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Jetting/ carb settings for exhaust

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Jetting/ carb settings for exhaust

PostAuthor: room14baz » Thu Jul 11, 2019 3:41 pm

Hi everyone, I’ve got an 81 xv750 which I am currently trying to work out the exhaust for, I’m planning on either a 2-1 or just short pipes 2” diameter. Both will be baffled as I live in Australia and the noise laws are pretty strict, the intake side will be pretty free flowing as I just have a screen filter- no air box. Does anyone have any suggestions on jetting/ carb settings that will work with that setup? I’ve put a couple of photos on to show what I’ve got in mind.
Thanks
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Re: Jetting/ carb settings for exhaust

PostAuthor: chrismalm » Thu Jul 11, 2019 8:33 pm

It's a crapshoot (US slang for unpredictable outcome) at best, but here are some tips I gathered from the forum :
If you have a flat spot off idle that you can't adjust out with the mixture screws, you can fatten up idle mixture by drilling out the #41 pilot jets with a #76 (.50mm) drill bit. This will help transition from idle to main circuit and cure flat spot. It will also give you a lopey idle. The downside is your idle mixture screw effective range will be reduced to 0-1 turn.

To fatten up your mid to 3/4 throttle range, you can add 1-3 washers under your needle.

To richen up the full throttle range, you can increase your main jets from 122 to 124-128
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Re: Jetting/ carb settings for exhaust

PostAuthor: room14baz » Sat Jul 13, 2019 4:31 pm

Thanks for the advice, I understand it’s hard to predict before actually firing the bike up and seeing how it runs but I’ve got a decent starting point now at least! I’ve had a lot of trouble with a previous bike (a Honda cb250) that I could never get running quite right so this is by far the part of my project I’m the most nervous about!

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Re: Jetting/ carb settings for exhaust

PostAuthor: Ita » Fri Aug 30, 2019 8:32 pm

Gedday from Melbourne...

I've just ordered these!

https://www.mikunioz.com/shop/tm38-miku ... c98ba2045f

They come pre-jetted to I assume they will be close enough to fire up and run, but them require further tuning.

Ita
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I need my high octane.

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