Bike wasnt running smoothly, pulled carbs now it wont fire

Seca 750

My bike ran, but it did not idle well and back fired occasionally, and poured smoke from the R exhaust. When the cylinders temp was measured the two on the right side were clearly not running well, and the left side was carrying them.

I pulled the carbs, and opened them. They looked very clean, and not gummed up at all, so I sprayed brake cleaner through all the jets and openings. All were clear.

I rescrewed the bowls on, and put the carbs back in the bike. But now it won't fire at all. The bowls are full of fuel, and the air intake is clear. The spark plugs are giving a medium-weak spark but are completely dry (so no flooding?)

The bike will run on ether, but not otherwise.

Help?? What could I have done wrong? Any ideas as to what my problem might be?

 

Put the floats in upside down?, got the main & pilot jets switched?, be sure your battery is fully charged, if it is low, it will spin the motor but give a weak spark.
Are the plugs wet?

 

Nope, plugs are dry. Floats are right-side up and jets are correct. We put a battery charger on it, and still wouldn't fire. Thanks though. Any other ideas? *looks hopeful*

 

Re: Bike wasnt running smoothly, pulled carbs now it wont fi

mine will do that sometimes until i jump it off w car that gives it an extra boost could be fuel air mixture screws being that you added two more carbs to the mix try to crank it w choke on hooked to car and let me know what it does

 

Try getting her to Pop with Starting Fluid.
If it Fires on Starting Fluid ... its "Supply" related. (carbs)

If it don't kick on Starting Fluid ... it's Spark related. (Ign)

 

Run's on starting fluid...

 

However, doesn't starting fluid have a lower ignition temp, so a weaker spark would ignite it, even though it may not ignite gas?

 

The test is to see if its a Fuel or Ignition issue. Period.

You narrowed it down.
You have a Fuel Supply issue.
Generally speaking.
Now, you need to troubleshoot and find out what's keeping the Bike from not getting gas.

 

Well that's the thing, because when I pulled my carbs a second time (after posting this) there was fuel clearly visible in the intake... Do you think I may have an air/vacuum leak that would be big enough to cause the bike to not even start?

 

I don't know where you are.
I'm near Boston.
My Bike's tuned-up pretty good. Well looked after.
There's 3 feet of snow outside my garage.
I KNOW my XJ ain't going to start until I charge the Battery for 45 Minutes and "Get it running" on Starting Fluid.

It's COLD outside.
XJ Bikes don't like it when it's cold outside!

 

*grins* I'm on Vancouver Island, BC, it was 12C (54F) outside today.

Thanks for the info. I'll charge it overnight tonight, and put the carbs back in in the morning, and if that doesn't help, I will try to jump it like rkjjdj suggested.

I suspected an air leak last season because of the way the RPM would vary when it was cold compared to warm, but couldn't find one when I sprayed it all down. If I can get it running I will check again. Perhaps I will have better luck finding it.