carb is sick at upper rpms

[lehiguy]

well finally got on the highway. most of my driving is in town. everything works like a charm. it appears after the new fuel pump, new filter and carb float adjustments all is good no flat spots no stumbles good power up hill so for those who said fuel supply i think it gets the prize. thanks to everyone who helped and provided the input i needed.

i do have one last question, what would cause the idle to fluctuate. some times it idles fine at 650 to 700 and some times it drops down in the 400 to 500 range until i drive it a bit. This is on a warmed up engine. carb uses electric choke and high idle cam works fine in the cold

i don't understand why there is no real idle consistancy ie the engine drops back to the same idle speed everytime??

Thanks again everyone
Dan

Your idle issue is one of two things. First, and most likely, is a vacuum leak. Second is still a fuel issue. Did you check the idle jets that are on the sides of the carb? They can sometimes pick up trash and become partially blocked. Take them out and look. If you still cannot locate the issue, there are a few other things that could be the cause. Repost with your findings.

 

[cfdlighthouse]

Your idle issue is one of two things. First, and most likely, is a vacuum leak. Second is still a fuel issue. Did you check the idle jets that are on the sides of the carb? They can sometimes pick up trash and become partially blocked. Take them out and look. If you still cannot locate the issue, there are a few other things that could be the cause. Repost with your findings.

i will pull them and let you know what i find. as far a vacuum leaks ive sprayed down everything and ahve detected any issues. i am desmoged and i ended up putting a npt plug in the, corrected by jim, vacuum port i thought was a switch. i had to go to the hardware store anyway so just put a pipe plug in.

 

[cfdlighthouse]

okay here is what i got. took out the primary and secondary idle jets. primary has a 65 stamped on it and secondary has a 47.5 on it. both were clean i cleaned them with carb cleaner anyway. double checked my three vacuum lines carb gasket and intake gasket no leaks. reset best lean idle mix and idle speed at 650 to 700. rechecked timing still set at 7dbtdc.

here is funny thing - funny haha - i was thinking about my earlier post of irratic idle that returns to normal when engine heats up. my carb has electric choke. checked the 12v keyed source and surprise surprise no power. so idle was not dropping it was getting choked out because the electric choke was not releasing until the carb got hot.

boy do i feel like a moron. put twelve volts to it and the choke opened like normal.

i do know the primary idle jet is too small because the idle mix is 3.5 turns out supposed to be 2 to 2.5 by redlineweber. any idea what jet i should have??? do i just buy the kit which comes with jets and other stuff????

Thanks
Dan

 

[lehiguy]

okay here is what i got. took out the primary and secondary idle jets. primary has a 65 stamped on it and secondary has a 47.5 on it. both were clean i cleaned them with carb cleaner anyway. double checked my three vacuum lines carb gasket and intake gasket no leaks. reset best lean idle mix and idle speed at 650 to 700. rechecked timing still set at 7dbtdc.

here is funny thing - funny haha - i was thinking about my earlier post of irratic idle that returns to normal when engine heats up. my carb has electric choke. checked the 12v keyed source and surprise surprise no power. so idle was not dropping it was getting choked out because the electric choke was not releasing until the carb got hot.

boy do i feel like a moron. put twelve volts to it and the choke opened like normal.

i do know the primary idle jet is too small because the idle mix is 3.5 turns out supposed to be 2 to 2.5 by redlineweber. any idea what jet i should have??? do i just buy the kit which comes with jets and other stuff????

Thanks
Dan

I'm glad your problems seem to be over. About the idle jets; the one on the primary side is the one feeding your motor at idle and off-idle situations. The one on the secondary does nothing untill the throttle blade starts to open on the secondary, so disregard that. I would take the reccomendations from Redline with a grain of salt. If the rig runs fine the way it is, leave it alone. If you want to try a richer jet, just buy the one on the primary side. As you now know, it's crazy easy to change them, just make sure you get the right one as they are physically different from side to side. You will see that when you pull it out of the jet holder (the brass screw head) Try to find a local shop that can get this for you so you can be sure you get the correct one.

 

[cfdlighthouse]

I'm glad your problems seem to be over. About the idle jets; the one on the primary side is the one feeding your motor at idle and off-idle situations. The one on the secondary does nothing untill the throttle blade starts to open on the secondary, so disregard that. I would take the reccomendations from Redline with a grain of salt. If the rig runs fine the way it is, leave it alone. If you want to try a richer jet, just buy the one on the primary side. As you now know, it's crazy easy to change them, just make sure you get the right one as they are physically different from side to side. You will see that when you pull it out of the jet holder (the brass screw head) Try to find a local shop that can get this for you so you can be sure you get the correct one.

Thanks man,

i think i am just going to let it be. it idles good and runs well. i am going to do a hundered mile trip this week to test and figure gas i am hoping to get 10 to 12 especially with the weight i have added with the bumpers and sliders and with the rack ( not the most aerodynamic thing). Not to mention the super swampers(not good for road mileage)

Thanks
again
Dan

 

[cfdlighthouse]

starting issues

well the vacuum police came a knocking my intake was loose to the block and loose to the exhaust manifold. tightened everything up... the engine died reset all the parameters. carb is within lean idle specs, got good power throughout all gears, cruise at 60mph 2100rpm and getting 13 mpg. the problem is now she does not want to start after it has run a while it will crank 6 or 7 times and barely catch and without a slow bump form the gas pedal it won't start. i am frustrated it started fine with vacuum leaks but ran poor, now it runs good but doesn't want to start.

thoughts?????

 

[JohnnyC]

i usually pump it one time in warm weather...then it starts fine.

in cold weather i pump it 3 times and it starts fine.

if you pump it once it doesnt start? till 6-7 cranks?

 

[cfdlighthouse]

i usually pump it one time in warm weather...then it starts fine.

in cold weather i pump it 3 times and it starts fine.

if you pump it once it doesnt start? till 6-7 cranks?

tried that and it makes it worse. i intially thought it was flooding, but it idles smoothly at 650 and doesnt load when you start off???????