Desperate for help GS450 wet fuel height

[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...

 

[Guest]

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/_for...b-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.

 

[Guest]

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?

 

[Guest]

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-Wor...h=item590c32501c:g:JUgAAOSwYIxX64Nu: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.

 

[Guest]

How certain are you that the diaphragms are good?

Reading your latest post reminds me strongly of my experiences with the stock 450 carbs when I was trying to get them right and kept adjusting jetting and fiddling and was having issues with surging at low throttle positions, and generally just not running right. I also had some symptoms like you describe although it was more like the carb was spitting rather than clicking, but we're talking a number of years ago here.

In the end, I discovered both diaphragms had minute tears in some creases that I figured out had been there for a while and I'd just not looked close enough to see them.

Tears in the diaphragms will interfere with the ability of the vacuum to life the slides, so they're going to give you inconsistencies, and my limited experience tells me you'll notice them more at idle and low throttle positions.

My solution was putting some GS500 carbs on as they're a bolt on replacement and are lighter, and most definitely were cheaper than replacing the slides and diaphragms. You won't be able to run the stock airbox though and will need to figure something out there. My choice was velocity stacks with a foam filter over the top.

 

[rekidiw]

Hey Pete,

Glad to hear back from you.

I've checked them both with a flashlight. Actually just check the right side again 2 days ago but maybe I missed something. I will have to take another look.

While I have you here. What do you know about the position of the signal generator plate?

Today, stumped and desperate, I started to check random things and came across the signal generator plate. I loosened it while idling and twisted it counter clockwise just the little bit that it could go(about 3-4 mm) and it started idling higher and stronger. It didnt have that loping sound of an unhealthy idle. I searched around to find exact information on where it should be positioned and didnt find anything. I have a manual but hoping to get a 2nd opinion since the manuals have proved to be wrong more than once.

 

[Guest]

With any luck your diaphragms are good, but thought it definitely worth a mention given the similarity of the symptoms.

Hmmmm good question! Been a while since I've had to align that for timing and pretty much all my mechanical work recently has been on the Kat.

If you rotate the plate clockwise, I believe you're retarding the ignition, rotating counter clockwise will advance the ignition. Be aware at idle if you advance it too much that when the RPM's get up and the advance counter weights kick in, the ignition may be too advanced. I don't think that's possible with the stock adjustment range though.

From memory the only adjustment you need to do with the signal generator plate is very minor and needs to be done in conjunction with a timing light to get it in the right position. The manual will tell you how to do that, I can't remember the marks to align with off the top of my head.

Which manual do you have? I'll endeavour to have a look in my factory reprint to see what it says on the matter.

 

[Gorminrider]

The timing plate of the electronic ignition is "set" in place. There's very little adjustment because it's not meant to be adjusted. You are barking up the wrong tree unless you discover a flaw in the wires- (check these for chafe) or even sensor coils (check these for looseness-I discovered one once that I had to glue!)