6000rpm & falls flat on face!

[knightrider092]

what is lowering the needles going to do for the problem?...Should i still run the 130 main jets?

[mrfreeze5]

Sounds like you are running rich. I would try stepping down a size on the main jet. Your needle position doesnt really matter if you have the wrong main jet.

As was mentioned, the emulsion tubes are likely shot if they havent been replaced before, and will cause a rich situation, but backing off an adjustable needle can mask it a bit, but wont solve the problem, and it will get worse eventually. Factory Pro has some nice replacement tubes. I run them myself and would recommend it if it hasnt been done yet.

[sweekster]

what is lowering the needles going to do for the problem?...Should i still run the 130 main jets?

The main jet comes into play for power at high end rpm range

The needle height / clip position comes into play for good power at mid range rpms

The Float Height comes more into play at the lower rpm range.

To answer the question, lowering the needles will lean out your mid mixture as, from what's been described, it sounds like you are too rich in the middle and the bike is bogging out. I would try that before you go about playing with the jet sizes.

[ragedigital]

what is lowering the needles going to do for the problem?...Should i still run the 130 main jets?

I meant for you to drop the needle into the emulsion tube, so use the slot #3 before changing the main. This will lean out the circuit a bit and should smooth your transition from 1/2 to WOT.

Other things on the list:
1) +1 to Freeze on replacing the emulsion tubes. I also purchased the ones from FP. I used a DynoJet jet kit though - loved it!
2) Get an Infrared Temp gun and make sure all of the cylinders are firing properly. You can also correct idle issues at the same time by adjusting the IMS (Idle mixture screws).


**Note to self: Hit submit as quickly as possible, sweekster is always looking to get the answer in sooner...

[mrfreeze5]

what is lowering the needles going to do for the problem?...Should i still run the 130 main jets?

The main jet comes into play for power at high end rpm range

The needle height / clip position comes into play for good power at mid range rpms

The Float Height comes more into play at the lower rpm range.

To answer the question, lowering the needles will lean out your mid mixture as, from what's been described, it sounds like you are too rich in the middle and the bike is bogging out. I would try that before you go about playing with the jet sizes.

Im guessing it is going to be more than just moving the needle. Even if its off a clip or two, it shouldnt completely fall on its face and require partial throttle and the fact that it has trouble getting to redline leads me to believe the main is off. Id try stepping down a size on the main first before trying to tweak the midrange. If the main jet is not correct, everything else will be off too.

[ragedigital]

Im guessing it is going to be more than just moving the needle. Even if its off a clip or two, it shouldnt completely fall on its face and require partial throttle and the fact that it has trouble getting to redline leads me to believe the main is off. Id try stepping down a size on the main first before trying to tweak the midrange. If the main jet is not correct, everything else will be off too.

It is a common problem with FZRs. There is an issue with the transition in that range and it involves worn emulsion tubes. I've corrected the issue on at least 4 FZRs...

That's not to say that it will be perfect for the set-up that they have. There is always tweaking that will need to be done.

Try the needles first. If anything, you can rule it out before tearing up the brass jets trying to get them out with a straight screwdriver.

[pinkchev71]

[
was the bike running ok before the jet kit, spark plug replacement etc? (wondering why you tried a different known good TCI) if so id back track, easiest would be to replace the old plugs (could be a faulty new plug/plugs) any reason you cant go back to the stock jets? to see if it runs ok.

No the bike was having issues last season as well so we were asked to help out during the off season. It turned put to be a partial rebuild if you will, at this point. A lot of cosmetic work was done to this bike as well as mechanical.

The bike was running extremely rich and burning way too much fuel last season. Our buddy was constantly running out of fuel before everyone else, so we knew there was a problem. We did the normal tune up stuff and still had the problem, but he wanted to put a jet kit in for better fuel mileage and performance. He bought the bike for short $, so we figured what the heck, it's a really awesome bike. LIke knightrider said, we are going back to square one to see if we missed anything.

[knightrider092]

Hey guys after a few weeks of head aches...we finally got it...its was the after market coils!!!!! bike runs mint now...thanks again for all your help

[thatkid]

It's a common misconception, to blame the carbs when the engine "appears" to be running rich, but sometimes very true.

To fully diagnose carb problems, everything else should be confirmed near 100% efficient first. I.E. cylinder compression, ignition system is delivering the required quality and intensive enough spark to the plugs (your case, duff coils), faulty/worn plugs. All 3 conditions will result in un-burnt fuel, giving the impression that the engine is running rich, when it is not. If you have the tools needed to test its cost free, only labour time, which could save a lot of not to mention wasted time stripping the carbs.

If any of the 3 conditions are true, then by messing/fiddling with the carbs, as we say in th UK "your pissing against the wind"

On rare occasions iv'e found the fuel pump to be at fault (the pressure cut off system/valve) just keeps pumping petrol/gas, rendering the float needle useless, first time was a real for me.

The good point, when you've had a difficult time resolving an issue is, you remember those ones! it's the simple solution you sometimes forget.

I'm guessing the after market coils were new or recently fitted (the reason you didn't suspect them) goes to show sometimes expect the unexpected. Anything can be faulty, new or otherwise.

Thanks for taking your time to share the solution, helps other's. I.E. a replacement part was at fault, caught me out many times.