Rejetting Carbs: In Search of Free Lunch

[TheCafeKid]

Sent you an email with "print screen" pics of the article.

Well, if the address is still something like the "godfather" through g-mail.

Can send the PDF version as well, but the pics are smaller in size. Might be easier to load.

Thanks!!! Im more than interested to see wth they were doing they had to jump 22 sizes to get it straightened out...

[tejasmud]

Thanks!!! Im more than interested to see wth they were doing they had to jump 22 sizes to get it straightened out...

I sort of took that 22 sizes with some salt.

2.5 sizes, but still doesn't really make much sense especially at the temps they stated the tests were run at.

If the dyno read out was an actual chart would help to see any goofy dead spots, but they show info in tabular form, which lists a little of the loss. Probably because there wasn't much real time charting capability back then.



Interesting read though.

[LeeGS550E]

I sort of took that 22 sizes with some salt.

2.5 sizes, but still doesn't really make much sense especially at the temps they stated the tests were run at.

If the dyno read out was an actual chart would help to see any goofy dead spots, but they show info in tabular form, which lists a little of the loss. Probably because there wasn't much real time charting capability back then.

Interesting read though.

I left the article at home underneath my pillow, but if I recall from reading it last night, they jumped up to something like a 160 main jet. They did not mean 2.5 sizes - it really required a main that big, at least that's per their tests. Didn't seam like they spent a hole bunch of time testing the main sizes on that portion of the trial, but still, pretty interesting.

I'm not necessarily surprised by that. I'm running an almost open kerker, UNI pods, and right now I'm at a 137.5 from the stock 122.5, and may go even higher. Bumping up my pilot to a 145 once it gets here in the mail. My 142.5 pilot is proving too weak.

[tejasmud]

I left the article at home underneath my pillow, but if I recall from reading it last night, they jumped up to something like a 160 main jet. They did not mean 2.5 sizes - it really required a main that big, at least that's per their tests. Didn't seam like they spent a hole bunch of time testing the main sizes on that portion of the trial, but still, pretty interesting.

I'm not necessarily surprised by that. I'm running an almost open kerker, UNI pods, and right now I'm at a 137.5 from the stock 122.5, and may go even higher. Bumping up my pilot to a 145 once it gets here in the mail. My 142.5 pilot is proving too weak.

Stock #110 to #165 in increments of 2.5 is what the article says. I would agree, a lot of mains.

Claimed to have gone down in pilot size as well, stock at #45 to a #30, and the needle was dropped by 0.052".

But, they are the experts.

One thing I keep in the back of my mind is that dyno pulls and 1/4 mile runs are a little different than streetable performance. So, the jetting may work out.

[LeeGS550E]

Claimed to have gone down in pilot size as well, stock at #45 to a #30, and the needle was dropped by 0.052".

They mislead you in that part of the article. If you read to the end, they go on to talk to a Mikuni engineer who points out there are different types of pilot jets. Turns out they're using the wrong ones when they drop to a 30, and by the end of the article, after getting the proper BS type of pilot jet, they jump UP to (if I remember right) a 47.5.

I think I'll end up shimming my needles up, not down. Still stumbling from just off throttle to 1/4 throttle.

[srsupertrap]

They mislead you in that part of the article. If you read to the end, they go on to talk to a Mikuni engineer who points out there are different types of pilot jets. Turns out they're using the wrong ones when they drop to a 30, and by the end of the article, after getting the proper BS type of pilot jet, they jump UP to (if I remember right) a 47.5.

I think I'll end up shimming my needles up, not down. Still stumbling from just off throttle to 1/4 throttle.

You are right, the CW guys were not experts. They were using VM jets in the BS carbs. The experts in that article was the Mikuni engineer that caught their mistake

[LeeGS550E]

My closest GS tuning buddy, Distraction628, has also recommended I use the pilots with the emulsion holes - were those available back in the day?

[tejasmud]

They mislead you in that part of the article. If you read to the end, they go on to talk to a Mikuni engineer who points out there are different types of pilot jets. Turns out they're using the wrong ones when they drop to a 30, and by the end of the article, after getting the proper BS type of pilot jet, they jump UP to (if I remember right) a 47.5.

I think I'll end up shimming my needles up, not down. Still stumbling from just off throttle to 1/4 throttle.

That makes more sense. Selective reading on my part. When the numbers were not adding up suppose I read through the rest with not much interest.

The pilot jet for the VM the orifice is above the emulsion holes, then the BS pilot is at the base. You would think with all the work they were doing jetting it would be obvious visually. From the article quiet a bit of difference in fuel delivery between the two. Dropping the height changes the pressure feeding the orifice. Interesting enough. Will put that into the mix of jetting these VMs just to see what happens with the AFR.

[blowerbike]

My closest GS tuning buddy, Distraction628, has also recommended I use the pilots with the emulsion holes - were those available back in the day?

IMO,
i believe the pilots with the bleed holes was around before the solid pilots.

[tejasmud]

So, the solid ones were more like a "Bandaid"?


Sort of like the little rubber caps.

Or, Mikuni decided that they need to switch it up some to gain more sales on parts, given most tuners had a vast selection of jets.

We may never know the truth...


I believe you are right on the pilots bleed holes came first.

[TheCafeKid]

ANyone have a set of 47.5s that are KNOWN to be not screwed with that have emulsion holes? I have a set of them, dunno if they'd been monkeyed with (drilled?) but MY 1100ES (which did NOT have emulsion type pilots) simply WOULD NOT idle with those jets...again, I dunno if it had to do with the emulsion holes, or if the jets had been drilled (i pulled them from a bike that was used as a drag bike..those crazy guys do all kinda stuff) but id be curious to see. I ALSO had VERY large Air Correction jets in my carbs (180) when everything ive read says they're supposed to be 160s or 170s... I wonder also if the type of jet had anything to do with it...