My 98 Thunderbird Sport has a custom made all stainless steel exhaust, 3 into 2, straight threw, sounds great, but is very loud and I would like to tone it down a little. I see there are 2 1999-2001 Legend TT mufflers for sale on a well known auction site, they look like they will fit, maybe with some adjustment, but is there anything else I need to consider? For example, will it impact jetting/back pressure etc? Bike, will only run with the choke nearly fully on (running lean I guess), but runs well when the choke is on, but turn the choke off and dies immediately, the bike hasn't been started for 10 months so the carbs might be gummed up. I have removed the fuel tank and ran a separate fuel supply with fresh fuel, but didn't make much difference, so the carbs will have to be stripped. I mention this the mechanic who might be doing the work also said that I really should install the quieter exhausts before he strips and tune the carbs. Another option I've looked at is fitting a DB Killer insert, but they seem to be 51mm, while my current set-up has ~40mm opening.
Yes, separate issue, which will be fixed hopefully. Order if work is something like this. Purchases new quieter exhaust cans Fit them Then take motorcycle to mechanic so he can tune and fix carbs.
You will definitely have to re-jet them, I've an EFI and every time I had to change pipes. BC PREDS to 2 into 1 to TORS I have to re-map them, Unless the fact it's not running right is that it wasn't re-jetted for the pipes you have now.
Thanks Crispey. So I need to source some pipes first, there is a company in Germany (I'm in the USA) selling new ones, but they haven't answered my questions yet. Also on ebay, a single one from a TBS (I need 2), and a couple from a Legend TT that look good, but not sure the Legend and TBS are interchangeable. My research has found this out. Two cans on the right are the 1998-1999 years only, with a unique sub-frame as well. 6 Differerent hangers Adventure trumpet Hanger Adventurer slash cut hanger Legend reverse cone Hanger Thunderbird pea shooter hanger 2 different thunderbird sport hangers. I'm going to look at the paperwork/receipts I got with the bike, find out who made the current pipes on there, they are very well made, just so loud!
Yes i agree with the fact the bike may not have been jetted to suit. And the possibility that the carbs are gummed up will not help. You need to check all the rubbers for cracks and leaks as well and baffles if you know someone who is handy with a welder and metal pipe they could knock something up quite quickly.
Hello there! Regarding exhaust DB killer inserts. Before buying new exhausts try the DB killer inserts. These come in various sizes. I'm in the UK but I've googled US companies and found a couple :- https://www.yoshimura-rd.com/collec...RFlXbsPOU_Ks_1RkJ4OXUy1gXNGIXIyMPyTBmRdADtuk4 https://www.competitionwerkes.com/products/wx125 Various options here :- https://www.ebay.com/sch/i.html?_nk...killer+&_sacat=0&_from=R40&_trksid=m570.l1313 I'm sure you'll be able to find a suitable item. I don't know how affective they are but if you also wrap them with acoustic exhaust packing, it will quieten the noise further. (This is from a UK site but you'll be able to find similar in the US, I'm sure) https://www.demon-tweeks.com/uk/aco...M0BJul6xlDWITj730TWj5Om5Z3LoRFjqLAwM4GLy-s7qa Hope this helps....
If the issue WAS caused by a freer flowing exhaust - what symptom Would you expect? A too-lean mid-range bog?
Yes, freer flowing could give a lean condition in the mid-range which would probably show as a flat spot. A reversionary pressure wave is created by the baffle and this can assist cylinder filling hence why some restriction can be a benefit. The result is more power and not just sound reduction. An over restrictive system, or baffle, could also show up at a certain rpm so without a feel for things, or a gas analyser on a dyno, often it can only be experience or a best guess situation. As time goes on, and emissions (gases and noise) get tighter, the net result is a poor performance sector in the rpm range to conform. My latest purchase a Kove 450 has now had x3 different ecu's (map change) and a fair bit of tinkering with the exhaust to get to where I'm satisfied with it now.
Gas flow through the cylinder head and the exhaust is a science in itself but broadly speaking, little or no restriction will help max power at high rpm and some back pressure in the low to midrange will help increase torque. Yamaha's EXUP system, introduced in the late 80's, was designed to offer the benefits of increased gas flow at high rpm for max power and back pressure lower down for max useable torque. It also helped in the drive by noise tests. The first GSXR1000 also adopted the system and is used quite widely now. It effectively provides a variably tuned exhaust with slightly more complexity and cost.
