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Carb help II -still won't rev

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I finally put the carb jetting back to stock, new jets, blasted compressed air thru all the passages I could get to, new float at 12.8mm, cleaned the needle and the jet holder tube.

Engine starts fine and idles fine.

It revs smoothly up to about 5k rpm where it falls flat and won't rev higher unless I twist the throttle fully open, thenthe revs shoot up to 9k (this with the bike parked, I'm guessing with the engine loaded it won't rev this high).

Thanks for any suggestions.

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Positive, looked at the numbers with a magnifying glass after installing the jets.

The slide spring looks fine, slide moves freely.

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I pulled the top of the carb this morning again, Oring's in place, diaphragm is not pinched, every washer is in place in the needle assembly according to the diagram.

The only thing I can find different is the needle in place is stamped "5DH37" instead of "5DH37-1" in the parts list. Is there a difference between these?

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One more thing I just noticed, the diaphragm spring is 0.024" dia wire.

I measured the one in the original carb and it's heavier gauge (0.026").

I would assume the heavier spring delays the slide opening, just don't know if the symptoms I described are from the slide opening too fast or too slow.

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Engine seems to rev better with the heavier spring. I can't test ride the bike now but I'll report as soon as I do. Thanks to all who pitched in.

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