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mikesbaron

XR600 and XR650 jetting similiar?

9 posts in this topic

I have a 1993 XR600r with some sort of flat slide carb and of course my newish 2003 650R. I think I have the main jet for the 650 sorted and want to know if I could expect the main on the 600 to bve pretty much the same size, given similiar bike mods?

It runs ok, the 600 but doens't seem to have much pull. I have yet to pull it's main jet but I got the plug out of it and it was black sooty!

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My guess is the 600 would be close, but is is not going to pull quite as much air. Perhaps one or two sizes leaner.

However, are these different carbs? Stocker on the 650R and a flat slide on the 600? In that case they jetting may be completely different. It would only be close if we are talking the same model of carb.

As I'm sure you know sooty black is way rich. The question is where, main jet, needle or idle.

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Here's a pic of the XR6 project. This is the latest mod: cut down side panels. Next up will be new bars, handguards, frnt fender, Acerbis fork guards. and headlight setup. The bike has a 628 kit, addtl cooling fins and flatslide I'm still trying to get sorted. I just had the kickstand tab welded back on as well s the right side footpeg mount area crack fixed. Eventually will be powdered coated frame.

Some before and after of this particular XR600 project I've been getting help on, still looking for some jetting help. But oh well, here's the sidepanels before and after shots.

BEFORE

xr600c.jpg

xr600.jpg

AFTER:

100_0109.jpg

100_0108.jpg

100_0111.jpg

100_0110.jpg

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I saw the photo on the jetting forum. It looks a lot like the TM38-85 that XRs Only made up for the 600. They also did the big fin add ons. If thats what it is they came stock with a 240 MJ,17.5 pilot,6FJ41-4 Needle,389-Q4 Needle Jet.4.0 slide for 3500 elevation. You would go richer on Main and pilot if lower El. Leaner if higher el. XRs only bored them out to 41mm and there should be an alumunium adapter on the filter side. I have one on one bike and it works very well. I like the cut down side panels.

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Thanks Daddky K, you are the man!

Glad you liked the side panels. It should all look pretty slick once we get the new bars, headlight and fender, handguards, fork guards setup.

BTW, any of you XR 600 fans know where I can view some good video of Scott Summers doing damage on his XR600? I tried You Tube and nada.

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not sure how much the fins are. I think they were done by XRs only. I'll see if I can look it up though from an old mag where they did this mod.

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