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Hello everyone!

I have a zxr import on a 91 plate, at around 8000 revs there is a massive flat spot until around 1100 or 1200, it means the bike will only do 100 at a push!!

Is there anything that it could be? I've already had the carb rubbers replaced and its had a service with new plugs.

Also the engine is very rattly, but i've heard they are all like that!

Any info would really be appretiated!

when you replaced the carb rubbers did you notice any restrictors? has this been doing this all the time you've had it?

It was my boyfriend that replaced them, so i'm not sure. Do u think there could be a restrictor on it?

I've only done a couple of thousand miles on the bike and the flat spot has always been there.

if its only doin about 100 at a push then maybe restricted, but you say it picks up again after 1100 revs? not sure if it'll do this with restrictors could be just carbs need setting up properly?

sweep22 wrote:Hello everyone!

I have a zxr import on a 91 plate, at around 8000 revs there is a massive flat spot until around 1100 or 1200, it means the bike will only do 100 at a push!!

Is there anything that it could be? I've already had the carb rubbers replaced and its had a service with new plugs.

Also the engine is very rattly, but i've heard they are all like that!

Any info would really be appretiated!

They're the rubbers between the cylinder head and the carbs right?

If your BF has replaced them, he might of not put them in right.

I had exactly the same problem on my bike. In the end I had 3 flatspots 1 at 3000rpm 1 at 4000 rpm and 1 at 10000rpm and it was all due down to leaking intake rubbers.
Give it a quick check by spraying some karb cleaner over all 4 of them while the engine is running and see if the engine revs high or bogs down on it's own. if it does, then you have a air leak on the rubbers. Simply take the carbs and carb holders off (2 allen bolts on each) and spread some gaskget sealent on the engine intake manifold, let it dry for a few minutes and then put the holders back on. Put the carbs on and then start the engine and spray some more karb cleaner over the intake rubbers to see if they are still leaking air.

Rich

When idling, my bike would sit at 2/3k, and the carbs rubbers were the likely suspect.
Got new ones and fitted them, and it turns out it wasn't the rubbers, but the sealant
that had been applied between the rubbers and the engine.
New rubbers, fitted correctly, shouldn't need any additional sealant. Just make sure the
metal surface the rubbers fit to, is clean and flat/even.

Dont the inlet rubbers have a rubber gasket that sits in a recess on the rubber?

Yep. It's like a large o-ring that sits in a recess on the underside of the
rubber. It's the rings that make the seal to the engine, hence the reason
you shouldn't need sealant.

Mine didn't come with those that's why I thought you need gasket sealer.

Ah well, wrong again.

MillaMeter wrote:Mine didn't come with those that's why I thought you need gasket sealer.

Ah well, wrong again.

Least you found out and learned tho!

I think that's why my bike had been all over the place, the fact that the o-rings
had been missing, so someone had used a load of sealant. The new rubbers
came with the o-rings fitted, otherwise I might not have known either.