First off, I would like to say that for the most part, the Wiki is very helpful. However, the jetting matrix is a crock of shaZam!. If at the very least, it could be edited to say that these sizes are "OPINIONS" as to what the proper jetting is, that would be fantastic. The "Jetting Matrix" is very misleading, and thanks to it, I have quite a few spare main jets! They are nowhere near the proper jets, far far too rich. I don't know if you people like your bike running very rich or have completely screwed float heights, but they are NOT correct. I am not saying that every bike is going to be identical, but 4+ sizes off is ridiculous. The "Jetting Matrix" presents itself as a tool, a helpful guide for those not familiar with the GS500 and how it responds to modification. In my case, and I'm sure in many others cases who like their bikes to run properly, listening to the jetting matrix led to a lot of horrible mpg, wasted money on jets, and above all, lots of wasted time. Anyone else have thoughts/experiences on this?

I agree. Not super helpful and not enough opinions on there.


I have a 2005 and I use a 20 - 65 - 145 setup. I have a K&N lunchbox and a sports exhaust and I am 100% happy with my jetting 

slowinthestraights -

But you didn't post your current jetting. What gives ?

By the way, there are alot of variables, like if your can is tight (exhaust can silly), if the carbs are tight, if your filter is clean, timing, your elevation, spark plugs (condition and age also), riding style, gearing (you'll use more / less throttle), tire size, wind etc.

Then there are the manufacturing variables. You don't really think every single passage, void, float, needle, etc are exactly the same, do you ? Hell you can pull out valve springs and find a nice 25% variance normally.

People also misalign intake boots, hoses, petcocks, etc.

I'm not knocking your opinion, just keep in mind this is by no means a perfect bike. Production pieces can be 'close' to one another but without testing every single piece to blueprint specs, you can't be sure.

For the record, I've only cleaned my carbs once on my 98. I haven't rejetted since whatever the 2 PO's did to it for the V&H and K&N stuff was installed. I could illiminate a lean spot at 5800-6000 rpm, but don't really care, or I'm lazy. 18,000 miles on the clock. Still love it.

peace out man 

My point is, those things may be wrong with others bikes. My carbs are completely gone over, float height is correct, filter is clean, exhaust is free flowing, compression is good, valves are in spec, ETC.

I have been going down sizes, still not at the right main jet. Started out with the 150 as recommended, YES, the bike did RUN, and it ran OK sitting on the freeway going 65mph, it did NOT run well trying  to go faster.

My point is, either people don't know what they are talking about, or do not CARE if their bike is not jetted perfectly and would rather be "safe than sorry" (hence the humongous mains). If they feel that way, they should not recommend their jet sizes.

You are an example yourself, you could care less about your flat spot. If you KNEW which jets you had, would you put your info into the jetting matrix?

slowinthestraights -

i see your point. yes, if i knew exactly which jets / settings were on my bike, and it was correct (to whatever degree is possible without a computer sniffer) i'd post my settings.

as i don't know, no, i have not posted there. i figured i would once i had enough time to tear into the carbs and actually make it run as perfectly as a carburator can.

i didn't realize folks were posting settings that were less than optimal. maybe the wiki and the matrix should should reflect a better setup ?

you know, if someone had a dyno  and a week or so to play with parts... doubt that will happen. guess the matrix is what it is , and everyone will have to tweak.


thanks for steering me straight slow - 

Quote from: galahs on September 22, 2007, 05:16:38 AM
I agree. Not super helpful and not enough opinions on there.
I have a 2005 and I use a 20 - 65 - 145 setup. I have a K&N lunchbox and a sports exhaust and I am 100% happy with my jetting 

Do I need to REALLY upgrade my setup (currently GSF 2005 - all OEM) if I just want to get rid of Airbox and put a K&N Lunchbox ?

Yep. Wack a K&N lunchbox on and your air/fuel ratio will go lean beef!

I tried it with stock jetting and I couldn't rev past 6,000rpm whilst riding (was ok when stationary in Neutral). Literally the engine wouldn't make any more power!!!


You can get away with keeping the stock pilot jets if you want (17.5) if you don't care too much about quicker warm ups and are concerned about around town/traffic jam fuel economy. Its the 1/3 to full throttle where the improved breathing of the lunchbox shows its head.

This is one reason I started the following thread:

http://gstwins.com/gsboard/index.php?topic=35237.0

Haven't added it to the matrix yet.

yep, the Jetting MATRIX is not very helpfull, but I like sanjay's post where one adds his/her configuration and opinions! usefull stuff - you just look for similar configuration - copy the idea and at least you have GOOD starting point to rejetting process.

pbureau69 with stock jets and lunchbox you'll be lean, so you do need to rejet the carbs - you'll be happy you did and you're gonna love the ROAR it makes

cheers
KaMeL

The recommended starting point for my setup is something like 20/65/147.5 (jardine - lunchbox - 2006).
As I wrote on sanjay's thread I found it to be too rich. Now I have 20/60+washer/142.5 and it's still rich.

So here is the question.
What float height do you use?
I've heard buddha and others (it's also on the wiki) say "You set the fuel level at the same height as the gasket of the float bowl".

BUT!!! With the recommened float height of 13mm the fuel level was much higher than the gasket surface.
Setting the float height at 18-19mm I got the wanted (per wiki) level.

Might this solve the mystery of the jetting matrix?

The matrix stuff does seem too rich to me also. With twin K&N filters and full Formula 1 exhaust I started at 22.5/65/147.5 and it was very rich - bogged down badly under full throttle. Then tried 20/62.5/142.5 and it felt perfect to me, stock (or better) economy, no flat spots etc. Then I thought I'd try the 147.5 again, so now I'm 20/62.5/147.5 and there is maybe a slight difference under full throttle - it feels slightly stronger, so I'll leave it at that.

I should say this was on a brand new 2008 bike.

Wow

There is a lot of great information here.  It is a little difficult to take it all in.  If only there was a place we could write down all these settings, jettings, and configurations in an organized way.  Like, I don't know, some sort of a matrix or something.

Quote from: lamoun on August 28, 2009, 08:52:24 AM
The recommended starting point for my setup is something like 20/65/147.5 (jardine - lunchbox - 2006).
As I wrote on sanjay's thread I found it to be too rich. Now I have 20/60+washer/142.5 and it's still rich.

So here is the question.
What float height do you use?
I've heard buddha and others (it's also on the wiki) say "You set the fuel level at the same height as the gasket of the float bowl".

BUT!!! With the recommened float height of 13mm the fuel level was much higher than the gasket surface.
Setting the float height at 18-19mm I got the wanted (per wiki) level.

Might this solve the mystery of the jetting matrix?

ZOMBIE THREAD!!!!!!

Are you sure you're checking your levels correctly?  I set mine to 13mm and am bang on for the "up to the top of the float bowl" external check. (well once I fixed the air lock that prevented my floats from working at all.)

Quote from: PachmanP on August 28, 2009, 09:24:04 PM
ZOMBIE THREAD!!!!!!

I know..   but it fits perfectly   

Quote from: PachmanP on August 28, 2009, 09:24:04 PM
Are you sure you're checking your levels correctly?  I set mine to 13mm and am bang on for the "up to the top of the float bowl" external check. (well once I fixed the air lock that prevented my floats from working at all.)

Yeap.. needle valve closed and float tang just touching (not compressing) the valve spring.
But if I was to measure it with the valve spring compressed it would give me the "right" height probably.

I agree with PachmanP.  From what I understand the whole point of the float height spec is to get the fuel level to the top of the bowls.  When you think about it it makes sense, doesn't it?  The idea is to keep the bowls full but not overflowing.

As far as jetting goes, I have the old two-stage carbs.  I only have a V&H exhaust so I left my jets alone because it runs good with no flat spot.  If I added a lunchbox I seriously doubt I'd need to go more than one size over on the pilot jets and two sizes up on the mains.  I think to go bigger than that would require head work.  I believe this because of what I've read here.  For every guy who's happy with main jets in the 140's it seems there are two others who say it's too rich and get poor fuel mileage.

And as Ohgood said, there are more variables to consider as well that makes this "matrix" fairly murky, but I don't think elevation change would require more than one jet size difference.  Elevation plays a part, but high elevations make the incoming air less dense due to the decreased pressure, so any jet change for high elevations would mean going smaller.  Then what would you do once you left the mountain?  

Having said all that, the only way to really re-jet a bike the right way is to have access to a dyno and an exhaust gas analyzer so you'll KNOW what's going on, eliminating all the aggravating trial-and-error.  Then you'll know you have it right rather than hope.