Problems at high speeds.

[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?! 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

[tommyardin]

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

I am with Daviee,
I have read so much about the S/S headers and collector, I have read stuff like if it doesn't have the 1-2 & 3-4 small diameter links between the base of the down tube the bike will run sluggish and have a loss of it's mid range power.


I replaced my original down tubes after they perforated at the base of the collector about 2.5 years ago, I also fitted a round S/S Pipewerxs Round Sports Can at the same time, (Road Legal with removable baffle in situ) and have to say that my experience had been the same as Daviee's.


My bikes hits 130mph in 6th (Top) gear at 10,000 rpm and will pull on until 142 mph top end with a 16 tooth front sprocket (Sat Nav not Speedometer as speedo is generous to the tune of 4 MPH), speedometer show 146 mph. Would the bike do any more? Don't know pure speculation.


The bike starts sweet, 25% choke in really cold weather, no choke at all if above + 2 or 3 degrees, do not touch the throttle, dab on the starter button bike fires instantly, back the choke off after 15 seconds and bike ticks over sweet.
I have found the bike to perform well with the S/S exhaust system on with no power loss issues what-so-ever, I'm not saying it's better than the Yamaha system, but, it is just as good and looks so much better.
I purchased my S/S Headers on EvilBay I honestly can not remember what I paid for the but I am guessing about £200-£220, and the Pipewerxs can was £180.


The RRP for the Yamaha end can is over £600 and the down pipe and collector over £1200, the £400 I paid for my system pales into insignificance compared to the Yamaha kit, and as said earlier IMO looks a lot better, it performs as well and does not rust, Win, Win.
I tried to go back through my EvilBay history to try to find the S/S headers, but, can only go back 2 years for some reason. 

[tommyardin]

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

If the original can fits on the link pipe I'm guessing it must be an internal pipe restriction, like a pinch point or pinch tube within the exhaust pipe?

[mr self destruct]

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

It'll be a larger internal diameter at the collector ref Fazerider's post. Fuck knows what I'm going to do as refitting original pipes doesn't seem to be an option any more.

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!

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

I think a strip and clean will be the way to go, but what make are your pipes?

[bandit]

Motad.

[tommyardin]

I am just wondering.
Has anyone ever cut through the 'link pipes' I.e. Small link pipes at base of down pipe that join 1-2 & 3-4 (obviously on a shagged set of pipes) to see if they are actually pipe or just solid bracing lugs that help stop flexing or vibration. Or if it is a piece of pipe/tube is there any holes in the down pipes to allow the bypass of gasses.
An FZS 600 boring along the road doing 10,000 rpm x 4 cylynders = 40,0000 piston strokes per minute, that equals 666 piston strokes per second (I know, it sounds impossible) and that every other upward piston motion is an exhaust stroke, that's one awful lot of exhaust gases howling through the downpipes is there any time or space for perhaps an 8 mm inside diameter or so link pipe to make any difference as the 1-2 & 3-4 will all be competing for exhaust space, especially as all four down tubes exit into a single collector before being forced into one single pipe as it leaves the front pipes and again being restricted by a baffle in the tail pipe.
Please excuse an old man's ramblings but it is something that has crossed my mind. 

[mr self destruct]

Is this a link between 2 and 3 further down the pipes on a stocker?

[bandit]

No the link pipes are other ones that's just a brace between 2/3 the same that's on your Motad exhaust.

[unfazed]

The main issue here is that you are unsure if it came on gradually or suddenly
Suddenly would point more to Electrics whereas slowly might point more to items wearing.
Since the Motad Stainless is a common replacement it is unlikely the fault lies there

The only way to resolve it is to rule things out with a check list and literally trial and error

Fuel tank breather
Plug Caps
Check the resistance as the internal carbon resistors can break down and put the resistance to meg ohms intermittently.
(I replaced the internal resistors with ones from old NGK Caps)
Coils & leads
Air filter (K&N is a good replacement)
Fuel filter
Fuel flow (Tap and Pump)
Choke operation
Carb Balance
TPS
Plugs
Intake Manifolds
Carburetor Diaphragms (can be removed with carbs in situ)
If all above check out and you have changed the Rectifier/Regulator (but no guarantee it is working properly as the faulty one I had tested OK statically)

Then remove the carbs and check them, including the Pilot screws.
When the carbs are off check the valve clearances

[tommyardin]

No the link pipes are other ones that's just a brace between 2/3 the same that's on your Motad exhaust.

There in lies the problem, a number of us seem to understand something different when we talk about the link pipes between 1-2 & 3-4.

In the re-hashed picture below is what I understand when people talk about the link pipes between 1-2 & 3-4, these are what I am asking about in the post above are they joining /link pipes or just braces that stop vibration and or flexing?


The other part indicated I understand to be the collector.
Someone with more knowledge please comment and help this old geezer understand

[daviee]

get the carbs cleaned it can cure lots of problems deffo the first thing i would do