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I had my bike serviced the other day, they shimmed the needle and "enlarged (drilled) low speed circuit one size larger" To my understanding, they didn't put in a new jet, just drilled out the low speed one, and made it 1 size larger. What exactly does that mean? The bike runs great now. I'm very happy with it.

Thanks

Shannon

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shimming your needle has to do with your main jet. raising or lowering this will richen or lean the main needle.

my brother told me about the "drill your own jets" You can go to a place like harbor freight or order it online tiny drill bits. He said it was pretty awesome cause then you don't have to pay $3-$5 per jet.

http://www.ehobbytools.com/contents/en-us/d111_drill_bits.html

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Thanks,

I was wondering if this was something that was done often? I was getting a little worried, but hey, the bike runs great. I was fed up of my "regular dealer" so I tried a new shop.

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Thanks,

I was wondering if this was something that was done often? I was getting a little worried, but hey, the bike runs great. I was fed up of my "regular dealer" so I tried a new shop.

The DR650 is one of the few modern bikes that does not need a larger pilot jet. Once the weather warms up be on the lookout for a 'rich bog' hesitation just as you open the throttle. It may be most noticeable when shifting gears and will be worse the hotter the motor gets. If you feel the momentary bog you may want to replace the drilled pilot with ah stock one. If you never notice a bog don't worry about it.

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The DR650 is one of the few modern bikes that does not need a larger pilot jet.

+1

There is no way to have a real sense of where you are at by drilling a jet. You'd need to have the jet in a drill fixture to keep from wollering out the hole. Certainly not a hand held operation if any type of precision was considered. Even a number drill set does not have the size steps required to make your own jetting changes without going way overboard.

Of course it's hard to argue with "The bike runs great now. I'm very happy with it." I wonder if the drilling they did was the slide mod for increased diaphragm response?

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Thanks all,

I'll keep an eye on it, especially as the weather warms up. So, did I get taken? Also, if I do run into problems when the weather warms up, do I just need to put the stock jet back in or what would I do? I've had several friends take their bikes there, mostly sport bikes.(It a Ducati shop)

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Mx-Rob, i respectfully have to disagree with you. I have been drilling and honing jets for the past 35 years and if done carefully and with some precision i have been able to maintain .003" increments. Perhaps some will say that .003" is not a tight enough spacing and perhaps it isn't, however again, you can't argue with success. I also have to admit to machining the occasional needle as well to enrichen the mixture at a certain spot (GASP!).

I have to say that the process is not to be taken lightly as jigs and fixtures are needed as well as a micrometer, so i would not suggest someone run out to their carpentry box and grab a drill and go to town.

Cheers.

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Mx-Rob, i respectfully have to disagree with you. I have been drilling and honing jets for the past 35 years and if done carefully and with some precision i have been able to maintain .003" increments. Perhaps some will say that .003" is not a tight enough spacing and perhaps it isn't, however again, you can't argue with success. I also have to admit to machining the occasional needle as well to enrichen the mixture at a certain spot (GASP!).

I have to say that the process is not to be taken lightly as jigs and fixtures are needed as well as a micrometer, so i would not suggest someone run out to their carpentry box and grab a drill and go to town.

Cheers.

Maybe I generalized too much? Point being what is the likelihood any MC shop (as the OP mentioned did the mod) would go to the work of "and if done carefully and with some precision" and "the process is not to be taken lightly as jigs and fixtures are needed as well as a micrometer" instead of just replacing a few dollar jet? I know I wouldn't bother with doing it so I can't even imagine a shop paying a mechanic to set-up a drill fixture to drill out jets. And like you mentioned with honing.... if the bore is not dead smooth, which is highly unlikely using only a drill, flow rates could be different between each jet drilled with the same size bit. My final problem with drilling jets would be... are they being marked with the proper size info after being modded? Wouldn't that next owner be bummed out when he "bumps up two sizes" on his main jet and the bike burns a hole in his piston from being too lean? :ride::ride:

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Good point MX_ROB. I would scribe a cryptic note on the side, if there was enough room, that simply said + 3 or +6 telling me that it had been "overbored" that many thou. The reason i went to all of the trouble was because the closest motorcycle shop to where i was living then was 70 miles away one way. But as i said you have a good point and one i never contemplated. Thanks.

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i would not suggest someone run out to their carpentry box and grab a drill and go to town.

Unless you're running straight methanol. :ride:

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I'm wondering if I really messed up now? i took the bike out for a couple of hours yesterday, and now I feel a little bog when I roll on the throttle, and it was only 35 degrees or so outside. Does the Dyno-jet kit have the low speed jet in it, and if I were to get it or something like it, could I "fix" this? I'm pretty stoked at how it starts now, and I don't have to leave the choke on while I'm riding it as I did before, but if it's not done right, I want to correct it. If this was your bike, and you lack my mechanical skills, what would you do?

Thanks again everyone.

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Thanks all,

I'll keep an eye on it, especially as the weather warms up. So, did I get taken?

Does the Dyno-jet kit have the low speed jet in it, and if I were to get it or something like it, could I "fix" this? I'm pretty stoked at how it starts now, and I don't have to leave the choke on while I'm riding it as I did before, but if it's not done right, I want to correct it. If this was your bike, and you lack my mechanical skills, what would you do?

Thanks again everyone.

I would not say you were taken. On pretty much any other bike bumping up the pilot jet size would be a pretty safe bet. The DR650 is a rare exception.

All it should need is a new stock sized pilot jet and to have the idle mixture screw properly adjusted. The jet should cost about $5. I suggest you talk to the shop. A good shop should be happy to make it right and it would be a good opportunity for them to make you into a loyal customer.

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It's extremely likely that the shop was not really drilling out the pilot jet but the silly EPA cover that prevents access to the pilot screw so they could richen up the circuit. :ride: This makes a whole lot more sense to me and when coupled with the needle shim would explain the faster warm-up period. :ride:

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The DR650 is one of the few modern bikes that does not need a larger pilot jet. ........

IMO the proper pilot jet varies so much with bike set-up, rider preference, and climate/elevation. I have 09 DR650 and my objective has been to get bike running as good as possible without compromising fuel range. I began with drilling out fuel enrichment plug, adjusting enrichment screw, removing snorkel, & shimming needle 0.030 in. Big improvement over stock but not perfect off bottom. Then I installed an 01 GSXR can and bottom end response felt slightly worse and adjusting enrichment screw did nothing. Tried to order 45.0 pilot jet, stock is 42.5, from Jesse and was told no need, they never change pilot jet, and needs Dynajet kit to run right. So I bought DJ kit. Because of concerns with loss of milage and especially fuel range I decided to try a larger pilot before trying the DJ kit. I installed 45.0 pilot and set my extended enrichment screw at 1-1/4 turns out. The improvement was significant. All the bottom end deficiencies are gone. Cold warm up is much quicker. I don't believe I will ever install DJ kit and open air box because of loss in fuel range and satisfaction with current performance. Average conditions were about 60 to 70 deg F and sea level. Pilot circuit is correct because with very little turn of screw in either direction results in noticeable reduction of idle speed and this was never possible with stock 42.5 pilot jet. If higher elevations and higher temps require different enrichment settings I don't have much adjustment remaining but I will test later and if necessary re-install stock 42.5 pilot but for now I am very happy with 45.0.

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Thanks all,

I appreciate all the advice. For clarity, is the pilot jet the same as the low speed jet/circuit? Also is the stock low speed jet, the one the dealer said they enlarged a 42.5? Lastly, if they drilled it to one size larger, how would you re-install a stock size one if the hole is larger? Sorry for all the confusion. I do have on my desk an old CV carb that I'm going to dig into to understand all of this.

Shannon

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IMO the "low speed jet/circuit" terminology implies the ENTIRE circuit including the pilot jet and the fuel enrichment screw setting. The pilot jet is just one part of the circuit. On my 09 the stock pilot jet was 42.5 so I believe they enlarged this stock 42.5 to "who knows what". Far better to buy a 45.0 jet, the next larger size. The only way to get back to stock would be to buy a 42.5 jet and toss the drilled out jet as far as possible.

So in future do yourself and especially the next owner trying to fix screw ups a big favor and spend $3.50 for proper jet and skip the drilling.

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Thanks Oldturtle,

Where's a good place to buy a 42.5 and a 45 jet? If indeed they did drill it out, would I be able to compensate the larger size with the fuel air screw? I'm going to find out if they did indeed drill and if so, what size bit they used. I believe that I should have waited until I had a little more information. But, it's done, now I just want the best way to correct it if need be.

Shannon

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Great. You all have been a big help. I get a little nervous on these issues.

I'll play it out and see how it goes.

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