FZR250 - had work done to my bike and . . .

OK then. The standard position for the clip on the needles is the middle position. The top 2 positions = lean. The bottom 2 positions = rich.

Should look like this



Backfiring when you have the throttle open can point to an electrical or other problem, but if it's just popping when you let off the throttle, you have an air leak in your exhaust system somewhere. It means that air is getting sucked into the headers or muffler and igniting. Nothing that needs worrying about, but if it annoys you, tighten up the exhaust headers a bit and the clamp for the muffler. New exhaust port gaskets should also help with that.

 

Just cut the plug ends, leave the coil ends alone, they'll be ok.
The plug caps screw off, you'll see how they work to put them back on when you get them off, there's a small tapered screw in the cap that goes into the lead core & holds it in, you'll feel the weight come on when you screw them back on.
You won't damage anything, they are meant to screw off.
The plugs will be ok, we don't pay much for plugs down here, surprisingly, we are usually raped for spare parts not by the dealers but by the importer, but things are changing, dealer parts prices are coming down.

 

I think we pay about $120 au for them, pretty cheap really.
Fixed all my problems. Interestingly I couldn't get 2 of the Pilot jets out & really butchered them with a drill but I remained calm & stopped to regroup, put the carbies all back together with all the new parts & ordered lh drills to remove the remaining brass. whats interesting is that the bike ran just the same as it had before, dull off the throttle at low revs & shitty idling & I started wondering if it was something more than carbies. Drills turned up & into it again expecting to ruin the jet housings & started after another set of carbies, luckily no one had any so I ripped into it. I got them out no problem & cleaned up the threads & screwed in the new pilots, put her all back together & like a miracle it's perfect, cracks off the throttle & it'll idle all day, Emma took it for a ride & came back with a big smile, couldn't believe it. So I wasn't game to say it was the pilots but seem to have been, maybe the old ones were blocked & couldn't see them or didn't really look. Something to keep in the back of your mind anyway.

 

Just have it as per my picture. The C clip in the middle position, the metal washer underneath, and then the nylon piece underneath that.

Since you have the correct size needles, emulsion tubes, and jets, you should replace the existing ones in case someone has messed with them before (ie put bigger ones in). Once you do that, you just have to tune the idle circuit and that's the carbs done.

 

Sounds like your on track for success,
The extra washers will lift the needle & it's un necessary, I can't remember washers on mine, I don't want to think about it.
Your going into a dark place re jetting the carbies because of the exhaust, are you just talking the muffler or the whole system ? The Exup valve gives you a nice all round performance, remove it & you'll be in a world of disappointment

 

Leave the muffler alone until you sort out the carbs properly. Inside the stock muffler there are actually two smaller pipes. The first one runs all the way up to the end of the can, but not out. The pipe that leads out has its opening up the other end of the exhaust where joins the midpipe. So basically the exhaust gasses travel the full length of the muffler twice. I cannot find a picture of it now, but have seen it before.

As for rejetting... mine seems fine but I haven't actually replaced all the jets in my carbs with the correct keyster ones, it's something I should probably do.

@Grasshopper's FZR was very poppy and even shot flames out the exhaust before he fixed up the carbies properly (needle clip position, replacing needles and emulsion tubes, and setting the idle mixture).

My bike doesn't pop when riding normally, but uhh running it to redline and then chopping the throttle resulted in a single loud POP one time.

As said before though, popping is a result of a leak in the exhaust headers or muffler. When the throttle is open, exhaust gasses are being pushed out of said leak. When you let off the throttle, the pressure drops and fresh cold air gets sucked into the exhaust system through the leak and autoignition happens from the heat. If you're running rich, fuel will also be in the exhaust and you'll get flames.

Float height?

GreyImport & Maelstrom to the rescue.

http://2fiftycc.com/index.php?threads/carb-fuel-level-everyones-favourite.3254/

 

I've got a Blue Angel muffler, came on the bike, they scream like anything no matter what, just gets louder.
I'll be in the market soon for a new muffler, I had a look at the Blue Angels & I won't be paying $310 US + shipping for one ! It'll be an ebay special.
Gutting the OEM won't work, it'll sound crap, you need something in there to absorb the sound. You could gut it & run a perforated tube through the centre with, say coarse stainless steel wool packed in around it, if your handy with a TIG or MIG welder & some patience.
What happens in winter if that's summer ???

 

Could be but if he's set them to something they'll be close & probably be ok, doesn't sound like you've got a float height issue.
I haven't been too fussy with mine & they have been set at different heights a number of times, god knows where they are at now but I remember the last height adjustment it was not measured just set by eye & all identical. Get a short length of clear fuel line & stick it on the drain nozzle on the bottom of the bowl & hold it vertical, open the drain screw & see where the fuel rises to in the tube compared to the fuel bowl, start there.

 

If you buy the JRE one and aren't after pure noise, get the 42CM one. It has a nice deep note. 30CM is the shorty and will be louder. The 42cm one is plenty loud. Keep the standard one as you'll need it for inspections/registration etc.