Backfiring 84
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Intermediate
Joined: Jul 2007
Posts: 30
Likes: 0
From: New York
RE: Backfiring 84
ORIGINAL: 83XLX
If the problem is the same or worse with a 170, then a 165 won't help. Maybe the float level is off, as you say. Did you check the gas cap vent and petcock? Has the inside of the tank been coated with something that's coming off and clogging the petcock? Kind of hard to diagnose over the internet, and I'm no mechanic, either.
If the problem is the same or worse with a 170, then a 165 won't help. Maybe the float level is off, as you say. Did you check the gas cap vent and petcock? Has the inside of the tank been coated with something that's coming off and clogging the petcock? Kind of hard to diagnose over the internet, and I'm no mechanic, either.
Think I'll try the 165 and see if that clears it up any. And if i get good and pissed off, I'll be lookin for an S&S.
Road Master
Joined: Jan 2007
Posts: 770
Likes: 2
From: East NM
RE: Backfiring 84
Sounds like the new jet is too big. Also sounds like a fuel flow problem. The float level instructions are really the same as far as results. With the older instruction calling for lifting the float to close the valve, they forgot that some folks lift harder than they should. Now, they have you turn the carb upsidedown so that the weight of the float closes the valve so you can adjust the level.
If all else fails, check the manifold mounting for air leaks. This usually only causes problems at low speed, but it is possible that more air flow can force the seals to move and let more raw air in.
If all else fails, check the manifold mounting for air leaks. This usually only causes problems at low speed, but it is possible that more air flow can force the seals to move and let more raw air in.
Thread Starter
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Intermediate
Joined: Jul 2007
Posts: 30
Likes: 0
From: New York
RE: Backfiring 84
ORIGINAL: Oldtimer of NM
Sounds like the new jet is too big. Also sounds like a fuel flow problem. The float level instructions are really the same as far as results. With the older instruction calling for lifting the float to close the valve, they forgot that some folks lift harder than they should. Now, they have you turn the carb upsidedown so that the weight of the float closes the valve so you can adjust the level.
If all else fails, check the manifold mounting for air leaks. This usually only causes problems at low speed, but it is possible that more air flow can force the seals to move and let more raw air in.
Sounds like the new jet is too big. Also sounds like a fuel flow problem. The float level instructions are really the same as far as results. With the older instruction calling for lifting the float to close the valve, they forgot that some folks lift harder than they should. Now, they have you turn the carb upsidedown so that the weight of the float closes the valve so you can adjust the level.
If all else fails, check the manifold mounting for air leaks. This usually only causes problems at low speed, but it is possible that more air flow can force the seals to move and let more raw air in.
If i spray water on the boots, am i looking for an increase or decrease in rpm's? Thanks for the reply btw.
And if I wasn't to add pressure to the float, then i have that set right. Although I'm not sure the weight alone of the float properly seated the valve.
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
RE: Backfiring 84
Check first fuel flow from tank, petcock clocked ? common problem for bikes that has been in storage for longer times. Paint from inner surfface of fuel tank is falling...
You wrote that you have rebuild carb ( butterfly keihin ?), so I expect that carb is clean.
Dragpipes and original airbox paper or foam filtter? usual modification is cut airbox backplate...
original electronic ignition ? jet sizes ? I have seen ironheads with open exhaust, opened airbox and ported heads with jet sizes 70/180. Normal engine should jet sizes could be around 60/160
Have you checked your pushrod adjustment ?
You wrote that you have rebuild carb ( butterfly keihin ?), so I expect that carb is clean.
Dragpipes and original airbox paper or foam filtter? usual modification is cut airbox backplate...
original electronic ignition ? jet sizes ? I have seen ironheads with open exhaust, opened airbox and ported heads with jet sizes 70/180. Normal engine should jet sizes could be around 60/160
Have you checked your pushrod adjustment ?
Thread Starter
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Intermediate
Joined: Jul 2007
Posts: 30
Likes: 0
From: New York
RE: Backfiring 84
ORIGINAL: sepixlh
Check first fuel flow from tank, petcock clocked ? common problem for bikes that has been in storage for longer times. Paint from inner surfface of fuel tank is falling...
You wrote that you have rebuild carb ( butterfly keihin ?), so I expect that carb is clean.
Dragpipes and original airbox paper or foam filtter? usual modification is cut airbox backplate...
original electronic ignition ? jet sizes ? I have seen ironheads with open exhaust, opened airbox and ported heads with jet sizes 70/180. Normal engine should jet sizes could be around 60/160
Have you checked your pushrod adjustment ?
Check first fuel flow from tank, petcock clocked ? common problem for bikes that has been in storage for longer times. Paint from inner surfface of fuel tank is falling...
You wrote that you have rebuild carb ( butterfly keihin ?), so I expect that carb is clean.
Dragpipes and original airbox paper or foam filtter? usual modification is cut airbox backplate...
original electronic ignition ? jet sizes ? I have seen ironheads with open exhaust, opened airbox and ported heads with jet sizes 70/180. Normal engine should jet sizes could be around 60/160
Have you checked your pushrod adjustment ?
fuel flow is good... tank was all cleaned out during re paint last yr as was filter and petcock..
filter is a aftermarket foam.
Carb is very clean, had it off several times lately as well. Yes butterfly Keihin.
took the 170 out and put the 160 back in, with float adjusted according to the book. Was too fat with the 170, and now it ran really good, but eventually, started the loss of power and backfiring at steady speed again. Not as bad as it used to though.
Not sure what other jet is in it.
Screamin Eagle Elec. Ignition
Have not checked pushrods either.. Carbs I can handle, pushrods I've never dealt with before.
Plugs did have some grayish crust build up, hinting towards burning oil I believe.
Sure wish i could get this figured out, or find a mechanic I could trust. Its almost impossible to take long rides, and rather unsafe on the highways as one minute I could be doing 70, and next I'm at 45 waiting for it to straighten out again.
Cruiser
Joined: May 2006
Posts: 157
Likes: 0
From:
RE: Backfiring 84
ORIGINAL: wfo
If i spray water on the boots, am i looking for an increase or decrease in rpm's?
If i spray water on the boots, am i looking for an increase or decrease in rpm's?
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
RE: Backfiring 84
Intermedia jet is located in middle of carb under that rubberplug ( assume that you have that ) in bowl.
Actually you can see it when you remove aircleaner, it sticks out from venturi bottom, you need to remove floatbowl to remove it. About that rubberplug, it need to be there ...otherwise you can't adjust your fuel mixture.
Adjusting pushrods aren't so big deal, it takes just more time in first time, if you can rebuild your carb you can adjust your pushrods
Cold engine (at least overnight) :
1. remove sparkplugs
2. remove pushrod covers ( check if you need new seals, there is 2 differend types, newer has O-ring type)
actually you need just take out those clips that holds pushroscover at full lenght, push covertubes inside
each other. Take some ducktape and secure them up, so you can see adjustment nuts.
3. turn engine ( I have put bike on 4th gear and lifted rear wheel up, turned from there) so that you see
when exhaust tappet is going down and intake tappet is start to go up.
Feel from sparkplug hole that OPPOSITE piston is in TDC, now you can adjust THIS OPPOSITE
cylinder pushrods you need 7/16" and 1/2" wrench ( if I remember correct) to do so.
Pushrods need to turn freely by fingers but there isn't any freeplay.
I have adjusted so that turning pushrod don't require any force...
Now turn engine so that other cylinder pushrods/tappets "switchs" and feel from sparkplug hole that
other piston is in TDC. Same method...
4. turn engine over and check adjustmets, secure adjustment nuts...check again, that's it.
5. put pach pushrod covers...this is litlle tricky, I have used 2 screwdrivers to push covers down
from that "lump" from pushrod cover
Actually you can see it when you remove aircleaner, it sticks out from venturi bottom, you need to remove floatbowl to remove it. About that rubberplug, it need to be there ...otherwise you can't adjust your fuel mixture.
Adjusting pushrods aren't so big deal, it takes just more time in first time, if you can rebuild your carb you can adjust your pushrods
Cold engine (at least overnight) :
1. remove sparkplugs
2. remove pushrod covers ( check if you need new seals, there is 2 differend types, newer has O-ring type)
actually you need just take out those clips that holds pushroscover at full lenght, push covertubes inside
each other. Take some ducktape and secure them up, so you can see adjustment nuts.
3. turn engine ( I have put bike on 4th gear and lifted rear wheel up, turned from there) so that you see
when exhaust tappet is going down and intake tappet is start to go up.
Feel from sparkplug hole that OPPOSITE piston is in TDC, now you can adjust THIS OPPOSITE
cylinder pushrods you need 7/16" and 1/2" wrench ( if I remember correct) to do so.
Pushrods need to turn freely by fingers but there isn't any freeplay.
I have adjusted so that turning pushrod don't require any force...
Now turn engine so that other cylinder pushrods/tappets "switchs" and feel from sparkplug hole that
other piston is in TDC. Same method...
4. turn engine over and check adjustmets, secure adjustment nuts...check again, that's it.
5. put pach pushrod covers...this is litlle tricky, I have used 2 screwdrivers to push covers down
from that "lump" from pushrod cover
Road Master
Joined: Mar 2006
Posts: 775
Likes: 2
From: OC California
RE: Backfiring 84
As Sepixlh says on the adjustments. Instead of using the duct tape to hold the covers up I have found clothes pins to work the best. Real easy on and off.
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Road Warrior
Joined: Nov 2006
Posts: 1,427
Likes: 763
From: Heart of Dixie
RE: Backfiring 84
ORIGINAL: 83XLX
Check your gas cap vent. If it's clogged, your carb will not get enough gas at constant highway throttle settings. Back off, or run at varied throttle settings, and the gas supply can catch up and it will run well again. Here's a test - with a half tank of gas (so gas doesn't slosh out), get out on the road at 60 till it happens. When it does, open the cap while still doing 60 and see ifthe engineclears up in a few seconds.....
Check your gas cap vent. If it's clogged, your carb will not get enough gas at constant highway throttle settings. Back off, or run at varied throttle settings, and the gas supply can catch up and it will run well again. Here's a test - with a half tank of gas (so gas doesn't slosh out), get out on the road at 60 till it happens. When it does, open the cap while still doing 60 and see ifthe engineclears up in a few seconds.....
Another wild guess - does your carb have a brace to hold it steady, or are the manifold clamps the only thing securing it? If there's no brace, the carb could be shaking so much at certain rpm's that the jet is picking up air with the gas.
Thread Starter
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Intermediate
Joined: Jul 2007
Posts: 30
Likes: 0
From: New York
RE: Backfiring 84
thanks for the replies guys... yeah it is very frustrating guessing at whats wrong. I'll check on the intermediate jet, and get the book out and adjust the pushrods. Although I think that was done when i had my clutches done.
The original owner told me he had this problem happen a few times as well...
My carb does not have the brace on it for some reason. I think that was taken off when the new air cleaner was put on. If i remember correctly, that brace went directly to the air cleaner originally??
I didn't try the gas cap trick yet, but I believei heard air coming out of it tonight after running the bike after an oil change. I get a steady solid fuel flow out of the line when i had it unhooked though.
Thanks again gents... Damn the internets great.
The original owner told me he had this problem happen a few times as well...
My carb does not have the brace on it for some reason. I think that was taken off when the new air cleaner was put on. If i remember correctly, that brace went directly to the air cleaner originally??
I didn't try the gas cap trick yet, but I believei heard air coming out of it tonight after running the bike after an oil change. I get a steady solid fuel flow out of the line when i had it unhooked though.
Thanks again gents... Damn the internets great.