Stinger question

[Suzukidave]

Isnt it best when the 3 stingers are the same length ?

[tz375]

Yes Dave. That's correct. Stinger length is one of the less critical dimensions and I suspect those pipes are a little small as well which tends to suggest a mild state of tune. It is possible that the stinger is inside that one cone.

We'd have to ask Filth to get the answers. Nice bike though.

[Suzukidave]

It is possible that the stinger is inside that one cone.

Thanx Richard .. thats something i hadnt thought about .

[Suzukidave]

Stinger length is one of the less critical dimensions

I thought stinger length and size are important to bleed off and back pressure ?

[tgrogan]

The stinger length on those pipes is very unequal, because it includes whatever is inside of the silencers. It's everything after the last cone including the diameter and length ('volume') of any and all pipes afterward. At best those pipes are decorative. With the 'stinger' length showing, they would not work for anything below about 10000rpm.

[tz375]

Pedro, That brings us to another point - why are Allspeeds so short? Jemco seem to be a copy or at least are similar and they have a tuned length that isn't close to being right. It's as if the design intent was to drag the top end of the curve upwards even though the ports don't support much higher RPMS.

That way the pipe appears to stretch, the curve and allows the motor to get that rev multiplication effect. Pipes don't necessarily have to be "correct" to make more power than stock. For example we studied a race motor where porting and pipe shapes appeared to be all wrong and incompatible but in effect they overlapped rather than being completely in synch. That way nothing was ever perfect but together they worked really well.

It's sort of like the idea behind a motor where ports are set to different values so that each resonates at a slightly different rev range to spread the power band at the cost of drop in peak. That makes for a bike that's easier to ride - especially with the old wide ratio 5 speed trans of those bikes.

[Suzukidave]

I kinda started this question line as i havent worked out the stingers on my chambers so started the question on the unequal length . My silencer placement would also be easier if i was able to run the stingers as Richard did .

[tz375]

Inserting stingers into the chamber reduces noise slightly with no loss of power as long as the inner end is not at the middle of the reverse cone which is the tuned length. Further in or not so far in is fine.

[Suzukidave]

This is more the idea of setup i was figureing to use but the longer stingers on Richards bikes do place the silencers at a more " sporty " looking spot .

[tz375]

Short little tail pipes there. I suspect that you'll find that the extra length may be just packaging/appearance. JollyMoto pipes for the RS250 Aprilia have long tailpipes that appear to be different lengths and they know what they are doing, so wither the difference is inside or they found it didn't matter much

[tgrogan]

sorry but most of the above post is nonsense, .......

A bit harsh and somewhat misinformed. While I may have been off on the rpm the the 'pipes' whould be useful for, I'm quite certain of the accuracy of my observation about the effects of 'stinger volume'. The resistance of any pipe is related to it's diameter and length, read about it. If a long skinny stinger pipe is added to any chamber it will cause reflected waves to be created at a very high frequency at best. There is no way those pipes could be used for anything but decoration - period. I have manipulated stinger properties on chambers enough to know what I am saying is true. Maybe you didn't like exactly how I said what I did, but that is your problem.

[Suzukidave]

Chamber info starting on page 30 http://edj.net/2stroke/jennings/2stroke ... ndbook.pdf" onclick="window.open(this.href);return false;

[titan performance]

While I understand the need for the race boys to eek out every available horse power from their race motors, I think it's fair to say, that it's not priority for road bike riders. If it were, then Allspeed and Micron etc would have sold far fewer pipes. The majority of road bike riders want improved looks, and a race sound......a couple of extra horses, or a few ounces saved are a bonus, but not essential. It may well be that the pipes on Filth's bike don't work as well as they might, but looking at the amount of cash the man has spent on the cosmetic appearance of his bike, I would guess that outright performance was not his priority.

[oldjapanesebikes]

While I understand the need for the race boys to eek out every available horse power from their race motors, I think it's fair to say, that it's not priority for road bike riders.

Quite true. There is another aspect that doesn't often get mentioned - putting racing aside, if you bang up your stock pipes and wanted to retain the original look then until only just recently you were scuppered as to options for new ones - for the average Joe, your only 'new' replacement choice was spannies ! Even now for most owners original look pipes are out of reach due to both availability, and just the total cost once import and shipping fees are factored in depending on your location, so I'd expect locally produced chambers to continue to be more common as replacements for many owners. Everything else - less weight, noise, looks, performance - is just a bonus

This actually starts to introduce another issue - there are jurisdictions in this country (specifically Quebec) where not having original manufacture exhausts can get you a ticket to the tune of $154. From what I'm been able to determine, they don't make allowances for vintage vehicles, but I could be mistaken. On the whole, I expect this sort of thing to become more common as owners of loud vehicles have successfully ruined it for everyone.

[tz375]

That's a really good point Ian, and still we see "Cafe Racers" running open pipes with no mufflers and there are people fitting "stinger" pipes on road bikes with no mufflers. One of the most annoying sounds to most people is the sound of an non-silenced 2 stroke.