Change jets without removing carbs?

Emlupi

Emlupi

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A question for the more experienced members, is it possible to change jetting on the 350 without removing the carbs? I can imagine that it would be a PITA but is it a viable choice?
I’m just casting a thought towards carb tuning. Having to keep removing and replacing/resynching seems like a long row to hoe.

IMG_8019.jpeg
 
In theory, you should be able to pull one carb at a time with the cable still attached (you'll have to remove the choke linkage connection to the other carb) and do it that way. The cables should retain their adjustments if you're careful.
 
It is absolutely possible to change jets on these without removing the carbs. A z-shaped screwdriver, or a small socket with a screwdriver tip works (Maybe hard to find in JIS the right size, but in my experience (and I know it's blasphemy) philips will work here in a pinch especially since it doesn't require a lot of force). One thing to make it even simpler is replacing the screws with allen head. And thin and nimble fingers help. That being said, since you have pods removing the carbs isn't a big deal anyway...
 
I wonder if you could replace the bowl screws with something that you could remove by hand (fingers) — otherwise I think those screws will slow you down a lot in doing this.

The dohc CB450 carb bowls are held on with a swinging spring clamp (or whatever the proper term is) and I have taken advantage of this a lot over the years. Before I switched to non-ethanol fuel this made it very easy to clear out the slow and pilot jets after the bike had been sitting for a while.

The early CB750 carbs have similar clamps on the bowls and I've wondered why they weren't used more widely.
 
ancientdad said:
Somewhere over the years I've seen what must have been metric "wing" bolts, someone used them on a screwed-on carb bowl and it was genius.

Found these in multiple sizes and lengths: https://www.ebay.com/itm/176445805552?chn=ps&var=476007915960
Click to expand...
I was thinking of something like these with long, thin spacers to put the wing nuts at a manageable distance from the float bowls.

That "wire clamp" is referred to as a "bail" and I've seen them on my early. CB750s and my CB160.

Wouldn't it be cool to have a retrofit kit to convert from screws to a bail sandwiched between carb bodies and float bowls?
Increased float height may be involved.
*anyone proceeding to develop this idea will owe me 1% of the proceeds in perpetuity.
 
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Alan F. said:
I was thinking of something like these with long, thin spacers to put the wing nuts at a manageable distance from the float bowls.
Click to expand...
Exactly, I originally thought double-nut as a stop for clearance with a longer screw, but tubular spacers would be best.
 
It’s totally doable. Easier with hex screws but I can do the CX’s and the GL carbs this way.

You need Allen (or screwdriver if you stay JIS) bits both stubby and long and one of these guys.


Take a couple of flathead bits and grind them ahead of time to precisely fit the slots of the jets.

Obviously, stuff like needle heights do require the removal finagling, but jets are easy.
 
stl360+450 said:
I wonder if you could replace the bowl screws with something that you could remove by hand (fingers) — otherwise I think those screws will slow you down a lot in doing this.

The dohc CB450 carb bowls are held on with a swinging spring clamp (or whatever the proper term is) and I have taken advantage of this a lot over the years. Before I switched to non-ethanol fuel this made it very easy to clear out the slow and pilot jets after the bike had been sitting for a while.

The early CB750 carbs have similar clamps on the bowls and I've wondered why they weren't used more widely.
Click to expand...
CB160 carbs too.
 
Alan F. said:
I was thinking of something like these with long, thin spacers to put the wing nuts at a manageable distance from the float bowls.

That "wire clamp" is referred to as a "bail" and I've seen them on my early. CB750s and my CB160.

Wouldn't it be cool to have a retrofit kit to convert from screws to a bail sandwiched between carb bodies and float bowls?
Increased float height may be involved.
*anyone proceeding to develop this idea will owe me 1% of the proceeds in perpetuity.
Click to expand...
I have thought about making a tool with an allen wrench but with a wing nut winder (or something like a clock winder). I'm gonna do it. When I get the time...
 
The 350 jets are pressed in with o-rings. Might be a challenge getting them out and back in.
CB 750 is much easier. Bowls are held on by bail clips and the jets thread in.
 
Well. Crap. The solution I’ve used will at least get the bowls - the jets should be fairly accessible?
 
Realistically I don't see this happening. Yeah, the float bowl can be removed but with the press in jets and the screwed in jet holder you're looking at messing up the floats, float height and possibly loosing the float needle.
 
I've changed the jets on my 175 carbs that way. Easy enough with the spring clip float bowls, then use 10mm 1/4" drive deep socket to remove the main jet holder complete with main jet, similarly 8mm deep socket for the pilot jet. What IS fiddly is refitting the float needle assembly after removal, sticking it in place with a dab of ( petrol soluble ) grease works. And being careful to get the float bowl gasket back in place correctly.

For float bowls fixed on with JIS screws, Morgan Carbtune angle driver would work.

Morgan Carbtune - carburetor synchronizer for balancingmotorcycle carbs

Carbtune motorcycle carburetor synchronizers;polycarbonate tool pouchs;for motorcyclists
www.carbtune.eu.carbtune.com
 
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