Hi All,

New to the forum and also to biking. Looking for some advice to a problem that has me stumped. Apologies if this has been answered elsewhere in the forum, I have searched (on my phone - no laptop) and can't seem to find an answer.

I purchased a 600F 4Y with 16000 on the clock; in excellent condition and ran like it was fuelled on double cream - very happy.

During winter my fuel pump went which I had replaced with an OEM Tourmax (Mitsubishi) and the bike was fine but seemed to only start with the choke even when it's only moderately cold. Progressively the issues got worse to the point where the bike would not go beyond 80mph, only start with choke. So I went to the garage and they advised my carbs were gummed up (bike was purchased from a weekend warrior - full service history). Garage found a broken screw in the car body the carb on removal so I replaced it with a used car from a bike with 12k on the clock. Garage ultrasound cleaned the carburetors and bike now goes above 80mph but will still only start with choke.

Now I understand it is cold so using the choke is normal. However the other issue I had with the bike was the bike now revving down when the throttle was released. I asked the garage to replace the cables but they said the cables were fine. I got the bike back but the issue is persisting. So yesterday I replaced both cables (which weren't in bad condition actually) with brand new lubed one. I've adjusted the throttle free play to the 1-6mm play recommended by Haynes manual (I went for about 1.5mm play).

Now when I release the throttle I'm still having the same issue in that the bike holds revs and you virtually have no engine braking so I'm really confused as to what the issue could be? I don't really rate the garage as they gave the bike back with 15mm throttle foreplay, lots of loose screws and also the adjuster nut on the throttle cable was quote literally free to dangle!

So we have an ultrasound cleaned carbs (hopefully correctly installed by garage - they have been cleaned as o opened the bike up yesterday and you could eat your dinner from them) though they weren't balanced, new fuel pump and brand new open and close cables adjusted to recommended tension, routed correctly, not snagging but a bike that just takes its sweet time to drop revs.

I am new to biking only having passed my test last July and this is my first bike. Apologies if the answer is obvious. Thank you all in advance.

Numan

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Looks like your running very lean, as you have put a new pump on , and carbs have been cleaned (correct jets and float heights) ,then it could be down to fuel supply from the tank, check that the fuel line isnt clogged , the tank is clean and carbs are tight on the engine inlet ports

 

Thank you for the response. I will have a go at the three items you mentioned next weekend and let you know if it solves the issue. Much appreciated

 

I should add that when the fuel pump was switched it was only the pump and not the connector hoses or the filter. Would changing the filter make a difference?

 

If the old filter is inhibiting flow, it certainly would.

 

Thanks echowars. Hopefully this weekend I can open her up again; weather permitting. Though I had it in my head that if the revs were not dropping this would be because too much fuel was getting through (sorry, I'm not naturally mechanically minded).