XR650R Carb on a XR650L

Would it be possible to modify the carb bracket that the throttle cables are connected to instead of cutting into the XRL cables? I was thinking instead of modding the stock XRL cables you could mod the bracket to bring the cables closer to the throttle assembly. I haven't received my XRR carb yet so this was just a thought but in the pic below it would seem like it could be possible.

DSC01605.jpg

Did you ever try the HRC needle? The carb I bought off ebay has the HRC jets installed already. I would be curious to hear if you had a chance to test this?

i guess it's possible...basically i believe it's just adjusting the length of the cable sleave/sheathing...but i'm not positive since i used the R throttle and cables...mess around with it before u mount the carb, it will make it much easier.

nope haven't done chit but now that Lent is over the restaurant is slowing down...:lol:

with the HRC needle i wud start w/ the second clip down :p

keep us updated and i will do the same :lol:

:cry:

I tried the XR650R carb with mixed results. While I am really impressed at the improved throttle response but I think its jetted lean because it backfires at idle but can it really be too lean with a 70 pilot? Maybe something wrong in the AJCV?

I can't seem to get this dialed and its getting worse.

I have 65s,160 jets,hrc needle 4th clip up, uni filter, stock motor, stock header (ceramic coated), suppertrap muffler.

The last time I rode, the idle was rough, and on the freeway at 65 it would run for a mile, then cut out and die. I would pull in the clutch and cost for 10-15 seconds and pop the clutch and it would start up and run again for mile or so and repeat. I pull off the freeway and ride surface streets home 10 miles, stop and go trafic 20-45mph no problems.

now:

it starts with full choke (lever up) runs ok (1400-1600rpm) adjusting the throttle, flip it to middle position, it starts missing runs poorly for a while and dies, all the way down, misses and dies.

Do I just need to clean it or is there something else? So what the hell is going on? its got me baffled.

1.) The last time I rode, the idle was rough, and on the freeway at 65 it would run for a mile, then cut out and die. I would pull in the clutch and cost for 10-15 seconds and pop the clutch and it would start up and run again for mile or so and repeat. I pull off the freeway and ride surface streets home 10 miles, stop and go trafic 20-45mph no problems.

2.) now:

it starts with full choke (lever up) runs ok (1400-1600rpm) adjusting the throttle, flip it to middle position, it starts missing runs poorly for a while and dies, all the way down, misses and dies.

1.) That makes me suspect a fuel flow issue. Check the tank vent and fuel lines.

2.) That points to a lean issue with the idle circuit. Clean the carb.

1.) That makes me suspect a fuel flow issue. Check the tank vent and fuel lines.

2.) That points to a lean issue with the idle circuit. Clean the carb.

Thanks HT, I have taken the carb apart and "cleaned" it with carb cleaner, pulled the jets, and float, wiped everything off, sprayed cleaner down the jet ports, and put it back together. Is there anything else to be done to clean it?

make absolutly sure the jets r clean...hold them up to a light and look through them to make sure nothing is blocking the flow...

...also make sure the float needle isn't stuck in it's seat...i've seen that before.

i agree that ur not get'n gud fuel flow w/ wut u describe :smirk:

mine's been run'n like a champ w/ 65s/160, stock needle raised to it's richest position. :excuseme:

:bonk:

Thanks HT, I have taken the carb apart and "cleaned" it with carb cleaner, pulled the jets, and float, wiped everything off, sprayed cleaner down the jet ports, and put it back together. Is there anything else to be done to clean it?

I use compressed air after blowing the passages out with aerosol cleaner, but I wouldn't take the carb apart again just to do it.

Hi,

I have just thrown away my 39 mm stock xr 600 carb and installed a xr 650r carb.

The results is the same as buying a mikuni tm 40-6 pumper. but for 1/6 of the price.

I got my R-carb real cheap, and i must say i couldnt believe this big amount of both hp torque increase. And throttle responce on MY bike is SAME as a pumper carb.. Maybe this sounds unbelieveable, but IT IS TRUE!

Noone are happier than me! :excuseme:

My mods are:

FMF Powercore 4 a/s

removed airbox snorkle.

Vented sidecover.

XR 650R CARBURATOR.

Final jetting: bike is running 100% and superstrong!

HRC b53e needle, 3rd clip position from top.

pilotjet 65s

Mainjet 175

Pilotscrew 2 turns out.

Before with the 600 carb the bike was slow,

and it bogged off idle all the time , no matter what you did to it.

XR6 owner read this:

Someone remeber themselves fippling around with the fuelscrew, (while driving) all the time, to make the bike respond, but it will never last, and you finally give up when your thumb and pointfinger is hurting??

Piece of shiet carb causing troble for the owner and a bad running bike.:bonk:

I can recommend swapping to the R- carb!

And 600r owners now have som jetting numbers.

Thanks// Richard

Edited by HondaXRider
1.) That makes me suspect a fuel flow issue. Check the tank vent and fuel lines.

2.) That points to a lean issue with the idle circuit. Clean the carb.

Thanks HT, I have taken the carb apart and "cleaned" it with carb cleaner, pulled the jets, and float, wiped everything off, sprayed cleaner down the jet ports, and put it back together. Is there anything else to be done to clean it?

I went through the entire fuel system from the tank to the carb, and blew out all the passages and cleaned jets and plug. But it is backfiring through the carb, that is the "miss" when the bike dies when I am warming it up. When this happens it will start up agian, and idle ok when it happens again. Whats the cause of carb backfireing?

Thanks

Backfiring back though the carb is an "ignition" problem, like a bad stator or cdi or pulse generator.

Backfiring back though the carb is an "ignition" problem, like a bad stator or cdi or pulse generator.

Hmm, well It has a new CDI, So the pulse gen can be checked by resistance, how do you check the stator? what about the coil?

Hmm, well It has a new CDI, So the pulse gen can be checked by resistance, how do you check the stator? what about the coil?

Backfiring through the carb usualy means it's firing at the wrong time, take your timing light and check your ignitial timing and full advanced timing.

Spitting back through the carb is usually a vacuum leak.

You need to double check a few things......

If it back fired before the carb swap, it's ignition timing.

I would be seriously checking the needle and seat. Take the carb

bowl off and invert the carb body.....lift the float up and down

while blowing thru the fuel inlet hose. Make sure it opens

and shuts off the air flow. Make sure the float is set approximately

parallel to the carb base. You've described an very low fuel

level in the carburetor or a partially/completely blocked idle

circuit. Next......remove the idle mixture needle completely

and blow air thu the opening. You will hear air escaping in a

few places. Cover the leaks with your fingers or tape until

you can feel air coming out the idle port on the intake side

of the carb. If you smoke (cough) blow some smoke to make

sure it's absolutely clear. These are tiny orifices and it doesn't

take much to clog them. When carbs sit for a period of time

I have seen them leave varnish deposits that block fuel delivery

across the pilot jet/main jet and idle ports. It dries semi-clear

or yellowish. Run a jet drill or needle to clear it. They run fine

above the idle circuit but won't idle, backfire and won't start

until you choke it hard and draw fuel up through the main jet circuit.

One other thing........make sure the vent lines to the carb bowl,

gas cap are open this could also prevent fuel delivery.

When you are sure the idle circuit is clear, reassemble and fire it

up. Make sure it idles with the choke fully open. Turn the idle

mixture screw out to 2-3 turns, slide just slightly off fully closed.

Hope this helps.........

HBLARRY

Thanks Hblarry that does help, I opened the top of the carb and notied he oring around the top had grown and bulged out of the groove, there was no way it was going back in. Piror to opening the top, I looked at the needle jet through the carb and noticed it was not even, but pulled to one side when I actuated the slide. When i pulled it out the clip was deformed. I order some new parts and go through your cleaning proceedure over the holiay.

thanks everyone for all the help

pdx thumper,

If that o-ring isn't broken or cut..........stick it in the refrigerator

for few minutes and try the fit again. It should shrink back to size.

HBLARRY

I have the Mikuni Pumper from XR's Only. After messing with jetting for a while now I think I got it running pretty good. The only issue I have found with it is the pumper pumps too much fuel in when its engaged. If I delay the pump it responds very well, but as soon as it squirts, it has a slight stumble to it. Wack the throttle a couple of times and it gets worse followed by black smoke comming out the exhaust. Then it clears and idles fine again.

My question is, would I be happier with the XR650R carb and get rid of the Mikuni? Or should I keep it and tweak this thing in a way I havn't found yet.

Have you tried a smaller pump nozzle? How about shortening the pump duration?

Do you have the HS40 manual from Mikuni?

Have you tried a smaller pump nozzle? How about shortening the pump duration?

Do you have the HS40 manual from Mikuni?

No I don't have a manuel for it. XR's only has been less than helpful. I have gotten this far with the help from TT. How do I shorten the pump duration and how do I put in a smaller pump nozzle. Are you refering to the small piston and spring that sits in the base of the bowl? Where would I get one?:excuseme:

Click on the red "HS40 manual" in my last post. It's a download link for the manual in my MedaFire account. That, or just Google "Mikuni HS40 manual."

Thanks Hblarry that does help, I opened the top of the carb and notied he oring around the top had grown and bulged out of the groove, there was no way it was going back in. Piror to opening the top, I looked at the needle jet through the carb and noticed it was not even, but pulled to one side when I actuated the slide. When i pulled it out the clip was deformed. I order some new parts and go through your cleaning proceedure over the holiay.

thanks everyone for all the help

Constant backfiring when reved(large explosion that can scare you) through the carb is a timing problem, a non-constant pop(tiny explosion)back through the carb is to much fuel. Constant popping is valve timing or poor intake valve sealing.

Spitting fuel back through the carb is a vacuum leak or poor intake valve seal.

Ok, which one of these scenarios is it than we can help you.

Some history of the bike would be nice, like did it run good before the carb swap, did you buy the bike in good running condition.

Much more info is needed on your part in order for us to make a clear decision on what the problem may be.

Also you have to do a process of limitation when diagnosing a problem, have you done that? Compression check, ignition check,fuel check,leak down check and the list goes on and on until you have found the problem area.

Edited by pwrpapa

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