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Discussion Starter #1
So I know the older TW200 carburetors perform much better then the newer CV carbs do. But my question is does anyone know how much better the fuel economy is with the newer carbs? I want great MPG but if they are comparable I would just use the older carb.
 

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How you ride and quality of fuel will make much more difference than which carb you use.
 

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Discussion Starter #3
If my riding was to remain the same I just wonder what the difference in MPG would be. Not sure if anyone has tested this. If not I might have to.
 

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So I know the older TW200 carburetors perform much better then the newer CV carbs do. But my question is does anyone know how much better the fuel economy is with the newer carbs? I want great MPG but if they are comparable I would just use the older carb.




I don't have anything to compare it to, but on my brand new 2010 with only 100 miles on it, I went 93 miles in the dirt, mostly in 2nd, 3rd, and 4th before going to reserve, then another 20, and still had some gas sloshing around, maybe another 15 miles. So I figure I went 115 miles on 1.5 gal., which is 76 mpg. I thought that was pretty amazing, considering the amount of washboard I rode that day (all but 25 miles of the ride), which must be at least a little deleterious to maximum mileage, and that I was carrying 195 lbs. of me and 40 lbs of gear on the rack, AND going from 1500 ft to 5000ft and back plus another 2000 feet in between. Oh, and I also have a 13 tooth front sprocket on, which could conceivably have actually helped mileage on that road.



I wish I had an older TW to compare to, but my bike worked just fine on the stock jet. I never felt like I didn't have plenty of power, it didn't exhibit any poor throttle response or starting or warming up idiosynchrasies. All I did before the trip to Death Valley from Idaho was raise the needle one 0.10 washer worth and backed out the pilot needle 1/2 turn. I probably didn't even need to do that!



Based on my experience, I'd have a hard time believing that an older TW could beat that kind of mileage in those conditions by much, and I wouldn't be at all surprised if an old one jetted with a 130 wouldn't get close to that. Frankly, I've read just about everything on this forum about the TW's carb oddities and folks complaints about the stock jet, and I'm having a hard time understanding what they are talking about. My bike, stock out of the box with only the three changes mentioned ran absolutely flawlessly from -200 ft to 6000. It did not exhibit any of the anomalies others have complained about. It had all the power I could want at the trail riding speeds (5-40) ran 55 on the pavement, didn't get hot, started instantly every time, was quiet after I wound an inch of fiberglass around the spark arrestor (which didn't seem to have any effect on power that I could tell), and did everything I asked of it except deep sand.



I really do wonder if there are some subtle differences between the older carb and the new one that make the new one better at handling large elevation changes. I was sure I'd have problems at sea level but they never materialized. The only subtle change that I could detect was that the rpms would hunt a little going downhill just off idle. It wasn't an issue that would even have made me stop and back out the pilot needle a little, which I can do in a minute with my sawed-off screwdriver.



Based on my experience, I would now expect to run my bike from 0 to 9,000 feet with NO ADJUSTMENTS at all! Now if I was going to move to Colorado or Southern Cal. I would optimize carb performance for either place, but in Idaho I ride from 3,500 to 9,500, and the amount of time spent above 8,000 is pretty small.



These little buggers are truly amazing and vastly underrated by the big bike crowd. (but then I'm not going to Dakar on mine, either
!!!!
 

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Discussion Starter #5
On my old 1989 TW (with the old carb) I was pretty much getting 80 mpg all the time. I do have one tooth up on the counter and as small as I could go on the rear. I tend to ride my TW very hard.



I have the same gearing on my new TW but have yet to do a MPG run. I can tell you the difference between the new CV carb and the old carb is large. The power is instant with the old carb and the new TW really has a lag and feels a bit underpowered - after all the butterfly valve is restricting some air flow. In a word, the new TW feels "friendlier".



But MPG is important to me - otherwise I'd have a dualsported CRF, Beta, KTM, Husaberg etc etc.
 

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I had a 2005 model tw that was getting 70-80 mpg depending how I rode it. My current 87 model TW gets 70-80 mpg depending on how I ride it. I beat a 2006 model TW last weekend in a light to light drag race up to 50 mph with my fat front tire mounted and a 45 tooth rear, so I beleve the older carb model is probably quicker but I must say they are very close.
 
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