Hi all

I have a 98 F3 UK spec bike, had it a few months and its been fantastic. Today the bike went to reserve so I filled up as usual at the same fuel station and same pump i always do on normal unleaded. Pulled out of the fuel station and noticed the bike would not pull hard on full throttle, if you roll on its ok ish. No hint of missfiring. Riding home tonight I was in top gear and gave it a full throttle and it has no go at all, roll off the throttle and it starts to accelerate again. it certainly is not right.

I have had a good read here before I do anything. After reading I have a few things to check but just want to run it by the more experienced people for advice.

I suspect its the fuel pump contacts, but I plan to also check the plugs and in good running order, plug caps are in good order and fuel filter is ok. I will check the airfilter as well.

It feels like a massive flat spot and that is new to me. Would hitting the rev limiter accientally yesterday have done anything?

Any suggestions before I start on the strip down?

 

The air filter is filthy and the fuel filter does not look like its ever been replaced so they are first on the list. I checked the contacts in the fuel pump and they look fine, plugs all look good as well.

To be honest it feels more like fuel starvation than ignition so I am going to replace the air and fuel filter and see if that improves it, if not I will replace the fuel pump contacts. If that does not work I will replace the plugs. if that does not work I will remove the carbs and clean them as that looks like a right pain to do.

 

If my memory serves me right, mine did the same thing. I swapped my air solenoid valve and it fixed the problem.

 

Thanks for the pointer, reading the symptoms I am not sure that's my problem. That said it will check all hoses are connected etc if the first few things don't cure it.

 

I just bypassed my solenoid altogether. Only takes a few minutes, and can't hurt to try.

Post with instructions:

https://cbrforum.com/forum/cbr-600f3...83/#post840830

 

You make a good point and for that reason I will give it a try. Thank you for the link.

 

Update - Bike is now fixed (thanks to this fantastic forum)

All, thanks for your help and input (and use of the search button), just a note to say my bike is now back to running as good as it ever did. I cleaned the K&N air filter as it was totally filthy and replace the fuel filter as that looked like it was on the bike from new. I also replaced the contacts in the fuel pump even though mine did not look too bad they certainly were not as good as new.

Upshot the bike runs really well again. One thing I did notice during my searches through the threads is that the K&N filter seems not to be a good filter for the F3, reports of flat spots etc etc. I dont have loads of mid range but as I have nothing to base it from its ok as it stands. I have purchased an OEM filter anyway and will be replacing the K&N too see if it improves the power delivery further once it arrives.

I will let you know my findings either way.

 

So, was there any one particular thing that seemed to fix it, or was it the combination of the things that you did ?

 

I dont know which one fixed it as i did all three at the same time. I would say either the air filter or the fuel pump contacts.