Any Interest In Revisiting Porting The 550XP?

[bryanr2]

I totally do, and I wish other builders would keep it civil or pick up the phone or discuss via private message. If they think they can do better, then they should take the time to post their own thread rather than critique another.

Quite honestly, it doesn't reflect well on the pot stirrer.

+1- builders should be required to stay out of builders threads (unless invited to contribute). If there is bad blood at least demonstrate some respect and propriety. And I do agree, if you want to challange another builder's approach to a saw...... get a hold of the same model saw and show the AS community what you would do different- in other words "put your money where your mouth is".

 

[blsnelling]

Randy was showing HIS WAY of doing HIS BEST results. It may not be the best way in some peoples eyes and if that's the case don't look

+1- builders should be required to stay out of builders threads (unless invited to contribute). If there is bad blood at least demonstrate some respect and propriety. And I do agree, if you want to challange another builder's approach to a saw...... get a hold of the same model saw and show the AS community what you would do different- in other words "put your money where your mouth is".

Guys, you are making out of this what it was never meant to be. In no way was I criticizing Randy's work. Quite the opposite. I was looking to learn why he did what he did. Evidentally, my attempt at having a conversation was poorly executed. I should have worded it differently than I did. I happen to know that Randy does his homework, and figured that he had tried different amounts of blowdown. Randy doesn't need to "defend" his methods. I'm not asking that he does. Carry on

 

[Jimmy in NC]

I think what we forget is how much time is spent uploading pictures and video to make a build thread. If you took a break I'd understand as that frees up time for you to build more saws per day or spend time with family and other commitments.

Keep doing what you do buddy! Some of us really appreciate it!

FWIW...I was playing with a rack full of new saws today thinking...which one do I want and what one will Randy wring the most out of?

Jimmy....mobile.

 

[procarbine2k1]

I've been meaning to do a build thread on my 066, but I didn't take no pitchers. If you aren't going to do more of these threads lemme know Randy, so I can upload my paintshop sketches of my work.

On a serious note... I know these threads take up some real effort and time. If you enjoy doing them and enjoy sharing your work, I don't see why the 99.99999% here should suffer because of the .000001% pissed ya off....

I am going to copy this thread, before Breaking Bad is over and it gets deleted :hmm3grin2orange:... Thanks for what you've done so far, I enjoy the build threads quite a bit.

 

[bryanr2]

the 346/ 550 debate has come up before between Randy and Brad- and I believe it is a "sore spot" between them. It's public record here bc it was made public record by Brad- what his experience with the 550 was. One could conceive that experience has cast a negative light on the 550 for Brad. Brad made it clear on the first page of this thread that he is "hoping the 550 will run like a 346". Point of fact- the 550 and 346 are not the same and should not be expected to perform the same. I won't ellaborate bc the info is in the threads as to what each thinks if one wants to look for it. While most consider the 346 the "holy grail" of 50cc saws, the fact of the matter is the 550 is the new kid on the block with the 346 out of production. Randy has clearly found a recipe for the 550 that is getting gains. Each model (no matter what model) has to stand on it's own as far as what we can expect to get out of it. Mastermind has done almost a dozen of these- so I suspect he is well on the way to figuring them out...... something that we all benefit from. And it stands to reason that those that make money from building saws would be mighty interested in any progress in a models evolution. 550 is where the builders are going to make their money in the future...... yall will eventually run out of 346s to build. I suspect it's not good business to compare "whats now avail to buy-550" to "what was avail- 346". Steering folks away from the new model by comparing it to the 346 will eventually cost builder's in their pocket.

 

[bryanr2]

I think what we forget is how much time is spent uploading pictures and video to make a build thread. If you took a break I'd understand as that frees up time for you to build more saws per day or spend time with family and other commitments.

Keep doing what you do buddy! Some of us really appreciate it!

FWIW...I was playing with a rack full of new saws today thinking...which one do I want and what one will Randy wring the most out of?

Jimmy....mobile.

Doesn't matter the model- I've never had a complaint or concern on a single saw.... and I have sent a variety.

 

[morewood]

I'm gone most of the day, get back a few minutes ago....BAM!! 4 pages of a brewing who can piss the farthest.....or it could be a misunderstanding. I believe the later, or hope it's so. True, Randy has done all my saws for me, but I hold Brad in high regard. I hate seeing lines formed, trenches dug, and volleys fired over inconsequential crap. I love all the build threads from different builders, but if it always gets turned one way or another it will turn people away. Reading an argument is a downer.

Shea

PS-If both of you would send me your best 550 I would be glad to test them out and give an unbiased report. Then we could send them to Chadhiman? And let him do the dyno.

 

[Mastermind]

Have you tried more blowdown, ending up with 346 like numbers? Just pointing out the obvious, but you could try that by simply not raising the transfers back up after the machine work.

BTW, very pretty work!

OK.....I've had a shower. It's pretty obvious that a lot of guys read VS how many post in these threads.

At this time this thread is at.......

Replies: 145
Views: 3,834

I want to address Brads question.....but first I'll explain a few things about myself.

I'd like to share my view on these strato engines for all those guys that are just reading this stuff hoping to learn something. I love to learn, and am constantly studying something. I came to AS not knowing anything at all about two-stroke engines, but thanks to guys that were willing to share (like Brad) I learned a lot and learned it pretty fast. I did have a few things going for me though, I took every small engine and shop class that was offered in school, then two years of auto mechanics training at Central Carolina Community College, worked as a mechanic for a while when I got out of school, and then drag raced and built engines for myself and others for many years. Hot rodding stuff is in my blood, but I have to know more than, it just works, I need to know why it works. This lead me to study how a strato engine works.

In this video you can see how the fresh air charge in blue flows down the transfer tunnels, then reverses when the case pressure forces it back into the cylinder.

[video=youtube;IY7zQKw4qsQ]http://www.youtube.com/watch?v=IY7zQKw4qsQ[/video]

That's why I said.....

That would be a bad move on a strato engine.......remember, it's just fresh air that's coming in when the transfers first open.

Brad answered.....

It helps make more power on other stratos.

It may or may not make more power to increase blowdown, but I'm more interested in making good gains over stock, while retaining the excellent qualities of this engine. I'd give up a few tenths of a second in the cut to keep the fresh air in the proper area at the proper time to purge the cylinder as designed, without all the exhaust fumes that two strokes are famous for. Now, I'm not an engineer, but I know some, The group of people that designed this engine I'm working on are very intelligent engineers. They have designed an engine that runs great, uses less fuel, and make less hydrocarbons than a "regular" two stroke engine by using stratified technology.

More blowdown would simply allow more fuel/air mix to go out the exhaust.......if you figure 5° of crankshaft rotation is just air (and that's just a hairy guess BTW) then the transfers would be allowing fuel mix to enter at 121° atdc the way I have it now. .

Please ask any questions you want to, but please consider the answer that was given before moving on as if nothing was said. I really enjoy this stuff. I'm just now starting to feel like I understand half of what I thought I knew two years ago......

 

[Officer's Match]

Good on both you guys. This is why I'm here.

 

[LowVolt]

I hate to see these threads go away. Randy's threads are hands down, by far, THE best build threads on the interweb. PERIOD! Just awesome to see his saws come to life!

 

[LowVolt]

Very cool video!

 

[MindFork]

Anybody want to see more build threads from Mastermind? I do. They add a lot to this place.

Just a noob to the forum, but I learned a lot from this thread, and hope to see more.

 

[cpr]

Niko, Bragging rights are a totally different category than practical cuttin......Pride baby Pride......

:hmm3grin2orange::hmm3grin2orange:

No offense, friend, but it's my experience that speed and success in life is the parabolic, non-linear inverse of one's ability to swallow, in one bite and without choking, the same "category."

Cheers.

Carry on, gentlemen.

 

[Terry Syd]

Randy, I've discussed this before and I think you have worked with and developed the Husky design quite intelligently.

As some background - The Husky stratos are an interesting design that negates some of the modding concepts of conventional saw engines. The short blowdown and long transfer tunnels appear to work together. After a Husky strato has been run for some time, there is quite a bit of carbon blowback down into the tunnels that shows how the short blowdown has been pushing exhaust gases way down the tunnels. What is significant is the blowback does NOT mix with the fresh air/intake gases - it is contained in the tunnels.

However, once the pressure in the cylinder and the crankcase are equal, things can really begin to happen and the exhaust blowback gets pushed back out into the cylinder where it can start the flow in the cylinder. It doesn't matter if there is some mixing - it's all exhaust gas. Once the flow begins up the back wall - then the fresh air and following fuel mixture can enter the cylinder and follow the freight train of the flow up the back wall.

IF, IF a Husky strato needs a bit more blowdown to pick up some revs - it doesn't take much. However, you have done the clever thing and simply removed the backpressure at the exhaust port - why raise an exhaust port when you don't need to. You've retained extra compression and trapping efficiency in your method.

As far as loosing some transfer time/area by dropping the cylinder - heck, what you are trying to do is get some more torque out of the saw, so by decreasing the time/area of the transfers it moves the torque peak down a bit - clever move old son.

 

[tbone75]

Anybody want to see more build threads from Mastermind? I do. They add a lot to this place.

Darn right we do !!!!!!!

Love watching his builds !!!!!!

 

[bryanr2]

Not really the video I was hoping to see....:hmm3grin2orange: but I guess it will do for tonight. Saturday we should have some cuttin videos.

 

[Mastermind]

Randy, I've discussed this before and I think you have worked with and developed the Husky design quite intelligently.

As some background - The Husky stratos are an interesting design that negates some of the modding concepts of conventional saw engines. The short blowdown and long transfer tunnels appear to work together. After a Husky strato has been run for some time, there is quite a bit of carbon blowback down into the tunnels that shows how the short blowdown has been pushing exhaust gases way down the tunnels. What is significant is the blowback does NOT mix with the fresh air/intake gases - it is contained in the tunnels.

However, once the pressure in the cylinder and the crankcase are equal, things can really begin to happen and the exhaust blowback gets pushed back out into the cylinder where it can start the flow in the cylinder. It doesn't matter if there is some mixing - it's all exhaust gas. Once the flow begins up the back wall - then the fresh air and following fuel mixture can enter the cylinder and follow the freight train of the flow up the back wall.

IF, IF a Husky strato needs a bit more blowdown to pick up some revs - it doesn't take much. However, you have done the clever thing and simply removed the backpressure at the exhaust port - why raise an exhaust port when you don't need to. You've retained extra compression and trapping efficiency in your method.

As far as loosing some transfer time/area by dropping the cylinder - heck, what you are trying to do is get some more torque out of the saw, so by decreasing the time/area of the transfers it moves the torque peak down a bit - clever move old son.

Thanks for a great post Terry. One thing I've noticed is the progression of the intake VS strato timing on these engines. A few years ago the intake and strato ports both opened at the same point of crankshaft rotation. These days, the engineers have started opening the intake 2 - 3° ahead of the strato ports. At the about same time they seemed to begin making the tunnels longer.

I have no way to know what these guys are thinking or what their models are telling them, but one thing I know for sure is that they are much smarter than I am. On the intake/strato side of these engines I let my machine work increase both intake and strato duration. That way I'm not changing the size, shape, or relationship of this induction system.

At one time I was allowing more blowdown.......but over a few builds I began thinking about how this engine actually works. I decided that if they had the intake side so well worked out that surely they put great thought into the other side as well, and that I may be upsetting the same sort of relationship there when I altered the intended blowdown time.

I didn't really find noticeable gains, but I found that the saws started better, got better fuel economy, and were spewing less hydrocarbons, when I left the blowdown short as the designers intended.

Sometimes just enhancing what we have is a better solution than trying to reinvent it. Other times a drastic remodel is in order.

 

[tbone75]

Thanks for a great post Terry. One thing I've noticed is the progression of the intake VS strato timing on these engines. A few years ago the intake and strato ports both opened at the same point of crankshaft rotation. These days, the engineers have started opening the intake 2 - 3° ahead of the strato ports. At the about same time they seemed to begin making the tunnels longer.

I have no way to know what these guys are thinking or what their models are telling them, but one thing I know for sure is that they are much smarter than I am. On the intake/strato side of these engines I let my machine work increase both intake and strato duration. That way I'm not changing the size, shape, or relationship of this induction system.

At one time I was allowing more blowdown.......but over a few builds I began thinking about how this engine actually works. I decided that if they had the intake side so well worked out that surely they put great thought into the other side as well, and that I may be upsetting the same sort of relationship there when I altered the intended blowdown time.

I didn't really find noticeable gains, but I found that the saws started better, got better fuel economy, and were spewing less hydrocarbons, when I left the blowdown short as the designers intended.

Sometimes just enhancing what we have is a better solution than trying to reinvent it. Other times a drastic remodel is in order.

Purdy smart fer a Monkey . :msp_rolleyes:

Great work as always Randy !

 

[Terry Syd]

Actually the early stratos (the 400 series) had a longer strato timing than the intake. It was usually about 10 degrees more than the intake. I tried some variations and liked matching the two timings. I figure the engine couldn't start generating crankcase compression until both ports closed - so why not close them at the same time.

It seemed that if you closed one port sooner - you would be short changing the crankcase. You could pick up some flow and still have the same 'intake timing' by matching the strato and intake.

When the new 500 series came out, the bloody strato timing is now the short changed port. Like you I don't know why. It doesn't seem logical, maybe there is some EPA reason, who knows. However, I'd like to find out if matching the ports on the 500 series will help the top end power.

Matching the strato timing on the 550 or 562 is easy - all you have to do is grind a bit on the top of the cutaway of the piston. It is an easy mod to reverse if it doesn't work - just replace the piston. If you ever do it, how about doing a thread to let us know what the story is.

 

[tbone75]

Gonna send another saw to you Randy , soon as I figure out what one ? LOL

To many to pick from ! LOL