XR650R needle jet question

This is probably a long shot, but does anyone know if the needle jet that comes with the B53E jet needle is the same needle jet that comes with the stock B53D needle? I ask because it would be easier/faster to make needle swaps if I don't have to change the needle jet also (to keep the needle jets and jet needles as matched pairs).

I'm getting a slight stumble/studder as I quickly chop the throttle from WOT to somewhere around 3/4 or maybe even 1/2 throttle. It will occur when chopping from slighly less than WOT as well. It sounds/feels like a loading-up, rich phenomenon. If I roll off nice and easy it's no problem. My suspicion is that the taper of the B53E needle is just too rich. I'm gonna go back to the stock needle and see if it improves. I think the studder is more severe in really hot temps but I'm still experimenting to confirm that.

Right now:

Stock internals

Moriwaki headers/silencer w/spark arrestor

172 main

68 pilot

2 turns

B53E 3rd clip

75-95+ temps

1300ft elevation

That's strange because at 1300ft or sealevel w/ an aftermarket can I'd say the 172 main is a tad lean. Try the stock needle in the 4th clip and see if that works.

I believe the needle jets are the same and the difference is of course the needles.

That's strange because at 1300ft or sealevel w/ an aftermarket can I'd say the 172 main is a tad lean. Try the stock needle in the 4th clip and see if that works.

Same here, stock needle 4th pos with 175 main worked great for me in the heat. Did you open the side panel yet?

Same here, stock needle 4th pos with 175 main worked great for me in the heat. Did you open the side panel yet?

No I haven't opened the panel up. I have a 172 main right now which gives here a tad more snap than the 175. If I'm going to ride alot of sand the 175 goes back in.

No I haven't opened the panel up. I have a 172 main right now which gives here a tad more snap than the 175. If I'm going to ride alot of sand the 175 goes back in.

Sorry, that was actually a ? for HawkGT, he posted a ? about opening the side panel the other day, but for you too, give it a shot, cut some vents in the side panel and put a fine mesh screen over them, give significant gain in the middle and on top, but you give up nothing on the bottom, I loved the way it made mine run, when you do, go up 1 main size, and use the 68s pilot, works great. :crazy:

I'm considering doing it but we ride alot of mud/water around here and it would limit how close the swamp water can come to the family jewels....some crossings are near seat height.

I'm considering doing it but we ride alot of mud/water around here and it would limit how close the swamp water can come to the family jewels....some crossings are near seat height.

In that case then, maybe not. I've never had a bike in water above the cases, seems like if it was close to seat height, you would get water in so many places that you don't want it. The top of the air box is below seat height anyways, but venting the side panel definitely lowers that by about 3". Maybe just have some duct tape on hand when you know your doing some submarine action. It sucks the side panels are so pricy, you could have one vented and one not for different rides, also once you cut it, there is no going back without some sort of rigging going on unless your real good w/a plastic welder.

In that case then, maybe not. I've never had a bike in water above the cases, seems like if it was close to seat height, you would get water in so many places that you don't want it. The top of the air box is below seat height anyways, but venting the side panel definitely lowers that by about 3". Maybe just have some duct tape on hand when you know your doing some submarine action. It sucks the side panels are so pricy, you could have one vented and one not for different rides, also once you cut it, there is no going back without some sort of rigging going on unless your real good w/a plastic welder.

Not above the cases you say.

36743029-L.jpg

WOW!!!! /\ /\ That's gnarly, the only place I know of that has crossings like that where I ride, you get FAT tickets if you get caught with a tire in the water.

No, my sidepanel isn't cut.

I went back to the stock needle on the 4th clip position. No change in the WOT to 3/4 throttle sputter. Hmmmm. Although, if anything the stock needle did seem to respond a tad better.

So, I went down to a 170 main and the sputter got better. Went to a 168 and it was better still--almost totally gone. The only time it does it with the 168 is when I hold WOT in a tall gear at lower speeds and then chop the throttle. Probably would hardly ever happen unless I'm trying to make it happen. Runs strong with the 168 but does seem to run a bit hotter. I don't like that but I also don't want to run it fat. Cooler temps vs. optimal performance I guess.

Air temp was 85 deg.

I'm thinking that the spark arrester in the Moriwaki silencer plugs it up more than I would have thought. It IS quieter than my old exhuast with the HRC tip.

MaxPower, that picture is awsome.

have any of you guys had luck with the air screw. stock setup uncorked with sidepanel cut with 68s and i am three turns out on the screw. which leaves me to belive i need a 70s. which i ordered. am i on the right track? it seems like when i am done jetting i am going to be one fatter on every setting on the bike since i cut the side panel. i.e.

68s vs. 70s

3rd groove vs 4th

175 vs. 180.

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