New Member A wild Yak appears.. 3LN3

Welcome.

There are a number of FZR owners on here that I am certain will be able to help you out.
As for the stalling, it could just be a case of getting used to the bike or a tuning issue. Without more info, it will be a little hard to work out. The little screaming 4s do need a few revs to get them off the line smoothly. You can not just let the clutch out and plod along like on other bikes. But you do not need to wring their neck either. Sensible revs and feathering of the clutch mostly works. If you are in a hurry, lots of revs and gradually feeding in the clutch.
My MC22 will bog with less than 10,000rpm when you are in a hurry to get off the line. Normally 4-6k is sufficient for a smooth, slower get away.

Have fun.

 

I am loving that Orange paint, any chance you know or can get the paint colour code.

They do need a few revs to get off the line, however as @jmw76 has noted you don't need to wring their necks to get moving.
The EXUP valve gives it useful power from relatively low down in the rev range, almost comparable with larger capacity bikes.

I'd expect that you may have to tinker and adjust simple things like clutch cable slack and throttle cable slack till things happen as you expect them to when taking off.

Idle speed should be 1600RPM, which is higher than a lot of other bikes of larger capacity.

With that many KM's you're moving into the range of emulsion tube wear causing idle issues and 'chugging' BUT from what you describe, you're not experiencing it yet...maybe.
Regardless the solution is known, it's keyster kits for emulsion tubes and reducing the slop of the needle slide with a 3.0mm thin wall brass insert which is reamed to ~2.6mm so that the needles don't flop about so much.

If the carbs have had a bit of this and a bit of that done to them, worth checking the fuel levels as it's non-intrusive and requires no disassembly - for 3LN3 it should be 10.5mm.
Mixture screw verification and adjustment might help, however if they've been well balanced and the idle is smooth - ain't broke don't fix it potentially applies.

There's heaps of sticky posts in the Yamaha 4 cylinder subforum, looks like you've had a peek already.

https://www.2fiftycc.com/index.php?forums/yamaha-250cc-in-line-4s.95/

Valve clearances are actually simple to do, there's a howto in there.
Usually taking a record of clearances, then checking the installed shims, calculating required changes and swapping between cylinders will leave you with needing just a few shims to complete the task.

Two points to note - the camshaft caps are stamped, it's faint on the LHS - they need to go back to their respective positions, cast arrow points to the right; and
The cams can be confused intake -v- exhaust - there is an I and an E cast into them on the LHS between Cyl's 1 & 2 if you mix them up accidentally

 

Greetings & Salutations!!!

Yak reminds me of "powdered toast man" scene from "Ren & Stimpy" !!!

 

Howdy

 

Welcome aboard my dude.
Checked out your YT channel, good stuff in there mate I've sub'd.
Your vid on XSR900 range helped out my own range anxiety the other day, rode to lunch with a colleague on reserve knowing I had around 70k's of fuel left.

 

Just though he may have the paint code - it's very close [almost perfectly] the colour I saw VW Beetle painted in, which had two matt black stripes which made my brain go damn that looks good.
My question was just in the hope that the previous owner might have kept the receipt or paint tin with the colour code or remembered the colour.

That's OK, If you have a good, trustworthy mechanic willing to do the work, go that route.
Many users land here lacking experience and loaded with questions AND local mechanics have declined to work on their bikes as they're grey market imports and can be a headache.
Whichever path you choose, this is the most helpful place on the net, there are no silly questions and respect comes first as we all remember a time when we began.
The answers to nearly every conceivable question are here.

You cannot go wrong with litetek bits, @maelstrom is fussy, fastidious and a perfectionist , which means his parts are perfect.

If you're going to go down the route of rebuilding the carbs, do the keyster kits for the emulsion tubes [needle jet]
NOTE - another forum user @my67xr first identified that the main jets between the inner outer carburetor pairs are in the incorrect boxes:
For 3LN3/5 the inner carbs should have #100 in the outer carbs and #97.5 in the inner carb pair

Those parts are for the rare FCR carb parts - a set of those carbs would set you back about $2KAUD - OUCH - only ever seen them available out of Japan

You want the keyster kits available for the Mikuni CV carbs
Good quality parts with just the mixup on the main jets as noted above, with the wrong main jets installed it will run fine but will really struggle to rev cleanly past 10-12K RPM - that was noted by @Joker

https://www.motorcyclespareswarehou...ir-and-parts-kit?_pos=13&_sid=06e714d6e&_ss=r

https://www.motorcyclespareswarehou...ir-and-parts-kit?_pos=14&_sid=06e714d6e&_ss=r

See my screenshot:

NOTE - I do intend to do a fill write-up of the below.
Summarised:
That is just as solution that I devised after examining some CBR250RR carbs.
I was concocting all sorts of complicated solutions to the sloppy needle retention mechanism in the FZR250 carbs, the actual solution is much simpler.

The hole for the needle in the slides is < 3mm - a 3mm drill [end without the cutting flutes] is a nice tight fit into the slides, which is good.

I got the 3mm brass tube which is a tight fit into the slides from the local hobby store.
From memory the wall thickness prevents a needle sliding all the way in, I had a set of reamers going from 2.5mm -> 2.59mm from my complicated 'solution'.
From memory the depth [thickness of the base of the slides] is about 8mm.
So I reamed a length of the 3mm tube to to 2.58mm and inserted ~6mm lengths into the slides, now the needles don't flop about nearly as much, but they're not held absolutely rigid, which would be as bad as too much slop.

Yes, that suggests that it's too rich on the idle circuit, which could be the mixture screw [too rich], a mechanic with a CO2 sniffer could answer that question easily.
NOTE - I am avoiding leaping to the conclusion that it's worn emulsion tubes straight off due the KMS your bike has done, BUT it will very likely be an issue sooner rather than later as it make the fueling at idle to rich.

So there's the same symptom [rich idle fueling] with more than one potential cause.

IMHO it's the worn emulsion tubes which blight the reputation of the FZR250R (3LN1/3/5) -v- the CBR250RR

We all start somewhere and I've never met a Labrador that I didn't like

EDIT - I should add that tuning carbs should come after valve clearances are done because valve clearance effect the engine running sufficiently that carbs tuned/balanced prior to clearances being done would likely need to be re-balanced afterwards.

 

I also keep seeing SUV's, an Isuzu I think it is, in traffic with just the right shade of burnt orange and matt black stripes, it makes my brain pop each time I see it - I just need to go down to the paint supplier and seek out that specific colour.

I'll make 4 brass inserts up for you and post them to you, that's the easiest way as micro reamers aren't that common, they're not something a lot of people have in their tool sets.

Check the EXUP valve and cables, I had a frayed cable on mine break ~5kms from home and I had to limp all the way home, it wouldn't rev past ~4K RPM and sounded absolutely awful which left me dreading the worst and imagining all sorts of horrors.

If it's the EXUP cable:
Venhill sell cable repair kits, although I managed to find very flexible cable of the correct diameter at a ship chandlers supplier, sold me 2M direct, there are several types of cable of similar diameters but not all are flexible enough.
IIRC it was thinner strands in more groups.
I never got around to checking if push bike gear change cable would be suitable.
Anyway point being the cable itself can be replaced as the entire cable pair assembly is NLA, although someone
I do recall someone on the forum recently, that didn't have any EXUP cables at all managed to source one from either a YZF1000 or an R1 and it was a straight fit

The fuel pump should just click a few times, faster at first then slowing till it stops.

Things fail, it's a fact of life, hopefully it's something simple, which it almost always ends up being.

 

what a dickhead haha.
Well thank Lindsay for me then.

 

The fuel pump simply clicks.

The EXUP valve motor should make a little vroom vroom sound as it opens and closes to test functionality on startup. That definitely sounds like the EXUP valve motor struggling.

The EXUP valve motor itself is below where your left inner thigh is under the seat cowling.

It could be a frayed cable which is stuck in the sheath or the EXUP valve itself could be sticky/sticking. Check at the valve on the exhaust first, that is where my frayed cable broke.

It's a visual check, two or three allen key bolts to remove the chrome cover and then if you get someone to hit the run switch to watch it open then close.

Don't worry about the beer, it's gratis, the reason I haven't trumpeted my solution is because my engine still sits upon the bench - one last puzzle to sort, so it's yet to be tested fully, although I am very confident in this part of the solution.

I'm just embarking on measuring the various bits for their respective diameters again.

EDIT - I just listened to the video again and that does sound like the fuel pump, sounds totally different with and without headphones.

 

Yeah I'm with rukusman mate, I reckon that's just your fuel pump

 

I just redid my brass inserts for the carb slides:
BRASS TUBE
The brass tube that I have is 3.030mm O.D.
It is incredibly close to 2.596mm I.D, a 2.595mm reamer slides in, whereas there is a tiny bit of resistance with a 2.597mm reamer.
I didn't need to ream the brass tube all the way through, it was the closed over, cut ends from the tube cutter that I reamed.
I cut them that way because the tapered/beveled end from the tube cutter makes it simple to insert into the carb slide to begin with.

CARB SLIDE
Using two separate 3mm nominal drills on the hole in the carb slide:
One is 2.965mm - it slides in
The other is 2.975mm - there is resistance to push this one in, so I'd say the hole in the slides for the needle is 2.970mm or very close to it.
The outcome, the brass insert presses in nice and tightly, no chance of it working it's way loose IMO as there's 0.055mm interference fit.

I only mention this because my engine is still partially disassembled.
I've been working on the carb issue for a long time and the clue came when I pulled down some CBR250RR carbs and saw the immediately obvious difference in the slop [lack of in comparison to the Mikuni carbs] in the slides on the Keihin carbs.

That's the first part of the puzzle.

So once my engine is reassembled I can install new emulsion tubes and monitor the wear.

I've done your four inserts, will post them tomorrow.