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Troubleshooting BS34's on my GS850

  • Thread starter Thread starter XXWoodmanXX
  • Start date Start date
X

XXWoodmanXX

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Ok, so I needed to replace the BS32's I had on my bike due to some seized mixture screws I attempted to drill out, and failed.

So I checked around and got some locally. Well, come to find out the guy I got them from didn't realize that the carbs were BS34's. *sigh*

Anywho, I jetted them out and fitted them on my 850, even though I know they're only for 1000cc and above.

Here's what I have:
- K&N pods
- V&H 4-to-1
- Dynajet Stage III jet kit (Ebay)

BS34's:
- Mixture screws 4 turns out
- 190 Pilot Air Jet
- 165 mains (Stage III)
- Float bowls at 22-23mm
- Needles set to 3rd from top, as per Stage III recommendations

Now, I can start the bike fully-choked, and the idle sets a bit high @ 2-3000 rpms, but after she warms up, she sits steady @ 2K. Now, if I dial the idle adjust down any, she'll lope down and eventually stall after a few seconds.

When I pull the choke when she idles, the RPMs ramp up to around 4500-5000rpm, but if I pull the choke out completely, she stumbles down and stalls.

I know this sounds like every other carb troubleshooting thread. But do I now need to compensate for the larger amount of airflow getting to my motor?
 
are you using the stock pilot jet? what is the difference between a 32 and 34 pilot jet?
 
Yep, using the stock pilot jets. Dynajet doesn't call for upgrades.
 
the stock pilot jets from which carbs? I would take the pilots out of the 32s and put them in the 34s.
 
I have a new petcock and will be replacing it ASAP. I doubt the one currently on the bike is the original stock petcock, but it IS showing signs of wear. Sounds like tomorrow's project right after work. :)
 
Personally, I think you are just a bit over-jetted. :-k

The 1000G and 1100G bikes used the BS34 carbs and had the same jetting as the 850G with the BS32 carbs. That would be 115 mains and 40 pilot fuel, 170 pilot air jet.

Stock mains are 115 (Mikuni). With your pods and pipe, you might need a 130 or so, which would be about a 138 or 140 DJ. With your 165s, it's way too much. If those are Mikuni 165s, it's WAAAYY to much.

.
 
They're 165 DJ's. The kit came with 155, 160, and 165's. Should I jump down to the 155, and see what happens, or order myself another set of jets?
 
i used 160 on my bike, but your start up problem has to do with the pilot jet, did you bench sink your carbs?
 
kdo58 said:
i used 160 on my bike, but your start up problem has to do with the pilot jet, did you bench sink your carbs?
Click to expand...

Really? I sync'd the carbs by wire before install. But the pilot jets are brand new from the rebuild kits I just installed and plugs are brand new aswell.
 
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I did not use any oil on my k&n air filters, I had read that it is easier to jet without oil, worked for me.
 
kdo58 said:
I did not use any oil on my k&n air filters, I had read that it is easier to jet without oil, worked for me.
Click to expand...
Yeah, then as soon as you apply the REQUIRED oil to the filter, it changes its ability to breathe, so you have to check your jetting AGAIN.
icon_shrug.gif


.
 
I would love to think that my troubles are attributed to a faulty petcock diaphram, since that is my next order of business. But there is no leaking out the assembly, nor into the vacuum port of carb #2. Regardless, ..... It will be replaced this afternoon. I also found several vendors that carry tons of various size jets for my mikunis.
 
UPDATE:

Well, went ahead and replaced the petcock. And, from the looks of things, it looks like it was LOOOOONG overdue. I inspected the old one and the diaphram was completely GONE. Probably disentigrated many, many yrs ago, I imagine. *sigh*

Well, thankfully, I replaced/rebuilt the carbs and she runs alot better now. However, my RPMs seem to hang after I give it some throttle. In neutral on the center stand, I'll crank it up to 6-7K, and it'll only fall down to 3K and hang there, slooooooowly dropping down to around 2500rpm. Ideas now?

EDIT: Oh yeah!! I have an exhaust leak at the header on cylinder 1. I'll get it fixed.....maybe tomorrow. heh
 
A "hanging idle" is usually the sign of a lean pilot circuit.

Try turning your mixture screws out about 1/4 turn.

.
 
Oh man!!! First day to peak over 50 degrees and I took FULL advantage of it.

Finally tuned the BS34s to my bike. I took Steve's advice and turned out my mixture screws, but it took a whopping 1 1/2 turns, totalling 5 1/2 turns out!! But when I blipped the throttle, it was just that....a blip. It quickly returned to idle. Sweeeeet.
:eek:

But she's now running ALOT better, and pulling strong thru the entire RPM range and all gears.

Just in time to have to pack it up and put her away for the winter. *sniff-sniff* :(

Overall, very, very happy!
 
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With them turned out that far, I would suggest going up one size on the pilot fuel jets (use 42.5, instead of the stock 40), and you will be able to get those screws turned back in to where you will still be able to adjust them. With them out that far, you are at (or just past) maximum, and can't really do any adjusting.

.
 
I JUST found a set of 45's, and I'm thinking I put the set of 40's from the BS32 genuine suzuki rebuild kits.

Uuuuhhhhhh, I think I just found the Achilles' heel to my carb problem. lmao!!
 
As I mentioned back in post #6, stock jetting for both sets of carbs for their intended bikes, used #40 pilot fuel jets. You are using these carbs on a bike for which they were not intended, so jetting will have to change. I think you have noticed that by now.

How much to change? One jet size is usually about the same as three turns of the mixture screw, so going up one size (to 42.5) should bring your screw settings down to about 2 to 2 1/2. If you were to go up two sizes to #45, you might have to run with your screws all the way closed, and it might still be too rich, because you can't slow down the mixture to where it needs to be.

For the price of a few jets, I would get the 42.5s, but it's your bike, feel free to install the 45s to see if they are, indeed, too large.

.
 
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