New to me bike, Starts for 2 sec. then dies.

Hi guys,

I recently purchased a 1984 GPz 550. The bike has not been run for around 8 years. The PO cleaned the carbs recently.

I have verified the following:
-Fuel petcock seems to be working correctly. When in 'on' or 'res' position and gas line disconnected from the carb, no fuel flows. When in 'prime' fuel flows.
-I have removed the carbs and checked that the main jets are not clogged. The bowls did not look dirty. I also checked the needle and seat and it appears to be ok.
-I did not check the pilot jet. To be honest when I had it apart I could not see them on casual inspection, however in doing research I think I know where to look now.

Symptoms:
-Bike will start and run for ~2 seconds only when choke is out full. If I try to immediately restart it after it dies, it will just crank and sounds like it is trying to catch. If I wait 30 seconds, it will start and run for 2 seconds again. It does respond to throttle inputs during the time it runs.
-Upon startup, it will rev up to 4k before dying, but I assume this is because the airbox is not connected.

Where should I be looking? Taking the pilot jets out and more cleaning?

Does the petcock flow a lot? It should be a stream and not a trickle.
Do you have an inline fuel filter? If so is it a see-through type with a pleated paper filter? That type can cause flow problems like you are describing. They are meant for cars with fuel pumps. Gravity does not provide enough pressure for that type of filter.

And yes, you will likely have to get at the pilot jets.

It's possible you are trying to idle on the main circuit. If you keep revving it, will it stay revving or does it stall no matter what throttle you give? If it dies no matter what, then it's more likely a fuel supply/flow issue.

Hi, thanks for the reply.

It seems to flow as fast as gravity would allow it to. There is no fuel filter in between the tank and the carbs. When I rev it, it dies no matter what.

You'll need to take out the pilots and clean them. The jets are very small so carb cleaner and a strand from a wire brush will be needed. On the 550 I got a couple years ago I had to use my smallest jet drill. I made them a little bigger so it started easier and ran better.
Steve
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882

even with the pilot jets clean, don't expect much until you hook up the air box and stock filter. Clean pilot jets and it may idle. But until you hook up the air box, don't expect it to take the throttle well.

jdvorchak wrote: even with the pilot jets clean, don't expect much until you hook up the air box and stock filter. Clean pilot jets and it may idle. But until you hook up the air box, don't expect it to take the throttle well.

Good point.
If the airbox is off, you will need to put it back on, or get a Dynojet kit to run without it.

Ok, thank you for all your replies. I will clean them out again and hook up the airbox before trying again. I left it disconnected because I figured that it should run more than a couple of seconds even with them off and connecting them is a pain in the ass.

I will report back with my findings!!

I should have mentioned, you might get it to run by placing a cardboard shingle over the intakes. It will act like a restriction. You have to carefully manipulate the cardboard so it is not completely blocking the intakes. Leave about the top 1/4 open for starting.

This test is easier than installing the airbox. It takes a few tries to get the nack, but not too hard.

Hmm, good idea, I'll try that first!

Update - I misspoke earlier. When starting on starting fluid, it will respond to throttle. When it starts on gas, any throttle input will kill the engine faster.

Also - the way I received the bike, the vacuum port on carb 1 is plugged into the vacuum port on carb 4. Same thing with carbs 2 and 3. Maybe someone did this to keep the hoses out of the way? I assume one should be connected to the petcock and the other 3 capped off?

czentner wrote: Update - I misspoke earlier. When starting on starting fluid, it will respond to throttle. When it starts on gas, any throttle input will kill the engine faster.

Also - the way I received the bike, the vacuum port on carb 1 is plugged into the vacuum port on carb 4. Same thing with carbs 2 and 3. Maybe someone did this to keep the hoses out of the way? I assume one should be connected to the petcock and the other 3 capped off?

Yes. Two of them would have connected to the air suction system, but if that was deleted, then those should be capped off. That leaves one for the petcock and the fourth one should be capped off as well. But it won't usually cause the symptom you describe by being connected 1 to 4 and 2 to 3. The only issue then is that you'd have to run the petcock on prime all the time... not really a good plan in the long run. It will leave you stranded, eventually, out of gas.

I have used a shop towel over the intakes acting like a filter for testing and evaluation. Just use wire or long twist ties to hold the shop towel over the intakes so you don't suck it in. I've used both the red cloth shop towels and the blue paper type with equal results.