I think i'm going to burn it - one seriously p*ssed off foccer!!

[gregwillclark]

Hi All,


Over the past few weeks i've posted about a misfire issue i've had in all gears between 7-8k rpm. The bike has been at the local garage (great guys!) for the past 2 weeks for various diagnostic tests etc but i'm afraid even they have failed to solve the issue!! I'm going to list below what has been done and if no one has any ideas then I think i will be throwing the bike from the nearest cliff!!


Carb rubbers changed.
Breather pip[es checked (Tank and carbs).
Rectifier/Regulator changed to a known good part (from noggy).
Coil packs anf HT leads/caps changed to a know good set (from noggy).
Carbs cleaned and rebuilt 3 times (Rebalanced after every strip down).
Rear wiring Loom changed to a know good loom.
Fuel pump changed to a known good pump.
Generator changed from a known good engine.
Carbs & TPS changed to a known good set of carbs (balanced before testing).
Electrical check of all components (TPS, Rectifier, Coils).


The one and only thing I have yet to change is the ECU/CDI unit, does anyone think this could cause this issue?


I am happy to throw a final few quid in to the fzs black hole to test this but i'm really getting to the end of my patients!!


Any help and advise is welcome.


Regards
Greg

[unfazed]

What kind of mileage is on it?
Is it a misfire or drop off in performance? Does it rev cleanly above 8k or not.

Does it backfire (misfire) through the exhaust or die and pick up again?

Misfire is usually, (not always) electrical and drop in performance is usually (not always) fuel/air related.

Have you changed the air and fuel filters?
Did you do a compression check?
Is it worse when hot or cold?
When they cleaned the carburettors did they check the tiny inline filter in the fuel line T piece on the centre of the carbs?

[gregwillclark]

Hi 'unfazed', thanks for the reply...

Its got 19k on the clock but by the sound of the cam chain rattle when cold it may be more in reality.

It revs and pulls clean all the way to 7k and from 8k all the way to the red line. If i need to overtake at motorway speeds I need to drop it down a gear or two to take it above the 8k mark and it pulls great!

It does not misfire at all, it just feels like a severe lack of power and missfire between 7-8k rpm. If I feather the throttle through 7-8k rev range it picks back up fine.

Fuel filter and air filter were recently replaced with OEM parts in a full engine service at the same time the carb rubbers were replaced.

I've not done a compression check but it looses no oil, does not smoke when cold or hot, I could easily do this though so I may later.

There is no difference in issue when the engine is hot or cold.

I assume they checked the small inline fuel filter, I will ask later tonight when I see the mechanic.

Soooooo frustrating 

[Paul]

Do you have a standard or after market set of exhaust header pipes?


And have you checked the spark plug colour?

[kebab19]

Has your bike always had this dysfunction or did it start to happen after an event, ie the service?

Have you looked in the airbox?
Although a different bike, I've noticed in the past that a couple of 1000 owners have either accidentally left a nut / bolt inside the box or restricted the open part of the airbox / air intake part and reported a similar problem.

 
Perhaps Red98 will be along to solve the problem, tho this thread will increase up to about 39 pages before that happens ;-)

[red98]

Hi greg.....know how your feeling mate...your missfire is exactly how mine started and slowly got worse to the point where I could'nt ride it.....you've swapped the same items as me with the same results.i did however get a good improvement with the regulator but I dont know why, I got it to a point where it was rideable but not perfect, booked it into a dyno session, they could'nt find anything wrong but tweeked the mixture screws a bit, it runs as good as new now but I dont know what the answer was for sure.i do have a spare ecu you could try but they seldom fail....dont give up matey, be worth it in the long run...

[thunderpantz]

I'm having the exact same problem. Happens since I changed my collector pipes, so im hoping its just the fuel mixture in the carbs. Its just finding the time to set them up again. Everything else is sweet. Just this little niggle

[gregwillclark]

Hi guys, thanks for all the replies, it may be worth adding a little bit of history:

I bought the bike as a semi-non runner for cheap money with the aim of slowly doing it up. Then time caught up with me so I had a garage help out. The down pipes were changed for a second hand set of Motad stainless as the originals were rotten. A NOS Motad Can was also added. The wheels were replaced with NOS wheels and Pilot storm rubber added. The carb rubbers were also replaced due to cracking and a full service including plugs, air, oil and fuel filter replaced.

The bike was then used weekly for a few months where is when the current issue was discovered. I had not ridden for 9 years so I was not being heavy with the throttle initially so the issue was not seen.

As confidence grew the throttle usage became more aggressive and the issue raised it's ugly head. It is then I changed a few things myself, mostly the bolt off bolt on electricals (rectifier, HT leads/coils, fuel pump etc).

Having made no difference I decided to get the carbs overhauled thinking a load of old fuel may be blocking jets and sludge in the bowls after years of non usage. I was right the carbs were dirty but not bad enough to cause this issue. The garage then tried a few things like the generator and loom after identifying a few issues that may have been caused by the loom looking like a halfords audio 'specialist' had taken a stanly blade and electrical tape to it (sorry MarkWales)! Still no improvement. I recently sourced some carbs off eBay with warranty which included TPS. Fitted, balanced, still the same.

I've had the bike back now and will put it away until I can be bothered looking at it again. I also think the ECU is fine but it may be worth ruling that out for peace of mind.

It then may be worth me sourcing some OEM downpipes to rule that out, although MarkWales has the same ones fitted with a scorpion can with no issues.

After that it's being burned :-)

Greg

[Davew]

have you checked the fuel/air mix screws.  Don't think you're supposed to adjust them but someone may have done in the past meaning its under or over fuelling at points.

[unfazed]

Since it does not misfire it sound more like a fueling issue.
Does not necessarily have to burn oil to have low compression. Leaking valves will do it.
Always safe to check the entire fuel line from the tap to the needle valves.

What appears to happen is the the fuel delivery is slow and the pump cannot keep the bowls supplied with sufficient fuel when the 600 comes on the power band at 7000 revs. Feathering it through seems to give the fuel pump time to fill the bowls up. It does not seem logical, but each time we cured the fuel flow problem, the problem disappeared.
Bikes which are left idle for long periods would need to have the inline filter and the fuel tap flow checked as both can become coated with fuel residue and cause a restriction in the fuel flow. No matter how good the pump is it cannot drag enough fuel through a smaller pipe
The pilot jets can be adjusted and the setting are 2 turns out from fully home on the 98 to 01 models and 2.5 turns out from fully home on the 02-03 models. I always check them as many carbs I have cleaned over the years had wrongly set pilot screws when mechanics tried to fix issues by adjusting the pilot jets incorrectly.
Picture shows the inline fuel filter and many people are unaware of its existence.

[gregwillclark]

'Unfazed' thanks for the info! I did not think to check the fuel flow from the tank. I know the in line filter got changed and the fuel looks clean but I suppose that does not discount old fuel build up or debris in the bottom of the tank after standing for so long. Any advise on how to check the file flow from the tap?? Is there a rate ltr/sec or something similar to check for??

I'll double check the t-piece filter tomorrow.

Regarding the carbs though, we tried 2 sets and both had identical issues, so either I'm massively unlucky to have 2 sets of carbs identically wrongly adjusted or the issue is before the carbs i.e the fuel tank?!

Greg

[darrsi]

Unfazed could you give any more info on that in-line filter, i really didn't know that was there at all?


Is it just the one like that, and does it really need changing at any particular intervals?


I noticed on this diagram that they list another filter as well, no's 50 AND 37, which is more news to me, can you enlighten me on that one as well please mate?


This is like finding something new on your body that you never knew was there all these years. 


https://www.yamahamotorcyclespares.co.uk/genuineparts/9657/11/yamaha%20fzs%20600%20fazer%2000-03/carburetor?uID=0

[Millietant]

Have you had Deefer666 check your bike out?  I know you say your locals are good guys, but Mark is one of the stalwarts of the Foccer world and has a lot of fantastic feedback on here.

[dcurzon]

Spark plugs gotta be worth a go

[Ruby Racing]

Spark plugs gotta be worth a go

That was my thoughts too.

[gregwillclark]

Morning gents,


Spark plugs are good, not sooty/dirty and gap is spot on.


Where is Deefer666 located?


Greg

[darrsi]

Morning gents,


Spark plugs are good, not sooty/dirty and gap is spot on.


Where is Deefer666 located?


Greg

http://www.motorcycle-republic.com/

[johnakay]

Morning gents,


Spark plugs are good, not sooty/dirty and gap is spot on.


Where is Deefer666 located?


Greg

that doesn't necessarily means that they work OK.
try a new set only then will you know if you've got a duff one or two.
I've had new plugs  fitted to my thundercat and she was misfiring alarmingly till I trace 2 plugs that where faulty.
got them exchange and she ran like a good'n so it worth a try.

[MarkWales]

Dont burn it