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xr650r jetting suggestions

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Hey everobody!

after years, first time ever i have registered to a forum and this is my first post obviously, so forgive me if i write something dumb))

so i got me a brp, my dream bike for the past 10years, ever since i owned my first dirtbike, a suzuki DR600 (1985).

once i got the bike which was in supermoto setup, gearing was 16/42, HRC cam (what the owner said, didnt get to check it yet), headers are fmf, regular no powerbomb
and K&N air filter, aftermarket  exhaust muffler (dont know the brand, probably GRP Ovale), stock crab, 45.000km on the engine.

seriously i was expected the bike to be killer fast, so i be scared to pull the gas, and pulling up wheelies in 3rd gear NO clutch. well this is what i EXPECTED. maybe just i have imagined it all from reading other posts.

riding the bike at first, well it was fast, but not that crazy horse i wanted. so i shortened the gearing (the bike couldnt even hit the rev limiter in 5th around 110mph/175kph, and i have no need to that fast) to 16/46 first and 15/46 now, which was getting the bike to wheelie in 2nd, and almost in 3rd, no clutch that is. the riding experience was very cool, getting much closer to what i wanted.

SO, now coming to the reason of this thread.

as in terms of carb, i am no expert but a general feeling was that it was ok. not great, not bad but ok.
bike would start 2nd kick if cold/overnight, then 1st kick through the day. i ride everyday (70-120km) as its the only means of transportation.
on the bottom end it would be very responsive, while mid to top end some hesitation but just a little.
one thing that was not to my liking was once the bike is hot, (and where i am riding now its 30C/90F on average in the city), at traffic lights the idle would start climbing up sometimes, and had hard time coming down, i had to put first gear in and slowly release the clutch to make it come down, put in neutral and hope for the beat. otherwise i just wait for the green while playing with clutch and brakes.

so after some thought i decided to inspect the carb, take it apart and clean it. I repeat, i am no expert in carbs but consider myself well prepared mechanically.

I ordered a carb repair kit (moose), got the workshop manual, and found a video on youtube of the whole process, a to z. also i rodere a new boot from carb to head, as i thought the increasing revs on idle may be due to an air leak.

so i took everything apart, taking down note of pretty much everything (so i think), like screw turn etc.
the carb was very dirty so i also left it overnight to get all those incrustations off.

what i replaced is

-main gaskets - 3 top, bottom, and bottom nut.
-small gasket in the air cut off valve
-fuel screw, ie oring, washer spring then fuel screw
-floater pin or screw, dont know how it is called

now coming to the jets and needle, and this is where i messed up, i believe, first of all i didnt write down which ones.
-main jet left the same one, that is a 175, just cleaned it, since the one i got in the kit was 125 (i think the whole kit might have been for us models).
- pilot jet if i m not mistaken was a 68S, and i put a new 68S,BUT i might be wrong and its a plain 68 no S
- needle replaced ann out the clip in same position, 2nd from the needle point, or 3rd from the bottom, flat. but i am pretty sure one was F and the other was E. like 53E and 53F. didnt write that down. 

one more thing i did is to take off the butterfly valve on the choke mechanism, smiley face, so now it has an opened mouth.

at the end i was also in a rush to put everything back that i forgot to check the floater level.

putting everything back i was really scared that the bike wont work anymore.

but after playing a little with the fuel screw and idle i was able to start the bike.

as in terms of performance bottom end was slightly better when engine wasnt too hot, top end had slightly more lag. but when heating up it just started going crazy, idle speed would go waaay up, no engine breaking, and what i noticed since the beginning is popping on release, which was not there before i layed hands on the carb. i increased the idle speed and the popping diminished but the idle at stops and traffic lights got worse.

when i got home i did the whole fuel screw procedure following the manual and some info i found on xr650r.co.uk

so it got better or so i thought.

today it took me about 6 kicks to start the bike but it kept dying, so pull the air => almost no effect, raise idle, and there you go. once heated up, had to diminish idle, this whole procedure was never necessary before.

now after first daily use i need 2/3 kicks to start the bike as opposed to 1 kick before taking the carb apart.

Now i decided to dedicate more time to it and will be taking apart the carb again next week since i will have time off and no need to use the bike, so to do a proper job.

i ordered
-new cut off valve
-moose jets kit stage 2

what i plan on doing is
recheck needle and jets installed now with installed initially when bike was easy to start, change cut off valve, floater level.

as i will get my hand on the carb, will post pics and updates. meanwhile i am getting an akrapovic exhaust this weekend so i guess will be experimenting with main jets as well, since a 175 is installed and that is stock. maybe increase?

any suggestions that you could give me would be very appreciated.
and any other insight on this beautiful bike.

PS. i wanted to get better power output form this bike as it doesnt feel anywhere close to 60 bhp (even though hrc cam, and exhaust should bee even more!) in comparison to my dr600 which was topend rebuilt and was around 45 bhp. feels slightly more powerful. maybe i should do topend?

sorry for such a long post but its my first and had a lot to get out


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Do not use the Moose jets.  They are aftermarket Chinese, and the quality control to actual Keihin jets can be pretty bad.  What is stamped on them is probably not what they really are.  Do your best to source actual Keihin jets and eliminate that possibility of error.

If the bike actually does have an HRC camshaft (or Hot Cams Stage 1/2), the main should be in the 185 range as a starting point.  The full HRC kit comes with 180-190 mains, and that main jet range would be typical to run in with an opened up airbox, exhaust, and cam.  I ran a 182-185 main at 1200m in base elevation depending on temp/season with the HRC kit, a similar exhaust, and the stock carb.

Stock pilot (68s) is what to run pretty much no matter the mods.

FYI, the actual stock main for the 650R was a 125 (!!!) when all choked up on the intake and exhaust, at least in US trim.

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Thanks for the info man!

will be looking for keihin jets then.

Meanwhile i just couldnt resist and spent the night in the garage)))

took the carb apart now and found out that:

needle was 53E, i was supplied 53f, dont know the difference, but cleaned the old one and put it back

pilot jet was 65s, i was supplied 65, cleaned the old one and put it back, I will try to get the 68s and see how it rides

this got me rid of pretty much all the exhaust popping, the bike is slightly smoother

But the idle problem stayed, I get to the traffic light, and and if I slightly pull the gas it won't come down, or take very long. 

So I did some testing will riding, pull the clutch, Rev it up, and it comes down right away, and tried in different gears and the result is the same, then I tried in neutral (in movement) and it comes down, and however if I do it at a stop it doesn't come down. 

Now I think it's the cable routing, since while moving I have my weight somewhere else respectively to when I'm stopped, so I think the tank presses on the cables in some positions 

so will do these adjustments and test it again, let's see what happens

Edited by supergabbro
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I misrouted my cable and had similar issues. As for the choke plate, I’m not so sure the stock plate with flap removed would cause an idling problem so much as it would make cold starting more difficult but I opted for the XR’s only plate. My intake is unmodified stock except a foam filter. I second the Keihin jets and You definitely want the “S” version Pilot Jets(65S or 68S). My exhaust is stock with a modified baffle (2” hole saw method). I have minimal popping during de-acceleration but the 68S is still a little rich so I’m going to try out a 65S. Currently I’m running a 170 which is right in the zone but every carb and bike will differ slightly depending on setup. Also keep in mind that any modification you do to exhaust or intake will more often than not require jet change. Altitude and nominal ambient rising temperature also play a key role. I’m satisfied with the stock carburetor but if I were to change it I’d likely swap it out for an FCR which some reputable professionals that I trust swear by. Here’s a valuable link to Carb settings:


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  • 1 month later...

Just an update if interested. As mentioned earlier I‘M merely uncorked with a drilled stock baffle. I was given a 65S which replaced my 68S that dramatically improved performance specific to my local riding conditions(single track 300m-800m ASL, 75-90°F). Those specifics mostly rule out attributing the improvement to main jetting(168). 
Starts 1st kick 90% of the time, Almost zero throttle lag, never stalls unless the rider does first(guilty), and easier to restart post fall/stall. The exhaust is noticeably leaner and the plugs dark brown vs the usual soot. 
Important note: I found UK XR650R carb setting guide invaluable. It accounts for altitude, temperature, cam, exhaust, and air box configurations with correction factors for pilot, main, and needle clip position.
My specific cf was a minus 1 for both main and pilot. It was right on. 
I second the recommendation for Keihin parts but they are expensive and hard to find if you are trying to arrange a kit. I was lucky enough to befriend a very generous custom parts guy who gave me the 65S. Keihin doesn’t even list them on their US site. 

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