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gtr-fxr

650L Hesitates Off Idle

22 posts in this topic

I just finished Daves Mods to my "01" 650L. It made quite an improvement. I went with the 55 pilot and 158 maint jets. Actually, I ordered the hex main jet so as a result of not wanting to wait on another round main jet, I drilled the the stock main to the same bore as the as the hex main I ignorantly ordered. Every thing seems fine except for this hesitation or bog it seems to have when I crack the throttle off idle. It doesn't last long, but enought to know it's there.

Do you think I might need a larger main jet?

I de-smoged and de-snorkeled it, installed a K&N filter and the jets. Set the fuel mixture screw between 2 1/4 and 2 1/2 turns out. Shimmed the needle @.024. Stock exhaust.

Any suggestions... or is it just the nature of the beast?

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i bet u never notice it when ur riding it.its hard to crack a throttle on a bike without a fuel pump and expect it to snap like a motor with a fuel pump.but with the mods ,id get an aftermarket pipe to open up the outlet.i dont think ur rich,i just did mine,dynajet kit, and daves mods,and put 58pilot and 165 main ,uni filter,fmf pipe,desmogged and desnorkeled and WOW!!, its a different bike,but if u sit there and slap the throttle real quick,it slightly hesitates,but u never see it when riding.drilling out a jet is hard to do also,i know i tried it too.with no luck,couldnt hold the tolerance that it should be,so ended up buying jets and doing it all over again.but i would change the pipe,in my oppinion.hope u getter.:thumbsup:

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I am at about 600', and I used a 55/160 with Dave's Mods. Still have the stock paper element (UNI is on the shelf still), and the stock exhaust with the baffle removed (or in sometimes for the neighbors). I do not have the hesitation.

Ensure all your hoses are correct, and that the needle is sitting correctly, and you used the proper tolerance shim washer.

Also, check your plug---make sure it is a golden brown--and not a bad burn going on in the cylinder.

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Thanks to all for the reply's...

How do I make sure the needle adj. is right? I used a .024" washer which is mid point for Daves Mods. Checked the hoses...good.

when I did the mods, I replaced the short pilot jet with a long one, which brought the top of the jet up flush with the carb body. I made no mods to the plastic slosh baffle that slips over the main. Could that be restricting the pilot? Could that cause the hesitation?

Obviously I don't know all I should about the mechanis of this carb. I'd just like to have as many ideas as possible before pulling the carb again.

Thanks

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IMHO until your exhaust is changed the operation is incomplete, that and I don't believe completely in Daves Mods, it works but the needle and washer thing and drilling the slide - seems hit and miss - to me anyway, others have had great results. That is why I carefully thought it through and decided on the DJ kit - which lacks the needed pilot jet but has everything else you need, The needle is engineered for the application and they provide a spring that alleviates the need to drill your slide. I ran my DJ kit without a pilot change and with the UNI filter and smog removed and stock exhaust and noted little improvement in drivability. It was not until I went to a White Brothers E-2 pipe and a 55 Kehien pilot and 165 DJ main that the bike ran much better. Crisp throttle response, ez cold starts and vastly improved cold idle. Just my .02 cents but until the bike can inhale and exhale properly there is no real improvement in doing just the carb, without also doing a pipe change. Thus enabling the bike to breathe in a mixture that is no longer so lean - but just right - fire that mixture and expel it quickly. it's like curing someone of asthma.

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I just did exactly the same XR650L with a White bother's pipe, 8 disks 55 158. Also noticed the hesitation off idle, but only when it's cold. Seems to get better but not totally disapear when warm. Pwer wheelies in 2nd now. So, pipe may not be the problem although for sure you want to change out to a better pipe. Wondering what my mileage will be with this set up...

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Thanks to all for the reply's...

How do I make sure the needle adj. is right? I used a .024" washer which is mid point for Daves Mods. Checked the hoses...good.

when I did the mods, I replaced the short pilot jet with a long one, which brought the top of the jet up flush with the carb body. I made no mods to the plastic slosh baffle that slips over the main. Could that be restricting the pilot? Could that cause the hesitation?

Obviously I don't know all I should about the mechanis of this carb. I'd just like to have as many ideas as possible before pulling the carb again.

Thanks

I had problems with my slosh baffle and the long pilot.

Took weeks to figure it out, 20 secs. with a razor blade to trim it.

Dave

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Great info on the reply's...Dave, did the baffle issue cause a hesitation?

I am planning on a new pipe also.

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I just did exactly the same XR650L with a White bother's pipe, 8 disks 55 158. Also noticed the hesitation off idle, but only when it's cold. Seems to get better but not totally disapear when warm. Pwer wheelies in 2nd now. So, pipe may not be the problem although for sure you want to change out to a better pipe. Wondering what my mileage will be with this set up...

mileage drops - from about 110 miles stock (tank full) to about 90. Not signiifcant but you notice it, for shorts rides the stock tank is okay - but I have a backup IMS tank with a new petcock installed. That way I can slip on the Big Mama tank at will and cruise .............

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mileage drops - from about 110 miles stock (tank full) to about 90. Not signiifcant but you notice it, for shorts rides the stock tank is okay - but I have a backup IMS tank with a new petcock installed. That way I can slip on the Big Mama tank at will and cruise .............

You change your tank back and fourth?

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I have it setup that way yes, brand spankin new IMS tank with XR's only graphics and a I ordered a new petcock for it too, so that at will I can swap tanks.

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Great info on the reply's...Dave, did the baffle issue cause a hesitation?

I am planning on a new pipe also.

When it blocks the jet, it causes a lean condition, which will cause it to hesitate when you open the gas up.

Can't promise this is it, but its one of those things where you have to eliminate things one-by-one.

Dave

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IMHO until your exhaust is changed the operation is incomplete, that and I don't believe completely in Daves Mods, it works but the needle and washer thing and drilling the slide - seems hit and miss -

...

Unbeliever! Infidel!

Joking, Joking!

I'm a firm believer in running whatever works.

Dave

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I have a new pilot jet that is flush with the slosh guard too. Do you have a pic of what I cut out? That might be causing my hesitation?

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I have a new pilot jet that is flush with the slosh guard too. Do you have a pic of what I cut out? That might be causing my hesitation?

No pic, I just beveled the edge of the baffle where it wraps around the main jet so I could not cover the pilot jet opening.

Dave

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