not performing on low revs {under 5000}

[Erika]

[*] bought a zxr4, brilliant little bike but is a bit poorly though. when it opens out its ok but anything under 5000 revs and it s and splutters and struggles to pick up speed.... i know nothing about engines but have been told that the carbs are in need of a clean as the bike was stood for a while before i bought it... is this the case? advise needed please...

[RedexRobB]

You need to be careful, ZXR's arent the best in low revs so might not be any problem at all. what gear are you trying to pull in?

When was it last serviced and what was done? Maybe worth giving it a new set of plugs and air filter, carb clean wont hurt either but my personal favourite is to put a shot of Redex in the fuel which should clean the carbs up a bit, always had good results with it and saves the disassembly of the carbs.

[Erika]

no service history according to the fella i bought it off, he gave me a set of new plugs as he was going to change them and said they did not need changing, cleaned the air filter that's okish, but will get a new one. it just does not like going slow, drop it down a gear to get a bit of acceleration and that's when it becomes poorly.
got quoted 126+ vat for a carb clean off a bike place that i contacted today, but your saying that this a common issue with these bikes, when it goes its like a pocket rocket but frustrating otherwise!

[Erika]

was looking at redex the other day, should have got some then, but i will give it a go, thanks for that

[ross46]

Another way you can use FedEx is to take the airbox off, rev the bike and pour a small amount into each inlet on the carbs, cleans the carbon off the valves, have you tried adjusting the pilots? Ride along, put the bike in 3rd and rev the bike from 3k, then try adding some choke, does it perform better when hot or cold?

[RedexRobB]

Thats one way of using Redex, I prefer to run it through a full tamk of fuel, you then have 100+ miles of it working on the fuel system and engine. Also saves dismantling the bike.

Might be worth having the valve clearances checked too, made a huge difference to mine in the past on how it runs down low.

[ross46]

I do both if ive got a problem, normally just chuck some in every so often. And +1 on valve clearances

[KwakKwak]

If the bike sat for a while, and there are signs of petrol residue, I would replace the gasket between the velocity stack and the air box, and the O rings on the carb holders, mine were caked in old petrol and pretty poor. Check the underside of the tank for pinhole leaks, fuel tap condition, inside tank too, if it sat with petrol in it. I'd also replace the fuel filter and check the fuel lines, I just replaced them all anyway.

The bike should not be that poor below 5000, especially dropping a cog, mine will pull happilly from 4000, never feels ill at low revs.