engine stutters

[kdawg127]

my 440 just got a problem and I am still trying to figure out how to fix it.

last week the engine would spin up very fast when you gave it thottle.

I stopped at a store and came out 1/2 later. After I started the bike, I take off and once the engine hits about 3500rpms the engine stutters and you have to open up the throttle much more than before to get it to spin up.

I neutral when I open the throttle, it now spins up way slower than it did before. The problem gets worse with the more load on the bike ( wind resistance, hills, etc ).

I had filled up the gas tank earlier that day and drive it about 50 miles before this issue happened.

So far I have checked ignition time at idle and at 3500 rpm. timing looks good. Checked compression, not great but no different than last week. Cleaned the spark plugs. Drained the fuel from the fuel bowls and opened the fuel petcock to prime to let gas try to wash out any debris that might have gotten into the carb. The valve lash is correct. The carbs are synced.

The bike starts good and idles good.

Any thoughts on this????????

[AndrewWoodard]

Hi there!

Well, it sounds like you've already done a lot to cure the problem, but still haven't found the remedy. If I had to put money on it, I would suggest you've picked up some nearly microscopic bit of garbage from the fuel source and it's stuck somewhere and causing a change in the fuel/air mixture. Being that it's on the low end, I'm guessing it's associated with either the idle jet or pilot air screw. (Yes, it could also be a spec of road dirt or "dust" that came in through the air intake.)

It's possible that backing the adjusting screw(s) out and screwing them back in to their original positions could cure the problem. It may also be that you need to get into a semi-serious cleaning of the carburetor(s). It's hard to give an exact answer to a vague symptom, but that's where I would look.

Whatever you do, I would strongly suggest a top quality inline fuel filter and make darn sure the air intake system is sealed tightly and air only enters through the filter to keep dust and dirt out.

The very best of luck.

Thanks!

Andrew....

[MFolks]

Add a can of seafoam gasoline additiveand go for a ride. Sea Foam

[kdawg127]

SEAFOAM. maybe I should keep a bottle under my pillow

I just bought a fresh bottle of the stuff and will add it tomorrow.

I also drained gas out of tank and filled up with 94 octane, just in case it was cheap gas issue.

I will add some Seafoam to the tank, and also pickup a inline fuel filter. How many times do I kick myself in the butt for not buying that filter 2 weeks ago when I go the stuff for an oil change !!!

If that doesnt do it then I will pull the carbs off and see about cleaning it.

I am also going to try to find a new set of spark plug wires, as the ones on the bike might be original.

I hope that does it. I had plans on rebuilding the engine over the winter, but I still wanted to ride it til it snows . Heck, I will just drive it in the neighborhood at 25mph. Its not fast, but its still riding

[86klf300guy]

hello have you checked the coils out yet they may be gettin weak and givein a bad spark if you have the manual it should tell u how to test them at home with a ohms meter/voltmeter-corey-

[kdawg127]

I hadnt thought that the coil was a problem, since it started up and idled fine and seemed ok at low rpms.

I will throw this on the list of things to check.

FYI, I am trying to check out everything I can that doesnt require too much dis-assembly and cost.

Time to pull out the manual again ( SIGH )

Thanks for adding to my list

[86klf300guy]

sorry about that but a coil getting weak or lack of battery voltage can cause this concern also and hows the battery by the way fully charged and in good working order? sorry to add another thing to the to do list lol-corey-

[kdawg127]

well, it turns out the problem was within the fuel bowl. The overflow tube had a crack in it and someone tried to fix it by covering it with silicon RTV. The silicon finally detached from the overflow tube and was floating around inside the bowl. When the bike was started, the silicon would float around and the flow of fuel would eventually cause the main jet to get covered with it and starve the engine on that side. when the bike was turned off, the silicon would float around again and it would idle fine, until the throttle was opened up. the the problem would happen again.

Well, I washed the bowl and soldered the crack in the overflow tube. Problem solved, even the fuel leak problem that I didnt know existed

[MFolks]

Silicon(or RTV compound) is never a good mix around gasoline. Soldering or brazing is the only good repair around brass overflow tubes.