fzs600s unrideable under load

[foccerjohn]

Hi,

03 fzs600s now just over 100k, runs perfectly and revs crisply at a standstill, but under load has become unrideable. This problem was at about 7,000rpm, but has got worse, so now at lower rpm.

My dad thinks it could be the ecu generating a weak spark, any ideas?

Thanks,

[Fazerider]

Possibly. Or it might be fuel starvation (muck in the carbs, water in the fuel, clogged filters, dying fuel pump, blocked breather). Or something obstructing the air intake. Or a damaged diaphragm in one of the carbs.
I'd have a good look at all those before spending money on replacement parts selected by guesswork.
Try the drain screws on the carbs for a start, catching what comes out in a jam jar to see if it looks clean.

[Jules-C]

My first check would be the air filter, swap it for a new one even if it doesn't look to bad

[foccerjohn]

Thank you for the replies, some things to check out. Will report back.

[His Dudeness]

Is your mpg down quite low?

[foccerjohn]

Yes it is, dropped quite a bit.

[unfazed]

Hi,

03 fzs600s now just over 100k, runs perfectly and revs crisply at a standstill, but under load has become unrideable. This problem was at about 7,000rpm, but has got worse, so now at lower rpm.

My dad thinks it could be the ecu generating a weak spark, any ideas?

Thanks,

Start with the easy/obvious bits first


Check/change the Air filter, fuel filter.
Check fuel tap flow
Check pump flow
See if anything changes

Drain float bowls to check for dirt and water in the float bowls
Drain tank  dry and refill with fresh fuel. See if anything changes

If problem still exist let us know as there are other simple things to check and rule out by trial and error.

It could even be something as simple as a dodgy regulator but rule oit the obvious ones first

[foccerjohn]

Thank you for your replies. I'll need to read up how to check these things and report back.

[sgpwwg]

When the problem happens check the exhaust down pipes. If one or two are cold it is more likely to fuel starvation due to worn diaphragms. Have had the same issue on mine at 86K miles. Bought a replacement set of carbs from fazer spares for £40 problem sorted.

[foccerjohn]

Hi,

I've made a  few checks, the downpipes are all hot when bike is running, regulator charging at approx 14volts as rpm is increased. I've put on an alternative set of coils and the problem is still there. It runs terribly at anything over about 30mph shuddering and possibly spitting slightly, but well under no load. Considering my increased fuel consumption I was thinking that fuel wasn't the problem but now I'm thinking it might well be. Also because it's running so badly, impossible to get over 40mph I was thinking that it it's likely to be more than a spent air filter. Any input greatly appreciated and also how to check fuelling, pump etc. I had the tank off and fuel tap seems to be ok.

[JoeRock]

Hi,

I've made a  few checks, the downpipes are all hot when bike is running, regulator charging at approx 14volts as rpm is increased. I've put on an alternative set of coils and the problem is still there. It runs terribly at anything over about 30mph shuddering and possibly spitting slightly, but well under no load. Considering my increased fuel consumption I was thinking that fuel wasn't the problem but now I'm thinking it might well be. Also because it's running so badly, impossible to get over 40mph I was thinking that it it's likely to be more than a spent air filter. Any input greatly appreciated and also how to check fuelling, pump etc. I had the tank off and fuel tap seems to be ok.

First things first - check your air filter. If it's really crapped up then you might well have these issues.

[unfazed]

Hi,

03 fzs600s now just over 100k, runs perfectly and revs crisply at a standstill, but under load has become unrideable. This problem was at about 7,000rpm, but has got worse, so now at lower rpm.

My dad thinks it could be the ecu generating a weak spark, any ideas?

Thanks,

Start with the easy/obvious bits first


Check/change the Air filter, fuel filter.
Check fuel tap flow
Check pump flow
See if anything changes

Drain float bowls to check for dirt and water in the float bowls
Drain tank  dry and refill with fresh fuel. See if anything changes

If problem still exist let us know as there are other simple things to check and rule out by trial and error.

It could even be something as simple as a dodgy regulator but rule oit the obvious ones first

Did you not read the above?
Poor running and high fuel consumption, first thing you check is the air filter

[snapper]

I dont have a 600 and know very little about then but i had this same problem with a mk2 escort ticked over reved but he second it was in gear it just had no power drivable but only just , turned out to be the timing had slipped ! and the advance retard was faulty ,
 sorry if it not very helpfull but  you nver know !
 
 

[crickleymal]

I had a similar problem on a ZZR after I'd cleaned the air filter. Turned out I'd not screwed the air filter box back together properly.

[foccerjohn]

Thank you very much for all the replies and suggestions.

It was the air filter as suggested.

I can't quite believe that it was this simple. I was resigning myself that the bike was going to Fazer heaven.

I should have looked at this much sooner and have neglected some of these service items. In my defence I had taken the bike to be thoroughly looked at for this problem towards the end of last year and the mechanic replaced the cam chain, he assured me he had gone over the bike in detail. I assumed he would have checked over the service items, although since then it has got much worse and the fuel consumption has increased.

Thanks again for all the replies, you have saved my bike and my back, as I have been commuting on my other bike which does cause me some back pain.

[Jules-C]

Good you got it fixed. Amazing how it feels like something seriously wrong with the bike when the air filter blocked you might've thought it would just give slightly reduced power

[unfazed]

Back to the old adage, check the simple stuff first.
Glad you got it sorted

[sinto]

Another lesson learned on here yet again, my book of notes is getting bigger and bigger