Problems at high speeds.

[mr self destruct]

The title of this post made me smile
Problems at high speed
By Mr Self Destuct

The ironc thing is, the worst injuries I've had on motorbikes have both been at less than 10mph. 

[mr self destruct]

Well, it's not the regulator but for the sake of £25 I'm glad I found that out.

[His Dudeness]

You could do a plug chop. You're not going to solve the problem by doing it but it should give you some direction. You hold the bike at the rpm while the problem is happening and while it's happening hit the kill switch and then take a plug out and check it's condition. If it's dry wet etc. You're trying to get some evidence of what's happening instead of guessing

[unfazed]

Well, it's not the regulator but for the sake of £25 I'm glad I found that out.

Strange, the symptom you described was exactly the same as we had, if you hold it at 7000 for a short while and then gun it it died and then picked up. Fine if revved straight from off to the red line. It happened suddenly. My son had it out one day and all was fine, next day fault was there. We put in a new air K&N filter and oem fuel filter, but no change.
We swapped the following part from my 600 to my sons,  coils, plug caps, carbs, ECU, fuel pump, and finally because it was the only thing left to change the rectifier/regulator. It was only when we changed the rectifier regulator did the problem go.
We put the original rectifier/regulator back, problem back.
The bike still has my bikes original carbs on it as it was to much hassle to change them back  :lol

[mr self destruct]

The odd thing is, during the recent cold spell the problem almost disappeared. It'd die for less than a second then pick up. Today it was warmer and it didn't die, but took ages to speed up. I got caned by Golf tdi for fucks sake!
I'll try the plug chop when I can find somewhere to pull over safely, but as it stands I'm thinking the next step would be a carb clean and balance. Trouble with that is it'll take longer than I can spend on the bike in one go, and I can't be without it right now as I'm working my arse off.

[Disorderlypunk]

i have been annoyed by this recently (2 weeks into owning a fzs) - and i have read that its just a common drop off in power in that area
do not add tesco higher octane fuel as it seems to get worse (trying hotter plugs soon with hi oc fuel though)
after two weeks i learned the rev range and where i need to be dropping it a peg or two for very quick over takes
3.5k - 7k = town quick //// 8.5+k = racing the back roads and ovetaking like a nutter
the tesco crap hioc fuel i added made things worse at top end
- - i say this before i do my normal new bike carb strip oil and plub change, but i dont see it making much differance


this is all IMO stuff but im 33, riding my own bikes since i was 10ish and around race teams since i was born
check out disorderly punk on youtube for a laugh.

[Disorderlypunk]

a reg/rec should not cause issues in this respect - give me a minute here
a reg rec is there to supply power to battery, try a voltage meter you can see, would tell you if anything is wrong there as voltage would drop from 14.5ish to a sub 12v at the problem rev range
i am suffering this same problem and working through it periodicly


DO NOT try using the tesco high octane fuel or pro-milage stuff whatever its called
(actually if someone can and say its shit aswell) as it changed my power characteristics for the worse


i will be going back to standard octane fuel ASAP or maybe some from asda as it is all different (remember it isnt for power its for milage)
i found using standard fuel it is easy enough to learn the rev ranges- remember the fazer is known as a great commuter bike for couriors and the reasons are there to see 4k-7k works great for town 8.5/9k + quick acceleration like a powerband for overtaking on major roads - these are not R6's remember


im with you totaly i want more power and a more usable smooth power range but there are lots of things to consider
- looking at a new 2nd hand exhaust system so will let you know - unless everyone wants to chip in a £1 or two and i will go down to fuel exhaust head quarters and try one out and blag a discount for foc-u users lol (they are actually really close and i want to see there warehouse lol)

[mr self destruct]

To be honest bud the reg/rec wasn't top of my list of causes, but it's cheap and easy enough to swap, and if it sorted someone else's problem out it was worth a go.
As for petrol, I've always stuck to the Texaco by me so that can't be it.
I wasn't looking forward to stripping the carbs down and cleaning them so I'll do that last. I'll balance them first and see if that cures it.

[Fazerider]

I doubt balancing the carbs will have any effect at those revs/throttle openings… if you've difficulty starting/getting a good idle or it's snatchy at low speed it'll help there.
It's much more likely to be one or more slides getting jammed especially if you're snapping the throttle fully open. Does it accelerate OK if you feed the power in gently?
Another possibility is that aftermarket downpipes aren't a totally accurate match for the OEM ones. Some have the link pipes between cylinders 1&2 and 3&4, but most don't match the diameter of the bit after the collector to what Yamaha tuned the intakes,carbs and airbox for. The OEM one is quite constricted at that point some have found sleeving down aftermarket downpipes to about 35mm internal diameter improves fuelling in the middle of the rev range.

[mr self destruct]

It does accelerate ok if I open the throttle very gently, and I do have aftermarket stainless headers and noticed the larger internal diameter when I fitted them. So would rejetting the carbs be the solution or would it be better to stick with the stock headers? TBH that would piss me off as I ride all year and the stock headers are notorious for rusting.

[Fazerider]

I don't think anyone's had much joy with rejetting the FZS600 carbs. A short length of suitable diameter pipe to slide into the collector might be a cheap solution... certainly easier than finding a set of OEM pipes that haven't already rusted through.
Or you could buy new!

[mr self destruct]

What the fuck?! :eek At that price I could get a replacement Fazer!

I think I'll stop caning it above 90. Seems to be the realistic solution.  :\

[unfazed]

Do your headers have the link pipes between 1 & 2 and 3 & 4 at the front of the engine like the stock headers. If not this would cause a dip in the revs, but it occurs more around the 5 to 6000 revs mark than 7000.

I was lucky when diagnosing mine in that I had a bike that worked and was able to swap parts to fix the issue and the Rectifier/regulator was the last thing we changed since I was running out of ideas. Both bikes had standard headers and exhaust at the time.

[mr self destruct]

It's a Motad stainless set with the link pipes between 1&2 and 3&4. I'd heard other types caused problems so made sure I got that spec.

[daviee]

i run pipe without link pipes didnt make any difference at all still runs clean through the ful rev range and pulls from anywhere in the revs full throttle partial throttle al very clean and crisp i would say your carbs need a proper clean ultrasonic is the best way to clean them

[unfazed]

It's a Motad stainless set with the link pipes between 1&2 and 3&4. I'd heard other types caused problems so made sure I got that spec.

I have the same down pipes on mine and it runs cleanly.
Did the issues come on suddenly or progressively?

Is the choke working correctly and the plungers seating properly when it is released.
This was the first thing I checked when it first happened on my sons bike because I had seen a similar problem on an old GS750 Suzuki when the plungers were not seating fully due to corrosion, a shot of WD40 sorted it out.
Have you checked all the usual items like wiring for corrosion.
Drain the float bowls to see if help first and then check the float heights using transparent fuel line.

[mr self destruct]

I have the same down pipes on mine and it runs cleanly.
Did the issues come on suddenly or progressively?

Is the choke working correctly and the plungers seating properly when it is released.
This was the first thing I checked when it first happened on my sons bike because I had seen a similar problem on an old GS750 Suzuki when the plungers were not seating fully due to corrosion, a shot of WD40 sorted it out.
Have you checked all the usual items like wiring for corrosion.
Drain the float bowls to see if help first and then check the float heights using transparent fuel line.

It's difficult to say, in the decent I take the B road route to work where you can't really do more than 60, so it may have masked when the problem arose. It's only been over winter I've stuck to the motorways and noticed the problem.
As for the choke, this might sound odd but I've never touched it. No matter how cold it's been, the bike's always started and ran a treat if you don't count last year's plug cap issue.
I think some carb stripping is on the cards but I'll check the wiring out before that.

[bandit]

Have you carb tuned since fitting after market downpipes as this will need doing & might help even things out,if you are going to replace with a K/N air filter
do this before tuning carbs.

[mr self destruct]

I haven't, as I thought the downpipes would be a like for like swap. I have no intention of fitting a k&n either so wouldn't have thought tuning was necessary, but may be wrong given the larger pipe diameter.

[unfazed]

Where is the pipe a larger diameter.
Mine was a straight swap, if anything the end of the pipe for the exhaust was slightly smaller.
I have a K&N fitted and so does my son on his