Wouldnt this depend a lot on transfer port timing? If the transfer ports are opening before the ring gets below the top of the exhaust port that would allow the expanding exhaust gasses to push backwards into the case potentially igniting all of that as well as actually stalling the intake pulse if the intake port was on its last degree or 2 of being open. But if the transfer ports aren't open yet the expanding exhaust gases are still pushing only on the piston, creating power and the case volume is decreasing, which also stalls the intake pulse but its not screwing with the direction of air flow in the transfer ports, they are basically dead air. So the exhaust opening (ring below top of port) only after the intake is fully closed (skirt below port) is important because then case pressure is building to prevent reverse flow of exhaust gases when the transfer port begins to open (ring below top of port) which i would assume you would want to happen just after the exhaust cracks open so that the exhaust is starting to escape through the exhaust port and there is more pressure in the case that will force the intake charge through the transfer ports with more speed and expell the exhaust gasses faster But then theres the intake shit that needs to be taken into account... fuck. It's been 20 years since I've actually thought about 2 stroke port timing and I used to have the concept down pretty good and now I'm playing mental gymnastics once again trying to remember the theories on how it all works. Plus, I keep thinking about things that would apply with reed valve cases when there is an actual valve preventing backflow if the transfer ports are open before the exhaust is open... I wonder if I still have all of my notes on port timing theory, exhaust scavenging and expansion chambers, and all of the other shit I made copies of and printed out back then... Why the hell do I do this to myself...
Excellent bit of information on that, and your correct on no one sharing information with anyone. I found that out years ago with the two stroke dirt bike engine builders back in the 70's and 80's. You would of thought you were asking for the secrets to understanding women, or how to convert lead to gold or something serious like either of those. So finding someone who isn't insecure about himself or his abilities to be above average in his trade craft is not the norm for such things as engine builders of any kind, especially preformance builders.
Thanks John....New to this porting hobby and this is the first I heard of this. Makes absolute sense. Off to the shop to check a 394 I have apart and waiting for parts. Thanks again.
Thank you for sharing. Just found your channel today and subbed. I’m wanting to learn all I can and for somebody just starting this is very much appreciated information.
Great video, very good point you are pointing out! For those who did not catch the facetious statement about taking out the top ring and trying compression check, basically It is because the combustion chamber is not sealed. You have a few degrees of crank rotation before it seals. If it's sealed earlier in the stroke it would give you higher compression. Like he said it will run but the compression would be lower than if the chamber was sealed.
That was a good tip. Thank you. Subscribed now. Always interesting to hear and see how you "over there" think about things differently. Like focusing on exhaust port opening and transfer port opening in the unrelated degrees after TDC in stead of total open duration that is based on degrees from bottom dead center.
Lowering intake for more torque. Highering exhaust for more top end. Damn dude. Thanks. You got a sub. Will try to port my own echo 3510. Not sure if I want it snappy or high end. Or a little of both lol.
Thank you for the heads up John, I've been building and working on saws since I was a kid and I'm just now starting to mess around with porting and any other ways to gain extra power out of most of my saws or when ever I get new power heads. A lot of the stuff that I have learned is either from your channel or the IronHorse and I have to say you both have a really good knowledge on the do's and don'ts when it comes to hopping stuff up. So once again thank you very much for the quick awesome trick on how to tell if your saws going to have good power out of the box.Also at least that was an aftermarket head, but still don't blame you for being pissed off on wasting your time when you could have prevented it like you said. P.S. I like the video for ya👍
Really appreciate passing on of info. But I dont get this one. What are we saying the problem is with the inlet opening before the ring closes the exhaust ? Is the probIem during compression stroke - seems to be what's suggested - but I cant see any pressurised mix reaching the crankcase let alone the inlet. Or is the problem on the exhaust stroke where there might be a pressure pulse generated in the exhaust as the ring crosses the exhaust port ....could generate a pulse into crankcase and inlet port maybe? Be great to get a reply !
I'm also interested as to why it screws up performance. It would have been great had he delved into the issue/problem that is created by this mis-match. Perhaps he'll see your post....
Perhaps the lack of seal for that portion of rotation negatively affects the quality of the vacuum, and the volume of intake charge being dragged down into the crankcase?? Guessing here...
So at 8:00 specifically. Where and what would you grind out. Would you focus 75% on dropping the intake and then 25% on the exhaust or 50% intake 50% exhaust or 25% intake and 75% exhaust. Thanks!!, Hope you see this comment, its been over 2 years since you put this video out
This is a great help to me. I bought 2 G111 saws and I considered cleaning up the ports. Roughish on the intake and polishing the exahaust. But I won't unless the saw is too disappointing. One bit of advice I got to make them run like the 200t was a gasket delete and to port the muffler. I'm not looking to make it a mini race saw. I just want it to cut as well as my 200t I use to have did. The 200t was brand new when I bought it and just stock.
If only everyone would be as kind as you, and share your hard earn knowledge, we wouldn't be wasting thousands (if not more) of man hours. Sadly this happens in most industries, entire business models are created on asymmetric information. Thank you!
Man i know you are super busy but id absolutely love to be able to learn even9re from you. I watch alot of your stuff and have just gotten into porting saws. I love my new hobby and i appreciate what you do
thank you John! as always.... you are a wealth of knowledge as well as a pleasure to watch. you're a 2 stroke magician man!!! Keep up the great work & keep the videos coming!👍👍👍
Don't feel bad. I've jumped the gun once to on not checking the fitment and kicked myself. We all have our blond moments when not checking aftermarket components beforehand no matter how experienced. But at least we catch it before major embarrassment occurs if we would have assembled and ran it. At least you got on top of it. Great learning video for the novice and thanks for the heads-up.
Not sure if I completely understand, but how does a ring that's too low while the intake is opening lead to "short circuiting" if the transfer ports are closed? I understand that the earlier you can get the ring to seal, the more compression you have, but what has that to do with the intake?
Glad I'm not crazy for having the same thought. Intake and exhaust being open simultaneously while transfers are closed would not lead to free porting. Unless I'm missing something major but spinning around my cutaway I don't see a problem.
I learned so much from your limb reaper 200T, I was able to do my neighbors for him and he loves it. Won't even touch his stock ones anymore. You passed on the knowledge and I'm thankful.
Game changer for guys. Great Information!!! This is what helps everyone in this community. Thank You. John, what about a husky piston in that cylinder... it should have a higher top ring.
I just ran across this video. I just happened to have a 046 & and a 064. I plan on some engine work on the 064. Thanks for the info. Great content! You rock!
Thanks John for the really important tip. Please don't even worry about the haters, just jealous of your skills and knowledge. BTW, would like to purchase one of the awesome 462 builds. Please message me on how I can get a hold of you.. all the best my friend 11:24
I understand you said you were taught by and older professional builder, but that may have been the older days. Why would that be free porting. Why would the motor lose power because of that unless it was and old McCullough engine Maybe ? Technology has changed a lot sense then. Now If the bottom of the piston shirt was open at the exhaust port at tdc then that would be considered free porting and some of the intake charge would escape and you would probably loose power in the low rpm range. But having the intake still open when the compression ring just cracks the exhaust port, would probably hurt nothing. No charge is being lost just exhaust gases exiting the exhaust port.. I have ported kart engines for years and don't really see a problem with what you have there, unless the rest of the cylinder is junk. And I Hate cheap China aftermarket cylinders too. Most are total garbage. Keep up the good work it's a good way to show your customers sometime it's not worth using the cheaper stuff .
I wish there was more explanation too. I can't see what that ring getting past the exhaust port has to do with the intake. They're on two separate ends of the piston. Only thing I can think of is backpressure from the muffler getting past the piston skirt while the intake is still open on the downward stroke.
That is something that was talked about in the 70's, 'free port' where intake and exhaust can be 'open' at the same time. Even though I've never done chainsaw motors, 'everyone' tuning two strokes should know about it and check. In early 2000's when 'pocket bikes' were everywhere, tuning them was a lot of fun , guess they were similar to chainsaw motors? Something else people don't realise, every time you raise exhaust you lower compression slightly which loses torque. Majority of two stroke run a corrected compression around 6~7:1, I always laughed when people started saying they were running 'race gas' and 14:1 (or more)
I learn something new every day, man. Makes me wonder if the first saw I ported (which I will never show anyone the cylinder because it's horrifying) had that issue on top of what I did to it...🤔
Is scavenging not a factor without an expansion chamber? Because with dirtbikes and snowmobiles they say having a slight overlap allows the exhaust gas exiting the cylinder pull a denser fuel/air charge into the crank case making more power.
But why? The crank case is closed already the transfers are closed so it is not affecting this i dont understand it can you explain it to me please? Thank you
Thanks John, i will check that on my Testsaw and rethink that to understand exactly the Functions. Is that the Point when a Saw barks back through the Intake , caused of to much intake Timing? I will check that on different Saws that show up in my Shop. Thanks a lot Man!
Amazing video! Can you share how much to shave off the bottom intake side? Is it in relation to the top ring above the exhaust port to the opening of the intake and shaving it down right before the intake opens? Thanks again for the impressive videos. A+ I am working on a 45cc rovan rc engine.
Thank you! I've watched countless hours on 2 strokes, not once have I seen this. Thank you, again...
This is one of the most helpful bits I've heard/learned about an engine in a long, long time.
Thank you for this.
Im doing things with saws I never thought I would do because of this channel, you're an inspiration mate
I just start cutting exhaust ports out😂
@@juledorenthink that’s where it starts. Didn’t last long hogging on mufflers myself before I decided grinding on the steel might help too.
Hey mate , checking in from brissie 🙌
I’m not a professional chainsaw guy but I loved the cut away. That really helped.
Probably the best video I’ve watched on porting. I feel comfortable giving it a shot now.
cheers from ireland ,i just do simple porting on my saws but you really explained it in a simple way .thank you.
Wouldnt this depend a lot on transfer port timing? If the transfer ports are opening before the ring gets below the top of the exhaust port that would allow the expanding exhaust gasses to push backwards into the case potentially igniting all of that as well as actually stalling the intake pulse if the intake port was on its last degree or 2 of being open.
But if the transfer ports aren't open yet the expanding exhaust gases are still pushing only on the piston, creating power and the case volume is decreasing, which also stalls the intake pulse but its not screwing with the direction of air flow in the transfer ports, they are basically dead air.
So the exhaust opening (ring below top of port) only after the intake is fully closed (skirt below port) is important because then case pressure is building to prevent reverse flow of exhaust gases when the transfer port begins to open (ring below top of port) which i would assume you would want to happen just after the exhaust cracks open so that the exhaust is starting to escape through the exhaust port and there is more pressure in the case that will force the intake charge through the transfer ports with more speed and expell the exhaust gasses faster
But then theres the intake shit that needs to be taken into account... fuck.
It's been 20 years since I've actually thought about 2 stroke port timing and I used to have the concept down pretty good and now I'm playing mental gymnastics once again trying to remember the theories on how it all works. Plus, I keep thinking about things that would apply with reed valve cases when there is an actual valve preventing backflow if the transfer ports are open before the exhaust is open...
I wonder if I still have all of my notes on port timing theory, exhaust scavenging and expansion chambers, and all of the other shit I made copies of and printed out back then...
Why the hell do I do this to myself...
The exhaust port always opens well before the transfers. This is called blowdown.
What about modifying piston skirt to open intake earlier?
Excellent bit of information on that, and your correct on no one sharing information with anyone.
I found that out years ago with the two stroke dirt bike engine builders back in the 70's and 80's.
You would of thought you were asking for the secrets to understanding women, or how to convert lead to gold or something serious like either of those.
So finding someone who isn't insecure about himself or his abilities to be above average in his trade craft is not the norm for such things as engine builders of any kind, especially preformance builders.
Thanks John....New to this porting hobby and this is the first I heard of this. Makes absolute sense. Off to the shop to check a 394 I have apart and waiting for parts. Thanks again.
Thanks for the information. I'm new to 2 strokes. Really appreciate it
Thank you for that! As a newbie at porting explains alot. Appreciated much!
Truly appreciate the info. Info I would’ve never thought of after 45yrs of messing with 2 strokes !! Thank you
Good stuff
Those big bore kits are all problematic, good tips man thanks for sharing. Keen to see this running
Thank you for sharing. Just found your channel today and subbed. I’m wanting to learn all I can and for somebody just starting this is very much appreciated information.
Great video, very good point you are pointing out! For those who did not catch the facetious statement about taking out the top ring and trying compression check, basically It is because the combustion chamber is not sealed. You have a few degrees of crank rotation before it seals. If it's sealed earlier in the stroke it would give you higher compression. Like he said it will run but the compression would be lower than if the chamber was sealed.
That was a good tip. Thank you. Subscribed now. Always interesting to hear and see how you "over there" think about things differently. Like focusing on exhaust port opening and transfer port opening in the unrelated degrees after TDC in stead of total open duration that is based on degrees from bottom dead center.
Lowering intake for more torque. Highering exhaust for more top end. Damn dude. Thanks. You got a sub. Will try to port my own echo 3510. Not sure if I want it snappy or high end. Or a little of both lol.
Excellent vid.this is exactly how I work out what I can do to a saw.
You explain things really well, appreciated. Liked, subscribed and left a comment.
Never heard anyone else talking about this and it makes total sense. Thanks for sharing, keep up the good work, appreciate all you do buddy.
Just compared a genuine to aftermarket and your spot on
The amount of knowledge I’ve gained from this channel is insane. Thank you
Thank you for the heads up John, I've been building and working on saws since I was a kid and I'm just now starting to mess around with porting and any other ways to gain extra power out of most of my saws or when ever I get new power heads. A lot of the stuff that I have learned is either from your channel or the IronHorse and I have to say you both have a really good knowledge on the do's and don'ts when it comes to hopping stuff up. So once again thank you very much for the quick awesome trick on how to tell if your saws going to have good power out of the box.Also at least that was an aftermarket head, but still don't blame you for being pissed off on wasting your time when you could have prevented it like you said.
P.S. I like the video for ya👍
Really appreciate passing on of info. But I dont get this one.
What are we saying the problem is with the inlet opening before the ring closes the exhaust ? Is the probIem during compression stroke - seems to be what's suggested - but I cant see any pressurised mix reaching the crankcase let alone the inlet. Or is the problem on the exhaust stroke where there might be a pressure pulse generated in the exhaust as the ring crosses the exhaust port ....could generate a pulse into crankcase and inlet port maybe?
Be great to get a reply !
I'm also interested as to why it screws up performance. It would have been great had he delved into the issue/problem that is created by this mis-match. Perhaps he'll see your post....
Perhaps the lack of seal for that portion of rotation negatively affects the quality of the vacuum, and the volume of intake charge being dragged down into the crankcase?? Guessing here...
Wow I’ve never heard this…appreciate the share of knowledge 💯
So at 8:00 specifically. Where and what would you grind out. Would you focus 75% on dropping the intake and then 25% on the exhaust or 50% intake 50% exhaust or 25% intake and 75% exhaust. Thanks!!, Hope you see this comment, its been over 2 years since you put this video out
Very good tip I’ve never heard any other channel mention. Thanks.
Thanks for sharing your knowledge to help us all out thank you!!
This is a great help to me. I bought 2 G111 saws and I considered cleaning up the ports. Roughish on the intake and polishing the exahaust. But I won't unless the saw is too disappointing.
One bit of advice I got to make them run like the 200t was a gasket delete and to port the muffler.
I'm not looking to make it a mini race saw. I just want it to cut as well as my 200t I use to have did. The 200t was brand new when I bought it and just stock.
Excellent site. Glad I found it. Thank you!
This is an awesome video. I still don’t understand a lot but I’m learning!
That cleared up a lot of questions I’ve always had about the intake charge
Without proper ring seal you have low negative pressure
If only everyone would be as kind as you, and share your hard earn knowledge, we wouldn't be wasting thousands (if not more) of man hours. Sadly this happens in most industries, entire business models are created on asymmetric information. Thank you!
Man i know you are super busy but id absolutely love to be able to learn even9re from you. I watch alot of your stuff and have just gotten into porting saws. I love my new hobby and i appreciate what you do
Thanks for sharing another cool video !
Great video man! I can absolutely understand what your explaining here and yes it makes total sense. Good job keep sharing your knowledge, thanks!
I watch a lot of saw modding channels and have never seen this. Instant new subscriber.
Great video and knowledge, I really appreciate this advice, thanks
thank you John! as always.... you are a wealth of knowledge as well as a pleasure to watch. you're a 2 stroke magician man!!! Keep up the great work & keep the videos coming!👍👍👍
Don't feel bad. I've jumped the gun once to on not checking the fitment and kicked myself. We all have our blond moments when not checking aftermarket components beforehand no matter how experienced. But at least we catch it before major embarrassment occurs if we would have assembled and ran it. At least you got on top of it. Great learning video for the novice and thanks for the heads-up.
First I've heard of it so thank you sir
Thanks John. Now I will have to check the cheapo big bore I pulled off of the 066 because of an odd miss. The intake was way too low out of the box.
Good to see you back in action i wondering why I hadn't seen any of your videos
Don't get mad, get even 😜 A great gift! Thank you.
Not sure if I completely understand, but how does a ring that's too low while the intake is opening lead to "short circuiting" if the transfer ports are closed? I understand that the earlier you can get the ring to seal, the more compression you have, but what has that to do with the intake?
Glad I'm not crazy for having the same thought. Intake and exhaust being open simultaneously while transfers are closed would not lead to free porting. Unless I'm missing something major but spinning around my cutaway I don't see a problem.
Interesting. Porting seems like such an art. I like rules of thumb like this..
I learned so much from your limb reaper 200T, I was able to do my neighbors for him and he loves it. Won't even touch his stock ones anymore. You passed on the knowledge and I'm thankful.
Game changer for guys. Great Information!!! This is what helps everyone in this community. Thank You.
John, what about a husky piston in that cylinder... it should have a higher top ring.
Hell yeah! Makes perfect sense, just never thought about it that way.
That's gold.👍👍
I just ran across this video. I just happened to have a 046 & and a 064. I plan on some engine work on the 064. Thanks for the info. Great content! You rock!
This has just made things so much easier for me
we don't have this very cool saw modding thing here, but we do have 2 strokes so this can very well be applied to scooters as well, great videos
John were with you 100% buddy. Thanks
Good advice 👍
that is a very simple check no one ever told me on any channel! thanks a lot!
Thanks John for the really important tip. Please don't even worry about the haters, just jealous of your skills and knowledge. BTW, would like to purchase one of the awesome 462 builds. Please message me on how I can get a hold of you.. all the best my friend 11:24
So how are you makin up the stroke difference? The 064 crank is wider than the 460.
First time here, have 2 031av saws to rebuild, guess I'll be binge watching for a while,
That was very helpful I kid you not that was very very insightful thank you 🤣👍👍👍👍
I understand you said you were taught by and older professional builder, but that may have been the older days. Why would that be free porting. Why would the motor lose power because of that unless it was and old McCullough engine Maybe ? Technology has changed a lot sense then. Now If the bottom of the piston shirt was open at the exhaust port at tdc then that would be considered free porting and some of the intake charge would escape and you would probably loose power in the low rpm range. But having the intake still open when the compression ring just cracks the exhaust port, would probably hurt nothing. No charge is being lost just exhaust gases exiting the exhaust port.. I have ported kart engines for years and don't really see a problem with what you have there, unless the rest of the cylinder is junk. And I Hate cheap China aftermarket cylinders too. Most are total garbage. Keep up the good work it's a good way to show your customers sometime it's not worth using the cheaper stuff .
I wish there was more explanation too. I can't see what that ring getting past the exhaust port has to do with the intake. They're on two separate ends of the piston. Only thing I can think of is backpressure from the muffler getting past the piston skirt while the intake is still open on the downward stroke.
Just came across your site. Impressed in the few minutes! Thanks
Thank you for this info!! 🙏
Very cool information thank u 4 sharing!!!
Got this on my main feed, looking forward to seeing more content
Thank you first time hearing that
Thanks for that Tasty piece of info 👽👍
Never heard this before. I’m interested if that’s why a few saws I’ve done don’t run as well as the others
Thanks for sharing. 👍
Thanks brother...I'm always learning from you...keeping it rowdy.
Great info my man, we def appreciate the knowledge you share!
That is something that was talked about in the 70's, 'free port' where intake and exhaust can be 'open' at the same time.
Even though I've never done chainsaw motors, 'everyone' tuning two strokes should know about it and check.
In early 2000's when 'pocket bikes' were everywhere, tuning them was a lot of fun , guess they were similar to chainsaw motors?
Something else people don't realise, every time you raise exhaust you lower compression slightly which loses torque.
Majority of two stroke run a corrected compression around 6~7:1, I always laughed when people started saying they were running 'race gas' and 14:1 (or more)
Thank you for the tip ,your a big help !
I learn something new every day, man. Makes me wonder if the first saw I ported (which I will never show anyone the cylinder because it's horrifying) had that issue on top of what I did to it...🤔
Thanks for sharing. Hotrodders will hotrod!
Great info. Thanks for sharing . It makes so much sense, now that you pointed it out.
Thank you so much for sharing!
Is scavenging not a factor without an expansion chamber? Because with dirtbikes and snowmobiles they say having a slight overlap allows the exhaust gas exiting the cylinder pull a denser fuel/air charge into the crank case making more power.
Great video!! Thank you for that information!
Hey Eric! Just subscribed to your channel as well! 🤘
But why? The crank case is closed already the transfers are closed so it is not affecting this i dont understand it can you explain it to me please? Thank you
I'm wondering the same
Always learn something watching your videos.Keep up the good work.
Well that explains a great deal. Thanks for sharing that.
Thank you John!!!
Thanks John, i will check that on my Testsaw and rethink that to understand exactly the Functions. Is that the Point when a Saw barks back through the Intake , caused of to much intake Timing? I will check that on different Saws that show up in my Shop.
Thanks a lot Man!
So can you add base gaskets to lower the upper exhaust port? I know compression would be less however, is the addition a benefit?
Quality info,cheers, much appreciated.
Awesome info big Thanks John
Great video
Thank you for sharing that info John 🫶🏿
Mr John can you port a ryobi saw and raise the CC's ?
Well I guess I now have to go look at my saws lol. Never heard of this rule and I've been watching a ton of builders
This is gold thank you very much John
Wow ya that makes perfect sense and I could see how that would be a easy miss!
Thank you so much :) best tip I have ever learned!!!
Thanks👍
Nice tip 👍 makes sense 👍
Great vid. Question does the shaved flywheel cool the saw for sawing notmally
Amazing video! Can you share how much to shave off the bottom intake side? Is it in relation to the top ring above the exhaust port to the opening of the intake and shaving it down right before the intake opens? Thanks again for the impressive videos. A+
I am working on a 45cc rovan rc engine.
Thanks a lot man, great video!