1980 GS750L with Mac exhaust, jetting question.

[streetlightpoet]

Hello all, I am about to rebuild my carbs on my new to me 750. The PO put on a Mac exhaust on there, but I'm not sure if he rejetted the carb to match. How would I go about checking that I am running the right jets? Assuming they are wrong how would I go about finding what jets I'm using. Still running a stock airfilter on the other end of things. Thanks in advance!

[chef1366]

I don't think the Mac pipe warrants a jetting change.

[streetlightpoet]

That's the answer I was secretly hoping for, but am still new to all this. I wanted to cover my bases instead of finding out otherwise after redoing everything.

[groundshock]

I don't think the Mac pipe warrants a jetting change.

I would disagree, as I'm running that very setup (mac 4-1, stock airbox, stock jetting), and I'm less than pleased with the way it runs.

Takes a bit too long IMO to 'heat up' and be ready to ride (at least 3-5 minutes idle from dead cold to not gag from 3-4K on takeoff) , also pops like CRAZY on decel/let-off, and lacks the low end kick I think it should have.

Now I will say that I'm not terribly sure if it's dirty carbs causing my issue as I've never run it without the Mac, but these are the issues I have and I can't help but attribute them to jetting issues.

I think a DJ 1 Kit would do this thing wonders. But I'm not a carb expert so take it for what its worth.

[almarconi]

Takes a bit too long IMO to 'heat up' and be ready to ride (at least 3-5 minutes idle from dead cold to not gag from 3-4K on takeoff) , also pops like CRAZY on decel/let-off, and lacks the low end kick I think it should have.

Could be dirty carbs or carbs that are out of sync.

[chef1366]

I would disagree, as I'm running that very setup (mac 4-1, stock airbox, stock jetting), and I'm less than pleased with the way it runs.

Takes a bit too long IMO to 'heat up' and be ready to ride (at least 3-5 minutes idle from dead cold to not gag from 3-4K on takeoff) , also pops like CRAZY on decel/let-off, and lacks the low end kick I think it should have.

Now I will say that I'm not terribly sure if it's dirty carbs causing my issue as I've never run it without the Mac, but these are the issues I have and I can't help but attribute them to jetting issues.

I think a DJ 1 Kit would do this thing wonders. But I'm not a carb expert so take it for what its worth.

Blame it on the carbs. I'm always ready to fix em up.

[sonnygs1100]

whats wrong with mac pipes ? i think thats whats on mine , it would be the small short can one.
my cams are webcams 70-282 anyone heard of them ? (i thought that was computer crap )

[streetlightpoet]

Mine isn't the 4 into 1 but instead the turned out ones that don't look too far off from the factory ones. I don't know if that makes a difference or not.

[sonnygs1100]

mines 4 into 1 with small turned out can

[streetlightpoet]

are you running stock jetting?