Does anyone know what size mikuni jets match dynojets 146-148 main jets? I run a Yoshimura slip on with 146-148 jets and a K&N filter with the Yamaha GYT-R adapter. Yoshimura recommends 150-155 mikuni jets. I'm curious as to how close to the Yoshimura recommended setup am I using the Dynojets. Also, has anyone had success with this or a similar setup ?

 

Check out this site. The link came from a thread on the Bombardier forum a few weeks back.

http://www.users.qwest.net/~tcamp30/jets.htm

It has a direct jet to jet comparison for Mikuni vs. Dynojet.

 

I actually came across this post today but it does not quite make sense to me. If this is accurate, then i would have to run like 158-165.3 dynojet jets to match to meet Yoshimua's recommended setup. Why would dynojet recommend 144-146 / 146-148 jets ? Seems like something isn't right here. It would make sense to me for 146-148 dynojets to match 155-160 mikunis.....but then again, that's why i'm posting this

 

There was some discussion about this on the Bomber site, and I can tell you that I just put a K&N in my DS650 and went with the recommended Dynojet for my elevation, a DJ175, the stocker was a mikuni 165. After inspection I found I was running lean with the K&N and stock airbox setup. This weekend I was going to try a DJ180 or 185 but decided to go up to a 190 and work backwards. Well, the 190 was too rich at WOT so I pulled the lid off the box, ended up just about perfect... I think the 180 or 185 would've been good with the lid on.

The explanation on the site is that the mikuni size is set by flow rate while the dynojet is rated by hole diameter, or something like that. So if you go by the chart, the DJ180 or 185 is equal to one to two sizes larger than the Mikuni 165 and the DJ175 is slightly smaller so I should have used the 185 from the start, not the 175. My experience ended up right on the money with the chart.

So, the recommendation is a good place to start, but reading the plugs and experimenting is the best way to find the perfect setting for your quad as it is set up.

 

OK so now I am really confused, when I called dynojet about this some time ago they told me the sizes were comparable, that a dynojet 150 was comparable to an oem 150 and that their jets were engineered for better fuel delivery with their needles. I looked at the http://www.users.qwest.net/~tcamp30/jets.htm chart, but noticed at the bottom "150 = a rating of 150 cc of fuel per minute" with 2 that would be 300cc of fuel a minute, that is 3 liters of fuel in 10 minutes, I find that hard to believe, if the raptor has a 12 liter tank (3 gallons) you could only run at full throttle for 40 minutes. just doesnt sound right

 

I'm starting to get confused too! All I can tell you is what worked for me. If you pull your plug what do you see? I would rather run rich and adjust down, rather than run lean.

What are the stock jets on a Raptor? If you look at Feb's issue of Dirt Wheels they had a Raptor pipe shoot out, depending on the pipe they ran anywhere from a 142/146mj for the White Bros. pipe to a 170/175 for the CT Sonic. The CT Sonic dyno run had no airbox lid and the White Bros. had a trimmed snorkel. The Yoshi in the test had major airbox mods, and 150/155mj's. In March they cut up the airbox and tried a bunch of different jets to get hp gains. I think they ended up at 150/155 w/ airbox mods and the stock pipe. So if you are running the K&N and a pipe I would go to at least the 150/155 mikuni (160/165 dynojet) or even start a little higher since you are flowing more air through the K&N. The bottom line is you're probably running lean now and would see better results by jetting up. Like I said before, experiment, read the plugs and go from there. Once you change jets you'll need to adjust the air/fuel screw(s) to get dialed in completely. The first thing I would do before any changes is read the plug, then change one thing at a time until you are satisfied.

 

GO TO THIS WEB PAGE HAS MIKUNI VS DYNO JET SIZES www.users.qwest.net/~tcamp30/jets.htm

 

Quadgod107-

Check out this thread, it confirms the information I've listed, look at what RichieRoadRash is running, sounds like a similar set up to you and he's running a lot higher jet.

http://forums.atvconnection.com/mess...hreadid=297732

 

Thanks for all the responses....i'll take a look at that thread and i'll be back soon enough

 

Quadgod please tell me what you found out I have the same set up and I,m going to install K&N power kit and yosh slip on this weekend and wondering if I should go with dyno jet recommendations don,t feel like jetting twice how does it perform and what jetting did you go with? thanks[img]i/expressions/face-icon-small-happy.gif[/img]