Author Topic: 96 B6 - carbs guzzling gas (Read 7590 times)

97RedBird · « **on:** March 10, 2005, 02:49:58 PM »

After many months of trying this and that documenting changes to my carbs and the research I did to find out what previous owner(s) had done.

my bike has stock everything, except 2 shims under each needle and 3 turns out of the A/F mixture (when purchased).

My mileage averaged 40-43 MPG (36-39 MPG before sync'g the carbs) commuting on the highway to work. I attempted 2 turns out after I found out my jets are stock 98-100-100-98 sizes and it drove great. Before my bike would die after the first stop sign on a cold morning drive to work, now it stays idling with no help!

I thought it was dying because lack of fuel or icing, but not running rich

Also blip'g the throttle seemed like it was hanging at 2.5 turns. I don't know what that was, but I'll test this out more.

I hope my gas mileage increases as well.

Red01 · « **Reply #1 on:** March 10, 2005, 07:46:20 PM »

I'd say you're pretty close now. B6's usually get ~45-50 mpg for most folks, so 43 isn't too far off.

Might wanna try just one shim and see what that does for ya.

tacoman · « **Reply #2 on:** March 11, 2005, 04:14:21 PM »

I had two shims on and mine ran rich. My pipe was really black and sooty. I dropped to one shim and I feel its perfect. It takes just a little longer to warm up but my mileage increased and throttle response is crisper. I would go with 100 jets all the way across.

97RedBird · « **Reply #3 on:** March 13, 2005, 02:17:39 PM »

I wanted to solve the mileage issue before changing anything. Just got 187 miles on a tank before reserve, but calculated 43 MPG again

Must have filled my tank really full last time.

One more tank of this setup and I'll try one shim each.

chupacabra · « **Reply #4 on:** March 14, 2005, 06:07:12 AM »

Tacoman, have you tried 102's in #2&3 ?
I just making plans to jet.

tacoman · « **Reply #5 on:** March 22, 2005, 07:42:30 PM »

I can't remember off hand what my numbers are but I matched the outer ones to the two inside. I feel these are optimal and Suzuki leaned the outer cylinders because they run cooler and were able to meet emissions.

Gnome · « **Reply #6 on:** March 23, 2005, 05:26:48 PM »

I'm lucky to see 120 miles on my 99 B6's tank!

I must learn to slow down a bit more....

B6Matt · « **Reply #7 on:** March 23, 2005, 11:54:38 PM »

I'm probably getting right at 40 mpg, but mine's a G2 with an aftermarket can and midpipe. I'm running a Holeshot Stage 1 kit with A/F at 2.5 turns, 2 shims, and #95 mains across the board. Pipe is black inside the outlet, but I don't know if it's TOO sooty.

I'm going to make sure my TPS is correct and have the carbs synched. May try one shim to see how it changes things. Hoping the warmer weather will help too.

Funny how a B12 gets almost the same gas mileage as a bike with 1/2 the displacement.

Chupa, how many miles do you have on that thing now?

chupacabra · « **Reply #8 on:** March 24, 2005, 08:04:26 AM »

I have somewhere around 45,000. I'm getting bad gas mileage right now 34mpg but I need to tune up everything on this bike. I've been putting alot of cash on fixing the wifes cage and letting my bike go.
I have plans to get it in order soon. I just ordered springs and I'm going to place the order for the new HS can any day now. I have spacers just need to pull carbs and do the carb work (jets and drill plugs and put spacers on). I'm running 15/50 sprockets that don't help with gas mileage but are fun.

97RedBird · « **Reply #9 on:** March 30, 2005, 12:22:09 AM »

Okay back after doing a couple of fill-ups.

using one shim(washer) under the needle and no washers yielded long warm ups with 2 turns on the A/F screw.

Here's the part I need help with. I noticed at cruise, 30-70 mph there is a dead spot in my throttle. If I pull it back (open the throttle) I get all the power back. Also going downhill even a small grade yields less load on the engine and this dead spot disappears a little. Going uphill the dead spot is even more noticible. I think the dealership or the previous owner hid this by turning the A/F out 3 turns and the washers, but I can't be for sure.
On this helpful website I think I may have identified my problem
http://www.factorypro.com//tech/carbtune,CV,high_rpm_engines.html
I think my float(s) may be out of adjustment? no problems below 2k and it is fine above 4.5k or 5k RPMs.

I think my floats are to high, I'm not fouling plugs, but one set were close.
<quote>
Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation.
</quote>

What else could it be?

Red01 · « **Reply #10 on:** March 30, 2005, 02:29:05 AM »

Could also be a vacuum problem - as in a minor vacuum leak. Possibilites are the carb diaphragms, poor connections between carbs/manifolds/head, or leaks in the manifolds themselves.

97RedBird · « **Reply #11 on:** March 30, 2005, 02:48:21 PM »

My petcock doesn't operate on vacuum anymore so it is pretty much on PRI all the time. So I forgot to hook up the vacuum line to carb #4 once and it effected everything from just off idle to high RPM's. The power drop was very noticible throughout the range.

I wouldn't think a small leak wouldn't occur at greater than 3k RPM's. I found a website on how to measure float levels without taking the carbs off using a clear hose and the bowl drain screws. I'll use this to test the float bowls tonight.

Thanks!

97RedBird · « **Reply #12 on:** March 30, 2005, 11:55:16 PM »

Since my petcock doesn't work I blocked off that vacuum passage to test for a leak there. I listened and felt around, but could feel or hear anything.

What do you suggest to do to find a leak?

Red01 · « **Reply #13 on:** March 31, 2005, 12:44:52 AM »

Do you have a little propane torch? If so, with the engine running, turn it on, but don't light it. Run the nozzle around all suspect areas and listen for a change in RPM. Wherever RPM changes, you have a vacuum leak.

If you don't have a torch, you can substitute starting fluid or WD-40.

For the carb diaphragms, you'll have to settle for a visual inspection of their condition. They should be supple and crack-free.

I don't know if the B6 has the little O-rings inder tha diaphragm caps like the B12 does, but if they do, make sure you're not missing any of them.

97RedBird · « **Reply #14 on:** March 31, 2005, 01:22:47 AM »

nope no o-rings.

diaphram looked okay the numerous times I had it off changing the shims.

I do have a propane torch. I'll try that.

Thanks!

I'm thinking I need to decommission my bike and do a valve tolerance check then carb clean/adjustment over the weekend. Might need to check everything for myself and not trust that the previous owner had done so. I'm just under 21k and I bought it just under 16k last August.