TT550 Exhaust

Hi everyone, Im new to this forum so go easy on me. I have an 1982 TT550 and it has an old 80's style 4in supertrapp system, and I was wondering if anyone has tinkered with their XT exhaust before? I would like to add an open end cap to my system but Im not sure if itd be to lean. It currently has 8 disks and the open cap acts like 10-12. any advice would be greatly appreciated. Also if anyone messed with the jetting on these bikes, how hard is it to rejet?  Thanks!

if it's the supertrap held together with about 6 screws in a circle on the end cap try putting spacers between the disks. 1/8 aluminium pop rivet washers work well. this spaces the disks out and frees things up a bit without making it obnoctiously loud. 

you say it's an 82 ? in 82 in the U.S.A. they were XT550's not 500's which is yours ?  the 550 is much more difficult with it's twin carbs. the older 500's are pretty simple in comparison.

Its an 82 xt550 I messed up by saying its a tt, and yes it does have the twin carb setup with the 6 screw end cap.

well then the spacer trick will work with the pipe but those carbs are a complete unknown for most folks, Me included.  What are they Hitachi or something like that ?  You might get some jets direct from Yamaha or maybe Sudco ?

its an teiki carb. I found some jets on jetsrus but they are only primary jets.

That's cause the secondary carb has a special jet that's darn near impossible to find.



Bad idea: open end cap makes a lot of noise and is gonna be a pain to jet.

Good idea: add a few disks, Supertrapp is a Supertrapp, see how the bike runs, plug chop, etc. Maybe you'll need to change the main and maybe you'll need to open the secondary later (or earlier, I'm not sure, my bet is later), and you probably don't want to go any farther than that point.


Big bore singles make a lot of torque, not much power, so uncorking it is primarily going to make noise, noise is bad because it pisses people off who then want to regulate riders. Regulation is worse than noise.


Love Supertrapp, BTW, had a lot of success with it, but never had one on a 550.

I really did mess up this post once I start reading it now that im not in a hurry. In the beginning I meant to say that I was going to remove all my disks and just use an open end cap that would act like 10 disks-ish, not using my current 8 disks PLUS an open end cap making it 18disks-ish. Sorry if anyone who read this was thinking the latter choice.

Open end cap, for all intents and purposes is diskless, "straight pipe", unlimited disks, etc. My advice is don't do it. However, adding 2 or four disks and seeing what happens, that's probably not a bad idea. Beyond that I don't think you're going to make any gains.

If you need to re jet the second carb you can get a mikuni jet that will fit I dont recall the body size of the jet (I think M4) but they do the job. The dont have a head so will screw right in to the carb

I have been messing with jettin on an xt 550 engine in a MX frame which has a straight though 2 into 1 pipe, much shorter than stock. The engine is quite loud but will pull a trench up the field. The engine is tolerant to change.

The stock 550 engine will not benefit from an open end cap or too many discs. If you want an XT550 to rev it takes more mods than just a pipe.


What do you plan to use the bike for? Dual Sport? Trail? Track?

The mikuni jets that will fit are pictured at look at mikuni jets and part No N100606 - Size for the secondary carb

This is a UK web site but I am sure available in US this jet I bought 3 jets 100 110 and 130 to try larger and smaller from stock which i recall is 120 (in the secondary carb) the bike is now runing on 110 fine but has a differnt filter arrangement and pipe from stock. The jet that I got for the primary were N102221 - Size and I used a 120 instead of stock 130 (But dont go too lean and keep checking if your changing jets) But also bear in mind the needle clip positions. (I could not find jets for the TEIKI carb but the Mikuni did fine)

Mikuni N102.221 is not the right jet for the secondary carb. It *might* work for the main, main jet - I don't know.


The secondary carb main jet is the one below the wrench in this photo:



Again, I advise you not to mess with the exhaust too much, a few plates, but finding the real secondary main jet is going to be expensive and time consuming, possibly fruitless as well.

Well, two days ago I purchased an 4in open end cap and received it today. I installed it and just drove 35-40 miles with it on, no re-jetting done. Ran perfect, love the sound and pulls like a freight train! this might have been re-jetted in some past life...

I'm sure the other Michigan riders will appreciate it when yet another riding area is closed down due to noise.

This is my cruising motorcycle, I have an 1978 PE250 for offroad use that is compeletly STOCK. Im sure that the local police are okay with a little more noise from my little dual sport.

I love the fact that the XT550 looks like a dirt bike with lights. I'm not concerned about the cops, they're idiots and unless it is going to make the city money, they don't care what you do. Noise ordinances are a PITA to prove and thanks to all the boom cars, noise ordinances are largely ignored. However, your neighbors and people who see you will think it's a dirt bike and thus become further prejudiced against dirt bikes. That's assuming you don't melt one of the valves down first of course. Further more, you may very well simply think the bike makes more power because it makes more noise, lots of people think this when it's false, more noise does not mean more power, nor does more power necessarily mean more noise.


Do what you like, of course, but there are consequences to your actions.

Look, I was just looking for some technical suggestions on my motorcycle, not life lessons.


Thank you everyone for your input.

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