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Slow revving?

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I just picked up an 03 DRZ250. It has a Full Yosh system and the snorkel out. I was told it has been rejetted but havent looked yet.

It seems to rev slow, almost like its loaded up. Sounds good, runs pretty clean ad fires right up thugh. Is slow reving normal? I have nothing to gauge it against except my old DRZ400 kicker though (the 450 is, well, a 450) so I may be expecting to much...?

What may cause this? To much oil in the filter? A vaccum leak somewhere? Valves maybe out of adjustment? Anything in particular I should look at? Would bad jetting cause slow reving? Ill check the plug, probably needs to be replaced anyway, to see how its burning.

FYI: The only graphics I can find for these things are from the factory at about $250! Ouch...

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Make sure you find out what jetting modifications were made so you know so you know where you stand in that area. My '01 drz250 has a ProCircut T-4 with jet mods, but I also run a CR8E(hot) sparkplug which replaced the stock CR9E(standard) plug.

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CV type carbs, like the CA version on the DR-Z250, are designed to rev slower. Basically, the vacuum of the engine pulls open the slide in the carb. This prevents the engine from ever running rich, which keeps emissions low. The 49 state version of the carb has a throttle pump to squirt some gas when the throttle is opened, and the throttle cable actually pulls the slide open. This produces quick responsiveness at the expense of emissions.

I owned a DR-Z400S which came with a CV carb. I replaced it with the Keihin FCR which is on the off road version. What a difference!

It may be that there is a jetting problem with yours, or it may be that you are experiencing the slowness of CV carbureted engines.

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