Desperate for help GS450 wet fuel height

[Gorminrider]

I can't see your pic with blue and green lines very well-it's too small - but I think the green line is the one you want if it's lower than the bowl gasket...my picture is a bit tilted but judging by the gas in the pipe, the carbs are pretty level when I took this.

[Gorminrider]

Carburetor FloatGauge close.jpg

I'm trying to use the level of fuel to straighten the picture but I think it's pretty close to showing the tilt of carbs when on the center-stand...

[rekidiw]

aright guys, i have appreciated all the help but i am still at this. i have one question that i’m dwelling on and it’s frustrating because it isnt talked about in the shop manual. when setting the wet fuel height the manual states to measure from the surface of the float bowl that contacts the carb body when mounted. my question is do i take into account that when mounted with the float bowl gasket, the bowl is actually 1mm lower than it would be without the gasket. just in case i’m not explaining this clearly, i have attached 2 photos. 1 without a float bowl gasket and one including the float bowl gasket. can you tell me which measurement is correct when trying to set a wet fuel height of 6.5mm? thanks again..bikes running pretty good but i’m trying to get this thing running perfect

float height example.jpg

[LAB3]

If I where reading the instructions and no pictures where used to show how it was done my impression would be to measure from where the bowl meets the gasket. Keep in mind that the tolerance for setting the hieght is + or - 1mm. I've gotten myself caught up in splitting hairs many times before without getting much in the way of results for my efforts.

[Gorminrider]

A wet level is taken below the bowl's "mating surface" or another way that Haynes has it: "below the carb body-to float-chamber-mating surface"

Yes of course this surface mates to a gasket which mates to the carb body...you can't practically do a wet test without the gasket...
and Anyways, the gasket isn't going to affect the bowl's fuel level that you are testing However, gasket thickness would affect the jets .... So being finicky, use the oem gasket .

[rekidiw]

Yea I get what you mean I am being finicky, I know. But Im just trying to know for the sake of knowing and a peace of mind that I am making true measurements. From where you measure will certainly make a difference in where you end up setting the fuel level. For example, you have a set amount of fuel in the bowl. You measure from the bowls mounting surface to that fuel line and it measures out to 6.5mm. Because of the gasket, if you measured from the carb body's mounting surface to the fuel line it would come out to 7.5mm due to the 1mm thick gasket separating the surfaces. Its not a crazy amount but 1mm is quite a bit when factory is 6.5 +/- .5mm.

Anyways, so you all think its safe to say I should be measuring from the bowls surface, and not the carb bodies surface?

[Chuck78]

one mor5 thing out of curiousity...how is it that the same bike and pretty much same carb can have such a big difference in jetting? one has a 17.5 pilot and one has a 45? how does that work? is there any way to identify the model id number on the carbs? almost wondering if someone mixed up the jet sizes combining specs from different carbs

The biggest factors for different jet sizes on the same basic model of bike would be different air jet sizes, that completely changes the requirements of the fuel (pilots & mains) jet sizing. More air flowing through will pick up more fuel. Less air flowing through a pick up less fuel. Also, different camshaft timing and valve lift specifications. As well as revisions in the carburetor design.


One thing that struck me beer was that you have not mentioned anything about letting it idle for a long time and then pulling the plugs and getting a good reading on them to see if you are too rich or too lean. If you have your float height set that over 27 mm, you are probably likely to be running on the lean side.

A Gunson Colortune is a really helpful device to use but I have heard that on the BS carbs, the mixture can't be dialed in quite as predictably. It is a clear spark plug used for low RPM tuning purposes, so that you can monitor the color of the flame as you make various adjustments. Blue flame is perfect, whitish-blue is lean, yellow and orange is rich.

Your ignition system also needs to be in Tip-Top shape as well. Weak coils, faulty wires, faulty plug wire resistor caps, plugs, faulty ignition box all good have something to do with it. Was it idling and running a significantly better immediately before the rebuild?

I neglected to winterize a gs425 two years ago, and bringing it into the basement shop last week I realized that the carbs were far beyond plugged up, it would not even idle, jets are all plugged up, main hets, too... Also bs34 carbs. So I will get to rebuild those in this offseason.

Best of luck,

Chuck

[Gorminrider]

so you all think its safe to say.......?

Finicky! You want Finicky? You can't handle Finicky! how about this? Alcohol in the fuel will change the (float) level due to a different specific gravity than the gas these bikes had when built...so better look that up if you use ethanol gas...

[pete]

The 80 - 82 model carbs are the odd ones out in the 450 range, and here's a post I made with the details out of the factory reproduction manual I have:

https://www.thegsresources.com/_forum/showthread.php?204475-1980-1982-GS450-Carb-Spec-s-(E-L-S-and-T)&highlight=float+height

[rekidiw]

beautiful will use all this info and report back. thank you everyone and pete for saving me with that chart.

[pete]

No worries, hope it helps! I've come to be suspicious of all spec's listed in Haynes and Clymer manuals after find a couple of incorrect torque spec's and other minor discrepancies. They're great for helpful hints on dismantling etc. but I always go to the factory source for spec's.

[rekidiw]

after searching around for a legit suzuki manual its a little confusing which is which. from the looks of what google images pulls up, i actually have the factory manual. but apparently not because mine says the float height should be 22.4. maybe the problem is there are many different manuals for different sub-models which carbs are actually a little different.

anyway you could post up a some pics of your manual, or have a link where to buy the legit factory manual?

[pete]

I got it from eBay seller e-classicbike.com, hopefully this link works: https://www.ebay.com/str/eclassicbikemanuals

This should be the manual: https://www.ebay.com/itm/SUZUKI-Work...64Nu:rk:1:pf:0

[rekidiw]

awesome thanks

[rekidiw]

So I'm still fighting with these fuggin bs34 carbs. Ive come a long way by adjusting things incrementally and recording results. The bike runs pretty good, I ride it everyday. No matter what I do I cant seem to figure out this hiccuping condition the bike has though. Especially when warming up on choke. If watch this video and listen closely the rpms drop for a split second and you can hear a clicking sound coming from the carb. Sounds like the diaphragm piston dropping and hitting momentarily. After all of my adjusting I have noticed that it seems to get better when I lean out the mixture. While the bike is warming up or running the "issue" seems to occur when the idle is really smoothing out and is subtly raising, then all the sudden"click!" rpms drop almost to death, then slowly idles back up. Has anyone ever seen anything like this?

My only idea is that is has progressively gotten better as ive lowered the fuel height in the bowls. Im below spec now though so Im not too comfortable continuing to lower them and disregarding factory 6.5mm fuel height. I'm at 7.5mm now due to trying to experimenting to solve the problem. Runs best now than it ever has.