Carb Probs BS38s

[MontyWales]

OK so something strange is happening. I took my carbs apart to clean them and get new jets put in. Now the Needle jet wont seat in properly and the float bowls won't do up. It almost as if they have grown.

 

[Jim]

Pictures of what's happening would help us.

 

[MontyWales]

not sure whats going on here

 

[DogBunny]

Looks like you need a new needle jet o-ring. Try putting the needle jet in the freezer, and lube the bore and new o-ring before you push it in.
I suspect you used a cleaning solution that made your o-ring swell.
Also, those aren't really the totally correct floats, but if they worked before, then I guess they are okay.

 

[MontyWales]

ahh now, the floats, the ones from it has a dent in, not sure if that would make a different, so I tried these from the spares box

 

[MontyWales]

I think I need new needle jets anyway, the seals are new but the jets are a bit beat up, Only place I've found the same ones is Germany. Z-8

 

[DogBunny]

Yeah, those needle jets look terrible -- are the little holes in it even clear? Your new seals (o-rings) look pretty bad too. You need to run something through the needle jet bore, like a strip of Scotchbrite and get it good looking. I think I'd put the correct floats back in.

 

[MontyWales]

yer i gave them a wipe over to find the numbers.

 

[5twins]

It also looks like you have two o-rings on the needle jet, one below and one above the step-out? They only get one, below the step-out and fitted into the little groove. A 1mm x 4mm o-ring size will work, but on the Z-8 needle jet, with the o-ring groove so close to that step, the needle jet probably won't want to push all the way into the carb body. That's OK though, the float bowl will push it all the way in and lubed up real good, it will eventually seat the o-ring into the carb body.

 

[5twins]

And as far as floats go, no need to pay big bucks for replacements from some 650 specialty place because the BS38s use the common Mikuni VM24-171 float which retails for around $14 or $15 ......

And it is recommended that you only use genuine Mikuni floats. The aftermarket ones can be "hit and miss" on the quality.

 

[MontyWales]

£30 each here

 

[MontyWales]

It also looks like you have two o-rings on the needle jet, one below and one above the step-out? They only get one, below the step-out and fitted into the little groove. A 1mm x 4mm o-ring size will work, but on the Z-8 needle jet, with the o-ring groove so close to that step, the needle jet probably won't want to push all the way into the carb body. That's OK though, the float bowl will push it all the way in and lubed up real good, it will eventually seat the o-ring into the carb body.

Thats just dirt
they was new O rings , But the needle jets are so mullered I'm not going to use them now , Float problem sorted

 

[MontyWales]

The old one was a bit dented, I don't think the hot water trick will work

 

[Adamc]

TRY: https://nrp-carbs.co.uk/shop/
For your genuine Mikuni carb bits.

 

[Its been a long time]

TRY: https://nrp-carbs.co.uk/shop/
For your genuine Mikuni carb bits.

To add, NRP are OK. Some of their stuff is Keyster, which is generally Japanese and is decent enough stuff.