Flatslide Carb Balancing

[isleoman]

Quick question.....I bought a Morgan Carbtune last month and just got a chance to hook it up last night.

I have RS38 Flatslides on my 1100ez. I assume that I first want to set carb two equal to carb three (which is the baseline carb) and then set carbs one and four at 1/2 bar (gauge notice mark) above 2&3.

This is the way the Suzuki manual suggest setting the balance. What's the reasoning for not setting all of them equal to each other? Pressure waves?

[tkent02]

Do you have 4-1 or stock exhaust with a crossover?

[Billy Ricks]

If you're running a 4 into 1 I think you want them all set the same. I always heard the reason for setting the two center carbs different on a stock machine was because of the crossover in the stock pipe.

Good luck synching flatslides with gauges. All I've ever done is bench synch mine and forget about it. Pretty much what everyone does. Once you get off idle small differences between the carbs disappears. These carbs are all about mid and high rpm's. I think you'll have a tough time doing a vacuum synch with the way the adjusters are set up.

[rapidray]

Isle, I do them with gauges also & you need to turn the idle up to between 2000 & 2500 rpm. Then set them all the same, DON'T stagger them. Ray.

[Billy Ricks]

Isle, I do them with gauges also & you need to turn the idle up to between 2000 & 2500 rpm. Then set them all the same, DON'T stagger them. Ray.

Well hell, now you two have me figuring I may as well do mine. Just going to be a pain with the frame rails in the way then trying to keep the bolt in place while tightening the locknut. How do you handle that Ray?

[isleoman]

Unbelievable,

Get answers to your questions in 10 minutes from great sources. I'll try setting them all the same at 2000-2500 rpms, I have a Yosh 4 into 1 with no cross over. Mine were pretty close last night but probably more than two notice marks difference between high and low. Of course the balance changes as the RPM change so you kinda have to select where you want to achieve the balance. Thanks Ray for the range. I do like how steady the Morgan gauges are.

Billy, With all those tiny screws and nuts you have to take your time on this adjustment.

Found out last night the washer on the air plug screws aren't magnetic, must be copper.

At least the flatslides open up pretty easily from the top without having to remove them from the bike.

[Billy Ricks]

Even when bench synching the adjusters aren't very subtle or progressive. Let me know how you get down to the slide tops and hold the bolt while you tighten the locknut down.

[isleoman]

Even when bench synching the adjusters aren't very subtle or progressive. Let me know how you get down to the slide tops and hold the bolt while you tighten the locknut down.

Billy,

Did the carb balance last night and it wasn't that bad. Took fuel tank off and put it on some plastic packing crates slightly higher than the bike, to use it as a remote tank. Had a 15" length of fuel line I keep around for this reason. Put the petcock on reserve and plugged the fuel tank vacuum line with a pencil.

Access to the RS38 carb tops was pretty good and all the caps were easy to remove in a couple of minutes. The adjuster nut and center locking screw are in convenient locations also.

I wasted a little time trying to determine if having the carb tops off has an effect on how they run. When I first started the bike it sounded like it was running out of gas. I finally figured out that fuel tank vacuum line not being plugged was the source of the problem. Once plugged the bike ran normally. If you put your hand over the open carb top you can feel a vacuum being produced but having the tops off didn't seem to effect how well the bike was running.

Once warmed up I re-checked the original balance at 2000 and 2500 and it was pretty close but I had come this far and I wanted to give it a try to see if I could make it closer. 3 and 4 were dead on so I only adjusted 1 and 2.

Your right the adjustments are subtle however, I'll also say they are linear (meaning slowly turning the adjuster creates a predictable movement in either raising or lowering of the column.

I'd say it took an hour from start to clean up. If you dropped and lost one of the small carb top screws or the allen head intake plugs that would suck.

Bike ran great afterward maybe a bit smoother, but it was running pretty well to start.

[Billy Ricks]

I guess I'll give it a go on mine then.

[trippivot]

K&L has a special tool to hold the screw and tighten the lock nut at the same time.

tolerance is 2 hg between carbs so a good eye and bench sync will have you in the ball park. getting it closer is a personal preference. There are no performance advantages at all, just a good idle . period

[Billy Ricks]

tolerance is 2 hg between carbs so a good eye and bench sync will have you in the ball park. getting it closer is a personal preference. There are no performance advantages at all, just a good idle . period

That's the way I've always felt about running flatslides. They aren't about putting around anyway. My bike pulls decent from as low as 2,500 rpm so I've never been concerned about vacuum synching them.

[isleoman]

K&L has a special tool to hold the screw and tighten the lock nut at the same time.

tolerance is 2 hg between carbs so a good eye and bench sync will have you in the ball park. getting it closer is a personal preference. There are no performance advantages at all, just a good idle . period

Good info, let me ask a question though, if its about getting a smooth idle why balance at 2500. My settings were quite a bit further off at 1000 rpm (idle) with the balance close to spot on at 2500.

With the Yamaha FZ1 owners (right or wrong) its all about trying to eliminate vibration in the handle bars by balancing carbs. I don't get much vibration in my GS bars (which by the way are off of a FZ1)

I have no intention of changing anything at this point, its running great, just curious.