Ok all you clever folk I have a 1999 ZX 7R and towards the end of summer it has...

Ok all you clever folk - I have a 1999 ZX 7R and towards the end of summer it has gradually started running a bit ropey below 7000 revs. Above 7k it runs fabulous. When the engine is warm it is awful to start so I assumed it probably just needed a good tune and get the carbs checked and balanced so was going to book it in next week. However today, the weather was really damp and miserable and she ran perfectly without any misfires or hiccups. Does anyone have any ideas what could be going on? Many thanks for any help.

  • Valve clearances

  • Is that a mechanic job or is it fairly simple Steve?

  • Not a simple job mate, a job for someone who knows what they're doing. They are shimmed and could end in tears if anything goes wrong. Very often overlooked during maintenance.

  • Haha!! It's due a service anyway so I will get the mechanic to check them whilst it's in. I ain't messing with something that could kill it!!

    Thanks for your help Steve.

  • No probs, a mate of mine has exactly the same model and year and it was a pig to start when it was hot. The clearances sorted it right out. Good luck

  • Fingers crossed!! When it's cold it starts beatifully - when the damn thing is hot it just won't have it and I have to wait till it cools down! Sounds exactly the same deal as your mate.

    Cheers :)

  • It could be as simple as the air filter, when was the last time it was changed or cleaned. Filters like most things expand and contract, which could be your problem.

  • That's an interesting thought Gary - I don't even know where the air filter is ... I'll have to dig out the manual and locate the stupid thing to check it!

  • It'll be under the fuel tank, undo the bolt/Allen key at the front of the tank and lift it up it's hinged. I have a bit of wood I use to hold it up, but when you lift it mind you don't pull the fuel pipe off. Once you got it up you'll see the big black filter box which think has eight screws on the top,undo them and you'll see the filter. Take it out and if you have got access to a compressor give it a blast, replace it and give it a go. If it is does run ok still buy another filter.

  • Cheers Gary - I appreciate that. Will have a try tomorrow night.