Fuel Consumption nd powerloss

Simplest thing to check would be the vent that is in the fuel cap.

Try to duplicate the issue, then open the cap and give it a run and see if that doesn't help. If it does, clean that vent with some wire.

If it isn't, then start looking at the other simple things, air filter, fuel filter, and plugs.

Then time and money come into play. Check the valve adjustment, carb sync, float bowl height, needles, jets, emulsion tubes....

 

I only ever get about 120k's per tank out of mine too. I heard someone mention something about jets wearing on the 250s after a while...maybe that's why the econ's so bad? I have a mate with a CBR250 who gets over out of a tank. Maybe something wrong with the jets...can anyone shed any light on this?

 

Welcome to the world of the early '90s 4 cylinder revv monsters that are FZR's. Yes, alot of the FZR250's out there will have worn needles and therefore will be running rich.

The only thing you can do is to re-tune the carbs to try and compensate for the needles; however then you run the risk of leaning it out at higher revs and that is rather dangerous for the engine.

The figures i've heard floating around for a carby rebuild with new emulsion tubes / jets & needles is something around the $400-$600 mark. Quite expensive to be honest.

 

it's not just fzr's - any small pure sports bike will tend to do the same (cbr's, zx2r's - both will probably have this trouble once they get about 40 000 k's on the clock). The needles are very small (comparitively speaking) and will wear faster than larger counterparts.

 

Hey Boz, I'm at 26K miles or roughly 40k Kilometers and I need to replace my emulsion tube soon. So it isn't just the smaller bikes that need it sooner.

 

Fair enough and thanks for letting me know! I was only relaying info from the mechanic. To me it made sense at the time - a minor change in a small tube will be more apparent than a minor change in a large tube.

A new tidbit of information to file away until next needed!

 

I'm curious now, as to the jet sizes in the 250's. How much different are they in relation to size? I'll ask the Guru's over on the 'Hood as to what the general sizes are for the 1000. Someone try to find out what the sizes are in the 250.

 

no idea on the needle sizes but i've got a semi-related problem -
Rode the bike on the weekend for about 200km with about 60-80km of that around 130kph - not really on purpose but i was just getting sore and wanted to get back home - now my bike would normally do about 190km before re-fuel and after this ride it ran out after 160km - so high revs certainly make it thirsty - the other thing which was more worrying was that the oil light came on (first time i've ever seen it light up) and i had to put in about a quarter litre of oil (only changed oil 2000km ago).
Was up to 160kph at one stage (not for long) so i suppose this would would affect oil consumption? Oh, i could only get car oil too, anyone see any problems with topping up with that (SAE 30W - 50)??

 

Don't know the size for the fzr - I will look to find sizes for the cbr though as it should be easier. I can only assume the sizes would be similar.

 

Oddly enough, on the ole 1000, I can cruise it back and forth to work and playing around town and get 30 mpg, or 125 miles before the fuel light comes on (5 gal total, 0.9 gal reserve). Yes, I have a fuel light. If you don't, sorry. Now this around town riding isn't all that spirited, but I do get on it from time to time.

The last time that I took it out for a romp through the twisties, I gassed up at the end of the main section, 116 miles on the clock and I put 2.3 gal in it. 50 mpg and that was keeping the rpms above 5k (11k redline) the whole time, well most of the time.

So what I have concluded is that I get better milage if I go faster. That's my theory and I'm sticking to it.

 

I get the worst fuel economy when im just putting around town (ok, screaming for a 2fiddy, but by my standards putting). OOddly enough i also get the best fuel economy out when im running through the hills.

Admitedly wear and tear on other parts of the bike comes into play when in the hills (byee bye tyres & brake pads).

 

I get around same km/tank no matter what i do.

Usually get around 150-160km before i hit reserve around town (normally using between 6 - 13,000 rpm)

and around the twisties i use a bit more, round 130-150km before reserve, although because my tacho is rarely below 15000rpm i tend to have to top up the oil at the end of the ride. Never had the light come on though.
Oh yeah and the tyres and brakes thing.....

by the way my bike doesn't use oil riding normally.

 

Well guys, from all your responses the only conclusion I can draw is that my bike must have done more than the k's shown on the odometer (it reads 20k...I wouldn't be at all suprised if it's been wound back - it's not many k's for a 1992 model bike).

So I guess my emulsion tubes and jets/needles are worn and therefore letting more fuel flow through than necessary, hence the higher fuel consumption. I'm jealous of you Greeny - 150/160 per tank!? ****..I get to about 115/120 and then have to flick it to reserve.

ah well...bring on my next bike (yeah right! when I win lottery) the R6!

 

I have just bought an FZR and found that sometimes around town that it wont accelerate when going up hills particularly at low revs, and even in 1st gear.

I pulled one plug out and it was fairly black. The exup cables are missing but the valve is wired open. The servo seems to work ok and I have cables coming from a wrecker. The problem disappears completely over 7000rpm and it goes well.

I spoke to a local mech on the phone about it appearing to flood at low revs and he said that he thought it might have plastic float bowl needles and seats. This would explain why it runs poorly sometimes at low revs. The down side was the estimated $4-500 for bits.

Has anyone had the carbs apart to confirm this..?

DAVE

 

I think the problem is that you need to rev it more! The fzr doesn't really have a usable power band until at around 6000 revs (and when you need to either accelerate or go up hills I would suggest 10 000 or over). If you are in first (and this may take some practice) feather the clutch so you maintain higher revs and use that in conjunction with the throttle.

If it was flooding then the bike would probably also stall. Since you did not mention this I presume this isn't happenning.

 

Thanks for the reply BOZ.

I got the EXUP cables today and slapped them in and went for a spin around the block - what a difference. Much improved at low revs.

I have a steep drive driveway and it now accelerates up at good pace. Whereas before i used to get a run up and it would just slightly accelerate.

It does stall occasionally if I pull up very quickly.

I also noticed that the EXUP box has very sloppy bushes where the shaft goes thru - I guess that I will pull that off sometime and bronze it up and re-drill the holes.

I will try and practice on the clutch as you suggested.

DAVE

 

Yeah I have had the carbies apart more than I would have cared to. I can tell you that the floats are made of plastic but the needle and seat valve that it is connected to is metal. I have never even heard of a plastic needle and seat valve. I have heard that in some of the older Suzuki’s the plastic float would deform and mess with the float settings for the valve but this is fairly uncommon. As boz said, if it where flooding as a result of the needle and seat then stalling would be more of a common occurrence. New floats and valves would be the most extreme measure if it where the problem, most of the time if the float heights are right then all that is needed is a good clean of the valves.

From what you have said about poor low-end power and stalling on quick stops I am leaning towards a good clean and balance of the carbies. My bike once suffered from the same problems till I synchronized the carbs.

Nice work with the exup cables and try shopping around when it comes to mechanics. Talk to other people in your area with the same bike, see who they will let work on their baby.