CNCMACHINIST
New Member
i have to hold the choke lever down, dont see any missing parts, any ideas?
Choke lever wont stay down
- Thread starter CNCMACHINIST
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A bit of a turn on the pivot screw.
I would also check your carburetor enrichener pistons, to ensure none are frozen in-place, and that when the lever is moved, the forked followers on each carburetor enrichener piston move a similar amount. That being out of adjustment could also cause issues with the lever function.
The upper-right enrichment piston is probably frozen closed; compare its brass shaft exposed to the other visible enrichener piston shafts.
I normally try to avoid splitting the carburetors completely-apart, but in the case of working on the 'inside' carburetor enrichment pistons (the ones in the middle of the rack of carbs) you need to separate them into four individual bodies. If you find this necessary, take plenty of pics, and be sure you do it from both sides, especially at the carburetor synch screws area, and label and bag things as they come-apart. The castings which contain the brass enrichment pistons are no-longer available! (new stock on the fiche pages at Ron Ayres Yamaha) Carefully-remove the potmetal castings from the side of the carb body, and soak the brass piston/potmetal casting holding it, in something like 50/50 ATF/acetone, in a sealed container, because the acetone will quickly evaporate from an exposed receptacle. Before using this ensure that acetone doesn't dissolve the receptacle you use. A glass babyfood jar would be ideal, big-enough to hold the piece, but small-enough to minimize the volume of mix used, and tightly-sealing to avoid evaporation.
I would also check your carburetor enrichener pistons, to ensure none are frozen in-place, and that when the lever is moved, the forked followers on each carburetor enrichener piston move a similar amount. That being out of adjustment could also cause issues with the lever function.
The upper-right enrichment piston is probably frozen closed; compare its brass shaft exposed to the other visible enrichener piston shafts.
I normally try to avoid splitting the carburetors completely-apart, but in the case of working on the 'inside' carburetor enrichment pistons (the ones in the middle of the rack of carbs) you need to separate them into four individual bodies. If you find this necessary, take plenty of pics, and be sure you do it from both sides, especially at the carburetor synch screws area, and label and bag things as they come-apart. The castings which contain the brass enrichment pistons are no-longer available! (new stock on the fiche pages at Ron Ayres Yamaha) Carefully-remove the potmetal castings from the side of the carb body, and soak the brass piston/potmetal casting holding it, in something like 50/50 ATF/acetone, in a sealed container, because the acetone will quickly evaporate from an exposed receptacle. Before using this ensure that acetone doesn't dissolve the receptacle you use. A glass babyfood jar would be ideal, big-enough to hold the piece, but small-enough to minimize the volume of mix used, and tightly-sealing to avoid evaporation.
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You really make this forum the success it is Fire-medic!
Something from another forum thread about the choke/enrichener: I have encountered enrichener mechanisms where the forked lifter apparently had been bent, probably from a combination of a frozen or sticky enrichener piston and too-much force upon the thumb lever activating the choke/enrichener.
This could result in bent tangs on the forked piston-lifter. Assuming that the piston has been freed to easily move up/down, it may be necessary to bend the forked lifter into a position where all pistons move the same amount.
The same goes for the shallow-V shaped rod which connects the carburetor pairs for the operation of the choke/enrichener. Ensure that when the side pair with the choke lever is moved, that the V shaped rod also moves the other pair of carburetor choke/enrichener pistons and that the pistons move an equal amount. I have seen a set of carburetors where the rod had to be bent to get the carb choke/enrichment working properly.
The set screw for each forked finger pair indexes into a shallow dimple on the rod which passes through each pair of carbs.
This could result in bent tangs on the forked piston-lifter. Assuming that the piston has been freed to easily move up/down, it may be necessary to bend the forked lifter into a position where all pistons move the same amount.
The same goes for the shallow-V shaped rod which connects the carburetor pairs for the operation of the choke/enrichener. Ensure that when the side pair with the choke lever is moved, that the V shaped rod also moves the other pair of carburetor choke/enrichener pistons and that the pistons move an equal amount. I have seen a set of carburetors where the rod had to be bent to get the carb choke/enrichment working properly.
The set screw for each forked finger pair indexes into a shallow dimple on the rod which passes through each pair of carbs.
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Sniffbooger
Well-Known Member
Yeah, I've had mine apart a bunch of times, make sure the choke pistons move freely and the forks are attached properly with no bends or binding...also, give that screw a good tightening with a screw driver right near the choke lever.... it should stay in place better so the choke won't let off until you move it open.
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