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Discussion Starter · #1 ·
For those wanting to know how to set a rocket key in a piston ported engine look at this......



Piston ported engines come inx1/X2/x3/x5/X6/X7/X8/X9/X10/Cateye,Harleybnike,MiniChopper,Stand-up scooters and one or two other things...Soon in the new Cags.....

You set the rocket key this way because the engine spins this way when looking at the flywheel.....



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Heres how to set the rocket key in a reeded cag engine...




These engines come in the half fairing Cags/full fairing cags/pocketquads/pocketdirtbikes/pocket sidecar racers and a model or two more.....


The reason why we set the rocket key this way in a reeded cag engine is because the engine spins this way..............

 

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Git R Dun PBracer
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Ive been looking at Rocket keys for my x bike. Does the x1/2 use the large key and cag/reed uses the small key? In the ebay ads ive been seeing thats what they say. Or are they really talking talking about the timing being offset small or large?
 

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Discussion Starter · #3 · (Edited)
Ive been looking at Rocket keys for my x bike. Does the x1/2 use the large key and cag/reed uses the small key? In the ebay ads ive been seeing thats what they say. Or are they really talking talking about the timing being offset small or large?
They both use the LARGE rocket key....Engines smaller than 39cc use the small key..........Like This ..........

 

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Git R Dun PBracer
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Ok cool. They had pictures of CAGs for the small rocket keys. But good thing i check with you first. Ill be ordering one this week. TY.

Check your PM. :)
 

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This is too advanced for me, however I'll do some more reasing on it. Looks like the previous owner messed around in there cuz it has 3 different types of bolts/screws on there.
 

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Discussion Starter · #6 ·
UPDATE...............UPDATE

Just wanted to add a bit of info about the way the rocket key is setup...

Since not everybody can blueprint and port their own cylinders and rely on bolt-ons for their power enhancement the way I have the rocket key oriented in the pictures for both engines are set ADVANCED...This enhances mainly the bottomend power because these small engines have difficulty taking off from a dead stop.......

If you build stout enough engine and want to enhance revs because youre running a lightened clutch with a high engagement rpm youre gonna want to do the opposite of the pics and "RETARD" the rocket key................

Also to bump this thread.........:tango_face_devil:
 

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I thought I would also add that it's been reported that the position of the machine slot for the key does vary in angle between engines due to Chinese tolerances. If so then then on some engines it might not give any improvements where wanted.

Now also related I have been told that these advance keys and 2-piece high compression heads are a bad idea, anyone want to give any input on this?
 

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I thought I would also add that it's been reported that the position of the machine slot for the key does vary in angle between engines due to Chinese tolerances. If so then then on some engines it might not give any improvements where wanted.

Now also related I have been told that these advance keys and 2-piece high compression heads are a bad idea, anyone want to give any input on this?
Of course it varies. I doubt any part you buy will be 100% identical as they will almost always have different flaws no matter how small. If you don't want to make any more power then yes a 2 piece high compression head is going to be a "bad idea". Obviously higher compression means stress on more parts, crank, flywheel, etc etc. But if you break it in properly and do all the right things before you install it, modify ports slightly, etc you should be fine.
 

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I've been talking to a guy who races pb's in Las Vegas. He says everyone that races cags don't use the two head pieces. That they all but the zh-1 head and port it. Stock carb, better exhaust and more so focus marrying the crank bearings to the crank properly. Talking about it made me excited to get a cag again.

Sent from my SM-G900V using Tapatalk
 

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Of course it varies. I doubt any part you buy will be 100% identical as they will almost always have different flaws no matter how small. If you don't want to make any more power then yes a 2 piece high compression head is going to be a "bad idea". Obviously higher compression means stress on more parts, crank, flywheel, etc etc. But if you break it in properly and do all the right things before you install it, modify ports slightly, etc you should be fine.
I could never figure out why there were variances if something came out of a CNC machine, once it's set up then it should be the same every time without fail. But somehow the Chinese are able to pull it off.

Alright I will get an offset timing key and try it once my engine is running. By memory the person who told me this was saying something along the lines of it not helping power, something to do with the higher compression ratio.


I've been talking to a guy who races pb's in Las Vegas. He says everyone that races cags don't use the two head pieces. That they all but the zh-1 head and port it. Stock carb, better exhaust and more so focus marrying the crank bearings to the crank properly. Talking about it made me excited to get a cag again.

Sent from my SM-G900V using Tapatalk
The original barrel / head has the advantage of having the offset plug which helps in having more even temperatures. Other than that I can't think of any other advantages, not to say there isn't though.

I would very much like to hear exactly what you mean by "marrying the crank bearings to the crank properly" should you be willing to explain in more detail.
 

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I actuality want to know more about that too haha. That's just what he told me. He said one guy, through disassembling and reassembling his engine so much that one time they just married so perfectly that it revved like a polini. His words

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I could never figure out why there were variances if something came out of a CNC machine, once it's set up then it should be the same every time without fail. But somehow the Chinese are able to pull it off.

Alright I will get an offset timing key and try it once my engine is running. By memory the person who told me this was saying something along the lines of it not helping power, something to do with the higher compression ratio.




The original barrel / head has the advantage of having the offset plug which helps in having more even temperatures. Other than that I can't think of any other advantages, not to say there isn't though.

I would very much like to hear exactly what you mean by "marrying the crank bearings to the crank properly" should you be willing to explain in more detail.
I would say that a rocket key can in no way, shape or form increase compression. It just adjusts advances( or if you put it backwards retards) the timing. Both have different advantages and disadvantages. CAM2 would be able to explain it in better detail.
 

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I would say that a rocket key can in no way, shape or form increase compression. It just adjusts advances( or if you put it backwards retards) the timing. Both have different advantages and disadvantages. CAM2 would be able to explain it in better detail.
No that is a given, unless they were talking about detonation due to the higher compression ratio then I don't get it either so there probably isn't any more point talking more about it
 

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Discussion Starter · #14 · (Edited)
I could never figure out why there were variances if something came out of a CNC machine, once it's set up then it should be the same every time without fail. But somehow the Chinese are able to pull it off.

Alright I will get an offset timing key and try it once my engine is running. By memory the person who told me this was saying something along the lines of it not helping power, something to do with the higher compression ratio.




The original barrel / head has the advantage of having the offset plug which helps in having more even temperatures. Other than that I can't think of any other advantages, not to say there isn't though.

I would very much like to hear exactly what you mean by "marrying the crank bearings to the crank properly" should you be willing to explain in more detail.

The one piece head offers a few advantages over a two piece design,,,,cooling as you mentioned is one.....being able to index the sparkplug to deliver true spark to get complete combustion is another and not losing any un-necessary compression like the two piece head cap when it starts to leak from having two different thermal rates of expansion is a third.....Plus the 44mm cylinder has a disadvantage over the 40mm cylinder no matter if its 1pc or 2pc...

IDK where you get your info on rocket keys but here in this forum theres more than a few that have experience with them and have done unbiased testing to conclude they do indeed work on any type of engine and based on the type of compression and portwork affects the effectiveness aswell as outcome of the modification that is chosen even though I cant recall anyone other than myself that has retarded the rocket key to get the max revs these things can deliver...........

Even on chainsaw conversion to kart engines advancing or retarding the coil enhances power where needed..

Ive come to find that the 43cc barrels can and do deliver more power and revs over the 44mm cylinder mainly for a couple reasons like a heavier 44mm piston and a compression relief notch that slights-off compression which slightly diminishes power on the larger cylinder...

One thing to remember is these engines werent designed for rideables or performance.....They were designed for power and longevity to run powertools of all types.........Theyre gutless and under 2 hp bone stock.......They in no-way bear any real power resemblence to any Japanese ,Italian , German or Chechoslovakin made 2 stroke engines the chinese ripped the designs off of..

In order to get the truest power out of these engines the cylinders must be sleeved where the piston is surrounded 360 degrees by a cylinder wall..............
 

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UPDATE...............UPDATE

Just wanted to add a bit of info about the way the rocket key is setup...

Since not everybody can blueprint and port their own cylinders and rely on bolt-ons for their power enhancement the way I have the rocket key oriented in the pictures for both engines are set ADVANCED...This enhances mainly the bottomend power because these small engines have difficulty taking off from a dead stop.......

If you build stout enough engine and want to enhance revs because youre running a lightened clutch with a high engagement rpm youre gonna want to do the opposite of the pics and "RETARD" the rocket key................

Also to bump this thread.........:tango_face_devil:
Thanks for this thread. Its very usefull information for me and the others

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The one piece head offers a few advantages over a two piece design,,,,cooling as you mentioned is one.....being able to index the sparkplug to deliver true spark to get complete combustion is another and not losing any un-necessary compression like the two piece head cap when it starts to leak from having two different thermal rates of expansion is a third.....Plus the 44mm cylinder has a disadvantage over the 40mm cylinder no matter if its 1pc or 2pc...
I have a few ideas on how to improve on most of these points, if I ever do something about it then I will make a new thread on it.


IDK where you get your info on rocket keys but here in this forum theres more than a few that have experience with them and have done unbiased testing to conclude they do indeed work on any type of engine and based on the type of compression and portwork affects the effectiveness aswell as outcome of the modification that is chosen even though I cant recall anyone other than myself that has retarded the rocket key to get the max revs these things can deliver...........
That info was actually from on here, but a real long time ago, but as I said it doesn't matter anymore

In order to get the truest power out of these engines the cylinders must be sleeved where the piston is surrounded 360 degrees by a cylinder wall..............
I agree, use barrel intended for a 44mm piston, turn up a cast iron sleeve, cut the windows in it, press it in, do the final cleaning up / surfacing, hone and then fit a 40mm piston.
 

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Discussion Starter · #17 · (Edited)
I have a few ideas on how to improve on most of these points, if I ever do something about it then I will make a new thread on it.




That info was actually from on here, but a real long time ago, but as I said it doesn't matter anymore



I agree, use barrel intended for a 44mm piston, turn up a cast iron sleeve, cut the windows in it, press it in, do the final cleaning up / surfacing, hone and then fit a 40mm piston.
I dont know where youre gonna improve on sparkplug indexing but whatever floats your boat,,,no two sparkplugs are threaded the exact same unless hunted for.....

As far as your comment about what doesnt matter anymore about two stroke timing then why even bring it up?...

Just keep telling yourself these are industrial engines .............

Ive built these small cc engines from 18cc to 108cc every which way to sunday and done quite a bit of refinements on these engines with dual carb hybrid engine builds over the years running them on alky/methanol and yet to this date people wont do or try it because of the technical standpoints to the builds that 70% dont have the capabilities of performing on these lil engines and are content on what comes out in the wash doing a straight up build with what they get through the mail......

Ive yet to experience any type of seizures n such problems the others have experienced throughout the years and have shared the horror stories.............reason being the industrial engines are built retarded naturally to deliver descent torque while maintaining life longevity.....even if you make them racing engines they arent truely race engines without resleeving and remapping the ports..........Thats a process nobody will want to tackle but has been done FYI but wasnt feesable as heat breakdown was its #1 enemy after 10 mins of runtime ...

The only way is to cast up cylinders similar to stihl 2 stroke engines and producing them for the reed inducted market...............

We had a member named Mexicano......He was a very very thorough guy.....He went through every aspect of two stroke tuning/engine building that most of us know but with this chinese crap isnt too critical seeings theyre Industrial tool engines....

Cant recall hearing the work of art ever start n run but was a thorough build thread none-the-less.........It was an all-time greatest documented build-up on a chinese cag engine Ive seen all of the forum and yet its gotta be found to know it exists......Even Benefields Wickedly built Polini powered chinese miniquad.........That quad was insane and the guy who built it was a madman also a genius ........

Id love to hear what you come up with on port calculation numbers and how youre gonna fix retarded porting without smashing the piston off the dome...

Basically what I want to know is,,,,Whats gonna be your major point to your thread?

Is it to educate others as to the correct ettiquette to building small cc chinese made 2 strokers and show your truley a more superior two stroke build genius amongst us all?

If so theres a member here named rcfish90 building a whiz-bang of an engine yet you wipe your feet here instead of lending your expertise there.....kinda tells me theres something a lil more to the plot so I may go grab some popcorn with light butter and wait for it to thicken.....:tango_face_devil:

I really dont think too many will care about the extra thorough buildsteps especially the guy buying the engine unless it breaks some world record or something along that highway............LOL...

The hits on the previous 2 stroke refinement build threads throughout the years have proven that point especially this thread count....

Back around 2008 you couldnt get a straight answer out of anybody about squish and porting a 2 stroker,,,,everything was super critical or hyper critical etc written in degrees and technical terms making the layman scratch his head.......

One day I made the process easier when I threw out the dimensions and the technique on a much different scale that 75% could grasp and actually perform over the 15% previously who were doing it with milling machines and not by hand with a dremel or files n emery paper.................not everybody has access to a milling machine so anything taught on the subject using such a device is kind of a moot point...........

Only a dozen or slightly more I know of tried refining an industrial engine to make it an actual purpose built racing engine over the many who said theyd love to do it but dont have the tools,talent or the place to do all the work...

Those that did the extra work were very happy they went the extra step because they were actually racing their chinese junk and it made a definate improvement.........

Do a build-up on a whole bunch of non-running bikes or build an aircooled cag that will compete with the watercooled 50cc eurobike racing classes and most will be more interested.......

Good Luck

 

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CAM2: I don't know if I am just coming across wrong or it's something else. Just in case there is any misunderstanding I thought I better state some things. I am usually doing a lot of questioning on peoples points and maybe this comes across as arrogant or me being critical of what's being said but that's not how it is. I just want to learn the theory behind what's suggested instead, otherwise I think there will always be shallow limit to what's learnt. So if I have irritated you in some way then I apologise and I want you to let me know if I have and ever do from here on. If you think things would be better without my posts on here then just tell me and I will just leave and you are welcome to delete my posts. I would find it regrettable though as I have been able to get some really good information on here.

I will also try and be more clear with what I am trying to explain technically as I see it's also been misunderstood a few times, easy to happen when almost all of my waking hours are in a seriously bad physical state.

As for me talking about custom machining work, I am not looking down on others for not having the same resources, nor am suggesting others should be doing that. Rather I just find it interesting to talk about the technical aspects and concepts, even if it's not practical at times.
 

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Now with my comments below you don't have to answer them, I know I do have the primary blame for this thread going off topic.

I dont know where youre gonna improve on sparkplug indexing but whatever floats your boat,,,no two sparkplugs are threaded the exact same unless hunted for.....
I am pretty confused here, it was you 4 days ago back in post #14 that suggested indexing the plug. Oh wait did you think I was saying that I could do something with a head to improve the indexing of a plug, because if so that's not what I meant. Anyway lets drop the subject.


As far as your comment about what doesnt matter anymore about two stroke timing then why even bring it up?
I asked originally because back on here quite a long while back it was commonly shared information that a "rocket key" and a 2-piece head was a bad combo. What I meant is that because you cleared that misinformation up there was nothing further to discuss about that one point.


Just keep telling yourself these are industrial engines .............
I know and you're right, I have a bad habit of getting carried away with the concept ideas that are in my head at times. I know these are very poorly made engines that are not at all originally intended for what we are using them for. I just think it's fun to explore ideas on how to maximise them that's all.


The only way is to cast up cylinders similar to stihl 2 stroke engines and producing them for the reed inducted market.............
Ha ha, well that isn't going to happen, I might like to talk about some idealistic concepts but there is only so far I am willing to polish a turd


We had a member named Mexicano......He was a very very thorough guy.....He went through every aspect of two stroke tuning/engine building that most of us know but with this chinese crap isnt too critical seeings theyre Industrial tool engines....

Cant recall hearing the work of art ever start n run but was a thorough build thread none-the-less.........It was an all-time greatest documented build-up on a chinese cag engine Ive seen all of the forum and yet its gotta be found to know it exists......Even Benefields Wickedly built Polini powered chinese miniquad.........That quad was insane and the guy who built it was a madman also a genius ........
Because of the amount of reading I have done in old threads over the last couple of weeks I did go through all of Mexicano's thread previously and I agree it's a really good read. I really wanted to see the result of it running though, in particular his CDI ignition idea as it's something I have been thinking about for a while. I also really liked the thread from Uncle Percy, I thought it was really clever.


Id love to hear what you come up with on port calculation numbers and how youre gonna fix retarded porting without smashing the piston off the dome...
From all the reading I did I worked out something along the lines of these numbers might work for me:

Exhaust= 100 degrees ATDC / 160 duration
transfers= 125 degerees ATDC / 110 duration
Blow down 25 degrees ATDC

I don't know if it's the right choice or not though. But as you have said yourself it's more than just the degrees, there are other factors too. I don't know how things are going to work out with adjusting the port timing and where the piston ends up in relation to the deck. I am a while off checking these and only once I do a test fit and start measuring will I see what my options are.


Basically what I want to know is,,,,Whats gonna be your major point to your thread?

Is it to educate others as to the correct ettiquette to building small cc chinese made 2 strokers and show your truley a more superior two stroke build genius amongst us all?
Definitely not, as I mentioned above I thought it would be interesting to discuss these ideas but it looks like it was just me. Once again I think you have misunderstood me, being blunt I have very little real world experience and I feel like I am barely scratching the surface with knowledge on these. If I knew more then I probably wouldn't have my motorbike out of action because I can't figure out why my Blata W50 isn't running right. The contradiction of a 2-stroke: Only 3 main moving parts but yet they hold such a complexity to them.


Back around 2008 you couldnt get a straight answer out of anybody about squish and porting a 2 stroker,,,,everything was super critical or hyper critical etc written in degrees and technical terms making the layman scratch his head......
I completely agree, I started reading on here in 2006 and like the example of the rocket key and 2-piece head combo there were so many "facts" on here that were accepted and now only in hindsight so much of it was crap. When I finally came back on here about a month ago I was not only pleasantly surprised by how much the quality of information had improved but also the fact that people like yourself and EPR are still regularly making really helpful posts.


Back around 2008 you couldnt get a straight answer out of anybody about squish and porting a 2 stroker,,,,everything was super critical or hyper critical etc written in degrees and technical terms making the layman scratch his head.......

One day I made the process easier when I threw out the dimensions and the technique on a much different scale that 75% could grasp and actually perform over the 15% previously who were doing it with milling machines and not by hand with a dremel or files n emery paper.................not everybody has access to a milling machine so anything taught on the subject using such a device is kind of a moot point...........
and I commend you for it, if I didn't respect what you had to say I wouldn't try and get more information out of you. Only once so far have I said something in regard to disagreeing with you, and that was only one one small aspect of a whole heap of really good information and also only when it was with one application.
 

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Discussion Starter · #20 · (Edited)
Wow I was right... you are a very confrontational guy but obviously doesnt comprehend too well so let me clarify a lil more for you ,,,,,Yes;- I did bring up indexing of the sparkplug and " you said" a point well worth improving on...........

FYI:......You use index washers to achieve this....hard to improve on a process thats been in practice a very long time without over-complicating it...........Index washers cost $6.00 per assortment pack where I get them.....

Please,,,,start your own thread....I want to see what a true 2 stroke genius can pump out using machinery most dont have.

Do it all by hand and most will be more impressed.

Show us-dont tell us or hijack threads to show your 2 stroke prowness youve researched up,,,,,build it and document it on your own thread like you said you were going to do...Whats the hold-up?

These engines arent very big at all and cost peanuts compared to what im building now but in any event it shouldnt take you but a day with very expensive time saving tools.....Make sure you do an in-depth on the brand of machines used,,types of jigs and how you jigged it down,,setup time,,program type,runtime,,kilowatts of power used to perform the task, expense per hour machine used makes in the real world,types of toolbits and cost to resharpen,,,etc...

Just be sure you get all that scientific terminology correct professor so you can try and rise above us all in a halo of greatness youre striving to achieve...:tango_face_glasses:

Look at the start date of this thread..You should of shown-up back then so we could all be corrected when it mattered like it really matters in the first place,,,being late to the party must be how you roll...

Maybe you should do a bunch of in-depth you-tube segmented videos on how to show CAM2 how to build real high performance chinese engines and not break the bank doing it....Now that would be highly original although I can take credit for the idea.....LOL
 
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