xr650r jetting suggestions

Discussion in 'Thumpers' started by supergabbro, Jul 30, 2020.

  1. supergabbro

    supergabbro n00b

    Jul 30, 2020
    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), aftermarket headers and 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. :baldy:baldy:baldy

    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:clap:clap:clap

    edit. headers are fmf, regular no powerbomb
    and K&N air filter