wingedwheel
CB750 Enthusiast
dd basically that's the whole reason, they were in the kit. I have no problem leaving well enough alone. Should I leave the guides in as well?
Jet Needle question
- Thread starter wingedwheel
- Start date
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- carburetors sohc
I personally would only replace the gaskets/orings and float needles, accel pump. If it aint broke dont make it broke. If you have running issues once you get it together then you can address them then, it will be less frustration in the long run.
amc49
CB750 Guru
YES post #20.
I almost asked the same 'why change the needle' question like 5 times. They RARELY cause trouble unless shimmed then not being loose they wear like lightning. Even the shimming can be done if careful, but the needle MUST be able to still wobble loose, it's what allows it to center to the jet and then zero wear. Just like with the labyrinth slides the DOHC uses with no rubber, you have enough flow there so that the flow itself guarantees that the sides stay centered. The sides in normal use then never touch at all.
I too have changed less than 5 needles on so many carbs rebuilt I cannot say, they simply do not wear except possible heavy dirtbike use and vibration like a big single 2 stroke makes. Of course possible corrosion due to being in a humid atmosphere could be an issue but I pretty much DON'T change them ever. Reason being, they worked good and you don't f-ck with that. And NEVER take sandpaper to them! I'll do that to every other part on a bike but NOT needles or slide tops, it's death!
Rule #1 is you NEVER change all parts simply because they are 'in the kit'.........................................ONLY what's needed and a good sum up there.
Man, if you knew all the posts I've seen after somebody changed needles and then bad result followed in short order.................can't stress it enough.
I almost asked the same 'why change the needle' question like 5 times. They RARELY cause trouble unless shimmed then not being loose they wear like lightning. Even the shimming can be done if careful, but the needle MUST be able to still wobble loose, it's what allows it to center to the jet and then zero wear. Just like with the labyrinth slides the DOHC uses with no rubber, you have enough flow there so that the flow itself guarantees that the sides stay centered. The sides in normal use then never touch at all.
I too have changed less than 5 needles on so many carbs rebuilt I cannot say, they simply do not wear except possible heavy dirtbike use and vibration like a big single 2 stroke makes. Of course possible corrosion due to being in a humid atmosphere could be an issue but I pretty much DON'T change them ever. Reason being, they worked good and you don't f-ck with that. And NEVER take sandpaper to them! I'll do that to every other part on a bike but NOT needles or slide tops, it's death!
Rule #1 is you NEVER change all parts simply because they are 'in the kit'.........................................ONLY what's needed and a good sum up there.
Man, if you knew all the posts I've seen after somebody changed needles and then bad result followed in short order.................can't stress it enough.
wingedwheel
CB750 Enthusiast
OK I re-installed all the original needles, guides and jets. they do close better and it makes me feel better about the end result. Got #4 all cleaned out while I worked on them so everything should be done this afternoon. I would have rather seen more o-rings and seals in the kit I suppose over parts I don't need.
What brand was this kit?
amc49
CB750 Guru
'...they do close better...'
Exactly what I was talking about, a needle dragging inside a needle jet likely...................death.
Exactly what I was talking about, a needle dragging inside a needle jet likely...................death.
wingedwheel
CB750 Enthusiast
I bought them from a supplier in Japan I've used for other metric bike parts in the past and everything has been spot on. I looked at all the other kits I could find and they all had the 5 groove needle and designation '76-'78. Any site that had a parts diagram listed the needles as NLA. No issue's, I'm all clean and back together. Thanks for the help guys.
I was just curious of the brand. Good source for all carb parts is jetsrus.com Only ones I use anymore.