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FCR41 on XR650R, stalling with rolling stop.

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please ignore the jetting of this post...I wasn't correct. it was actually 195 main. I corrected it on my reply below.

Sudco FCR41 on bored XR650R with Stage 2 cam and open side panel and aftermarket header and muffler.

Current jetting. 182 Main. EMP needle (have tried 3rd and 4th from top) pilot 52. fuel screw (has little effect) Idle is set for ~1500 usually when warm. has the Adjustable slow air jet (don't know of its current setting) I ride at ~400 msl, and current temps are 50-70 but it did it while colder as well.

My issue = When coming to a rolling stop from a constant speed it dies unless I purposely keep the RPM's up. (like stopping with the clutch in at a split in a fast trail to wait on the group to catch up or, stopping with clutch in at an unexpected stop light.) It does pop and backfire on deceleration with closed throttle BUT I think my pilot is too large since I can seat my fuel screw and it will idle so I ordered the next two sizes smaller.

My priority is I need to fix the dying because it did it at a traffic backup on the interstate and I couldn't get it started in time for the traffic to resume and almost was hit.

I'm confused.

I thought my symptoms of Decel popping was lean but I think my pilot is too rich?

Could the Adjustable slow air jet need tweaking (out is lean and in is rich right?) I've tried larger and smaller Main jets and other clip positions with the same results, haven't adjusted the slow air jet.

Thank you...this carb has been a learning experience and I love the tinkering but its time to ask for help!

JT

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That main seems really small to me. I am running a 185 with the HRC kit motor and XR's Only full race pipe (100 octane fuel). This is at a primary elevation of 5000 ft. I would think you'd need to be at least in the 188-190 range with the stage 2 cam (since mine is the lower lift/duration HRC cam).

I am running the air screw at two turns out. I am like you with the pilot. I've got a 48 in there right now and the fuel screw can actually do something.

How long have you had the carb in?

One issue that I ran into is I made the mistake of cleaning out the carb once with carb cleaner (Gumout spray can). This swelled up the rubber oring between the slide and the throttle plate resulting in the situation that you are describing. At least something to check.

I look up my needle tonight to see what I've got in there and let you know.

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That main seems really small to me. I am running a 185 with the HRC kit motor and XR's Only full race pipe (100 octane fuel). This is at a primary elevation of 5000 ft. I would think you'd need to be at least in the 188-190 range with the stage 2 cam (since mine is the lower lift/duration HRC cam).

I am running the air screw at two turns out. I am like you with the pilot. I've got a 48 in there right now and the fuel screw can actually do something.

How long have you had the carb in?

One issue that I ran into is I made the mistake of cleaning out the carb once with carb cleaner (Gumout spray can). This swelled up the rubber oring between the slide and the throttle plate resulting in the situation that you are describing. At least something to check.

I look up my needle tonight to see what I've got in there and let you know.

I'm an IDIOT!!!:banghead: I have three main jets and 190, 185 were in the box so I assumed 182 was in the carb...Boy was I mistaken:bonk: :banghead::foul: ...it was a 195!!!:)

So that explains alot:smirk: . tonight I installed the 190, set the EMP needle to 3rd clip from top. put the slow air jet one full turn out. (according to http://www.factorypro.com/tech/carbkei.html he says its similar to a 100.) The pilot is a 52 and still won't stall if fuel screw is closed so I left it at 1/2 turn out. But it fixed the stalling at rolling stops. It idled but it was just OK, bounced around a bit and wasn't just steady but better.

It Does NOT return to idle very quickly still with a blip of the throttle as it used to with stock carb (from what I read is a lean pilot circut???) so I don't know what that means. but when the smaller pilot gets here I'll see what that does. Sorry for the confusion. SO I'm still open to suggestions but I guess I need adjust my first post.

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