Help need some help with a fzr250r 3ln1

The part you are referring to is known as a jet housing.

They are out of production so chances of getting a new one is zero. You will need to source one 2nd hand from either ebay, here on the forums, or someone wrecking a bike or selling a set of carbs. Be aware that later 3LN models use a different carb body and different jet housing. They are not interchangeable.

As for aftermarket carbs, all that is available is Keihin FCR by JB-Power on webike Japan. Big bucks though, and you need to sort out an airbox/filtration system for them too.

Also while you have the carbs apart you should inspect the needles and emulsion tubes (needle jet and jet needle), they are known to wear out on models 3LN1, 3LN3, 3LN5.

3LN6/7 and 3YX (FZX 250 Zeal) models have improved needle retention mechanisms to prevent wear.

You should also check the pilot merge chamber plug and its' o-ring.

You can get carb overhaul kits from Keyster. This is an aussie link but I imagine someone sells Keyster in the UK too.

https://www.motorcyclespareswarehou...air-and-parts-kit?_pos=2&_sid=d0421ed78&_ss=r

https://www.motorcyclespareswarehou...air-and-parts-kit?_pos=4&_sid=d0421ed78&_ss=r

 

If you can clamp it securely in a vice, with aluminium wrapped around it, then squirt some INOX down into the where the jet is, then give it a gentle heat with a propane torch - I've had luck using that technique to free up brass parts that seemed to be stuck in aluminium parts - most recently it was a carb plunger that would not shift.

Not sure if it was the INOX, the heat and the slight difference in the thermal expansion coefficient, or everything combined, but it worked and wasn't risking damage.

One other thing I have learned recently is that to judge the temperature when heating aluminium - don't want to turn it into a blob, you can use either a carburising flame to put a layer of carbon on the aluminium, which then burns off at ~400 degrees.

OR

Something which I may yet to try, wiping some soap onto the part and apparently that also changes colour to black at about the same temperature

 

You should be able to clean them out with a product like Threebond Engine Conditioner (Petrol). I don't know if you have it in the UK but it's also the same stuff as Subaru Upper Engine Cleaner. Basically any product for petrol engines that is designed to clean intakes and combustion chambers, and is foaming.

Basically you soak your alloy or brass parts in this stuff and they come looking completely clean and brand new.

https://2fiftycc.com/index.php?threads/cleaning-carburettors-using-threebond.3800/

 

OK, so it was galled, that's a bugger when that happens - don't recall off hand what that jet thread is, but there may be another mikuni jet with a larger thread that can be drilled and tapped to suit.
I know that some are M5 0.7mm thread and some are M6 0.8mm, with luck you may be able to find one with a larger thread in the jet size you require

https://mikunioz.com/product-category/jets/page/2/?v=13b249c5dfa9

 

You could have it repaired. TIG weld it up, re-drill and re-tap. Job done. Take a good one as a comparison

 

@Linkin - tig welding would be perfect but that the one jet which is hidden down a hole - it could be potentially mig welded blind...

Consider that there's some low temperature aluminium solders available - with the jet housing held in a slow turning chuck it may be possible to add some of that solder to enable it to be tapped back.
Jets shouldn't be fitted with strong arm torque to begin with

 

If it's the main jet then yes, there is another under it. Not for the pilot jet though. The solder is a good idea but I worry it might be a bit soft.

 

I've seen some tests with the solder on youtube - the smaller, thinner rods that do flow out like solder when the temperature is right - they seem to hold up well, would probably take a thread and as long as the jets aren't strong armed again, should hold up

 

Hey Ryan, I saw your post on facebook - sent you a link to one facebook marketplace listing

There's this listing on gumtree also which isn't turning up in the search curiously - he looks to have many many boxes of bits, there's even a set of carbs in a box in one picture and the blue/black 3LN1 in another

Just remember that the jet housing isn't interchangeable between 3LN1 and 3LN3/4/6/7/Zeal
https://www.gumtree.com.au/s-ad/wit...ts/yamaha-fzr250-2kr-and-3ln-parts/1187188126
A full set of carbs 'should' go for ~$120SAUD IMO

 

I remember that other guy that left whopping great chunks of the stuff on there that wasn't even properly flowed in.

 

where are you located? I'm In new Zealand and have a parts carb set and a bunch of parts so let me know and I can check what I have.I have 3 of the towers you mentioned and if is the right ones we can figure it out from there if you want.

cheers buddy

 

also if you need a cheaper option there are some on AliExpress that have the diaphragm and floats as well, not too sure about the quality for 100nzd for a 4x kit