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Jetting Debacle

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91 DR350 Dual Sport Model - Modded Airbox, Exhaust and Raptor Petcock. - located in Seattle WA, Sealevel 85% of the time.

The bike has not run proper since I owned it and this being my first bike it is a learning experience with lots of trial and error.

In May, not realizing that the mods required non stock jetting - I returned the jets all back to stock. Actually saw no change in performance. The bike still idled like garbage, popped on decel but had power through the range. The jets I bought the bike with it with were aftermarket, old and worn. I ended up throwing them away so I never paid mind to how the previous owner had it baselined. My bad :banghead: 

So I bring it to the local shop and $450 later I have a bike that idles starts, doesn't run rich or lean except at WFO, but still has no balls and won't get over 50mph. I know, I could have bought a pumper carb for that much but I didn't expect it to cost me that much. They said they ran out of main jets but on my own start with a 160 and keep swapping up until it gets the power back and NOT TO TOUCH THE PILOT OR NEEDLE!! :naughty:   So what do I do today, I touch the pilot and Needle.  :devil:

Here is what I learned. The shop had a 37.5 Pilot, stock needle with 1 spacer and 1 washer, and I had a 182.5 main. Oh and the fuel mixture screw was 5 full turns out!

I have been through the Kientec info and know that I need to start with a 40 pilot jet, 140 main and having a needle with 5 positions in it would be ideal. I went to jets R us purchased the pilot jet for the dirt model by accident in 40 (drilled). I will get a non drilled one in 40 and 42.5 just in case.

I also picked up the needle with 5 positions and it is not even close in shape to the stock needle. See pic below. Will this be a problem? Everyone says to place it in the 3rd position to start. But do I need a washer or plastic spacer under the e-clip. Can I just use the OE needle and add a few washers? I got the needle that Jet's R' Us recommends on jet page http://www.jetsrus.com/individual_parts/007_004_su.html The carb I have has the Round black top on it. Not sure what model specifically. I think it is the BTS33 which I did not see in their page anywhere.

That's all for now. Thanks for your help! 

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Either use the stock needle raised 2mm with washers and the #140 main, or, much better, use the aftermarket needle, clip middle position, and no more than a #130 main.

 

Its no good putting bigger mains in as a stock engine does not breath enough to increase power at high revs. Opening the airbox increases power low and mid range.  Anything over 130 main will *lose" top end power as it makes it too rich.  Try it!

 

 

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As an aside, the CV carb can be made to work pretty good if set up correctly (aftermarket thinner needle with opened airbox).

 

I have two DR's, one with a Keihin FCR pumper which is fabulous, so punchy and responsive, but the CV carb'd DR is very smooth and refined and its top end power is essentially the same! 

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Oh man! you guys always make it seem so easy. How is it that a shop guy who's been doing this since the 70's was so far off base?!

My parts are on order and should be here before the weekend. It should be easy enough and hopefully not as much trial and error with the knowledgebase here.

Fingers crossed

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