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Discussion Starter #1
Hi guys- My GF has a tw200 and I need to rejet her carb for between 9000-12,500 feet. She's on a modified ride upon which the previous owner slapped a faster flowing muffler and a straighter pipe, and lashed the valves for better airflow (all according to her via the previous owner). A few holes have been drilled into the airbox. I know this isnt much to go on, but a general ballpark for jetting and needle settings at that altitude would be fantastic. Cheers, fellas!
 

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Yep, 122 should be about right. I would not use that in my 2010 below about 8,000, but it was good to 13,000. Putting washers on the main needle is for lower altitudes, you would not need any at 9,000 or above. The pilot needle is similar, at that altitude 1.5 turns out would probably be fine. I adjusted my pilot at 2.5 turns and never changed it, even at 13,000, but I know I was running rich at low RPM's.....but since you need to keep the RPM's up at altitude just for adequate power, it was never an issue. If I lived in Telluride I would screw it in a bit. :p

I did find that about a 13/55 gearing was ideal at that altitude, although I managed with a 13/50 a year earlier. None of this matters until you try to go up something steep. :eek:
 

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With the exhaust and airbox mods the jetting will need to be richer than what you would normally do for a stock set up at altitude. The PO modded my airboxes I taped them over and I have DG pipes. My bikes run pretty good up to @ 10,000 and then start cutting out. 130 main jet , 2 shims on the needle and a 34 pilot jet. I would try a 128 then a 126 main jet, 34 pilot and maybe shims if midrange is sluggish. A different exhaust throws off all the carb settings along with airbox mods. Do you have pop back on decel at lower altitudes now?
The valve lash comment is troublesome. I would check the valve adjustment.

How about a pic of the bike and exhaust.
Edit: Rocky's advise is good just try bigger than stock for your modded bike.
 

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Discussion Starter #9
The airbox has a number of holes drilled into it. Im still trying to sort out her clutch issues. it doesnt slip in that the bike can manage the forward momentum, but it over revs inconsistently with the acceleration rate. Motor oil is dinosaur for wet clutch motorcycles, bike has 3500 miles so clutch should be fine. Its cable adjusted at the engine housing and lever. Might have to buy a gasket and open the case to inspect. Anyway, apologies for the digression. It is standard gearing btw.
 

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i run a 130 with a shim and stock exhaust in Indiana which has no altitude maybe a few hundred feet. 128 main and you will still be studdering and missing out about 9-10,000'. I ran out there the first time with stock jetting and i did make over 13,000 but old girl didnt like it and either did i. If i was a bigger guy it prolly wouldnt havr happened. Stock gearing or a little lower is great for Colorado. First time with stock jets and 14/47 wasnt very good. I couldn't muster over about 46mph from Gunnison to Crested Butte. Last time with 122 main and 15/54 i could run 55-60mph

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