colortune #3 carb issues

For some odd reason i cant color tune #3 carb. When i try all i see is the spark but no combustion colors and is making me think it isnt firing. When i put my thumb on the vacum plug/line i sometimes get something but typically nothing. Is this a common problem tuning #3 or do i need to pull the carbs again.

Also i did a bench sync and i when i hook up the motion pro syncpro it just sucks everything out when i try to calibrate it. Not sure what is going on. I know i am using the sync properly go figure... maybe i need to reduce the jet from 130 to 125.

 

No it isn't a common problem. It may not be getting enough fuel or has a big air leak. I had the same issue on # 1, and found that if I opened the "choke" I got a flame. Then I found that if I opened the pilot screw to about 5 1/2 I got a flame. It turned out that I had a badly torn intake gasket and once that was replaced everything worked well.

Is the sync problem also on # 3?

 

Yea, when i connnect the tool to 3 to calibrate it, the vacume is too intense and sucks out all the fluid

 

Yea, when i connnect the tool to 3 to calibrate it, the vacume is too intense and sucks out all the fluid.

I like to color tune first and then do a carb sync and then colortune it again for accuracy I know it's not the norm but its just something that I like to do. I also do a bench sync first

 

No fuel thru that carb pilot circuit, try adding the choke just a tiny bit and see if you see flame, if so, that shows that it's a clog or some other issue with that pilot circuit.

Which jet are you referring to?

 

sounds to me like your bench sync is off. I've never used the motion pro syncpro (I use the two bottle system), but it really doesn't take much out of balance to make one cylinder to suck up the fluid--at least in the two bottle method.

 

I installed a 6 sigma jet kit and the main jet was changed to 130 vs 112.


I am making a 4 bottle sync as we speak hopefully i can get her running right.


I am going to pull the rack and check the pilot circuit like len advised and then try syncing again.

 

The size of the main jets doesn't matter a lot if not at all when syncing the carbs. We are more talking about idle circuit and pilot jets.

 

+1 What they ^ said. Problem with fuel delivery in the hole and or air leak. A good bench synch should put the carbs within 1" of each other which should allow it to fire so the running synch can be done. Many of the old heads don't use gauges after the bench synch. They set the mix by reading the plugs. As Polock stated..."the plugs don't lie".

Gary H.

 

<rant>
well, i am frustrated to hell with this bike!

Pulled the carbs went through #3 with a fine tooth comb cleaned out every nook and cranny and blew air and carb cleaner to make sure there was movement and everything seems good. Redid the bench sync and re attached the carb started it an boy did she purr. I got excited and hooked up the diy bottle sync and the plastic water bottles i used just collapsed in on itself from the suction. After laffing and just kicking a rock i decided to retry the Motion pro carb sync.

Boy does this tool suck donkey pole. I used it 4 times before and it worked fairly well. Despite it needed new o-rings and fluid after the second time i used it. The 3rd & 4th time it worked like a dream. This time not so much. Fluid got sucked into the motor, then I filled it up with power steering fluid and the same thing happened. Not to mention... While i was trying to calibrate the tool while connected to #3. I ended up taking a step backwards to avoid the exhaust and i trip and fall over a wooden stump. Yes a wooden stump used for front yard decoration. (dont ask). My hands plus the crapy sync tool goes flying into the air and the world went into slow motion. Afterwards i couldn't stop laffing.

After hating this bike I decided to go out and retry the "diy" bottle carb sync with sauce mason jars with a closed loop so the oil doesnt get sucked into the motor. While i can see the merit in doing a diy. I was not happy watching power steering fluid fill up one bottle in the middle of a sync and get sucks into the motor. Hopefully nothing bad happen to it.

Then i had a OMG let me reset the mixture screws to 2.5 turns and try again, walking over to the bike to turn it on and try i find my battery is dead! So now i am done till after the holidays.
</rant>

I did the choke test and flame did appear but it also appear when i would put my finger over the vacuum port. When i inspected the manifold boots they look brand new. but i know there still could be a leak at the nozzle that i cant see. I'll try replacing the gasket and i plan on buying a carbtune pro 4 F this liquid crap.

 

what vacuum port are you putting your finger over to get the flame?

 

I laughed when you said you collapsed your plastic bottle--cause the same thing happened to me. I initially made the 2 bottle set-up using plastic baby bottles and it collapsed them almost immediately. So, since I already had the tubing and rubber plugs I bought glass baby bottles and it works perfectly. I don't think changing the type of manometer you use is going to help much. You're going to have to address the excessive vacuum before anything will work. I'm not a valve expert by any measure, but if you had a very tight intake valve, which opens early and shuts late that might account for the excess vacuum. But the fact that you can get a flame by adding choke and/or blocking the vacuum port still points to an air leak or a pilot circuit issue, and since you have re-cleaned the carbs I would suspect an air leak. Try opening the pilot screw while it is running and see how far you have to go to get a flame. I got to 5 or 5 1/2 before I replaced the intake gasket. In short, I think you have two problems: an excessive vacuum issue and a fuel issue.

 

Sybe, do I understand that you're trying to sync your carbs without checking if your valves are in spec first? If i'm right, it is totally useless.

 

Values are in spec. Did that back in march and the bike was synced and all was well.

When i cover the vacuum port on the manifold boot #3 combustion shows. Prior i left the hose that ran to the petcock on it and just placed a screw on the hose to create vacuum. This time i took the hose off and just covered it with my finger, So I am thinking it might be the hose that is connected to it or possible the boot.

All the values are in spec i did them back in March and I was able to tune and sync the carbs with no issue. I am thinking it might be a vacuum leak at boot or gasket like you said.

So to break things down this is what is happening and why i think its either the hose or the boot.
When I did the color tune i got combustion when i pulled the choke because gas was free flowing. No Vacuum needed. When i shut off the choke it stopped showing there was no suction. When I put a screw in the #3 petcock hose i got combustion but not constant. Showing signs of suction but weak.

When i got it to a point where i was some what happy with it, i decided to balance the carbs and go back to the tune. When i plugged the Motion pro carb sync onto #3 to calibrate it the sucking/idle was to high and it sucked all the fluid out. Prior to this the idle wasn't high at all.

So my hypothesis is that the vacuum issue might have been a bad hose not getting a good seal on #3 or the boot. Now i could be completely wrong and I measured the wrong shim thickness, or a piece of clear silicone lodged itself in the carb body (OP sealed the bowls with clear silicone and on the gaskets) or even that small gnomes are messing with me and is sabotaging my bike.

what do you guys think?

 

did you put the fuel tank on prime when you removed the vac hose?
get an extra port cap from the auto parts store and clamp it on number three when color tuning. or switch the hose to port 2 and use that cap on 3 with clamp.
as far as the boot having a leak spray carb cleaner or use propane on to the boot bike will increase in rpm if there is a leak.

 

Gas tank is not on the bike. I run gas directly into the carb via a hose and a thermos with a shutoff valve.

 

It seems like the carbtune isn't working right. When you calibrate it all four lines should be connected to one port. How could it suck out the fluid if it's all sealed.
But if it isn't sealed it would be a vacuum leak and the idle would go up.
Set it up to calibrate and suck on the hose, if you can keep sucking air through it, somethings wrong.

 

Do you have restrictors like welding tips in the lines to slow the pull?

Gary H.

 

don't need restrictors on bottles

 

I haven't tried the carbtune yet just the motion pro and diy bottles. The motion pro isnt a closed system at all. I think the o-ring seals that hold the plastic tubes went bad again. and now i need new liquid. All in all it was a waste of money. http://www.motionpro.com/motorcycle/partno/08-0411/


I orderd a morgan carbtune and it is on its way!