Can you drill jets in XR650L larger than the Baja kit provides?


9 replies to this topic
  • arlord quick

Posted June 30, 2006 - 09:11 PM

#1

Baja jet kits come with a 160 and 165 main jet. I could not find the correct bit to produce a 165, but did drill a 167 and threw 2 flat washers(Daves mods)on the needle. Turned the float adjuster to 2.5 turns back from all in. The bike fired right up and seems to pull pretty nice. Does any one know if this will be too rich or cause any problems?? :ride:

  • HawkGT

Posted July 01, 2006 - 08:49 AM

#2

Why not just buy correctly sized jets?

  • FOUR STOKED

Posted July 01, 2006 - 07:23 PM

#3

It is not advisable to drill jets ever. You might luck out and have a flow rate that will work with your combination, but a drilled hole has an inconsistent flow rate compared to a standard jet of the same diameter.

  • XR650L_Dave

Posted July 03, 2006 - 08:32 AM

#4

Baja jet kits come with a 160 and 165 main jet. I could not find the correct bit to produce a 165, but did drill a 167 and threw 2 flat washers(Daves mods)on the needle. Turned the float adjuster to 2.5 turns back from all in. The bike fired right up and seems to pull pretty nice. Does any one know if this will be too rich or cause any problems?? :ride:


Not sure what you mean about drilling to produce a 165- the jet kits out there that don't have keihin jets use a different numbering system.
Example- a BD/DJ/etc 165 jet is smaller than a keihin 165 jet.
What did you use for comparison when you drilled a '167'?

The adjuster you turned is a low-speed fuel screw, it adjusts the amount of fuel in the mixture at idle and part-throttle.

Do you know how thick the washers were you put under the needle?

Dave

  • HawkGT

Posted July 03, 2006 - 09:03 AM

#5

It's actually the other way around. A Dynojet 165 is approximately the same size as a 185 Keihin. There isn't a precise cross reference though because Dynojet jets have a slight taper.

ETA: Errr wait. After re-reading your post, maybe that's what you said. A DJ165 has a larger hole than a K165, so a DJ and a K with the same size hole will be a smaller number for the DJ than the K.

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  • XR650L_Dave

Posted July 03, 2006 - 09:07 AM

#6

It's actually the other way around. A Dynojet 165 is approximately the same size as a 185 Keihin. There isn't a precise cross reference though because Dynojet jets have a slight taper.

ETA: Errr wait. After re-reading your post, maybe that's what you said.


Well, its possible that the steps between BD numbers and keihin numbers are very different.

I'm just going by the fact that the DJ160 seems to be about the same as a keihin 158 or so.

Its possible the 'tables are turned' by the time you get to the 165DJ- just like deg.F and deg.C

Dave

  • HawkGT

Posted July 03, 2006 - 09:16 AM

#7

Food for thought: http://www.thumperta...=dynojet Keihin

Also, from Dynojet:

We are often asked for a "cross reference" sheet that compares our main jets to Mikuni or Keihin. The fact is you cannot directly interchange the jets for a given size. Many things affect fuel flow through a jet of the same orifice size. The entry and exit tapers of our main jets differ from those of other companies. Due to this, the fuel flow changes as a function of velocity through the carburetor venture. This means that two jets of equal orifice size will have a different fuel flow curve relative to intake air speed. At a certain speed the two may flow equally, but a change in velocity changes the flow characteristics. The Dynojet main jet hole size is measured in millimeters. For example, a DJ142 has a 1.42mm hole.


Michael Cory
Research & Development
Phone: 800-992-4993 EXT. 108
Michael@Dynojet.com
www.Dynojet.com
www.Powercommander.com



  • Maniak

Posted July 03, 2006 - 10:51 AM

#8

Never, Never drill jets, they are too cheep and too easy to get and come in a huge size selection to bother with drilling, and once you drilled and you have to rejet what do you do then, if you are going to do a "Daves Mods" then do what he says and it will work, if you want to change jets then go to Honda or any vendor on the web that sells jets and buy a selection of jets and do a plug check and jet your bike for your conditions, bigger is not always better, to rich and you loose power. By using factory numbered jets you will always know what is in there and after a plug check you will know which way to go, up or down. If you are drilling and go to big you are :censored:and have to buy a new jet anyway. Save yourself a lot of time and trouble, buy some jets.

  • arlord quick

Posted July 04, 2006 - 01:13 PM

#9

I have read all the replies and they all make sense, however for the sake of venturing into the unknown was my main motivation. Perhaps saving the $60 for the specified jet kit by making my own was the wrong move, but after riding the XR for an afternoon it definitely seems to run less restricted. Time will tell, and I'll keep you all informed. Thanks...

  • HappyCurmudgeon

Posted July 05, 2006 - 05:08 AM

#10

Jet Kits cost 60ish bucks, they usually include a needle, a clip or two, possibly a spring, maybe one or two different sized jets and a really cool plastic box to hold it all after you just get the right jets and realize you really didnt need the kit at all (been there, done that).
I think what everyone is saying, is if all you need is a bigger or smaller jet, they can be purchased for between $2 and $4 each at most motorcycle shops. The aggravation of trying to drill & polish that soft brass , to most people isnt worth the few bucks it costs to just get a premade part. I can understand & appreciate your innitiative in giving it a shot at doing it yourself, but i think Maniak is right. Using factory jets will keep you knowing what you have in it, and you can easily adjust up or down without guessing at drill sizes.





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