Cranks but no start after rebuild.

Okeydoeky.

So I rebuild my bike's engine ( 1980 ).

It isn't the battery - I jumped it with my jeep.

It shouldn't be the carb. I drained it when the engine came out, and nothing was clogged prior.

I am getting spark as well.

Upon removing spark plugs and shining a light inside the engine I feel it blasting air at my face when engaging the starter.

I tried starter fluid but it wasn't helping.

 

Are the ignition coils hooked up to the correct cylinder?

 

I believe so, my 2-3 cylinder one doesn't have a label on it. It is worth double checking.. What is the coil order from left to right?

 

What bike? On the 550, the left coil (usually) fires 1 and 4, the right coil (usually) fires 2 and 3. The other alternative that somewhere along the way, the timing plates got messed up. To me, if you're getting compession and using starter fluid, spark is the issue. You can have spark, but if it isn't getting fired in the right order, she still won't light.

 

Well yea, I checked the order and read up on it. Yahama uses a wasted spark system in the 650. You can swap 1 and 4 ( the outers ) and 2 and 3 (the inner ones) and nothing would change. The coils where correct.

However, is it possible the coils have gone bad after sitting too long? I checked the spark color and it is a purple / white-ish spark.

It was decently cold, but I'll try again when it is warmer tomorrow morning. "

Now .. is it possible for the carbureator to somehow block the starter fluid? Or maybe the fluid went bad? I had very little fluid left as well when I tried it.

 

Bad coils are a possibility. Mine were cracked and putting out bad numbers when it was humid. Have you checked the coils with a multimeter?

How did you inject the starter fluid? From the nipples on the intake manifolds? Or at the carbs entrance from the airbox? If you sprayed from the airbox, the butterflies need to be open or cracked to let the fluid through.

 

If you're getting a bluish/purplish spark , you got strong spark..

If you don't have enough starter fluid it still won't fire.... But if you have too much, you'll get a good backfire, too

Did you time the engine correctly? Valve clearances?

Is the tank full? Is it connected? Did you put it on PRI to refill the bowls first? Enricher on? How long were the carbs off?

 

Yes sir, did valve clearances and timing when the engine cams went back in. So about a week ago.

Tank was full, PRI to refill carbs, choke was on.

Carbs were off from october 2014 to yesterday.

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Is there something in the carb that could stop the starter fluid to getting to the cylinders? Assuming valves are correct.

Also, it was a wee bit cold lastnight when I tried to start it. I ran out of starter fluid ( I had very little left in the can to begin with. ) I wonder if I was actually out of fluid, and it was just spraying whatever out.

Upon cranking the engine with the carbs on, ( never been started ) should there be a gasoline smell on the plugs?

 

maybe a compression check is in order. I would also verify that the float levels are correct.

FU

 

Sound like fuel valves are stuck shut.....

Could simply be out of starter fluid---you should at least grt it it to pop, but if no gas smell on the plugs, you're not getting fuel to the cylinders. Spray a squirt into the plug holes first reinstall the plugs and then try again

 

I bought a new can of fluid today. After the first squirt of fluid, and the bike running and the dying.. ( Forgot I needed choke ). The bike would start without fluid. Woohoo!

Turns out my old can must have just been releasing any left over pressure. Now it is time to adjust the carb.

 

Ok - I didn't fully tighten down the exhaust.. I remembered after starting the bike.

It was kind of squeaky.. I'm going to tighten it down and see if that changes anything. But holy crap, squeaky loud.

 

It actually sounds like the squeak is coming from the carbs.

 

The carbs? Or one of the intake boots?

 

If you don't have the filter in, you might be hearing more whistle.... If the filter is in and the box is closed, you may be hearing a vacuum leak

 

http://vocaroo.com/i/s12SDwLiMPyu

( This is the exact sound, I recorded it, and uploaded it. )

It sounds like a belt is squeaking. If I let the bike idle it is constant.

Edit:

Maybe it is similar to this squeak?



or



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Maybe it is a leak.. and something isn't correctly tightened down.

 

Find a long tube. Vinyl. Fuel line. Cardboard. Whatever. Hold one end up to your ear, and move the other end around till you can pinpoint the sound (thanks to Polock for that tip).

 

Do the propane test to see if idle increase at a spot.

 

I ended up pulling the carbs last night for an overhaul. Just going to doublecheck the gaskets, and make sure the diaphragm isn't ripped or holes.

I vaguely remember only having 2/4 mesh like filters inside the carb. I can't think of what it is called.

 

Beanie filter..... You don't really need those if you already have an inline filter

 

Then I just need to tweak the carburetor and call it good.

 

You have FOUR carbs

 

Fair enough.

 

You have to make sure all four are in top condition and synced with each other. That, couples with correct valve clearances.