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Post by vic6169 on Dec 22, 2019 18:47:23 GMT 1
My needle jets look like someone has taken them out and damaged the top thread in the past.
Do you know the size so i can retap them as they are still usable.
Cheers
Vic
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Post by JonW on Dec 23, 2019 0:16:51 GMT 1
Do you mean the main jet thread in the needle jet? if so thats a very standard M5 thread (0.75 i think).
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Post by LC_BOTT on Dec 23, 2019 9:35:42 GMT 1
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Post by vic6169 on Dec 23, 2019 11:17:01 GMT 1
Do you mean the main jet thread in the needle jet? if so thats a very standard M5 thread (0.75 i think). Yes Jon. I took my jets out to ultrasonically clean the carbs and bought a new kit from legend motorcycles to refit but the jets wouldn't go in. The tubes looked damaged from who ever fitted the last jets in. I thought as they are brass it would be easy to run a fresh tap in there but the jets look like they have a taper so im a little confused if they are metric?? |
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Post by vic6169 on Dec 23, 2019 11:20:28 GMT 1
Thanks LC BOTT. That helps but the top jet is all metric with a 1BA thread. Why do they do that???
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Post by JonW on Dec 23, 2019 12:44:00 GMT 1
Ahh... theres your problem... you have the word Legend in the sentence :/
Im 99% sure its an M5 standard (not fine or course) thread as I screw in a long allen headed bolt to mine to remove and refit the needle jets. Should be very easy to re thread with the right shape tap.
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Post by oldelsieboy on Dec 23, 2019 12:46:35 GMT 1
Im 99% sure its an M5 standard (not fine or course) thread as I screw in a long allen headed bolt to mine to remove and refit the needle jets. Should be very easy to re thread with the right shape tap. I use the same method to remove the needle jets & I'm 100% sure it is an M5 thread. OEB |
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Post by LC_BOTT on Dec 23, 2019 12:47:04 GMT 1
That was why I posted it up, it's quite a coarse thread on the jets from memory, and I don't have any 1BA taps or screws now I don't think. It did sound a strange combination to me since all made in Japan presumably. I'd wait for someone else to confirm before doing anything silly  That was two quick replies when you say remove jets, I'm guessing you both mean emulsion tubes??? |
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Post by JonW on Dec 23, 2019 12:48:30 GMT 1
Maybe its M5 x 1.00 then Bott? Its defo ok with a metric thread bolt, screws in nice and smoothly.
I can check my taps for you tomorrow if you like Vic? Its just a bit late to go padding around to the garage.
You also say 'top jet', whats that mean? I talk about these as the main jet that sits on the end of the needle jet (emulsion tube).
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Post by midlifecrisisrd on Dec 23, 2019 13:04:08 GMT 1
Looks like a wierd size Found this Steve  |
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Post by Deleted on Dec 23, 2019 16:00:19 GMT 1
1BA corresponds to 0.209"
5.3 / 25.4 is close enough to 0.209 (0.20866 to be a bit more precise)
So i would go with the picture Steve has posted
It's not metric after all but British Association thread
Very interesting, I would have initially suspected a gas thread, obviously not
And that thread pitch is even more bizarre
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Post by midlifecrisisrd on Dec 23, 2019 16:22:59 GMT 1
That is bizarre that a Jap company would use a British thread
Good news is taps are on ebay from £2.89 delivered
Steve
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Post by hoist1 on Dec 23, 2019 19:07:33 GMT 1
That is bizarre that a Jap company would use a British thread Good news is taps are on ebay from £2.89 delivered Steve Didn’t they start off using then copying Amal ? , could still have used metric. Wheels is the other one, diameter in inches and rim width, but metric width tyres. |
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Post by JonW on Dec 23, 2019 21:27:40 GMT 1
Well there you go, learn something new everyday.
Bizarrely tho an M5 bolt screws right in, might be a little slack but defo screws in happily enough.
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Post by vic6169 on Dec 23, 2019 22:07:53 GMT 1
Thanks for all your help guys. I started something here. I’ll have a look over the next few days. I have some BA taps here from my engineering days so I’ll check both. I agree it looks metric but the new jets definitely have a tapered thread. Strange eh??
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Post by midlifecrisisrd on Dec 23, 2019 22:17:20 GMT 1
Thanks for all your help guys. I started something here. I’ll have a look over the next few days. I have some BA taps here from my engineering days so I’ll check both. I agree it looks metric but the new jets definitely have a tapered thread. Strange eh?? I did notice when I looked on ebay there was a 1BA tapered tap Steve |
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Post by JonW on Dec 23, 2019 22:18:23 GMT 1
I'd defo ditch the new jets if they look different to the pic as they are just some aftermarket rubbish. Start with what is right or you'll be chasing your tail for ever. ie if you make something tapered fit and then later need to go back to normal threads after when tuning.
Maybe just buy two new needle jet tubes... and fit new Mikuni jets.
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