[kennethshaw]

Well I can't believe I'm doing this, but I am downgrading my 2006 TW with a 1998 TW that needs work. Call me a glutton for punishment. I got it at a killer price ($575) plus it has the kick start. So I'm going to start modifying it as much as I can. I plan on installing a TT250 header, DG or FMF slip on, Clarke Tank, cyclerack rear rack, and Stainless hex allen screws.



I went through all the carb mods for the 2006 bike, but have heard the older models are a little different. Can anyone here recommend main jet size for a 1998 model, # of shims to start, and # of air mixture screw turns out?



Thanks.

 

[small's]

Where are you located? Elevation? I put a 116 in my 98 and it runs good but im in indiana which is fairly low in elevation. I am going to shim it but havent yet.

 

[kennethshaw]

Hi,



I'm at sea level. I know the 2006 model required a 130 main. I had read somewhere that the older model tw's were much smaller than that.

 

[dakman74]

Hi,



I'm at sea level. I know the 2006 model required a 130 main. I had read somewhere that the older model tw's were much smaller than that.

Yours is, I believe a 114 stock, like mine was. Like Small's said you can probably go to a 116 with the elevation you're at. I'd try shimming to I believe it's a max of .05" and of course pull that brass plug and adjust pilot. 2 1/2 turns out as they say is a good starting point. Make the Qwerty tool (3" power screwdriver bit with duct-tape around the Phillips side for a handle). I carry mine around with the bike.



For me at >7000' elevation, I have actually gone a little more lean than the stock 114, am STILL chasing the correct shim thickness, and depending on the shim the bike likes between 2 1/4 and 3 out on the pilot. I think I'm gonna settle on a shim thickness of approximately .025" and pilot 2 1/2 turns out and deal with a little bit of lean running on COLD mornings.



The fun with carbs...trying to find a state of tune that will work when you start your day below freezing on the ride to work and can be in the 70s by the time you ride home.

Oh yeah...IF you mod the exhaust, like has been said again and again on this forum, you're gonna have to play with the carb. settings again.



Have fun!

 

[crossent]

Where is the plug on the older carbs that you guys are removing for adjusting the pilot?

 

[TWBARR]

Where is the plug on the older carbs that you guys are removing for adjusting the pilot?

The plug is on the bottom side front of the carb.#32 on the parts diagram. First little stub from the engine side of the carb. You can either turn the carb to get to it or pull the carb. I would suggest just taking the cables off the carb and turning it.

 

[qwerty]

As far as I know, only North American market TWs need rejetting.



Up to 2000: Rest of the world gets #118 or #120 main, needle with circlip slot in location to raise it about 1mm compared to north American , and ~2.5 turns out on the pilot screw. Canada and California markets get #116 main, lower nnedle groove, and 1 1/2 turns out on the pilot. 49-state bikes are the same except #114 main. Swapping the main to #118, raising the needle with a 2.5mm washer under the circlip, and 2 1/2 turns out on the pilot screw results in a similar state of tune to what happens in the rest of the world. Remember, Yamaha likes the rest-of-the-world tune, but America's tree-huggers don't.



2001 to current: Rest of the world gets #130 or #132 main, needle with circlip slot in location to raise it about 1mm compared to north American needles, and ~2.5 turns out on the pilot screw. Canada and California markets get #128 main, lower nnedle groove, and 1 1/2 turns out on the pilot. 49-state bikes are the same except #125 or 126 main. Swapping the main to #130, raising the needle with a 2.5mm washer under the circlip, and 2 1/2 turns out on the pilot screw results in a similar state of tune to what happens in the rest of the world. Remember, Yamaha likes the rest-of-the-world tune, but America's tree-huggers don't.



Keep in mind the biggest main jets were used in markets with low altitudes and high temperatures, such as Australia. Running slightly rich protects the top end from excess heat. As far as I know, the #130 main was never used in TWs anywhere, but is probably the best choice for most late TWs.

 

[dakman74]

raising the needle with a 2.5mm washer under the circlip

Maybe I'm having a math Monday...but 2.5 mm....is almost 1/10 of an inch. At least on my carb, I don't think I can get a shim over maybe 5/100 of an inch under the needle clip.



Am I missing something? Still trying to figure out how some of the "new carb vs. old carb" mods translate.



Oh and good catch on the 118...guess the first question to kshaw should have been "where EXACTLY are you located?"

With the exhaust mods...maybe even a 120 huh?