Hello new here need help with fuel system/carbs.

[Faltang1090]

Also forgot to mention I checked and adjusted the floats wasn't off by much a mm or so at most.

[Faltang1090]

It is running!!!!! Took her up and down the back alley! There are times where it hung up a bit for Rpms but settled down again. Now I need to finish the seat cover. Brakes stopped me in a hurry. She is acelerating nicely all the way through 7k rpm, with no back fires and extra noises.

Thank you guys/gals so much!!!

[TopCatGr58]

Hey there,

Sounds great that you're making progress...yes setting the needles lower helps to lean the F/A mixture a bit which is a good thing for your elevation. However, you had the carbs off and separated and so your vac. synch is probably OFF again and so that's why the rpms hung a while, you need to vac. resync them again to retune them to work together.

T.C.

[Faltang1090]

Ok so vacuum synced the carbs as best as I could without a proper gauge set up. Made a simple one with oil and clear hose. Synced 1 to 2 then 2 to 3 then 3 to 4. Got them to level but once the bike warmed up it started to rev up slowly and keep going higher. This is really confusing me never had this many problems with bikes before. The carbs are returning to normal operating placement, vacuum lines are correct, plugs are on. I did lower the jet one clip space, readjusted the floats where it was needed. Sealed any vacuum leaks that I could find. I know I am missing something small but significant. Everything looks to be in place while I was assembling the carbs and after adjustment. Anything that might be off still after adjustment I don't mind pulling the carbs again getting good at it!! Just throw it out there and I'll give it a shot!

[3Phase]

You did a good job synchronizing the carburetors!

But you did them in the wrong order.

Keep the idle at 1,100 RPM and the order is: 3 - 4, 1 - 2, 2 - 3

3 is the base carburetor, always set it first.
Match 4 to 3
Match 1 to 2
Match 2 to 3 and it will bring the 1-2 and 3-4 pairs together

If the idle climbs, shut off the engine and remove the vacuum advance line from the #2 carburetor, then restart the engine.

If the idle stays at 1,100 with the vacuum advance line disconnected then the #2 carburetor throttle plate is probably open too far at idle and it's adding vacuum advance when it shouldn't.

That means the carburetors are still out of synch or something else is wrong and the carburetors have to be opened more than normal to idle at 1,100 RPM.

.

[Faltang1090]

Ok when I get home I will re sync them, I knew I had it too easy!

[MPittma100]

Diaphragms

When checking the diaphragms for cracks, also make sure that they are also tightly mounted to the slides. If you are able to move them on the slide, they will leak there as well. This can contribute your high idle issue.

[Jeffintampa]

snyc order?

Keep the idle at 1,100 RPM and the order is: 3 - 4, 1 - 2, 2 - 3

3 is the base carburetor, always set it first.
Match 4 to 3
Match 1 to 2
Match 2 to 3 and it will bring the 1-2 and 3-4 pairs together

3 you don't have to set factory correct?
Match each one to 3

[Bonz]

Pine Sol is a heckuva carb cleaner, and unlike the Yamaha stuff, is a great floor cleaner... Heh, heh, heh...

Made a vibratory cleaner with a cartridge case cleaner and strapped a plastic food container to the top big enough to hold the carbs in broken apart fashion, and cover them fully with 50-50 Pine Sol/H2o. Pine Sol won't hurt any rubber parts so soak away! Done multiple sets of carbs over the years, and it is the real deal.

[3Phase]

Howard: Thppppbtbtbtppp!

3 you don't have to set factory correct?
Match each one to 3

Jeff,

If #3 is wrong they're all wrong so, yes, #3 has to be set 'factory correct' or at least as close as you can get.

You don't have to get all four exact on the first pass because unless you're an experienced motorcycle mechanic with an Exhaust Gas Analyzer, a Sub-genius, or just lucky as all get out then it's going to take a couple of passes to get it right but #3 is the reference.


Faltang1090,

There is nothing magical about motorcycles, you should be able to get 18 to 22 inHg of vacuum in each cylinder just like a car or light truck. The vacuum comes up as you close the throttle plate and goes down as you open the plate.

If you can't get 18 to 22 inHg of vacuum at 1,100 RPM, the engine needs fuel and it's not getting it from the Idle Port so it's forcing you to open the throttle just enough to get it from the three Transition Ports.

The three Transition Ports are not adjustable so you can set the idle speed when they're supplying fuel at idle but it won't be anywhere close to stable or reliable.


You really should have a good tachometer and I assume that you have already set the Idle Mixture Screws to 1 1/2 to 2 turns out from closed and didn't break off the tips of any of the screws.

Use the Master Idle Speed Screw to turn the idle down to 800 RPM or the lowest smooth idle speed you can set and maintain.

Starting with the #3 carburetor, open the Idle Mixture Screws on all four carburetors a half turn and wait for the idle to stabilize.

Make sure the Idle is still 800 RPM and check the vacuum on the #3 carburetor.

If #3 is still not pulling 18 to 22 inHg of vacuum, open all four mixture screws another half turn and make sure the Idle is still 800 RPM..

Keep doing this until the #3 carburetor is pulling 18 to 22 inHG of vacuum, then go through the other three carburetors until all four are pulling the same vacuum. Hopefully they'll all be more on the 22 inHg side of 20 than the 18 inHg side.

When you have all four carburetors synchronized and pulling 18 to 22 inHg of vacuum you have to close the Idle Mixture Screws to lean out the idle fuel supply.

Again, starting with #3 carburetor, slowly close the mixture screws 1/8 turn at a time and wait for the idle speed to stabilize. You looking for the idle speed to drop and stay down about 50 RPM, then you open up the mixture screw 1/8 to 1/4 of a turn. I know, it's difficult to hear 50 RPM, that's why you need the tachometer.

When you have all four carburetors set, use the Master Idle Screw to turn the idle speed back up to 1,100 RPM and check the vacuum again.

All four carburetors should be pulling very close to 18 to 22 inHg but if you do have to resynchronize them, leave the Idle Mixture Screws alone and only adjust the throttle plate set screws.

If the climbing idle speed problem was caused by carburetor synch/idle mixture problems and it holds steady now at 1,100 RPM -- that's it! You're done!

If that doesn't fix it, it's probably not the carburetors.

.

[Faltang1090]

This is great everyone!! I didn't have much time to mess around with the bike lately but it running a smoother now. I will have time this weekend to really tinker with it! By the way anybody know where I can find cheap vacuum gauges that don't start at $50 each? Ideally local to Canadian stores, looking to build a proper gauge set up so I can do this again but all four at one time. Is that a better option? Just wondering if I can save some hassle next time I yank everything apart?

[DiverRay]

a quick search on ebay and a few come up! Here is the set I use:http://www.ebay.com/itm/Pro-Vacuum-C...797475&vxp=mtr
There are sets for about $70us, and I think you can find some that are in Canada so they will be a good price without the VAT problems....

[Rasputin]

Or ride it or truck it down to Lacombe next sunday and I can set them up for you.

[Faltang1090]

That works as well Rasputin! If I wasn't so constrained for time already, wife is mad at me already with how much time I have spent playing on the parked bike. :/ Although now I am having a low end bogging when I first start out and when it's warm as well. I have the carbs off now. Any ideas? I also still have an hanging idle issues I can bring the idle down with down shifting and braking under 2k rpm...? Is this a tuning issue? Also found out my carb #4 was not filling so I have adjusted the floats again hopefully for last time. It was the float needle not having enough room to drop.

[Faltang1090]

The main jets are the same ones that were in the carbs. They have "130" stamped on them don't know if that's the measurement or part number?