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Question on response after needle shim

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So I think I successfully did the needle shim and I replaced the fuel screw. I'm trying to get it tuned but think I'm having trouble. It seems to run fine but starting out in first it's a little hesitant to light up. Seems like there is a second or two lag between throttle twist and response. I've played with the mix quite a bit and it does seem to perform a little better overall but not sure I'm happy with the results so far. Have tried the fuel screw adjusted at anywhere from 1.25 to 2 turns out from seated. I'm not getting the wheel up in first like some have reported but it does get with it in short time.

Any suggestions? Possible things to check or something I missed?

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Do you have the shim above the plastic spacer? When I first shimmed my old BST I left it below the plastic spacer and ran about the same way as you have described. How big of a shim are you using?

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If you are running the stock airbox or just the snorkle removed I think you have shimmed the needle too much. You only need to shim the needle .030" (.762mm) - .040" ( 1.02mm) Might also want to recheck the slide diaphragm, to make sure it's not pinched, or mispositioned.

Tech25

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I believe with the two 3mm washers I'm @ .040 and I do have the snorkel out. Will that make it too lean? Is .040 shim and snorkel out the right way to go?

Will check the diaphram too. Thanks.

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With just the snorkel removed you should be on the right track. I ended up shimming my needle.060, that was with an air box mod and FMF muffler. I was using a Mikuni 155 main jet. It worked decent for a BST and my milage was in the high 40's. BTW my A/F screw was set between 1-1 1/2 turns out.

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I believe with the two 3mm washers I'm @ .040 and I do have the snorkel out. Will that make it too lean? Is .040 shim and snorkel out the right way to go?

Will check the diaphram too. Thanks.

Two 3mm washers are .236. Way over .040.

1mm = .040

Yes, .040 and snorkel out.

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Two 3mm washers are .236. Way over .040.

1mm = .040

Yes, .040 and snorkel out.

This is correct, if you have two 3.00mm shims (6.00mm) under the clip and just the snorkel removed you are too rich in the mid range. The jet needle is 5.00mm too high in the needle jet. Remove the air box cover and see if it runs better.

Tech25

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