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Discussion Starter #1
Hi All,

I've tried searching but haven't managed to find a definitive answer. Is there a direct replacement carb that would fit a 1999 nx650?

I was going to strip and rebuild mine as it's got the usual tickover issue but if there is a better replacement that could be used I may well just go down that route.

Thanks
 

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Short answer is no, BUT if you are prepared to put in a lot of effort jetting and getting different sized carbs to work then You could fit Keihin FCR or Mikuni TM type carbs but it is not plug and play unless you spend a lot of time and money.
Clean yours, BobN has a very good post on these carbs and I would also add that you should make sure the atmospheric reference port on the carb has a rubber hose on it going up and down, air into that port can lead to funny carb behaviour.
 

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Discussion Starter #3
Cheers, I've seen posts about flatsides and XR carbs but nothing about whats needed to get them fitted. I'm currently running 50/148 jets and it surges slightly in the midrange and can cut out at tickover after coasting unless you give the throttle a blip before selecting neutral.

Carb kits aren't that expensive but I would have just replaced it for something more reliable if it was a simple enough swap.
 

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There isn't much wrong with the stock CV carb if its running correctly, it will never be a firebreathing animal but that's not really the nature of the bike anyway.
Clean the 4 holes in the bottom of the throat at the butterfly/airbox side. That can help with tickover issues.
Make sure all the hoses are present for aircut valve and that there are no leaks. I have a 155 main and 50 pilot on mine and its fine. Try a slightly bigger main jet than 148 as well especially with an aftermarket pipe its probably lean.
https://www.xrv.org.uk/forums/dominator-fmx/139281-tickover-problems-cure-here.html
 

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Discussion Starter #5
Thanks for that. I've ordered a rebuild kit, a couple of spare jets and a service kit so Saturday is going to be a busy day I think ;)
 

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Sorry to jump on someone else’s thread, but I’m just about to refit my carb, and was wondering, bike was running perfect before I took carb off.
I’ve cleaned outside so it’s spotless, would you strip and clean it now, before refitting it, cos it’s off the bike.
I took photos and put hoses back in place, but one hose has a y connection on it, I reconnected the one side, but can’t see where there other side of the y goes to???
There’s no spare connection on carb, does it plug on something else, like airbox it something???
 

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Discussion Starter #8 (Edited)

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Sorry to jump on someone else’s thread, but I’m just about to refit my carb, and was wondering, bike was running perfect before I took carb off.
I’ve cleaned outside so it’s spotless, would you strip and clean it now, before refitting it, cos it’s off the bike.
I took photos and put hoses back in place, but one hose has a y connection on it, I reconnected the one side, but can’t see where there other side of the y goes to???
There’s no spare connection on carb, does it plug on something else, like airbox it something???
That sounds like the air pressure reference tube, it connects to the side of the carb and goes down into a Y fitting and the lines run up under the tank and down by the rear of the engine to provide a stable air pressure for the CV carb.
There should be another pipe from a nipple on top of the throat to the air cut valve.
 
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