Help.. Carb Snyc (Morgan Carb Tune)

[deshkae]

I was syncing my carbs last night with my Morgan Carb Tune. This time I had a service manual and I wanted to do it right per manual. Here is what the manual says.

Adjust:Engine idling speed
Engine idle speed:
1,350 ± 100 r/min
(1,250 - 1,450 r/min)

Synchronize carburetor #4 to carburetor #3 by
turning the synchronizing screw 2 in either
direction until both gauges read the same.

Synchronize carburetor #2 to carburetor #1 by
turning the synchronizing screw 3 in either
direction until both gauges read the same.

Vacuum pressure at engine
idling speed
35 kPa (0.35 kg/cm2, 4.98 psi)
The difference in vacuum pressure between
two carburetors should not exceed 1.33 kPa
(0.01 kg/cm2, 0.19 psi).

Looking at the engine by standing in front of the machine. Carb 1 is the clutch side and carb 4 is the chaincase side. I have the line restrictors installed in the carb tune hoses.


Here is what I am seeing. Carb 1 and 4 sync together and Carb 2 and 3 snyc together.

I cannot seem to get all 4 carbs to draw the same amount of vacume on the Morgan Carb Tune. If I do it runs like #*$&@. However I can get Carb 2 and 3 draw the same vacume, Carbs 1 and 4 draw the same vacume.

On the Morgan Carb Tune, what is the reading suppose to be for each of the carbs?

Anyone else useing the morgan carb tune have any ideas whats going on or is this normal. [/img]

 

[SIMMER]

Deshake, sorry to be negative and I know this may not answer your question "specifically" but take it from me...DO NOT turn those screws too much at once or you will lose your reference point and it will be hard to find your way back. :?

Don't worry about the numerical value. I just used mine as a checking tool to relaize that my dealer did'nt know what he F&^K he was doing...I smartened up and took it to a R1 engine guru and when he was finished they were DEAD on. He did tell me that the reading as stated by the manual are impossible to get....just focus on getting all the reading to line up evenly and as close as possible and you will be fine.

 

[deshkae]

RX Wonder

When you say all the reading to line up do you mean that the rods in the Carb Tune should be straight across on all 4 carbs.

 

[kmer]

After reading both the service manual and the carbtune instructions.... it appears that the carbtune instructions were more helpful. :? This is only my interpretation based on screw adjustment (vs. carb no.). No guarantees expressed or implied. :lol:

There are three adjustment screws - one carb has no adjustment screw (it's #3 i think). Anyhoo.... how i remember it and what works for me is the following sequence....

Basically there are 3 overall steps.... I think it doesnt matter where you start in the sequence, just as long as you repeat the sequence over and over until adjustments become finer and finer. Mine took 3 repeats to reach a balance.

1) Start with the left side screw..... bring 1 and 2 together.... blip throttle
2) then right side screw.... bring 3 and 4 together.... blip throttle
3) then middle screw... bring all together.... blip throttle

Repeat....(left, right, middle, left, right, middle, etc...)

Adjust idle as necessary.

If things get away on you and you lose track... you can reset the screws... pull the airbox and closely examine the adjustments on the screws... back the center screw off until there is only a slight pull on the throttle cable... then center the left and right screws between their adjustment limits. Reinstall the airbox and try again. :wink:

Mine was out quite a bit to start with so it was difficult to get a sense of baseline until i reset the screws and started from scratch. :wink:

 

[Buckeye]

Carb sync

The idea is to get the other 3 carbs to match the one fixed carb in vacuum. As long as they are all the same you will be fine. By adjusting the screws you are opening or closing the butterfly valve and increasing or decreasing airflow and vacuum through the throttle body. They need to be equal. That guage is one way of measuring it.

 

[Toolman]

Synching these carbs is not super critical. Mine were way off from the factory and definitely needed it but, don't get too overly critical because the slide actually limits the airflow once you are into the throttle. So as long as you are close on the bottom and get WOT then let it buck!!

 

[ski-bum]

I always start in the middle and sync 2&3, 3 is your baseline because it does not change.

Then sync 1 to 2, and 4 to 3. If you do the middle last, you will have to make more iterations to get it.

screws are very sensitive, all you have to do is breath on the screw driver to get a change.