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XR200...Really high altitude!

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I decided to open up my air box the other day and see if I could give my bike a little more air since it is ridden from 10,400-14,000+ feet above sea level. After doing so, the bike's revs were a bit slower and it did not idle real well. Having no prior knowledge of jetting, I decided to open up the carb anyway. I found a size 100 jet (reccomended for a 10,000 foot elevation according to manual). Just to play around with it a bit, I moved the clip from the 3rd position (up from the point) down to the 2nd. I may have been going the wrong way, I have no idea, but the bike ran way too fast, so I just put it back to its original position. I am thinking I need a 102 main jet, but I really don't know. What would you suggest for main jet, clip placement, etc.? Also I might take out the baffle on the exhaust eventually, so if that changes any of the jetting I would like suggestions for that as well.

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Increase the main jet in 2 step increments and compare performance, keeping the clip position where it was. Depending on how restrictive the airbox was, the #100 could jump to 110-120 as an estimate.

James

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Thanks. Anybody have an idea how much those jets cost, because I can see it going up pretty high considering I may be buying 5-10 different jets?

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They're cheap, $2-4 a piece. I would recommend that you make your exhaust changes and jet the bike accordingly. Don't waste your time jetting it and then change the exhaust only to waste more time figuring out which jets to use.

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Will modifying the exhuast require leaner or richer jetting? In other words, an 2001 XR200R with a modified airbox and pipe riden at 10,400-14,000+ feet needs _______.

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I hope a more experienced rider will chime in on this....

I don't think it matters what elevation you ride, if you open up the engine to breathe better you will have to allow more fuel (richen the mixture). If you make both changes: free flowing airbox and after market exhaust (or any increse in exhaust flow) you will need to significantly increase the fuel.

Start by jetting the idle circuit. All this means is tuning the bike to start. If you can kick the bike without touching the throttle I'd say you've got the idle circuit set correctly. Do not cheat by increasing the idle screw. Adjust the fuel screw between the carb and the cylinder: lefty-lucy=more fuel. If your fuel screw is turned out more than 2 1/2 turns I'd suggest a bigger pilot jet. The pilot jet and fuel screw together control the ease of starting and the roll-on power from closed throttle to 1/8.

Main Jet: Check your needle position but do not make any changes. Your bike is breathing better now so it needs more fuel but where exactly does it need more fuel? In the first 1/4 turn on the throttle? In the 1/2 turn of the throttle? or from 3/4 to full throttle? The main jet size controls (SOMEONE PLEASE VALIDATE) from 1/8 - 3/4 turn. If you need more fuel (sometimes it feels like you need more power) you should consider increasing the jet by one step.

Needle Position: Only move the needle clip when you need more fuel at full throttle. This would be moving the clip down (raising the overall height of the needle).

I hope this helps. I get jetting confused so take this information with a grain of salt.

-----------------------------------

XR600R - '95 fully loaded

XR200R - '86 Powroll Stroker crank and torque cam, Race Tech Gold Valve emulators and progressive springs, FMF Power Core IV, 5" air filter with airbox removed, CR High Bars. 12T front/50T rear (Girlfriends Bike)

XR200R - '93 FMF pipe, CR High Bars

XR200R - '94 stock

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