Engine bogging at speed. Sometimes wants to die at idle

[broilmebk]

I'm sorry to make a new thread about this topic, but I've been researching for several days and haven't been able to find the solution for this specific instance. And sorry again for the novel below.

TL;DR - Bike bogs after 15 miles into ride on freeway. nothing in air intake, hoses look fine. Ride for maybe 20-30 more miles with fluctuation in power/bogging, and then issue disappears. Berryman added to tank next day, no issues whatsoever riding locally. 3rd day bogging returns after 5 miles locally, goes away after ~30 miles on freeway. 4th day happens again after 15 miles into ride on freeway (same place as first time), open gas tank, issue still stays. 5th day, fuel filter checked, hoses again. Ride hard and bogging seems to begin. Engine wants to die at idle; loss of power revving from idle. Ride back home and revving and idle is fine. Last thing done to bike was oil change, shimming, and snorkel removal 1500+ miles ago.


The issue is pretty much the same as all the other similar threads. On friday, bike started fine, and ran fine through 5 miles locally. I hit the freeway and ran for another 5-10 miles when it started bogging like I was running out of fuel. I let off the throttle and tried to open her up again but it was bogging a lot. I was able to keep it going with partially open throttle and got off at the next exit. I tried check all the hoses and nothing seemed out of place. I opened the airbox and checked the filter. Nothing is wrong. Bike starts up fine. I randomly think maybe the 87 i filled up with wasn't so 87, so I try and top off with 91. I abandon my ride, but take it to a home that's closer than mine. I'm able to stay above 65mph while keeping throttle at most half open. Once in a while I'm able to go faster but then bog down again. About 20 miles later, everything clears up; I can go full throttle. I can let off, and WOT no problem. At this point I'm thinking I burned off whatever was causing the issue in the fuel. I get to the house and let it sit til the next day.
Next day I add some berryman and take it out for a spin and there are no issues whatsoever. Wasn't able to get up to freeway speeds, but I did WOT many times, bike warm, and get up to about 60mph no problem. Figured the issue fixed itself. Except now, on Sunday, after about 10 miles locally, I hit the freeway and as soon as I get upright from a 180 onramp it starts to bog. Kept throttle half open able to get up to speed and then eventually it all clears up again just like the first time. WTF?
Monday I try riding a bit again, everything fine, freeway, starts bogging. I got off and opened my gas tank this time (thinking vapor lock) but the problem continued. It never did clear up and stalled out when I got home. It wouldn't start again so I just let it be for the night.
Tuesday I drain float bowls just for s!@#s and giggles. Nothing out of the ordinary there. And I also pull off the hose from petcock to carb and check stock fuel filter. Nothing wrong there either. Make sure no kinks in hoses and everything is secure. Button everything back up and ride around. After like 4 miles of hard riding (bike was already warm), bogging just barely starts to show. Notice low idle, and reduced power when revving from idle. All symptoms seen before. When I return home, the bike idles and revs just fine.


I guess I should point out that I haven't dumped the fuel in the tank nor have I pulled out the carb. I DID notice when I pulled the hose off for the fuel filter, fuel would drip like once every 10 seconds. I've had the tank off before and it never leaked. I will look into the petcock leak, but is this really causing my other problem? There is no fuel smell or puddle around the bike.
The last thing done to the bike is an oil change, shimming, and snorkel removal 1500+ miles ago.

Any solution I have found or can think of has gone out the window for me because of the fact that the bogging went away twice while riding. I'm going on vaca so can't check or work on the bike for a few days. Just wanted to see what you guys thought about this situation. Some steps for troubleshooting I'm looking to do is dump the entire tank of fuel, check the petcock, and then eventually pull the carb out for cleaning if need be. Should I just do all three from the start or check status after each one?
The issue going away after some riding has me really confused.

[gptoyz]

when was the last time you had your carburetors synced?

what does it idle at when warm?

how is the throttle return? how much throttle play do you have?

have you checked your spark plugs? what's the condition of those?

How many miles does the bike have? have you done a valve adjustment?

[jkv45]

Sure sounds like it's starving for fuel for whatever reason.

Because you opened the tank and got no change, I would look at the petcock, or damaged vacuum line to it, as a possible cause. Put a vacuum pump to the line from the carb vacuum (use the existing line) and apply vacuum to the petcock with the fuel line off and see if you get decent fuel flow.

I would dump the fuel in the tank and look at it, as well as inspecting the inside of the tank.

Get some fresh 87 and add 1oz per gal of Techron Concentrate for good measure.

Pull the plugs and look at them. Notice the general condition/color and if one cylinder is different than the other.

[broilmebk]

when was the last time you had your carburetors synced?
Never

what does it idle at when warm?
~1200

how is the throttle return? how much throttle play do you have?
It hangs just a little bit before closing, but that is due to the grips i installed. This and the play are fine and have been the same way for thousands of miles

have you checked your spark plugs? what's the condition of those?
no

How many miles does the bike have? have you done a valve adjustment?
27,xxx. valves adjusted at 23,636

[broilmebk]

Originally Posted by jkv45

Sure sounds like it's starving for fuel for whatever reason.

Because you opened the tank and got no change, I would look at the petcock, or damaged vacuum line to it, as a possible cause. Put a vacuum pump to the line from the carb vacuum (use the existing line) and apply vacuum to the petcock with the fuel line off and see if you get decent fuel flow.

I would dump the fuel in the tank and look at it, as well as inspecting the inside of the tank.

Get some fresh 87 and add 1oz per gal of Techron Concentrate for good measure.

Pull the plugs and look at them. Notice the general condition/color and if one cylinder is different than the other.

I couldn't figure out if it was starving or it was flooding. My friend said it was starving as well. I have to ride the bike elsewhere to start working on it, during this time I'm going to move petcock to prime and see if the problem comes up.
I will definitely dump the fuel in the tank and take a look as well as pull the plugs if I have to.
I was gonna use some seafoam this time, but will possibly grab some techron.

[jkv45]

Originally Posted by broilmebk

I couldn't figure out if it was starving or it was flooding. My friend said it was starving as well. I have to ride the bike elsewhere to start working on it, during this time I'm going to move petcock to prime and see if the problem comes up.
I will definitely dump the fuel in the tank and take a look as well as pull the plugs if I have to.
I was gonna use some seafoam this time, but will possibly grab some techron.

Flooding is a possibility also. It would sound different - like the choke is on too much. When it's running poorly you could add some choke to see what it does. Running better with enrichening would confirm a lean condition (assuming it had fuel in the floatbowl to enrichen with).

The plugs will also tell you if it's on the rich side or not.

I don't think Techron will solve the problem, but it's just a good idea to run it once a year. Seafoam is OK, but contains alcohol where Techron doesn't. I have a friend that works in auto emissions testing and has seen Techron remove some heavy deposits on intake valves over the course of one tank. He was surprised - and impressed. That's what sold me on it.

[Motofool]

Originally Posted by broilmebk

I couldn't figure out if it was starving or it was flooding. My friend said it was starving as well. I have to ride the bike elsewhere to start working on it, during this time I'm going to move petcock to prime and see if the problem comes up.
I will definitely dump the fuel in the tank and take a look as well as pull the plugs if I have to.
I was gonna use some seafoam this time, but will possibly grab some techron.

Open the tank cap and blow into the hose backwards while petcock in prime.
That will clear the filter in the internal pick up tube.

You need a free constant flow of fuel into the bowls not less that one cup per minute.
Anything less will induce starvation at high rpms and little engine vacuum (throttle only partially open): typical highway conditions.

Another thing to check if the problem persists is the temperature of the engine.

Don't forget cleaning this little baby:

[broilmebk]

Ok, I know it's been a while, but I hate finding troubleshooting threads with no conclusion or update.

I tried several things which actually ended up making things worse. One of the things was pulling off the kleen air system; I followed the DIY and used Vex's post to help with the CA tank. At this point, it ran fine for a while and then went to absolute crap like before. Another day of riding and it was as if my engine was only running on one cylinder. I tried opening the gas tank again, but still the issue persisted. I made sure the spark plugs and boots were tightened properly (these were taken out during troubleshooting) and capped the blue vent and opened the red vent on the gas tank instead. The bike has been running flawlessly now for about 200 miles.

I'm still not sure what caused my original problem, but the most likely culprit was bad gas. I could have also inadvertently fixed something with all the tearing down I did.

[Asspire]

next time it happens try disconnecting the cdi and reconnecting it. by the random way its happening it sounds like a ignition issue. I had some thing similar happen to me and ended up throwing in a used cdi to fix the problem.

[broilmebk]

Originally Posted by Asspire

next time it happens try disconnecting the cdi and reconnecting it. by the random way its happening it sounds like a ignition issue. I had some thing similar happen to me and ended up throwing in a used cdi to fix the problem.

Well I hope the issue doesn't come up again, but in the case that it does I'll check this out. Thanks.

[nbleak21]

Glad to hear that you seemed to have cured it, whatever the cause may have been...

My first instinct would be a venting issue in the tank. If the tank isn't breathing properly, a vacuum can form in the tank causing the exact issues you described.

If it does happen again, pull over, open the fuel cap, shut it, and ride on. If the issue is resolved, then you know what your problem is ;-)

[broilmebk]

Originally Posted by nbleak21

Glad to hear that you seemed to have cured it, whatever the cause may have been...

My first instinct would be a venting issue in the tank. If the tank isn't breathing properly, a vacuum can form in the tank causing the exact issues you described.

If it does happen again, pull over, open the fuel cap, shut it, and ride on. If the issue is resolved, then you know what your problem is ;-)

Hey Nick. That was a solution I tried but it didn't fix the problem. Suuuper strange, but as long as it's running good now I'm happy.