I should know this (jetting)

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Dan

I should know this (jetting)

#1 Post by Dan » Sat Oct 15, 2005 8:10 pm

I just rebuilt my RZ's clutch and took it out to<br>see if the slipping is gone. Sure enough, no<br>more wasted power. Sadly not all is well...<p>Off idle is solid, and top end pulls very strong,<br>but the middle sucks major. The last time I rode<br>it I thought I had is nailed.<p>Specs-<br>Stock internals<br>Nikon pipes, ceramic coated<br>28mm flat slides with indiviual pods<br> - 240 mains<br> - 27.5 pilots<br> - R-8 needle jets<br> - 5L1 needles (top slot)<p>The bike doesn't want to rev through the mid-range.<br>If I feather the throttle I can get it past the<br>'dead zone' and it takes off.<p>I thought it was too rich, so I moved the needle<br>clips up one position, but that did not really <br>help, maybe a touch worse. So that makes me think<br>I am too lean in the needle. Rather than poking<br>blindly, I thought I'd ask.<p>I did try running with the choke on two carbs, and<br>it ran about the same, or maybe a small but worse,<br>again pointing towards too rich, but I don't trust<br>that only two chokes will make much difference.<p>Any thoughts?
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dan_austin@fitawi.com

wolfgang

Re: I should know this (jetting)

#2 Post by wolfgang » Sun Oct 16, 2005 12:17 am

All I can say is that I run 28mm flatslides with individual filters too (UNIPOD), JollyMotos, but engine is tuned not stock.<br>I run 290/300 mains, 25 pilots.<br>I would assume that both the pilots and the main jets should not affect midrange that much (if at all).<p>regards<p>WOlfgang
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wolfgang_hromada@aon.at

Dan

Re: I should know this (jetting)

#3 Post by Dan » Sun Oct 16, 2005 12:50 am

I think the pilots and mains are close, since<br>off idle and top-end feel 'right'.<p>The 5L1 needle has the most agressive taper in<br>the series, and has generally worked well. The<br>R-8 needle jet might be too much, and I may end<br>up stepping down to the P-8, or the same impact<br>of moving the clip up 3-4 postitions. That is <br>if it is too rich in the middle. I guess I can<br>move the clip down and fatten up the middle to<br>see if that is the problem,<p>The 28s seem to be pretty popular, but most folks<br>appear to only adjust the mains, pilots and clips.<br>Needles and needle jets are almost never mentioned<br>when someone lists their setup...
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dan_austin@fitawi.com

Wyn Belorusky

Re: I should know this (jetting)

#4 Post by Wyn Belorusky » Sun Oct 16, 2005 6:05 am

Dan - did you buy the 28s brand new? If so go back to the needle jet and needle they came with. By going with the stock RZ needle and needle jet, you turned your 28s into the stock carbs!!<p>I kept the needle and needle jet my 28s came with, P-8 and 5DP39.
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RZVWyn@aol.com

Dan

Re: I should know this (jetting)

#5 Post by Dan » Sun Oct 16, 2005 1:49 pm

I bought them used about six years ago.<br>The previous owner had them on a race RZ, but<br>wasn't happy with them. They came with the<br>P-8 and the 5L1.<p>I put the R-8 needle jets in, since I felt I<br>wasn't rich enough in the mid-range and already<br>had the most aggressive needle.<p>I'll order a set of 5DP39 needles and stick the<br>P-8s back in.<p>Thanks.
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dan_austin@fitawi.com

Dan

Re: I should know this (jetting)

#6 Post by Dan » Sun Oct 16, 2005 5:27 pm

I figured I'd take one more stab before ordering parts.<br>Heck it was a quiet Sunday, why not?<p>I move the needle clip to the 2nd from the bottom<br>slot, and confirmed the problem was that the bike<br>was too lean in the middle.<p>Now I've got a freight train-like pull from bottom<br>to top. If anything it higlighted that the top was<br>not as clean as I thought. I might have to step up<br>the mains again.<p>Thanks for the hint about the 5DP39s. I'll give them<br>a try soon.
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dan_austin@fitawi.com

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