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Discussion Starter · #1 ·
I see so many different answers in dozens of different threads, and I'm not even sure if my new '21 has the same equipment as some of the older bikes.. I ride at sea level and am wondering what main jet size, pilot jet size, number of turns on the fuel screw I should start out with. All for the stock exhaust, but then also what settings for a DG exhaust would be greatly appreciated. Regarding the needle, it seems like most people just use shims, but is there a performance needle available for the TW? Also, which fasteners should be replaced with higher quality ones, and is there a list of hardware info like length, thread pitch etc? I would like to just have them ready before pulling the carb.

Thanks guys
 

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Bottom line is, if you hack the brass blank that covers the (whatever it’s called, we tend to argue over this) screw, and back it out around two or so turns, it makes starting a lot easier

Of course, you could simply pull the choke, start her up and wait a few minutes, but in the event that’s too complicated, feel free to start ripping into the carb

The mating surface of the needle and the jet is more critical, so be aware that unless you have a matching pair, it requires close scrutiny

The DG has greater flow, so increasing the main jet is normal procedure. To know exactly what jet size is best, we will need to know whether you are intending to use the “quiet” insert or not, and your precise altitude range to within six inches

As you may have gathered by now, I’m absolutely no help at all with this stuff, but I’ll leave you with this question …

Other than the removal of the brass blank (some of the TW’s are lamentably lean), what do you seek to achieve ? – do you actually have a problem starting on the choke ?

Likewise the DG option. Unless you find noise attractive, you’re unlikely to notice the difference unless you gauge HP by your ears

Ditto the fasteners. Stainless steel and alloy make for strange bed fellows

I understand your enthusiasm, but if I were in your place, I’d ride it for a bit and get to know it. Does it run fine without a DG pipe, does it run OK without taking the carb apart, because once you open that can of worms, you’ll never be happy with how its set up, always chasing that “little bit more”

My understanding of the 2020+ models, is that the JIS crankcase screws have been replaced by hex bolts at the factory. As that’s the only improvement I’d recommend, and as you already have it, and as they have not moved once since you’ve had the bike ……

Dude – slow down and smell the roses. Hand guards, improved lighting, new front tire, bigger foot pegs I can understand, but think hard before you worry about exhausts and carbs – you don’t “need” any of it ……
 

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‘04 TW200, Jets+Shims, DGV2, S-moto fender, Acerbis Guards, ProTaper KX, JNS DOT LED BLK, Moose Rack
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I’m also @ sea level, with carb jets & shims changes (as below)
I have a DGV2 pipe in the box & DGV2 1 3/8" Quiet-Core insert
Plan to install after prep/paint of engine head.

My carb tune efforts were prompted by lean OE tune + a vacuum leak
Problems: Slow warm up, 5+ mins until bike could be ridden without stumble, exhaust popping under engine braking, engine pinging & hot running.

2004 TW200/49-state
Sea level, avg temp: 80F
Exhaust: stock
Airbox: stock
Plug: NGK Iridium
Main jet: #130 (Up from OE #126)
Pilot jet: #34 (Up from OE #31)
Main needle: shimmed to 0.03" (3 x 0.01" washers)
Pilot screw adjuster: set @ 2 turns out, to start

1) Engine cold-started easily with no choke/enricher. (Full choke only, before).
2) Idled smoothly, immediately. (3-4 mins on choke for same, pre-tune)
3) Parked, roll on throttle blips within 1 minute were crisp, responsive, no more stumble/stalling.
4) Engine warmed to rideable (not @ max RPM) within 2 mins. (Stumbled/stalled before)
5) Test ride: crocodile smile
6) Throttle responsive throughout the rev range, no flat spots/plateaus, engine definitely pulled a little bit harder & throttle response was snappier, in stead of "wait for it..."
7) Exhaust popping on deceleration/engine braking; overheating, lean running: GONE.

I did still have popping with the #128 main jet + #31 pilot jet + 0.03" needle shims during a previous tune & test session, but I also replaced an intake manifold o-ring before the most recent tune & test session. Certain I had a slight vacuum leak with the old, tired one, allowing unmetered air into the manifold throat, leaning out my air/fuel mix. I experienced racing (automatic rising) idle, which is gone after the intake o-ring replacement.


After DGV2 install, I’ll assess any further carb adjustments needed with the new pipe, & the DG 1 3/8” Quiet Core Insert - but I’m running very slightly rich now & happy with current carb setup. The DG pipe may bring my tune right into that sweet spot.


FYI: DG Support recommended to me their 1" version Quiet-Core Insert for use with the TW200 in otherwise factory tune, for best tune. I sized up to the 1 3/8" since my carb is tuned & I already have an assortment of jets/shims to further tune with & didn't want the DG pipe's sound to be too stifled or too wide open.

I’m balancing a few things now - will update with specifics, when my project gets to the DG & carb point.

Also, a word of advice: I read you’re shooting for 75% off road use & considering changing your rear sprocket for a lower tooth version to drop revs on road. As a bigger guy, seriously consider what that’s going to do to the limited power you have to work with on low-speed or technical trails. Depending on type of off-road you plan for, some guys actually add teeth for granny-gear grunt in 1st & 2nd. With 12hp come compromises. Same deal with the carb tuning on these little TW’s.

I run a 47 tooth rear, but I weigh a buck sixty & am 90%ON/10%OFF road. I like this setup for me, but YMMV.
 

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My personal opinion on this... This bike is only 12ish horsepower. You aren't going to gain anything over the stock configuration except a little boost at midrange with any mod that I've tried with the intake or exhaust that is worth the while (again... just my opinion). What you will do is just burn more gas and not really have anything noticeable to speak of on the trails/road. The pilot screw is the only thing that is set poorly to meet EPA standards from the factory and set way too lean (requiring choke much longer to get going without issue). When you get this adjustment set right it will be up and running in less than 30 seconds with no choke at around 2 1/2 turns. After that, tiny adjustments are great for that "just off idle" to 1/4 throttle position acceleration. You want to have it set so it pulls good off throttle when accelerating, and it drops back quick to idle quickly when you let go of the throttle. Universal rule of thumb with any carburetor bike's pilot mixture.
 

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2021 TW
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I would wait until you actually have the bike and put the break-in miles on it. I have a 2021 with around 700 miles on it now and have no problems. With the warm weather in the 70"s it starts with out the choke, doesnt stumble off idle or surge. The spark plug looks good as well. So why fix it if its not broken. I would like to see real unbiased dyno numbers on the aftermarket pipes and rejetting. Just to know if its actually doing something or just making noise.
 

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Discussion Starter · #6 ·
Bottom line is, if you hack the brass blank that covers the (whatever it’s called, we tend to argue over this) screw, and back it out around two or so turns, it makes starting a lot easier

...

Dude – slow down and smell the roses. Hand guards, improved lighting, new front tire, bigger foot pegs I can understand, but think hard before you worry about exhausts and carbs – you don’t “need” any of it ……
I'm not desperately trying to squeeze out an extra 1/2 horsepower or anything, I know what I'm dealing with. I'm just trying to improve whatever I can. On the KLR650, switching out to the more tapered needle from the KLX650 with lower c-clips (equivalent of adding shims) and then upping the main jet makes a HUGE improvement in how it runs and feels. Again, advancing the timing chain by one tooth also adds a massive increase in performance. Feels like a different bike. As for the exhaust, it's all just about appearance and quality of the noise, not just the volume. Again, I only have the KLR to compare to, but the factory exhaust sounded like a lawn mower, and a nice pipe opened it up and gave it some mean growl. I'm just trying to do similar mods to the TW.
 

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Removing the taper seal and adjusting the fuel screw is definitely worth it from a runnability standpoint. Messing around with the main and pilot should only happen after you get a feel for the bike. It is not a dramatic improvement as it is with other bikes (like the old Super Sherpa).

Get a feel and then order a bunch of jets and mess around.

Larry has a great post with part numbers here:. TW carb jet part#s
 

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Does the darn thing work as is? Yes. Don't mess with it!
or
Does the darn thing work as is? No. Adjust fuel screw 2- 2 1/2 turns out.

Now does the darn thing work? Yes. Fidget no more.
or
Now, does the darn thing work? No. Purchase a #34 low speed/pilot jet. Yamaha part #5LB-14342-17-00

I would suggest not doing anything else till you try the above first. Easiest and cheapest carb adjustment you can make. Easier starting often without the choke and much faster warm up. And increases fuel flow slightly at midrange and highspeed as well. It may even provide the extra fuel flow you want/need to please the additional noise the DG requests of your wallet. Anything more is most likely going to decrease mileage.

As @Purple pointed to above, all this depends on the various 6" increments of altitude change as well.
:):cool:
But, as long as you are below 7,999.5 feet . . . .

Marty
 

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It runs as good as it is ever going to with the stock setup and adjusting the fuel screw. You are never going to get a whole lot of responsiveness from a CV carb.
 

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Someone's about to experience the joy of perfectly tuning their tdub and having a day of pure happiness and then finding out the next day when it's ten degrees different temp that it runs like shit again. Mines been a tempermental twat about it. 80°F+ 132.5 main 34 pilot, below 80 130, below 50 128 main and 31 pilot. Below freezing 126 , 8-900 feet above sea level.
Gave up until the piston and cam are installed and if she's still on her period I'm getting adjustable jets and be done with it.
Here's a fun project idea for the engineers of the group. Rig up a thermal spring to an adjustable jet setup so it corrects itself as the temps change?
 

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Yamaha should have an altitude compensating knob on the carb like Honda did on the little 3 wheeler ATV's of the early-mid seventies.

Marty
 

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Discussion Starter · #15 ·
Never been good at carb stuff, have a question.. Putting in this Dynojet kit, and the instructions seem a little backwards. It says to place the e-clip on the third groove from the TOP, but then it says to place the washer ABOVE the e-clip.. When they say the TOP of the needle, they are talking about the flat end, not the pointy end, right? And the shim is supposed to go ABOVE the clip, meaning you don’t thread the needle all the way through the shim, placing the shim below the clip?

Which end is the top and bottom on the needle?
 

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Discussion Starter · #16 ·
Disregard last post. Dull side of needle = top, and I put the shim on top of the clip like instructions said. Bike runs like shit with settings per the Dynojet kit manual. Throttle response is very slow and feels like it wants to bog down.

Dynojet instructions said #128 main jet, needle with clip on 3rd notch, shim on top, drilled out the slide lift hole with the “DD#39” drill bit, whatever that is.

When removing the needle from the carb, is it normal for that little white plastic piece above the tiny spring to stick in that tunnel? It did not smoothly travel up and down..
 

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Should've tried it before drilling the hole. Some of them it makes it worse. Yes the white thing sticks some times. By the time you ever figure out your settings it'll be worn enough not to.
 

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Discussion Starter · #18 ·
That little white thing really sticks, I don’t see how the vacuum alone would allow that to pop up, I have to put some force down on the needle to get that white thing to pop up. Also, what the hell does putting a shim on top of the e-clip do? The e-clip is supposed to go in between the clip and the little spring right? I just don’t see how that does anything. If the spring were underneath the clip instead, it would slightly raise the needle and I can understand how that would make a difference, but I do not understand the inverse.
 

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If i had to take a guess, i think it may be too keep the end of the spring from getting hooked in the c clip. I wondered if i was reading that right when i did it too lol.
 

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Discussion Starter · #20 ·
Kind of guessing at this point, but I put the shim underneath the clip, meaning I threaded the pointed end of the needle through the shim and slid the shim all the way up against the e-clip. Then I turned the air screw to 2.5 turns out, and it seems to run much better. Not perfect though.

Side note: fuck that throttle return spring. I’ve put it back on like 4 times now so I’m getting pretty good, but I invented a tool that makes the job wayyy easier. Credit to Tdubskid on YouTube for making the video showing how it all goes back together.
 
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