Author Topic: jets for 836  (Read 1220 times)

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Offline lash

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jets for 836
« on: September 03, 2017, 04:10:16 PM »
1972 cb750, all stock except for Wiseco 836. What would be the starting point for jetting ? It currently has #40 lows and #110 mains. Bedore I start doing any chops I would like to have it close.
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: jets for 836
« Reply #1 on: September 03, 2017, 05:01:47 PM »
Start where you are. Were the 110's even original? Often times larger jets may not be needed. Wanted? yes, but may be extra work for nothing. The larger vacuum created by the larger volume may be able to pull more fuel through the existing jets. Changing the mains after the fact is a minor procedure without removing the carbs. It's adjusting the needle that gets more difficult. If you just have to play then MAYBE raise the needles by reinstalling the clips in the next lower notch before reinstalling the carbs. Then, if you need, you could also change mains afterwards. Don't over carb the engine! You haven't done much to it. Plus you didn't say you installed a better cam which, IMO, MIGHT necessitate more carb attention than a bump in displacement if that were the case.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline 754

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Re: jets for 836
« Reply #2 on: September 03, 2017, 06:01:17 PM »
Probably would be safe to order 120 mains.
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Offline disco

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Re: jets for 836
« Reply #3 on: September 03, 2017, 06:17:22 PM »
Probably would be safe to order 120 mains.

+1 to that. I found with my CI 836cc with 105 mains that it was starving for fuel at high rpm. It felt like it was hitting a rev limiter. Changed to 120 mains & all good.
1976 CB750 K6 Sapphire Blue
1972 CB750 K2 836 Orange Sunrise
1972 CB750 K2 Candy Red
1972 CB750 K2 Candy Gold'

Offline lash

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Re: jets for 836
« Reply #4 on: September 04, 2017, 09:56:49 AM »
I havent done anything to it yet, just wanted a starting point for the jets. Whats in it is what it came with. I will ride it and maybe go to 120 if it needs it.
« Last Edit: September 04, 2017, 09:59:23 AM by lash »
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