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FC501 Cuts out/smokes on highway

hondaguy

hondaguy

Joined Feb 2006
12 Posts | 0+
Frankfort Indiana
Hi all, i recently got taken on a deal for a 1995 FC501. The problem i have is that when driving down the road at relatively constant throttle, the engine wil begin to cut in and out as if someone is hitting the kill switch, and then smoke (its unburned fuel i think). It only takes a mile or so for it to start doing it. It will not want to idle afterwards and will usually die. If i try to start it right back up it will run at low rpm for maybe a second then die, even if i try to hit the gas. The radiator doesn't feel excessively hot.

I've got the cold start procedure down, it starts up like most husabergs. The thing is that it will act completely normal when i am just tooling around the yard (varying the throttle a lot, engine warmed up to operating temp), it just happens when holding the throttle constant.

Any ideas? The carburetor is clean as a whistle, and it has a new plug. I am going to test the stator tomorrow but i wanted to make sure that the values on the Hard Start Guide were accurate for a pre-1999 because i have ran across values in some posts (for pre 1999s) that differ from the ones in the guide.

I am going to try to get readings when cold and then again when hot after it acts up.

Also will the KTM LC4 stator, part no. 580.31.002.050, work in this bike? I read somewhere that it would work but it would throw off the timing because the stator is inboard on the pre-1999s. How much is a stator from Husaberg (America)? I see lots of diffirent prices in the posts...

Thanks
 
firsst of all mate your problem is in the carb. you have a worn emulsion tube and needle. because essentially it's the same engine as much later i would think of updating any jetting. have a search around but the K35 needle is the one of choice and a DR270 or DR272 ET. change the main jet as well while you're there and also look at the slide in the carb, look for where the idle screw 'digs' in at the side and look for swear on the bridge over the entrance to the carb. that face of the slide always gets it.

do this first and last and if that's not the cure then i'm probably a dutchman!

hurdyburdyburdy!!!!!!!!!!!

regards

Taffy
 
do this first and last and if that's not the cure then i'm probably a dutchman!
hurdyburdyburdy!!!!!!!!!!!
Click to expand...

taf,
you may not be a dutchman, but you are indeed a piece of work! :lol:
 
re

Thanks for the quick reply. I called the closest Husaberg dealer and it looks like they will have to order them. Before i do so, i just wanted to know if these seemed like the correct jets for an elevation of around 900 feet AMSL.

Main: 170
Needle: K32 (on 3rd setting from top)
Emulsion Tube: 258FN

It seems to run fine before it acts up, should i switch to the newer jetting or just go with the "if it ain' t broke don't fix it" theory? I'm a little weary about carb work because it seems like whenever i try to jet one it gets worse... story of my life.

Also just as an update, i rode it back today from where i left it yesterday when it acted up and i sort of rode it like a 2-stroke, just varying the thottle input a lot and it did great and didn't really do anything funny, other than sometimes it will die on idle...

I can't visually see any wear on the needle or emulsition tube but is there a way to measure it? Lastly there is a little wear where the idle screw touches the slide, would this affect much throughout the rpm range?

Thanks again!
 
Does this poor thing have a flat slide carb? My 96 did, but not sure on a 95. If so trash it and beg,steal, or borrow a round slide Dellorto and follow Taffys jetting advice.
dan
 
have another look at that fresh spark plug.i bet it will not look very clean like it did before.if it is wet is it oily or fuel saturated?
 
re

Actually the plug looks just about perfect, nice dry pancake color. I don't think the engine is worn out, it was rebuilt 12 hours ago to the tune of $2100 (ouch) when the oil pump got clogged and grenaded the engine.

It is a flatslide carb, but are they really that bad? I mean we surely know it ran good at one point with that carburetor, so it should just be a matter of replacing wear parts in order to return it to original condition...
 
if you have the tank that uses the vaccuum pump to get gas up top, it could be on its way out. except the smoke doesnt make sense for that.
at high rpm you can be pulling in oil thru the frame, that would cause both the ruff running and smoke.
tuts
 
is the smoke from coollant?a head gasket leak that gets worse as the bike warms up?i cant imagine the carb changing how a bike runs that much as it warms up.how much time have you actually had riding this bike? has it ever consistently ran well for you?dan
 
re

Hi, thanks for all the replies. It does have the enduro tank on it with the transfer pump, but there is more than enough fuel in it to eliminate the possibility of it starving the engine (the pump just moves fuel from the low side to the higher side so it can be gravity fed into the carb).

The coolant level is remaining the same...

I just bought it so i am still working out the bugs. Just to clarify, the problem doesn't happen after it warms up, it happens after holding the throttle constant at higher rpm (when going down a road).

Thanks again for all the help
 
So is there a general consensus that it is a worn out emulsion tube and needle? I just want to make sure before i order them, it will take the dealer a few weeks...

thanks
 
1995 does not have an oil pump. It does have a water pump And if you are riding it and you can hold your hand on the radiator it's not doing it's job.Could be a costly mistake!
 
Flat slide can be made to run ok if repaired and set up correctly. When you change altitudes (you may not do that) they get way off. Sensitive to jetting. If you choose to use that carb, keep in mind that jetting specs for it are different than for a round slide. Try replacing needle and needle jet with stock parts and check that main and pilot are stock. Inspect slide for wear and replace if needed. Set float level. Should be a good starting point. On a different note, might check the reed valve that controls the bottom end oil level for silicon debris or the likes.
 
Hi, that reed valve is what i meant when i said oil pump. He suggested every ten hours i take the clutch out to inspect/clean the valve. I'm going to go ahead and order the jets and will let everyone know how it turns out.

Thanks
 
on my 98, i could get to the reed valve without pulling the clutch, just gotta pull the cover. 15 minute job.
 

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