MERLIN CARBS AGAIN!! - Idle Adjustment Screw
Managed to get two hours down the workshop yesterday.
One job that has been on the back burner is the problem with the Idle Adjustment Screw. The screw is only threaeed half way along its shank and It is a fine thread guage. I was unable to screw it in sufficiently for it to open the butterflies slightly to get the bike to fire up and idle. I tried to find a longer screw locally and on the web to no avail; what to do.
The screw end pushes against a button insert in the fixed bracket on the carb body. The button is an interferance fit that is peened over on the back side. I decided to remove the 'peen' and drift the button out from the rear.
I just about had enough butterfly movement now but the button was only just holding in the hole. I could have used some fixing product to secure it, or solder it, but went a different route. I removed the button pin entirely.
I then drilled the hole the pin went into and run an M3 tap down the hole.
An M3 Allen Head Screw was inserted from the rear and secured with some mild loctite and bolts.
All the above is reversible if required.
Job worked a treat and I now have ample adjustment of the Idle Screw.
It cannot be seen when the carbs are on the bike so Happy Days!
Now need to fluid test the carb assembly for leaks before re-installing on the bike.
Managed to get two hours down the workshop yesterday.
One job that has been on the back burner is the problem with the Idle Adjustment Screw. The screw is only threaeed half way along its shank and It is a fine thread guage. I was unable to screw it in sufficiently for it to open the butterflies slightly to get the bike to fire up and idle. I tried to find a longer screw locally and on the web to no avail; what to do.
The screw end pushes against a button insert in the fixed bracket on the carb body. The button is an interferance fit that is peened over on the back side. I decided to remove the 'peen' and drift the button out from the rear.
I just about had enough butterfly movement now but the button was only just holding in the hole. I could have used some fixing product to secure it, or solder it, but went a different route. I removed the button pin entirely.
I then drilled the hole the pin went into and run an M3 tap down the hole.
An M3 Allen Head Screw was inserted from the rear and secured with some mild loctite and bolts.
All the above is reversible if required.
Job worked a treat and I now have ample adjustment of the Idle Screw.
It cannot be seen when the carbs are on the bike so Happy Days!
Now need to fluid test the carb assembly for leaks before re-installing on the bike.
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