Rejetting Carbs: In Search of Free Lunch

[srsupertrap]

In the GS Forum, I have seen many threads concerning the issue of dialing in carburetors and the various topics such as Flat spots, plug chops & jetting in general. Since this is a timeless issue, I have scanned the Cycle World magazine article ?In Search of Free Lunch" written by Steve Anderson Jan 1983. I believe you will find the information relative & informative since the article testing was done on a 1982 Suzuki GS1100E w Kerker 4 into 1.

The files is 7 pages (4.0 MB) be patient. So, if you find this interesting perhaps I can scan the rest of my articles from Joe Minton, Peter Egan etc.

http://www.mediafire.com/?7ttgomzmmjz

 

[Steve]

OK, call me exhausted from a road trip, but I could not wade through all the promos and offers for free toolbars to actually download the pdf file. Whenever I clicked on the "click here to download" area, all it did was open a new window with the same information.

When I finally did get something else to appear on the screen, it was saying that my user ID was invalid. Evidently you need to have an account with these people to retrieve the file. I would be interested in downloading the file, but I don't want to jump through all those hoops.


.

 

[Steve]

OK, my bad.

I finally looked more carefully at the selections on the page. The one on the left that says "Start Download Now" or something like that will work just fine. 8-[

It must be time for bed about now. 44 hours ago, my son and I left for a road trip. Went to a town about 90 miles west of Minneapolis/St, Paul, hooked up to a 32-foot RV travel trailer for a friend, brought it back to southwest oHIo and set it up in her yard. About 2000 miles in the last 44 hours, it's beddy-bye time. :-$
.

 

[Matchless]

Excellent article and download worked well thanks for sharing!

 

[Guest]

yep,

very good read. It reminds me of the time I spent trying to get the carbs right on the VM GS 1000 woth pods. Probably 4-6 hrs, and it's not perfect.

I would definitly be more hesitant to attempt to do a CV type carb, and If I did, I would seriously consider an oxygen sensor. Preferably a wideband, but a standard car's narrowband would work too.

 

[srsupertrap]

I believe this article reinforces the fact that carb jetting, exhaust & filter modifications do not operate in a vacuum. Quite often any one these modifications by themselves results in unforseen negative driveability characteristics.

We here in the USA literally hear this symptom on any Sunday, how many times have you heard a sick running Harley after the owner installed a S/S Carb & drag pipes?

Next week after X-mas, watch for Post Carb Jetting II "What the Factory Never Told You"

PS: Many thanks to Matchless for answering all of my questions about Mediafire.

 

[posplayr]

In the GS Forum, I have seen many threads concerning the issue of dialing in carburetors and the various topics such as Flat spots, plug chops & jetting in general. Since this is a timeless issue, I have scanned the Cycle World magazine article ?In Search of Free Lunch" written by Steve Anderson Jan 1983. I believe you will find the information relative & informative since the article testing was done on a 1982 Suzuki GS1100E w Kerker 4 into 1.

The files is 7 pages (4.0 MB) be patient. So, if you find this interesting perhaps I can scan the rest of my articles from Joe Minton, Peter Egan etc.

http://www.mediafire.com/?7ttgomzmmjz

Nice article; Can I still buy some of those Marzocchi's for $159 (see last page)

 

[srsupertrap]

Nice article; Can I still buy some of those Marzocchi's for $159 (see last page)

That sounds like a good price

 

[Suzuki_Don]

The files is 7 pages (4.0 MB) be patient. So, if you find this interesting perhaps I can scan the rest of my articles from Joe Minton, Peter Egan etc.

http://www.mediafire.com/?7ttgomzmmjz

Hey SR did you ever scan those other articles by Joe Minton and Peter Egan for us avid GS readers.

 

[49er]

Become a believer

Become a believer

Great article on intake tuning.

Interesting how the Mikuni Techs confirm the positive effects of sonic resonance provided by a well designed airbox!!

 

[srsupertrap]

Hey SR did you ever scan those other articles by Joe Minton and Peter Egan for us avid GS readers.

Hi Suzuki_Don
Here is a couple of Joe Minton's Self Service articles on basic carb circuits & components. Nothing to deep but there are a couple good rule of thumbs which every GSer who tweaks carbs needs to remember. I have more period technical articles but I no longer have access to a scanner.


http://www.mediafire.com/download.php?1gwzy3nmf1s

http://www.mediafire.com/download.php?5bmfmxmngyf

 

[Suzuki_Don]

Thanks SUPERTRAP, it's a shame you dont have access to a scanner. It would have been great to get a copy of those other articles too.

Great information and an enjoyable read of the articles you did provide us with.

Much appreciated.

 

[LeeGS550E]

Great articles! I've spent the last few weeks working on pods on my CV's, and this will really help out. After reading this, I spent another $80 on pilots and even bigger mains. Amazing that they had to go up 22 sizes on their mains to get it right!

It was a revelation to me to read about the effect of the pods on the vacuum. Makes me kind of wonder if a bit of an insert plate at the carb inlet that made for some restriction would help them pull more vacuum and eliminate the need to go so large on the pilots. In my case, I can't fit an airbox in my bike's frame, so I'm putting on pods as a necessity. A bit of restriction in the flow would not hurt anything. Any thoughts?

 

[TheCafeKid]

Great articles! I've spent the last few weeks working on pods on my CV's, and this will really help out. After reading this, I spent another $80 on pilots and even bigger mains. Amazing that they had to go up 22 sizes on their mains to get it right!

It was a revelation to me to read about the effect of the pods on the vacuum. Makes me kind of wonder if a bit of an insert plate at the carb inlet that made for some restriction would help them pull more vacuum and eliminate the need to go so large on the pilots. In my case, I can't fit an airbox in my bike's frame, so I'm putting on pods as a necessity. A bit of restriction in the flow would not hurt anything. Any thoughts?

WHAAAAT!?!?!?!?! 22 sizes?? WTF??? What the hell were they doing?? Thats the most rediculous thing ive ever heard....man i wish i could see this article.

 

[tejasmud]

WHAAAAT!?!?!?!?! 22 sizes?? WTF??? What the hell were they doing?? Thats the most rediculous thing ive ever heard....man i wish i could see this article.

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.

 

[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.