Carb servicing time! - Success!!!!!!!

[koko64]

Size 70 is usually for the starter/enrichener jet (big flat head one holding the main jet retainer plate/clip. The Pilot jet should be around size 40 for a stocker (some models have a 42.5 and there are 37.5 available). If it's stinky rich you can check your float levels or check that your enrichener/choke cable isn't too tight.

If it's still too rich after those things checking out you may have to reconsider the needle height if it's adjustable and your idle mixture screw adjustment. Needle adjustment notches are counted from the top notch (leanest).

Check that there is no fuel overflow from the carbs overflow hoses. You will see fuel dripping out of the hoses with the bike idling. If there is, you will have to clean out the float bowls and float needles/seats. Some people tap the float bowls with the back of a screwdriver to seat them like smacking an annoying toilet sistern. Some remove the drain plugs and let fuel flow into a recepticle held under the carbs to flush fresh fuel over the faces of the float needles to clean them. These are the dodgy and bodgy ways to clean your carb float needles without pulling them apart. It has worked for me, just do it with a cold engine in case you spill fuel.

This is assuming it's running rich. Black plugs will confirm this.

[the_Journeyman]

Well, here's the breakdown of what I found.

I have 1 black (rear) plug and one whitish plug (front) and once she gets good and warm, everything but the 1/8th or so throttle opening stutter goes away.  I'm going to try to lean up the fuel screw on the rear a half-turn and see what happens.

JM

[the_Journeyman]

Well, I've smoothed things out for steady-throttle with the fuel screw adjustment.  Got the idle about right, it's just a "it sounds good" verification since I have no tach.

Lets review:  OEM jets, 14mm (best I can tell, not good at measuring it) float level, fresh emulsification tubes.  Sync?  Haven't done it, don't have the stuff to do it. 

Starting:  Choke, thumb starter, maybe a slight twist on the throttle and she roars right to life.  Once idle starts to drop, push choke back about half-way, after another minute or so, cut off choke entirely.  Idle is a little lumpy, but smoothes out as engine warms up.

Taking off from a stop = stumble, chug, bog etc, but then throttles on up if I hold the throttle open.

Mid throttle - Fine & snappy, plenty of go.

Full throttle - Still ok, but a tad off, not sure if lean or rich yet, but the neighbors are all coming out the see what the hell I am doing.  Maybe a hair lean since it surges slightly as I ease off throttle

Engine braking is normal at higher RPMs, but seems very light at lower RPMs.

I STILL have the bogging/chugging/hesitation when first opening the throttle.  It is MORE evident if I am loading the engine (releasing the clutch to take off) than if it is just sitting idling and a twist the throttle.

What would shimming my needles with a thin washer achieve?  If I am lean causing the off-idle bogging, I seem to think it would help.  If I'm slightly lean higher up, the needle would be slightly richer throughout it's travel, and might fix that full throttle surge on throttle close, I think.

More experienced folks, what do you think?

[ducpainter]

I think you need to synch the carbs before you try to make small fueling adjustments to correct a problem that might not really exist.

[the_Journeyman]

I don't have any type of vacuum gauge.  Is there any other way for checking the sync?  

Plug ends are grayish-white if that is worth noting.

JM

[ducpainter]

I don't have any type of vacuum gauge.  Is there any other way for checking the sync?  

Plug ends are grayish-white if that is worth noting.

JM

You can make a tool for like $10. You will need a way to connect to the manifolds via the 5mm plugs.

Google 'homemade carb synch tool'

[the_Journeyman]

I'll check that out and see.  I also had a local wrench guy tell me about a mechanical sync method that used feeler gauges & the butterfly valves.  He had done it several times & checked it with a vacuum gauges and it had balanced them properly. 

Basically you run the idle speed all the way down, put the feeler gauge in the master carb, compare with the secondary, adjust until they match.  It's purely mechanical, and it seems there are lots of other variables that could affect it, but at the same time, it might work.

JM

[ducpainter]

I'll check that out and see.  I also had a local wrench guy tell me about a mechanical sync method that used feeler gauges & the butterfly valves.  He had done it several times & checked it with a vacuum gauges and it had balanced them properly. 

Basically you run the idle speed all the way down, put the feeler gauge in the master carb, compare with the secondary, adjust until they match.  It's purely mechanical, and it seems there are lots of other variables that could affect it, but at the same time, it might work.

JM

That was the way we did it back in the day with multiple cyls and separate cables for each carb. Those were slide operated carbs though

It's better than nothing, but may not solve your problem because of the vacuum pistons in the carbs.

Small differences in cylinder condition will affect vacuum and overall mixture.

[the_Journeyman]

I'll try it and report back.  If it doesn't improve things, I'll make a vacuum gauge.  He did mention that if there were major difference in leakdown it wouldn't work as well. 

Speaking of the 5mm nipples.  It seems mine are simply connected to each other by two hoses that are clamped together in the middle.  Is that normal?  Seems a cap on either side would be just as good and less prone for leaks.

JM

[ducpainter]

I'll try it and report back.  If it doesn't improve things, I'll make a vacuum gauge.  He did mention that if there were major difference in leakdown it wouldn't work as well. 

Speaking of the 5mm nipples.  It seems mine are simply connected to each other by two hoses that are clamped together in the middle.  Is that normal?  Seems a cap on either side would be just as good and less prone for leaks.

JM

That's how whoever did the canister removal did it.

You can use the two hoses for fogging if you store the bike, or you can use caps. Either way works.

[the_Journeyman]

Good to know about the hoses.

The feeler gauge method doesn't seem to work with the carbs on the Monster.  I can't get a feeler gauge between the carb bore & the butterfly valve.  Off to look up vacuum gauges ~

JM

[Ahks]

I used this tutorial to make my sync tool...


I ended up using these for the bottles as I needed a pick-me-up that day :p
http://www.starbucks.com/menu/drinks/bottled-drinks/bottled-frappuccino-vanilla?foodZone=9999

I've used my 2bottle kit to sync my 4 cylinder yamaha. It really is very easy and cheap to make and very reliable as long as you dont destroy your rubber stoppers like I did the first time. Putting the hole int he rubber is easier if they are cold. But not frozen. Frozen can make them crack (ask me how I know).

Also, I didn't use water. I used mixed 2stroke fuel. I've heard people use heavier liquids like ATF or the like as well.

[the_Journeyman]

So, after looking around at my local stores, I could find everything but stoppers.  So, I found a vacuum gauge for $20 at my local auto parts.  

My findings:

Both carbs at idle pull 7lbs of vacuum.

Next issue.  As soon as I open the throttle - Vacuum is GONE.  Same on both carbs.  Am I doing something wrong?  Or is it supposed to loose all vacuum when you open the throttle.

I notice once I coax it into revving up, vacuum comes back but only in a small amount until I close or even back off the throttle it runs up to between 10 & 15 pounds of vacuum and drops as the RPMs drop back to idle.

I just opened the carbs back up, and my pilot jets are clear too.  I'm completely stuck at this point.  It ran fine before I put new emulsification tubes in.

JM

[the_Journeyman]

Success!!!  Finally. 

One carb was rich on idle mixture.

It seems there was a bit of a learning curve to using the vacuum tool.  I found a slight difference and adjusted it out.


Thanks everybody for all of the help!!!

JM

[ducpainter]

Success!!!  Finally. 

One carb was rich on idle mixture.

It seems there was a bit of a learning curve to using the vacuum tool.  I found a slight difference and adjusted it out.


Thanks everybody for all of the help!!!

JM

Imagine...

learning.