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number 1 & 2 exhaust not getting hot and motor popping

  • Thread starter Thread starter esmithers
  • Start date Start date
E

esmithers

Guest
recently got my carbs back from Chef from having him clean and rebuild the carbs on the bike.

the bike idles but sporadically pops/backfires. the two exhaust pipes on the left side are not getting hot while the other two on the right side are hot as hell.

currently waiting on stock filter cage to place in the bike.. i figure this would cause the problems of the popping but the two exhaust pipes not getting hot at all makes me wonder something else is wrong.

What is known. i am getting spark to those cylinders and would guess i am getting the gas per Chef just got done rebuilding them.

If you have any suggestions please let me know thanks
 
The popping is from the engine fighting itself to run. 1and 4 fire together and then 2 and 3 fire together. Basically you have the right side of the engine alive and the left side dead. It also is intermittently igniting in 1 and 2 obviously making it pop even more. Anyway, I say you need to redo them yourself.

You need to tear them down and dip them yourself for a full 24 hrs on the carb bodies in GOOD newer dip. Then dip the hard parts ( jets, float seat, pilots, etc) for a full 12 Hrs minimum.

Spray lots of carb spray in all the holes ands see that it comes out the other end as you spray in..do this going both ways. Then lots of compressed air thru the passages..again both ways.

Poke all the holes with a fine wire and pay special attention to the hole in the tips of the pilot jets..it must be clear also. Be sure to rinse in carb dip and lots of air to blow fouling out of the jets.

Be sure the rubber caps for the pilot jets are sealing tightly. If they are really hard replace them.

Check the mixture screw tips aren't broke off and look down the holes to see there isn't anything stuck in the bottom to clog up the hole..and look for anything that looks brass to be sure somehow and older needles tip hasn't broke off...even if the ones youn take out look nice and pointy CHECK THE HOLES!!!

Verify float hts per the manual and note you have to set each side of each float set to the same hts. Move the floats with a bowl gasket in place to be sure the floats don't hang up on the gasket material as well. If they touch or hang up you may need to trim the gaskets a tad so they don't interfere with the floats normal operations.

If you use a gravity feed bottle when starting the bike without the tank on, be sure to cap the petcock suction nipple on carb 2 or youll have a massive vacuum leak.
 
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I agree with Chuck. Just because someone "rebuilt" your carbs doesn't mean diddly squat. Humans can make mistakes. There is really no way to know for sure every single passage is squeaky clean. So don't rule out the carbs yet.

Did you pull the plugs to see if they were soaked? Sometimes jets aren't tightened and fall in the bowl causing the cylinder to flood. Although the popping may indicate it is starving. What happens if you pull the choke will it start firing on the dead cylinders?
 
Pilot jets are clear. Float height was set. No main jets in the bowls. Pilot plugs good. A bench sync was done. Each idle mixture screw is out 2.5 turns. I suggest he does the highest rpm method on those.
His airbox and filter are not on properly and the carbs are set up stock.
 
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True that CV carbs wont run "the best" without the airbox on....but they will still run on all 4 cylinders if they are clean inside.

You can dispute that all you want but I know better..I have had CV carbed bikes and they DO RUN without an airbox..not optimally but they DO RUN!! AND all 4 of his cylinders should be firing and HOT regardless..period. That's a stone cold fact!!

The carbs are dirty inside and need redone.

And if anyone would like, I can go right now to my TX or my buddies KZ750 ( both with CV carbs and take the airboxes off and video them running AND revving without airboxes.
 
chuck hahn said:
True that CV carbs wont run "the best" without the airbox on....but they will still run on all 4 cylinders if they are clean inside.

You can dispute that all you want but I know better..I have had CV carbed bikes and they DO RUN without an airbox..not optimally but they DO RUN!! AND all 4 of his cylinders should be firing and HOT regardless..period. That's a stone cold fact!!

The carbs are dirty inside and need redone.

And if anyone would like, I can go right now to my TX or my buddies KZ750 ( both with CV carbs and take the airboxes off and video them running AND revving without airboxes.
Click to expand...
You don't know that and I will not argue with you about it.
I'm out
 
I in fact DO KNOW that a CV bike will run on all 4 without the airbox and have throttle response..not optimally as I said, but it will run.

2..The only logical thing is that 1 and 2 are dirty inside...otherwise they would be firing.

Spark, air, and fuel are the three necessary elements for igniton.

He states there is spark on all 4 plugs...element one covered.
He has air obviously around the bike...element two covered.
He isn't getting fuel to the cylinders...element three FAIL.

What causes element three from getting to the cylinders?? Thats right junior scientist!!!!!! DIRTY PASSAGES IN THE CARBS!!!!!!!!!!!!!!!!
 
i'm not going to read this thread but i will say this....
with the airbox removed(GS vacuum carbs) the bike idle perfect and will rev to there abouts 4k RPM.
beyond that your screwed without a st.3 jet kit.
facts...just facts....
 
Exactly!! And this guys bike SHOULD be running on all 4 at idle and some throttle if the carbs were done right and they weren't dirty inside. As you said..Facts..just facts.
 
the Carbs were torn apart to be dipped and soaked. from all that was seen everything was spotless and clean. for the sake of assurance i have them soaking in berrymans and it will stay in there for the next two days.

Additionally i am gonna check the compression to ensure that there is no major fluctuation from all the cylinders since i last checked them..

What i have learned from working on all these metric bikes is that they are very sensitive and when one component is failing it affects others.. I will wait for the Cage and filter to come in so that before i do anything else i have it factory stock and have no excuse to work and then see what happens.
 
Ok I have reassembled the carbs and they are spotless and clean as they will ever get. this is after sitting for 2 days in Berrymans and blowing out the ports and holes. Same was done with the jets. they are clean and clear through and through.

Now its a matter of waiting for this damn filter to show up so i can place it on the bike and have it there to start diagnosing any problems. i am going to wait for this filter before i even place the carbs back on.

All fingers crossed lets hope this cures the previous problems and she runs like a raped ape.

Additionally: I have set the Pilot Screws 2.5 turns out and will work off this setting as a baseline. if you have any suggestions please let me know,. thanks
 
Loosen the fuel drain screws and see if you are even getting fuel to those 2 carbs. I bet you aren't, this has happened to me twice after putting rebuilt carbs on. I take a rubber mallet and tap the carbs until the floats drop and allow fuel to fill the bowls. I bet it something simple.

People tend to jump to the more complex solutions before checking basics.
 
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chuck hahn said:
I in fact DO KNOW that a CV bike will run on all 4 without the airbox and have throttle response..not optimally as I said, but it will run.

2..The only logical thing is that 1 and 2 are dirty inside...otherwise they would be firing.

Spark, air, and fuel are the three necessary elements for igniton.

He states there is spark on all 4 plugs...element one covered.
He has air obviously around the bike...element two covered.
He isn't getting fuel to the cylinders...element three FAIL.

What causes element three from getting to the cylinders?? Thats right junior scientist!!!!!! DIRTY PASSAGES IN THE CARBS!!!!!!!!!!!!!!!!
Click to expand...


You missed the fact that there may not even be fuel in the bowls. Calm down mad scientist.
 
See Crage..I talked to himon the phone right after he made the firat post...so you need to get some facts before you tell ANYONE to calm down!!
 
Crage said:
Loosen the fuel drain screws and see if you are even getting fuel to those 2 carbs. I bet you aren't, this has happened to me twice after putting rebuilt carbs on. I take a rubber mallet and tap the carbs until the floats drop and allow fuel to fill the bowls. I bet it something simple.

People tend to jump to the more complex solutions before checking basics.
Click to expand...

when i notice they were not getting hot enough the first thing i do for both a overflowing and non flowing carb is tap the boats with a wooden dowl and a rubber mallet.

Additionally i tap them once i get them on so to not have them leak on me because of the aggressive movements.
 
Cool, I just know this has happened to me a couple of times after rebuild.
 
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