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1980 cb750K rejet

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Catcher24rs@aol.com

1980 cb750K rejet

I'm running stock airbox and mac4-1 exhaust. Does anyone else have a similar set up and know a jet combination that works? Thanks in advance

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Re: 1980 cb750K rejet

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Just exhaust changes do not usually require rejetting.
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
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1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
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Catcher24rs@aol.com

Re: 1980 cb750K rejet

I went from a stock 4-4 exhaust to the max 4-1 exhaust and now it needs a rejet.

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Re: 1980 cb750K rejet

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Is that the only criteria you are going by to determine you need to rejet? How is the bike running? Does it bog or have a flat spot mid throttle? What color are the plugs?
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Re-run

Re: 1980 cb750K rejet

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In reply to this post by Catcher24rs@aol.com

Very seldom does an exhaust change require a re-jet. If you went from a full system to drag pipes, then maybe. Now, you DO likely have to re-adjust your idle mix.

However, you could possibly be feeling the change in pipe style. See, a 4-4 has a full range. No rpm range is really stronger than any other rpm range. With a 4-1, that isn't true. A 4-1 will enhance top-end rpm range, but low rpm power will suffer slightly. Also, there is no way that mac system is moving more exhaust through 1 pipe, then 4 you had before. Therefore, there is no real way your A/F mix is going to be significantly leaner.

So, grab your manual, hook up a more sensitive tach, and tune that idle mix.

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