Observations on my carb main needles

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lonestarmedic

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I am still fighting an overall low vacuum problem on my 1986 Venture. However I have it running what seems to be good. Synced the carbs using a few pieces of 24 gauge wire in the throttle plates. Then of course curiosity reared its head. Could my main needles be affecting the idle circuits? Popped out the diaphragms and checked my washers as the were stacked on the needles. Stock fat plastic at the bottom and a stock metal above the clip. So I pulled the stock plastic off and found some thinner ones. About half as thick. Re-assembled and fired the bike over. On choke I had to use a lot more. Warmed up i had to raise the idle screw about 3 full turns. Try to rev the motor and it just flat stalled out. Could not even feather it to get to mid range. Put the stack on the needles back to original. Now idling at 3000 rpm when warmed up. Adjusted back to 1000 and plenty of throttle again. Question answered on the lean side. So, off to scrounge washers to shim needle out a bit further. Grabbed 4 spare metal washers that usually go on top of clip next to spring. Installed under the clip on top of stock plastic washer. Fire over bike and idle is up a couple hundred rpm. Pulls strong and no hesitation. Backed off the curb idle to 1000rpm again.

So now brain is smoking as I think. If throttle plates are too far open at idle the vacuum should be low. If I shim out needles a bit more will i end up closing throttle plates a bit more? And is this my vacuum problem I have had all along? Needles are original and do not have any wear ridges. I have a set of new ones from Kester carb kits but did not use them. Their taper profile looked a bit less gradual than the original ones. Center emulsion tubes are new and yes, from the Keyster kits. Installed with new gaskets and o-rings.

At this point I should send the rack to Dannymax and be done with it! But I am old and hardheaded. Rack is working correctly. I just want to understand what I am seeing at this point.

And like others, I am saving up for a Digisync. I polished my Morgan carbtune rods and the bushings with 4/0 steel wool. If I turn them upside down and rap it with a screwdriver a couple times the rods are fairly level. So I can take them into account when checking the sync. My wire trick brought the carbs so close I am not moving them using the Morgan.

Thanks all for reading this and any input you might have.

JB

Sent from my SAMSUNG-SM-T217A using Tapatalk
 
lonestarmedic said:
I am still fighting an overall low vacuum problem on my 1986 Venture. However I have it running what seems to be good. Synced the carbs using a few pieces of 24 gauge wire in the throttle plates. Then of course curiosity reared its head. Could my main needles be affecting the idle circuits? Popped out the diaphragms and checked my washers as the were stacked on the needles. Stock fat plastic at the bottom and a stock metal above the clip. So I pulled the stock plastic off and found some thinner ones. About half as thick. Re-assembled and fired the bike over. On choke I had to use a lot more. Warmed up i had to raise the idle screw about 3 full turns. Try to rev the motor and it just flat stalled out. Could not even feather it to get to mid range. Put the stack on the needles back to original. Now idling at 3000 rpm when warmed up. Adjusted back to 1000 and plenty of throttle again. Question answered on the lean side. So, off to scrounge washers to shim needle out a bit further. Grabbed 4 spare metal washers that usually go on top of clip next to spring. Installed under the clip on top of stock plastic washer. Fire over bike and idle is up a couple hundred rpm. Pulls strong and no hesitation. Backed off the curb idle to 1000rpm again.

So now brain is smoking as I think. If throttle plates are too far open at idle the vacuum should be low. If I shim out needles a bit more will i end up closing throttle plates a bit more? And is this my vacuum problem I have had all along? Needles are original and do not have any wear ridges. I have a set of new ones from Kester carb kits but did not use them. Their taper profile looked a bit less gradual than the original ones. Center emulsion tubes are new and yes, from the Keyster kits. Installed with new gaskets and o-rings.

At this point I should send the rack to Dannymax and be done with it! But I am old and hardheaded. Rack is working correctly. I just want to understand what I am seeing at this point.

And like others, I am saving up for a Digisync. I polished my Morgan carbtune rods and the bushings with 4/0 steel wool. If I turn them upside down and rap it with a screwdriver a couple times the rods are fairly level. So I can take them into account when checking the sync. My wire trick brought the carbs so close I am not moving them using the Morgan.

Thanks all for reading this and any input you might have.

JB

Sent from my SAMSUNG-SM-T217A using Tapatalk
Click to expand...

Lonestar, personally i would try the kester needles. I'm certainly would not try to take any business away from dannymax but he uses a carbtune also. Your carbs would be synced to his motor and would have to be resynced to your motor when you get them back. I assume you are storing the washers on top of the needles as they do not make a difference up there.
Your needles have nothing to do with idling unless you have stage 1 or stage 7 and are using mikuni jets instead of the jets in the kit- they seat differently. The chart below will show you what works where- i hope it helps.
http://www.sudco.com/Carburetor02.html
 
Thanks Dragmaxter- Yes I have the spare washers above the e-clip. I truly believe my carbtune is the major culprit for my low vacuum readings. I played with my Mityvac and I can drop the throttle plate down with a sync screw and run the vacuum all over. But it is one gauge.

On the needles I only know what I observed. Drop the needles deep and I had to run the idle screw up. Space the needles out and drop the idle screw back down. Needles deep in and give any throttle past idle and bike stalls. No rpm increase at all. Needles spaced out and throttle is smooth. Right now I have the stock plastic washer with the little tit and one washer below the e-clip. Throttle response is good and no flat spots. This would be a bit richer than stock. Now, I intend to repeat the experiment with the Keyster needles. See what happens.

Oh, momma and I went to Houston and back. That loaded the bike with about 475 lbs including packed saddlebags and trunk. We were hitting 35 mpg at 65 mph. Of course winding it up dropped drastically. We are both 5' 10" tall and both right at 200 lbs.

At this point I am experimenting more than anything. Need to wait another paycheck then order the Digisync.

As always, thanks for taking the time to ponder the situation.

JB
 
lonestarmedic said:
Thanks Dragmaxter- Yes I have the spare washers above the e-clip. I truly believe my carbtune is the major culprit for my low vacuum readings. I played with my Mityvac and I can drop the throttle plate down with a sync screw and run the vacuum all over. But it is one gauge.

On the needles I only know what I observed. Drop the needles deep and I had to run the idle screw up. Space the needles out and drop the idle screw back down. Needles deep in and give any throttle past idle and bike stalls. No rpm increase at all. Needles spaced out and throttle is smooth. Right now I have the stock plastic washer with the little tit and one washer below the e-clip. Throttle response is good and no flat spots. This would be a bit richer than stock. Now, I intend to repeat the experiment with the Keyster needles. See what happens.

Oh, momma and I went to Houston and back. That loaded the bike with about 475 lbs including packed saddlebags and trunk. We were hitting 35 mpg at 65 mph. Of course winding it up dropped drastically. We are both 5' 10" tall and both right at 200 lbs.

At this point I am experimenting more than anything. Need to wait another paycheck then order the Digisync.

As always, thanks for taking the time to ponder the situation.

JB
Click to expand...

Are your carbs syncing and ALL level?
I synced a fellow vmaxers the other day and his #3 carb showed nothing on my morgan carbtune. I turned the sync screw about 6 turns and it came up and met #4 carb. Then i turned the next screw to the left and synced #3&4 to #1&2 perfectly. Responce was amazing and it ran great.
Again i am not trying to put Digisync out of business but i am just saying that over 35 years of carb work i have had many carb syncing tools and the morgan is the best i have had so far.
 
Flip the carbtune upside down and they are all within a few lines. Right side up and all at the bottom and not moving.

I know what you mean about the Carbtune. I always trusted it. Have done 8-10 bikes in a couple hours at a maintenance gathering. I thinkna buddy on the other side of San Antonio has one. Going to get his and see what we get.

Would almost like to find out I have something wrong just to get an explanation for the readings. In mid 2013 it was good. In 2014 I had surgery in August. Bike sat from then until November. Carbs gunked up and the problems started. Tried the peashooter and shotgun a few times. Ran like crap but a bit better. Ordered the carb parts. About $400.00 worth. Got it apart and needed the cut off diaphragms. Ordered those and assembled. Ran decent but needed sync. Also found bowl drain dribbling. Ordered 4 new ones and o-rings. So now it seems synced decent. All are almost even when Carbtune is upside down. Gas does not dribble anyplace.

By the way, six full turns is a whole lot! Never seen one get that far out unless it was worked on..

Thanks for the thoughts.
JB

Sent from my SAMSUNG-SM-T217A using Tapatalk
 
lonestarmedic said:
Flip the carbtune upside down and they are all within a few lines. Right side up and all at the bottom and not moving.

I know what you mean about the Carbtune. I always trusted it. Have done 8-10 bikes in a couple hours at a maintenance gathering. I thinkna buddy on the other side of San Antonio has one. Going to get his and see what we get.

Would almost like to find out I have something wrong just to get an explanation for the readings. In mid 2013 it was good. In 2014 I had surgery in August. Bike sat from then until November. Carbs gunked up and the problems started. Tried the peashooter and shotgun a few times. Ran like crap but a bit better. Ordered the carb parts. About $400.00 worth. Got it apart and needed the cut off diaphragms. Ordered those and assembled. Ran decent but needed sync. Also found bowl drain dribbling. Ordered 4 new ones and o-rings. So now it seems synced decent. All are almost even when Carbtune is upside down. Gas does not dribble anyplace.

By the way, six full turns is a whole lot! Never seen one get that far out unless it was worked on..

Thanks for the thoughts.
JB

Sent from my SAMSUNG-SM-T217A using Tapatalk
Click to expand...

When you cleaned the carbs did you get the 2 jets inside the jetblock under the rubber plugs- the smallest one is the one that will clog if the bike sits for any amount of time. Shotgun and peashooter will not get a stubborn one clear.
 
Last edited:
And like i said before when i synced a friend vmax last week with my carbtune i was suprised to see the #3 carb with no vacuum and the #4 carb almost to the top.I turn the right sync screw about 5 turns and they matched up in the middle. Then i turned the left and all 4 lined right up. He and i heard the difference immediately.
 
Dragmaxster said:
And like i said before when i synced a friend vmax last week with my carbtune i was suprised to see the #3 carb with no vacuum and the #4 carb almost to the top.I turn the right sync screw about 5 turns and they matched up in the middle. Then i turned the left and all 4 lined right up. He and i heard the difference immediately.
Click to expand...

This can happen if the bike gets knocked over or takes a side impact, the sync tabs are quite soft and get knocked out of position easily....possibly exaggerated by the springs....:confused2: but had to straighten quite a few to get the travel needed for a good sync.

Pretty unlikely this is Lonestar's problem tho.
 
dannymax said:
This can happen if the bike gets knocked over or takes a side impact, the sync tabs are quite soft and get knocked out of position easily....possibly exaggerated by the springs....:confused2: but had to straighten quite a few to get the travel needed for a good sync.

Pretty unlikely this is Lonestar's problem tho.
Click to expand...

+1
I am saying because once i got a spring hooked on a tab and could not get it to turn far enough.
 
Ok all back to stock on the carburetors. Warmed up and then revved it. Had to adjust idle mixture screws a bit. Now I think I may have found my main headache!! The idle has been a bit variable while working on all this mess. But I just adjusted it. Now as I was listening to it run very pretty at 1100 rpm while standing 3 feet away the idle shot up to almost 3000 rpm. Grabbed throttle and it was at idle. Pushed on linkage and it was at idle. Shut bike off for safety. Scratch head and think. Restarted and at curb idle then it began to climb. Do not know why but I thought ignition box. Yanked the vacuum advance off and it dropped to idle!! Plugged off the advance and idle solid as a rock. So either the little box is getting hot and going nuts or it is my ignition. Had an old vacuum advance so I put it on and same results. But both advance units are from 1986. Need to test on a bench. Cannot imagine that much advance from vaccum. Can an ignition box cause this?
 
Vacuum units are right on the money. Tried spar TCI and it is bad. Dropping the tach and sputtering. Got an ignitech on the way.
 
On its way. Will be in my hands tomorrow. A buddy in Ft. Worth had a brand new one and no bike he wanted to put it on. So got unit, map sensor, wiring, CDs, and a programming cable for less than brand new.

Now to read the Ignitech threads and look for the best program for my application.
 
So I got an Ignitech unit. Plugged it in and it fired off pretty good. Adjusted the idle a bit and waited for a good warm-up. Got hot and started going from 1000 RPM down to 600 RPM. Found a cylinder not firing right. Pulled wire off of right front and no RPM difference. It did throw spark to a plug when grounded to engine. But looked a bit weak. Kind of a purple cast to it. Figured a weak coil or a bad connector. Made up my mind to pull and check everything. And I have a COP setup on its way. Plugs and COPS from a Honda CBR1000.

Pickup coils Ohm out at 120 across the board. No continuity to ground.
Ignition coils all at 3.9 Ohms and 13.5K-13.7K. That is cold on the bench.
No cracks etc. in the coils.
Plug wire from cylinder that is dead sits at 4.9K Ohms.
Did not check the other 4.
Shaking head I decide to see where and how to mount Ignitech unit. Pick it up and a wire that goes to the 6 pin pickup plug falls out of the back!! Bad crimp on double wire connection jumper. So at this point I have no idea if the system was firing right or not. Was the wire making contact or not?

Too many variables right now. So I pulled the connector apart, checked and soldered all the wires. Decided where to mount the Ignitech unit and got it finished.
Now I am putting the fairing back together that had to be split in order to pull the coils out. And thinking that they were perfectly good and a wire crimp caused 6 hours of labor. But, I did get the coils out of the bike, convert the coil rack into a dandy Ignitech mount, clean every possible connector in the ignition system. And verify I have a good set of coils :) :)

Working on the Coil On Plug conversion right now. Going to get it done to eliminate any and all ignition problems. Then see where I am at.
You Vmax guys may pull carbs and tune more often than us Venture guys. But be glad you do not have to tear off tupperware like ours to do it.

Lonestarmedic
J.B.
 
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