Thumper Club Forum

Technical => Bike Problems/Questions => Topic started by: littledave on December 21, 2021, 04:10:24 PM

Title: SRX400 secondary carb mainjet sourcing
Post by: littledave on December 21, 2021, 04:10:24 PM
Hi there, I'm struggling to find any suppliers of mainjets for TK carbs fitted to my 1987 yamaha srx400 jap import. The carbs dont have an identification mark on them for definitive jet sizing but i do know that the iJL model should have #122 main jet in primary carb (which it has) and #88 main jet in secondary carb (which it doesn't have!). the current jet in the secondary carb is #84 which has been drilled out. Its running stupidly rich as a consequence (throwing out soot when on throttle hard).. Would any one happen to know where I could find a replacement jet? I'm trying to avoid the plan B option of filling jet with solder and drilling out...
Thanks in advance for any help anyone can give,
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: themoudie on December 21, 2021, 11:39:38 PM
Aye Littledave,

Fowlers of Bristol have an exploded diagram of the carburettor on their website and I post the link below.

It appears that the #88 Main Jet (Part No.:30X-14343-44) is no longer available as OME parts!

1985_SRX400-1JL0_carburettor (

The other possible supplier could be NRP Motorcycle carburettor repairs specialist, who also supply carburettor diagphrams, used by members of this forum, with success.

This is the link to the NRP website and the SRX400 3VN carburettor service kit. I realise that this is the later model from yours, but they may be able to help.

NRP_SRX400_3VN_carburettor_service_kit (

I am not familiar with other Yamaha models but there is the #88 jet from an XT350. This has the same part number as the 1985 SRX400 main jet and Fowlers are selling one on their eBay page!

Link to Fowlers eBay sales page for an XT350 main jet, part number, #30X-14343-53

Fowlers_eBay_sales_Lot_No.:362539851505 (

Finally, one of the other owners of 1987 SRX400 who read the forum may have other info or even a spare #88 main jet.

I hope this helps, good health, Bill

Title: Re: SRX400 secondary carb mainjet sourcing
Post by: littledave on December 22, 2021, 12:42:20 PM
Hi Bill and thanks for all the trouble you've gone too..its much appreciated. Unfortunately the XT jet isn't compatible as apparently its not an #88.. I've left a message with NRP; they dont list one but you never know! Someone from this site might have one knocking about so fingers crossed they read this query/cry for help.
all the best,
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: spooky on December 22, 2021, 01:27:09 PM
You could try the chap at Saisei in Darlington,  01609 773486... below is some info about them:

Vintage Japanese Motorcycle Parts
Saisei is born out of passion!

Located in North Yorkshire, Saisei is putting over 40 years of passion for Japanese motorcycles into helping other enthusiasts preserve and revive their classic Japanese bikes we all nurse and cherish so much.

Like a child our birth is the start of an exciting journey. A journey that will see us grow into the number 1 choice for vintage Japanese motorcycle parts in Europe. How do we grow? Simple! We nurture everything we do! We provide exciting products at keenest prices, most importantly we aim to give you great service every time!

We Are Saisei

Passionate about classic Japanese!

Passionate about parts!

Passionate about prices!

Passionate about service!

Have your Passion Reborn with Saisei
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: Steve Lake on December 22, 2021, 08:44:56 PM
right, i have 2 YDLS srx carbs here ... both appear to be identical, certainly the diameters are the same (32mm & 30mm)

i have removed the jets,  and one pair definitely look larger (hole dia) than the other, so my supposition that these were both off 400's may be wrong, and probably one is off a 600.

i can see no markings on the jets whatsoever.

you are welcome to have both pairs for comparison and, if required use. i'm sure we can come to a mutually agreeable settlement should you want to keep them (they are out of some old carbs that have been robbed for parts over the years and the jets are about the only useful bits left)

if you want them drop me a line with your address


ps.... i lied! ... with torch and magnifying glass i have foun some markings

carb 1, primary/main (the one on the emulsifier tube)  jet 118 . secondary 100
carb2,  primary 136 .  secondary 100

the mystery is .... on carb 1 both jets appear to be a similar size hole on carb2, again same size hole BUT considerably larger than carb 1, even though both secondary jets carry the same number ... i'm wondering if carb 2 had been subject to some form of tuning, i know dynojet did a kit that involved opening up jets (i think)

anyway, if they are of use.... drop me a line
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: littledave on December 23, 2021, 03:39:29 PM
Many thanks Spooky and Steve for the info and for your time. I'm a bit bowled over with the member input on this site. I knew I should have got a single years ago.
Spooky.. I will contact  Saisei, see if they can help and let you know the outcome.
Steve.. thanks for taking the time to remove and check out the jets in the carbs you have. Unfortunately the secondary main jets you have are too big. The main jets for the primary carb are all still out there and relatively easy to get. Its the buggers in the secondary carb which are now obsolete.

I found a chap locally who can machine me a jet (maybe a couple) for not too much dosh so I have a realistically achievable plan B if Seisai cant supply any.

The one that is fitted is an #84 which has been drilled out to over #100. The resulting mid-upper range over fuelling (and sooting!) makes me think I may opt to get an #84 and and #88 machined and try them out (assuming I cant get them from Seisai)..

Thanks so much to you all, I will let you know the outcome of this journey!!
Merry Xmas and Happy New Year..
all the best,
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: Moto63 on December 23, 2021, 04:56:54 PM
Yes and don’t forget little Dave that the thumper club is for life NOT just for Christmas 😉🎅🏻
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: mthee on December 23, 2021, 05:27:24 PM
Well in there, Michael 😂
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: littledave on January 12, 2022, 07:52:14 PM
Happy new year!!
Thanks for the suggestion Spooky but unfortunately Saisei (Cybikes) couldn't help with the jet..
However...Success!!  I've managed to get one machined by my friendly neighbourhood machine shop (Goodturn Engineering, Redditch)..They have been great and have machined off a few without bore just in case i need larger ones!! If any one else needs one of these elusive jets then try Goodturn as they will be very happy to help out and they are very reasonable..
Now to reassemble everything and take her for a hypothermic spin..
All the best,
Title: Re: SRX400 secondary carb mainjet sourcing
Post by: Moto63 on January 12, 2022, 08:12:21 PM
Happy new year to you too littledave.... sounds like this just may be a happy ending and as most on here will already know... I just love a HAPPY ENDING 👍👍
Cheers, Michael