Wanted Needle Jets for GT550 172 P-4

[Harrymail]

Does anyone have 3 Needle Jets of the correct spec for the later chrome bore GT550. They will be stamped 172 P-4. I am trying to get my carbs to the correct spec for my bike which is a UK GT550A. The earlier 550's had a jet three sizes smaller, 172 P-0.

I have already asked Baz, who does not have any. They are no longer available from Suzuki, and Mikuni have deleted the entire 172 Series of jets from their range. Any carbs from a chrome bore bike would have these jets fitted from new.

Any help greatly appreciated.

Cheers

Paul

[yeadon_m]

Paul,
Would you please remind me why you need these? Is it that you have the ‘wrong’ type? Or are yours just old?
I seem to recall that Teazer / Richard on here is a guru on carbs & has posted elsewhere on this topic. I can’t recall if he found a supply or an alternative solution, but you’re not alone in having this problem!
Cheers,
Mike

[Harrymail]

Hi Mike. Thanks for your reply. I currently have the wrong jets in my carbs, 172 P-0. I do have the correct needles which are 5D1. The taper on the 5D1 needles is very different to the 5DH21 needles which are in the early carbs, and the jets are bigger by 3 sizes to suit this needle. The needles and jets should be matched as follows:

5DH21 Needles with 172 P-0 Jets (fitted to iron bore engines)

5D1 Needles with 172 P-4 Jets (fitted to chrome bore engines)

I currently have 5D1 needles with 172 P-0 jets which is not correct. If I could find some 172 P-4 jets then I would have the correct setup for my engine.

Cheers

Paul

[barney01]

Paul if you look on the below link it says # 172 has been replaced by # 169 ? Maybe a call to someone to confirm that.
https://jetsrus.com/a_jets_by_carbureto ... mikuni.htm

[Harrymail]

Paul if you look on the below link it says # 172 has been replaced by # 169 ? Maybe a call to someone to confirm that.
https://jetsrus.com/a_jets_by_carbureto ... mikuni.htm

That's very interesting Barney. Motocarb have the 169's listed. I will speak to them tomorrow.

Thanks for spotting that

[teazer]

Mikuni do list the 169 as a replacement for the NLA 172 and it's almost the same jet. 169 is 1mm taller with a 1mm thicker top flange, but since stock needle jets sit slightly low, that should not present any issues.

If you have a local carb specialist with jet drills they may be able to drill out your jets, but I'd try a set of 169s first. According to my notes, the #169 use Hex main jets and I think that the 172 used large Round. If so you will have to get main jets with equivalent flow rates - not the same numbers. If your bike came with hex jets, you should be OK to replace them with same size new hex jets.

FYI, J/K 550 came with 192 needle jets in the US at least and they were really short, so they had main jet adapters fitted so that also converted them from round thread form to the take Hex main jets which are a different thread pitch..

[Harrymail]

Thanks Teazer. Main jet is large round. Will check threads before I order from Motocarb. I have now read in two places that the 169 are a replacement for 172 . So fingers crossed I can get some ordered tomorrow.

Cheers, Paul.

[teazer]

Here's the conversion table from Round to Hex. Should get you close.

[rodent]

Paul if you look on the below link it says # 172 has been replaced by # 169 ? Maybe a call to someone to confirm that.
https://jetsrus.com/a_jets_by_carbureto ... mikuni.htm

http://3cyl.com/mraxl/partid/carb/jetid/jetid.htm

[Harrymail]

Thanks Teazer/ Rodent. It does look like a hex main jet is needed for the 169 needle jet. Threads are close, but not identical.

Cheers all, Paul.