Name that tune

roots to wings /
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New build tuning question. Could a nearly identical build on two different bikes require different jetting? My first airsal 44mm bing 15 build is totally dialed in with 79 jet on an estoril radical sidebleed on 16/40. My second airsal 44mm bing 15 build (79 jet) has a cranks sidebleed and is a bit sluggish on takeoff on 15/40. Both bikes have extra stiff kickstart springs 3 turns in. I dropped the clip (to 3rd from top) and took off the airfilter and takeoff was slightly better. Cool temps on build 2 in the 270's. Plug seems a tad rich even after taking off filter. Low temps, rich/oily plug, seem to point to going smaller on the jet, yet the bike responded to more air. It gagged a bit @wot also, so I'm totally confused. Timing perfect at 16. Starts first kick.

Re: Name that tune

Absolutely. Two completely identical builds could require entirely different jetting, they may even ride different. They each have their own personalities, with different wants and needs.

Re: Name that tune

two different pipes different flows different tunes not all pipes hit the same

Re: Name that tune

Dirty30 Dillon /

So your identical builds have different pipes?

Hmm.

Re: Name that tune

roots to wings /

Nearly

Re: Name that tune

Dirty30 Dillon /

> roots to wings wrote:

> -------------------------------------------------------

> Nearly

This makes them specifically not identical. The pipe more than warrants a few key size change. Let alone small differences in assembly, etc. That are enough to make similar builds key differently

Re: Name that tune

at this point, you need to be using pin gages to make sure your jets are actually the size they say they are.

Re: Name that tune

roots to wings /

Gonna go high first. Can always go smaller jet later. Cranks pipe has stronger midrange and less low end than estoril. Estoril is more even power thru the range so I am looking to flatten the cranks a bit for better low

Re: Name that tune

the pipe design is also 100% different from the cranks pipe to the estoril, with the estoril being the superior design.

just visually inspecting, there is no "belly" on the cranks pipe versus the clear flat "belly" section on the estoril. it looks like the estoril is shorter. without gearing involved, the estoril should rev higher.

Re: Name that tune

Dirty30 Dillon /

1 and 2 speed builders throughout the ages have tried to avoid it, but the Estoril was designed for the majority of builds on any applicable platform. You cannot fault a pipe that just works well.

Re: Name that tune

roots to wings /

It’s a fantastic pipe. What other estoril does as well as the radical sidebleed would you say?

Re: Name that tune

Dirty30 Dillon /

Any estoril works great, TBH. The sidebleed is only there to soften and widen the powerband on an already wide-banded pipe. I typically prefer the end-bleed models in general as I have found they have less of a harsh drop-off at the top end of your RPM range. Sure, the adjustable end bleed on the sidebleed can slightly mitigate that, but I've just always preferred the traditional Estoril build.

Re: Name that tune

roots to wings /

I just went for a quick rip with an 80 jet clipped 3rd from top and it ran well. Not perfect yet, but pretty good. At 30mph, the Cranks pipe really moves out, more than the estoril, but for the money, the estoril is an awesome pipe, especially the fully chrome one. The non-chrome rusts a bit. The Cranks pipe clacks a bit off throttle at 30 then as soon as you hit it, it takes off and goes away. I can live with that. It's definitely stronger where you want to have something. You could pass with it. Of all the 45 mph and under (low/mid/all around) pipes I've tried, the cranks side and estoril are far and away the best of the ones I've tried (over mlm cali (high end), dos botanas (high end), proma gp, proma circuit, techno circuit, stock cigar). The techno circuit is a sleeper tho, as it's quieter than the proma, and will get you there, but for the price difference, the estoril is the way to go for the budget blaster I'd say. On a 45+ setup, I think the Cranks would beat the estoril, but that's not my setup so I just guessing. (edited)

Re: Name that tune

Each leak air differently.

Re: Name that tune

> LSLB RXb wrote:

> -------------------------------------------------------

> the pipe design is also 100% different from the cranks pipe to the

> estoril, with the estoril being the superior design.

>

> just visually inspecting, there is no "belly" on the cranks pipe versus

> the clear flat "belly" section on the estoril. it looks like the estoril

> is shorter. without gearing involved, the estoril should rev higher.

Yeah I’m gonna say the cranks defs is the more superior pipe in terms of design and build quality. Plus I know that cranks pipes rev out past 10k so I’m not sure how that’s less than a estoril

Re: Name that tune

Those airsal 44 are really conservative porting, if you want to get it going with the cranks pipe it will probably need some exhaust porting, but realistically it's probably just a odd match, better off running the cranks pipe on a better kit and running the airsal with a proma circuit or estoril.

If your temps really are that low you can probably bump up the timing a little bit. I think mine is about 18. You might find it picks up a bit with a little hotter timing.

Re: Name that tune

> Garrett The Kid wrote:

> -------------------------------------------------------

>

> Yeah I’m gonna say the cranks defs is the more superior pipe in terms of

> design and build quality. Plus I know that cranks pipes rev out past 10k

> so I’m not sure how that’s less than a estoril

Build quality, sure. small batch made pipes should have higher build quality then something mass produced. I didn't say anything about that tho. I said superior design.

and i honestly if we are talking about superior design, I think the estoril still has the cranks pipe beat.

Look at what's going on in the world of Malossi MHR and Polini Big Evo scooter stuff...I don't see any pipes without belly sections. even look at all the MLM pipes over the years, only the Razz and Kreidler pipes got chambers without belly sections and I suspect that happened for a specific reason (fitment and not performance related)

They seem to be a mainstay in nearly all modern 2-stroke exhaust and a pipe having one built into it's design would qualify to me as a superior design.

And alright, lets say you really were revving past 10k, that truly is cool and great and neat.

but what is more important about revving to 10k is what your setup was. and even more important than that is what your exhaust duration was.

actually, I don't know why I'm beating around the bush, but does anyone know exactly what the tuned length on the cranks pipe is? and the estoril, too?

I know a stock estoril is right around 31" or so last time I checked, but I could be wrong.

Re: Name that tune

Ryan makes a few different sizes, both of the ones I have blow the doors off of an estoril but there isn't enough blow down energy from that kit to make them work. Even if it had the same ex timing but bigger port area it would light it up because they do make good power in the midrange.

It's not about a superior design, it's about being the wrong tool for the job. If you switched out to a polini it's night and day, easily 1500+ rpm higher peak power and lots more everywhere from 6000 rpm up. That airsal is basically a stock cylinder porting wise.

Re: Name that tune

> Graham Motzing wrote:

> -------------------------------------------------------

> Ryan makes a few different sizes, both of the ones I have blow the doors

> off of an estoril but there isn't enough blow down energy from that kit

> to make them work. Even if it had the same ex timing but bigger port

> area it would light it up because they do make good power in the

> midrange.

>

> It's not about a superior design, it's about being the wrong tool for

> the job. If you switched out to a polini it's night and day, easily

> 1500+ rpm higher peak power and lots more everywhere from 6000 rpm up.

> That airsal is basically a stock cylinder porting wise.

gaining 1500 rpms sounds like a lot to me and my handy dandy exhaust nomograph.

On the Polini cylinders that I got in from Dos and Treats, I got ~162.5º of exhaust duration and ~26.5º of blowdown. do these numbers correlate to the cylinder that you have?

According to the nomograph, the cranks pipe would have to be like 4.5 inches shorter than an estoril to gain 1500 rpms, unless we are getting into over rev, but hey, what do i know without any sort of tuned length info.

Re: Name that tune

if you got port timing numbers off of the 44mm puch airsal kits too, please share!

I'd love to add that info to my data base :)

Re: Name that tune

Ahh man I haven't port mapped a polini in ages but I'll take your word for it. Obviously just looking at tuned length and ex timing is a pretty incomplete picture, the nomograph is suggesting peak power which might not be wrong but it doesn't say anything about the shape of the powerband or how much it's adding so it's kinda garbage in garbage out.

The estoril shuts off pretty hard just past peak around 9000 on an unported polini. The airsal 44 won't ever even rev that high so it's not a big deal. The polini can pull to 10,5 or a lot higher with porting or a 4 petal, so with the crank pipe it will keep pulling with lots of power up there. If you gear for 10,5 at top speed you'll have good useable power all the way up there and pull hills no problem. If you do the same thing with an estoril you're stuck with crappy Ken roff gearing and slow to take off, and slowing down on hills.

The ones I have are about the same length as an estoril but they are better suited to making big power on big boy kits. Transfer time area, exhaust time area, blow down power the pipe. If you don't have enough energy coming out the exhaust port when it opens to move air in the pipe it won't give you any supercharge effect.

The cranks pipe will pull hard down low but it still needs to have a lot more energy coming out, the airsal just can't make that happen regardless of how long the pipe is. As for what is a 'better' design you're comparing trumpets to tubas, they are both great in the right application but you can't just one size fits all based on the length.

Re: Name that tune

I'll grab you the airsal timing tonight, I actually have a spare on the shelf!

Re: Name that tune

One more anecdotal point.

I had my 50cc A55 cylinder ex timing near 165 with blowdown of about 25. I had some Frankenstein sidebleed circuit pipe with a bigger header. It seemed about perfect.

I swapped a 102mm belly cranks pipe on and it didn't really 'hit'. I increased my exhaust timing up to 180 with a blowdown of 30 and the pipe came alive.

I think I gained ~500-1000 rpms from these changes. I don't have a tach so it's all just by top speed (single speed).

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Also I guess if we want to get real technical blowdown time area is probably more important than just generic blowdown. So a 50cc blowdown vs 70cc would react different I think? Same concept for exhaust timing?

Re: Name that tune

roots to wings /

Awesome dialogue. At least I wasn’t crazy. My son is so happy with the zippy midrange he can live with the take off. He also weighs 120 lbs. the cranks did get to 42.6 mph which is only a touch slower than the estoril on the 44mm kit.

Re: Name that tune

> roots to wings wrote:

> -------------------------------------------------------

> Awesome dialogue. At least I wasn’t crazy. My son is so happy with the

> zippy midrange he can live with the take off. He also weighs 120 lbs.

> the cranks did get to 42.6 mph which is only a touch slower than the

> estoril on the 44mm kit.

42.6 on stock suspension and brakes is a nice place to gel.

Re: Name that tune

Also if no one has mentioned this because I"m not reading all that, but bing jets are not consistent in their actual sizes, so two different 76 jets are probably different physical sizes in the hole. Good luck!

Re: Name that tune

Ditch the big for a vm18 and blast city

Re: Name that tune

> Jesse Stephenson wrote:

> -------------------------------------------------------

> Also if no one has mentioned this because I"m not reading all that, but

> bing jets are not consistent in their actual sizes, so two different 76

> jets are probably different physical sizes in the hole. Good luck!

PIN GAGES :)

https://www.ebay.com/itm/254430133633

Re: Name that tune

roots to wings /

thanks adam. so i'll hobble sheepishly back to my workshop now with my tail between my legs. I should check my jets and get that kit, but first i need a tach for the new build.

so, according to your nomograph above, if my tach is accurate, my estoril tops out around 9200rpm at 44.6mph, and if my tuned pipe length is what it depicted, that would put me at about just over 150 degrees, so the tuned length of the cranks pipe would have to be a bit longer than the estoril to hit 9200 rpm, OR the rpm's are higher on the cranks pipe with a shorter length. top speed is irrelevant on the nomograph because they are a function of rpm and gearing, both bores being equal, correct?

Also then, how did I happen to get to 150 degrees of exhaust timing on the estoril to max my rpm at 9200? All I did was time and tune the bike to get there? Graham seemed to suggest that I could port the exhaust port to increase my exhaust duration. Not sure i want to fuck with that, but just trying to understand. thanks.

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