? for TK

[mark voorhies]

I was reading in the "Two Stroke Tuners Handbook" on this issue, The "Handbook"was loaded on this site by Topfuel443. It states that "there was no notable change

in performance with the "inside stinger" in the full back or in the full forward

position but a noticeable drop with the stinger inlet "halfway" in the "baffle cone"

But when the "inlet" was slightly forward of "the weld" as we call it,,a slight

increase was noticed"    OOPs, that was wrong,,"when it was pushed foward

of the "weld" it showed less sensitivity to stinger length" h34r:

Gene! Did ya Hear That??

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Jerry,

I know this has been asked before, but, where and how can I get a copy

of Jennings "Two Stroke Tuners Handbook"

Thanks much,

Mark Voorhies

 

[Jerry Wyss]

TopFuel443 could tell you better than me. Its gotta be back

4 or 5 pages by now and I cant remember what forum its in either

would make sense being in "General" forum. But I think the "Topic"

was opened for that Book,,,give er a shot.

Wow! I looked Mark,,14 pages back in "General", I guess James is your best

bet.

 

[Mike Hughes]

http://www.chuckbunnell.com/kart/jennings/jennings.html

 

[Jerry Wyss]

http://www.chuckbunnell.com/kart/jennings/jennings.html

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OH, Bless You Mike

The one that James put up had the original covers of the Book,,"tattered"

corners and "duct" tape on it to hold the binding together,,pretty Cool it is

 

[John Finch]

I just wan't John Finch to know that I'm working on the Thunder Tigers,not exactlya Major performer the way they come.But theres a Major Fire in those little things

thats just "beggin" to come out

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Thunder Tiger? I know someone who modified one so that it out performed a Nova Rossi on the Dyno. Can't remember who's engine it was, but remember it was super strong but also didn't last very long. Good luck with the mods. I don't want to be a negative on mods, just being realistic. Yes, the pipe manufacturers test and test and test. I have a file cabinet full of all most every pipe ever manufactured. Some are better than others. No doubt. What I doubt is that someone could design one for a particular engine and get it right. Trial and error seems to be the best way to get the best combo for the engine , prop, and hull.

I say that because a good engine can look really bad in a bad boat and a bad engine can look really good in a good boat.

John

 

[John Finch]

OK!,,I'm Out From Behind Couch Now :lol:   Everytime I think I've learned sumthin'I get "John Finch" :lol:   :lol: I've Got Nuthin' But Shirts With Holes in em :lol:  

Well I've Never done any Dyno work , and I'll bet most haven't either,,,But What

I wonder about,,How many pipe maufactures( in our hobby) done that kinda work?

I trust the Engine manufacturers,,I've ran their products,,some are just better than

others, (so what else is new) but theres so many pipes and so many engines,,and

with limited knowledge finding the right combo can be long and expensive. I'm

starting to learn now that I can use one of my pipes and by using the "math " that

I didn't know before I can alter the engine to get the most out of the pipe I have.

With that I can be in the "ball park" like I never was before.

I did notice one thing John while reading this book is that our header Inside diameters seem to be a bit small according to the book info. The info tends more to a larger dia,,like in the neihborhood of a 150% of the exhaust port window.

What are your thoughts on that area??

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The holes in your shirt are probably from all that nitro. I like to try to make the pipe header match the engine header as much as possible. I think the stinger affects things more so than the rest of the parts of the average pipe.

 

[John Finch]

Speaking of the stinger. A lot of people miss the fact that changing the stinger diameter changes the pressure to the pipe pressure fitting and then the needle valve. I don't think they mentioned pipe pressure in the book because they are talking motor cycle engines.

Just a gator popping up for a chew.

 

[Jerry Wyss]

:lol: :lol: Thanks for the responses John,,I have the Utmost Respect for Your Skills and Knowledge,,,And Your Humor Is Pretty Good Too! :lol: The Dyno engine

you talked about is good in as much as giving me a cautious methoed of modifying

these things. I modified in a couple areas such as headspace and exhaust port

timing,,as well as expanding the closing on the induction timing on one engine.

I think the area i probably messed up on is the simple,,doing all those other mods and just not running the pipe short enough. When i did finally run the pipe at 8"

did the engine really take off,,and Take Off It Did! But i was already using 184deg

Exh port timing and .005 to .006 headspace ,,so the effect of the pipe length change was a little Too dramatic,,backing down to lower specs on the former Two

mods would maybe give me the performance I want without taking the engine

into "The Danger Zone" that will Kill the engine parts. I want a strong running

engine,,I'm guilty of that,,but I don't forget about and the boat and prop either.

I personally don't have to Win at all costs,,as long as the boat runs well and I

drive well, I'm Happy,,Taking the thing home in one peice is Job 1 for me.

I really Do appreciate your thoughts and experience on these things John, and

I'm SURE others here do as well

 

[Jerry Wyss]

Concerning the stinger buisness,,I sleeved mine down to .244, and it was to give

it a little more fuel pressure,,Your Right again there. Jim Irwin relayed this info

to me 6 or so years ago and its had no negative affects on the engine parts and

it did help performance,,so I guess I modified more than i said.

A Gator Poppin' up for a Chew :lol: :lol: That Was Good!

 

[Jerry Wyss]

One more thing Tim Duggan from Australia recomended making a new head button

and making the "squish band "50% of the area of the button(within the cylinder)

and mill the "bubble" to .18cc,(this is in the book). I measured the stock bubble

and it has more distance across than the new one will have,,I had no idea the New

one was going to be accually smaller than the stock,,I thought it be opposite :blink:

I haven't "CC"D the stock one yet but I'm goin' to just so I'll know :huh:

 

[John Finch]

I don't know what the stock exhaust timing was, but if you raised it.........that means there is less time for the fuel air mixture to be compressed, so perhaps the smaller bubble will work out.

John

 

[Jerry Wyss]

I don't know what the stock exhaust timing was, but if you raised it.........that means there is less time for the fuel air mixture to be compressed, so perhaps the smaller bubble will work out. 
John

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Thanks John, The stock exhaust timing was 155deg,,perdy low

 

[John Finch]

Back on the original thoughts about stingers. I have a Garcia pipe here that has no stinger at all on the end of the pipe. the stinger (relief valve) is welded into the center section of the pipe and curves back towards the rear of the pipe so the exhaust leaves the rear of the boat. It works pretty good and there are no stingers inside the pipe, while the location of the relief is at the center of the pipe. Thought it was an interesting way to get noise reduction. I don't remember what the noise reduction was in db. Maybe a test this spring will be in order.

John

 

[Jerry Wyss]

Back on the original thoughts about stingers.  I have a Garcia pipe here that has no stinger at all on the end of the pipe.  the stinger (relief valve) is welded into the center section of the pipe and curves back towards the rear of the pipe so the exhaust leaves the rear of the boat.  It works pretty good and there are no stingers inside the pipe, while the location of the relief is at the center of the pipe.  Thought it was an interesting way to get noise reduction.  I don't remember what the noise reduction was in db.  Maybe a test this spring will be in order.
John

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Would the same "rules apply" for sizing and length in the above setup?

I have a "machinest" Bud up in Portland (Oregon) his Name is Gary Gilbertson

that did a pipe for "Hodaka" motorcycles many years ago and He's been wantin'

me to do this very thing on a RC pipe. His pipe accually went into production

on one the models they sold back then. I should talk to him some more about

that, He's been helpin' me make a couple parts for a Mini dune Kart with a 600cc

Snomobile engine and utilizing the snomobile clutches for a "shiftless" type drive.

.

 

[John Finch]

I believe the same rules apply. The Garcia pipes had very short convergent cones, so they were very peaky. When they were "on the pipe" they were awesome, but too peaky for heat racing under various conditions. Stinger diameters are the same as the regular pipes. Get your buddy to mod your best pipe. Cap the stinger flat where it meets the convergent cone and stub it in at the center of the pipe. I would like to know how it works for you. Good luck.

 

[Jerry Wyss]

I believe the same rules apply.  The Garcia pipes had very short convergent cones, so they were very peaky.  When they were "on the pipe" they were awesome, but too peaky for heat racing under various conditions.  Stinger diameters are the same as the regular pipes.  Get your buddy to mod your best pipe.  Cap the stinger flat where it meets the convergent cone and stub it in at the center of the pipe.  I would like to know how it works for you.  Good luck.

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I have a CMB "Big Belly" pipe that I could try that , it goes on a Picco 67 thats in

the boat you see I'm holding. It would solve the problem of having a silencer

"pokin'" out back there even if it didn't perform any different

 

[Slideblues]

Jerry that is so wild you brought up the Hodakas, A buddy of mine had some, always swap'n parts back and forth from other models, He always raced one and had two fer spares.

Hated the gastank on em looked like a toaster :lol: :lol: :lol:

The absoulte wildest MXer I ever swung a leg over was a open class Maico 400,

That dang thang was SOOOOOOO fast it was scary, the weird thing was the pipe, you would think it would have a broad midsection for torque in a midrange powerband, but this one was long and slim, totally different from what you would expect,

Gene

 

[Jerry Wyss]

Hey Slidey, I almost bought one of those Hodaka toaster gas tank things, but I didn't wash dishes long enough :lol: I used to wrench for my buddy that owned

a brand new 400 Maico,,I use to ride it all the time,,could ride it better than it's

Owner :lol: Sure was HELL to kick start that Tri-skellion lookin SOB,,It accually

was a better "flat tracker" than an MX bike once you got that 21in tire offn' the

front. The Maico had a Really Broad powerband,,too broad for an MX, and that

was probably due IT'S Pipe! Hmmmmm

My Dang, and I Mean DANG power has been out for the last 4hrs so I would have

answered sooner.

How'd ya like all the convers with the "Gator" Perdy sharp cookie and a great

sense of humor to boot. But it took a guy,,Who Thought he knew somthin' to bring

em out :lol: :lol: 'cetch me

 

[carlnoki]

Hey John;

another place you can install the stinger is JUST IN FRON Tof teh meeting place where teh Div. coane and stinger meet. install it at a 90% angls to the normal setting of the stinger. results are noise reductiona dn no power loss. if you remember my little 20 hydro when we were stationed at Langley, i had a pico 21 car pipe that was set up like that. great power and you coul dactualy hear the water on the spnson bottoms.

anyways, will be glad to race with/against you folks there in the ODMBC again. we are now in the DC area.

later for now

carl cisneros

 

[carlnoki]

DAEM!!!!!!!!!!!! i can't type worth beans tonight, can i?

carl