FZS 600 '98 model Under powered at 3/4to full throttle

[Fudge007]

Hi all I have a Fazer 600 98 model and I'm experiencing poor power output from half or three quarter throttle to full throttle . When I give it full throttle it almost dies totally and feels like its being strangled and the only way to maintain any further acceleration is by feathering the throttle back and forth . Also the bike always struggles to start with the choke on and mostly I have to use no choke and just use a few attempts if starting by using the throttle to get it started from cold ( hot starts are ok ) when it starts from cold it very often cuts out until it is warm. When I am riding it and I have been accelerating , when I throttle off , very often the bike back fires on over run. The intake rubbers are showing signs of external cracks but I haven't taken them off to examine if cracks go through to inside. Air filter has previously been cleaned but as long as i have owned it I don't think it has been replaced. Also the bike foes just over 100 miles to a tank of fuel , so not very economical , probably doing about 25-30 mpg. Bike really struggles to go faster than 100 mph too.  Does any one have any ideas.

[positron]

I know very little about bikes in general, but losing power and having to feather the throttle down to get power sounds like what I went thru recently, and in my case it was the air filter. Just cleaning it made it better and changing it to K&n made it really good. However like they say everything looks like a nail to one with the hammer etc. I am sure more knowledgeable folks would be along shortly.

[His Dudeness]

I'd agree with you positron it sounds like the air filter is totally blocked. I don't mean to be rude Fudge but why would you ride around for so long knowing you're only getting 100 miles from a tank and not do something to fix it? If it is a dirty air filter it must have been blocked for absolutely ages. And it's so cheap and easy to put a new filter in. You even hinted at the problem in your post so you could have sorted it yourself with a little poking around. Hope that doesn't cause offense I just don't understand how you could ignore it so long. You should definitely go for a K&N for once I think you'll definitely get the amazing performance gain that they promise on the box

[gregwillclark]

Hi Fudge,


I've had this exact issue since getting my fazer, its currently in at bare motorcycles in south wales (http://www.baremotorcycleservices.com/) (http://ultrasoniccarbcleaning.co.uk.websitebuilder.prositehosting.co.uk/) having the carbs reconditioned (ultrasonic clean and blasted) to try to solve the problem.


I changed all the electrical components to rule those out first (fuel pump, rectifier, Coils/HT leads, plug caps), then the air filter was changed to a brand new Yam one, no change to the issues we are collectively having.


The last thing before burning the bike or throwing it of the nearest cliff was to get the carbs done, as soon as i get it back ill let you know if it fixed the issue.


Greg

[reddave101]

By the sounds of it its just your carbs need a good clean. Stick some silcoline carb cleaner through the fuel and see if that helps? K&N is definately the way to go. if you are getting the pop over run you are over fueling. You need to check everything, Exhaust all tight and sealed, All rubbers not split, breather pipes all clear, fuel lines all clear, air filter clean, carbs clean. Mine over runs and pops on deceleration but that is what ive set mine up to do. As for the 100mile a tank, this isnt that bad, could be better but I average around 110 mile per tank. I do get more if motorway travelling but streets you dont get as much as the book says..

[darrsi]

By the sounds of it its just your carbs need a good clean. Stick some silcoline carb cleaner through the fuel and see if that helps? K&N is definately the way to go. if you are getting the pop over run you are over fueling. You need to check everything, Exhaust all tight and sealed, All rubbers not split, breather pipes all clear, fuel lines all clear, air filter clean, carbs clean. Mine over runs and pops on deceleration but that is what ive set mine up to do. As for the 100mile a tank, this isnt that bad, could be better but I average around 110 mile per tank. I do get more if motorway travelling but streets you dont get as much as the book says..

These bikes average around 10 miles a litre, whatever tank size (there's 3 sizes) unless you are absolutely thrashing the nuts off it all the time.
110 miles on an 18 litre tank seems very low to me.

[richfzs]

Agreed darrsi, I only ever dropped to 110 to a tan when absolutely caning it. Unless you're going everywhere at 11k rpm, there's something wrong.

[His Dudeness]

I think this problem is mostly from an ancient blocked air filter causing the bike to run rich. New air filter and new plugs would probably be a good idea too as I'd guess the ones in the bike are probably sooted over. A carb clean couldn't hurt but I don't think it's the main problem as dirty carb with blocked jets would be leaning the mixture not causing it to run richer and dropping the mpg so badly.

[Porthllwyd]

My intake rubbers are cracked and were when I bought them. They had electrical tape covering the cracks and I never took it off and have covered some 20,000miles with them like this. However, the other day I decided to sort them out, so I removed the tape and when ridden it behaved very similar to the way you decribe, once you reach about 4,000rpm it become very sluggish and when you open the throttle in bogs down and sometimes dies. I have now replaced the tape and I'm looking for some replacement rubbers (£90 new). Looks like a bit of a job to change them though, I need to see how many bits and pieces I need to remove and how much I can moved the carb back in order to remove the rubbers.

[darrsi]

My intake rubbers are cracked and were when I bought them. They had electrical tape covering the cracks and I never took it off and have covered some 20,000miles with them like this. However, the other day I decided to sort them out, so I removed the tape and when ridden it behaved very similar to the way you decribe, once you reach about 4,000rpm it become very sluggish and when you open the throttle in bogs down and sometimes dies. I have now replaced the tape and I'm looking for some replacement rubbers (£90 new). Looks like a bit of a job to change them though, I need to see how many bits and pieces I need to remove and how much I can moved the carb back in order to remove the rubbers.

I had one of my carb rubbers fitted incorrectly before (folded in on itself) and as you say if there's an air leak then the bike will bog down and ride really ropey on acceleration.


I noticed the OP has said the bike won't even think about starting with the choke on, which would suggest it needs either more air, or less fuel.
The backfiring on overrun would also suggest unburnt fuel as well, so same scenario again, too much fuel or not enough air.


Air filter would be an obvious start, but do not get a cheapo one, get either K&N or an OEM one, whatever takes your fancy.
I bought a cheap Hi-Flo air filter before and it felt as if the paper was double the thickness, it was really noticeable to ride, so i binned it very quickly and replaced it with a K&N which was like feeding the bike a packet of Fisherman's Friends, i could feel the bike thanking me. 


If that doesn't do the trick then i'd guess you have a problem somewhere within the carbs.

[Fudge007]

HI all ,in response to your advice on my issue with rtf he razer being under powered and back firing....... I removed the fuel tank and replaced the fuel filter and air filter and took the bike out for a spin. It never really revved out to more than 7 or 8000 rpm before, and now revs freely up to 12 or 13000 revs and the performance is great. I opened it up once to see how it pulled to my surprise the clock registered past 120. Thanks for your help and speak to you soon .

[darrsi]

Always nice when the easiest and least expensive option worked, glad to hear you got it sorted. 

[Fudge007]

HI Darrsi, thanks for your response, I agree that sometimes you can over look the basics.......but it's great when you get a problem sorted.    Speak soon

[bobertsoft]

Hi all. I'm new here. Please excuse me if I ask a question. I have the same problem as the chap above. I don't have any prob starting hot or cold. When the engine is in neutral the rpm's will struggle all the way up......smooth up to about 4500 to 5000....struggling from there on. But when riding its a different story. It struggles to get past 4500. Same bike...same year in fact. Any thoughts....or am I looking at the same issues as you've all discussed already. What confuses me is that the rpms will go all the way up in neutral but not when riding. 
I'm a real newbie at all this...sorry to impose. Thanks, Robbie

[His Dudeness]

Hi all. I'm new here. Please excuse me if I ask a question. I have the same problem as the chap above. I don't have any prob starting hot or cold. When the engine is in neutral the rpm's will struggle all the way up......smooth up to about 4500 to 5000....struggling from there on. But when riding its a different story. It struggles to get past 4500. Same bike...same year in fact. Any thoughts....or am I looking at the same issues as you've all discussed already. What confuses me is that the rpms will go all the way up in neutral but not when riding. 
I'm a real newbie at all this...sorry to impose. Thanks, Robbie

Do you know when it was last serviced? Has it been parked up or not used for a while? Is it running on all of the cylinders? It's probably a fuelling issue but might not be the same as Fudge's problem. His was fairly obvious from the really low mpg and struggling to start on the choke. So that pointed to running very rich which is where you're adding more fuel for the same volume of air or in Fudge's case restricting the amount of air for the same amount of fuel which is usually caused by a blocked filter. Yours might be going the other way and leaning out at higher RPM which would usually be caused by blocked carbs especially if the bike hasn't been used in a while. You could try a fuel system cleaner additive or if you've got a bit of experience using tools you could take the carbs out and give them a clean with carb cleaner.