tooth holding the metal plate alone. Personally it would of been more efficient to short stroke the gearset and corrected the AOE alone.

[badas]

Re: What piston do i want for high rof in an AK?

I short stroked both the piston (towards the the front end (back of hte metal strip spikes)) and the geat that pulls the piston back.

I need to remove gears from both otherwise its not going to work at all :S

[JOE90]

Re: What piston do i want for high rof in an AK?

If the metal last tooth is still on the piston then how is the short stroke being effective, as that last tooth (metal one) is still allowing the piston to be drawn back to its foremost position, where as if it wasnt there it would allow the piston to be released by the sector gear earlier. Where as with yours its obviously done incorrectly and the metal tooth is sliding back and forth and not doing nothing apart from jamming everytrhing up.

What i was saying, was whether you short stroke the piston or the gears (correctly), by three teeth, then either one of those two, no matter which, will allolw the piston to be released earlier.

[JOE90]

Re: What piston do i want for high rof in an AK?

Just realised that three teeth on a piston nearest the metal one should be and probably is enough for it to be able to release, but there is definately an issue to how you removed those teeth, the metal one shouldnt slide back and forth, the tooth behind should still have enough substance behind it to atleast hold the metal plate/tooth in place.

[North West Outpost]

Re: What piston do i want for high rof in an AK?

I don't understand why you have attempted short stroking when you are lookng for 20 a sec. 20 a sec isn't considered high speed. All you needed to do was correct aoe, with maybe 2 teeth removed. Sometimes it varies. Torque or speed motor wouldnt make a difference with an M100 spring, correct aoe, 9.6 or a 7.4 and away you go.

If you want to take teeth off the release end of the piston you need to make sure you leave at least one metal release tooth. So it is better to buy one with 7 metal teeth.