Project 1998 ZZR250

This afternoon I put the battery in, tank back on, splashed a bit of fuel in and she fired right up.

Unfortunately there's still a few problems and looking like I might have to strip and clean the carbs. She's running really rich and blowing a bit of smoke (unburnt fuel) and won't hold an idle. If you rev it up it will drop to about 3k revs but sit there. You can use the idle adjust to drop it back down again but then it usually dies.

 

Definitely no leaks. I'm going to start with syncing the carbs and making sure the mixture screws are correct. With everything else that's been done to this bike it wouldn't surprise me if they had been messed with. Someone has probably tried to tune it to run without the airbox when they couldn't get it back on the carbs.

 

I've been trying to tune this bike all morning and finally had a bit of a breakthrough.

I would get the bike started and warmed up, tune the carbs and have it nicely running but then the bike wouldn't start again after being turned off. This was repeated several times with mixed results but all ending up with the bike not being able to start again.

I finally resigned myself to pulling the carbs again to clean them but as I was pulling the tank the main fuel line didn't have any fuel in it so I decided to check the petcock.

It's vacuum operated so I attached a small tube turned it to Prime and sucked on it.... a couple of drops came out. Turned it to On, sucked on it.... same result, only a few drops. Turned it to Reserve, sucked on it... fuel comes rushing out. So it turns out the petcock only works on Reserve.

Put the tank back on and managed to get it reasonably tuned, idling nicely and the revs don't hang anymore.

But now I have to find another petcock or rebuild kit.

 

Have been a bit lazy this weekend but happy to say the bike is now tuned. Starts straight away when cold with a bit of choke, idles and revs nicely.

The only other thing I achieved was finally drilling out the front broken off bolt that holds the tank down. Whoever over tightened and snapped that off

At least I got another use out of my expensive timesert kit I bought to fix the CBX oil pan.

 

It has been a while since I updated this thread, the little ZZR has just been sitting in the shed.
I had the kid home sick today so thought I'd take the initiative and rebuild the carbies.

Long story short, I'm still having issues and need some advice.

Carbies were cleaned and rebuilt with the Litetek kit I've had sitting around for quite a while now.
Managed to get it all back together with only a minimal of swearing at the air box.

After getting it all back together the story was the same as last time. I got the carbs synced, fuel mixture screws adjusted and idle set. The bike starts, idles fine, revs cleanly and drops back to idle. Then the trouble starts... after it gets warm it's acting like it's flooding. The idle slowly drops until it dies. If you give it a bit of throttle when it starts to die it bogs down a bit then revs and sits back on the set idle again for a few minutes until the process repeats.


After it dies it's usually hard to get started again exactly as if it was flooded. Sometimes you can open it full throttle and it just manages to idle until the extra fuel clears up, other times I have to leave it sit for 10-15 minutes before I can get it started again.

So is it float heights? The float needles don't seem to be leaking, as you can see in the video I was pouring fuel into a funnel while syncing the carbs and the level in the funnel would hold steady with the engine off.

Valve clearances? I would have thought I'd have issues when starting cold if it were valve clearances but it starts fine cold with a bit of choke, it's only once it gets warm that the problems start to appear.

What is going on with this bike? I think I've got it sorted but then this issue keeps coming back.

 

I have been adjusting when it's warm (fan kicks on and off). I know it's a bit rich at the moment but it doesn't seem to matter where the mixture screws are set.

Originally I thought this was the problem and I'd have it all set and running nicely then these issues would start and I'd think I'd done something wrong so I'd take the screws back to 2 1/2 turns out to start again but still couldn't get the bike started due to flooding.

Anyway, that was a bit rambling but I don't think it's mixture screw settings.

 

Thanks. I have done the valve clearances but I'll go back and double check them. Easier than getting the carbs back on the airbox yet again.

 

After nearly 6 months I'm finally happy with how the bike is now running. After replacing the float needles the flooding issue when hot seems to be completely fixed. I had it running for close to half an hour today and took it for a ride up and down the road with no stumbling or flooding issues.

The clutch needs a bit of adjustment, rear brake needs more bleeding, and I need to get some new brake and clutch levers for a roadworthy but I think I'm just about at the end of the road. After rego it still needs a bit of a cosmetic touch up but might just pass it on to a learner how it is.

This one has definitely been a learning experience. Often frustrating when you can't work out what's going wrong but definitely a feeling of accomplishment in the end. It turned out to be not as much of a bargain as expected and I won't get back what I spent on it but this is my hobby and the amount of enjoyment and knowledge I've gained has been worth it.