KTM bogging down under load?

[Rod WalkerMember]

The ’94 KTM400 I picked up on the weekend is bogging down under load. Went fine when I test rode it and when I got it home but yesterday and today it is like the choke comes on or it runs out of fuel all of a sudden when I get up it. I am having a look at the carby tomorrow but is there anything in particular I should look at?

If I can’t work it out I will run it into the bike shop and get them to have a look at it and give it a tune up.

On another note, the build quality on these is fantastic.

[Anonymous]

Sounds Lean…. Not sure about the 94 model, but later models had a problem with the AC Pump.

I had trouble with a rich bog on my 2007 250exc-f, I have been mucking around with the squirt on the AC pump, seems to be running heaps better now.

[Rod WalkerMember]

That’s what I thought. When I pulled the plug it was pretty black so I thought it may have been too rich.

[Anonymous]

Try here and ask for help.

http://ktmtalk.com/index.php?showforum=10

I thought it might be the AC Pump, but the 94 model doesn’t seem to have one??

http://www.ktmworld.com/ktm_oem_parts_schematic.asp?schematicId=58572&itemNumber=57031555000

[MalMember]

How old is the fuel capt.? If it had some really old fuel it can turn into little balls of jelly stuf in the carbi. I just cleaned a bike out at home that was doing the same sort of thing. I cleaned the tank and carbi and it runs like a dream.

Just a thought.

[Rod WalkerMember]

That will be tomorrows job then. Clean out the tank and carby. God I hate doing carbies. Always terrified I’m going to stuff them up and never get the bike going again.

[MalMember]

I’m not a fan of carbi work either capt. But if take your time and don’t drop any bits on the floor it’ll be easy. Good luck mate and let us know how you go with it.

[Anonymous]

About a month ago I started mucking aroung with the Keihin 39mm Carby, on my KTM 250f, I knew next to nothing, so I had to do a bit research first. Yours is a Dell’Orto right? Have a look on Youtube, You could try searching google as well. I found the experience really enjoyable, especially when I got it running better, and tried a few different mods.

http://www.ducatimeccanica.com/dellorto_guide/dellorto.html

[TrentMember]

Are you sure its getting good spark? Did you put a new plug in it or just clean the old one? I’d take a look at that too I think.

[drewMember]

i’m almost tipping it will turn out to be a dirty fuel issue.

a while ago my 640 was doing the same thing, it would run ok through the rev range, but if i tried to give it a big fist full it would die and the run rough for a few seconds.

i took the drain pug out and had some sort of stringy hard stuff come out. no idea what it could have been, i turned the fuel on put my finger over the hole and shook the bike and let the fuel run out a few times. and it seemed to work out what ever it was.

it’s been said on here ‘premium’ fuel is only any good for a week or so in the tank. then it starts to go off.

[Rod WalkerMember]

Thanks guys. I had to drop a bike off up the mountains that I sold so swung into the Lithgow BikeStop on my way home to pick up some Enduro grips that they have. They are they only bikeshop I have been to that keeps them in stock. Love these grips, I put them on all my bikes, road bike included.
Anyway, had a good chat with the guy there, can’t remember his name but I used to go there 15 years ago when I had a go at racing and he was there then. Nice guy and has always been great to deal with.
He said the same thing you guys have said, dirty fuel, sitting too long etc. So I am just starting by dropping the drain plug off the bottom of the carb and cleaning up inside the float, draining the tank and cleaning it out and putting a crab cleaner additive through it to start. New plug to go in as well and clean the air-filter and change the oil. Do all the basics before I actually pull the carby off..

[MalMember]

Bikestop are good guys capt. If have been going there for 10 or so years. I droped in the other day to have a chat drool over the 300 Sherco in the window.

How did you go with the bike?

[Rod WalkerMember]

Hehe, I had a drool over the Sherco as well.

I think I may have got it. There was a lot of crap in the carby and in the tank. Gave them both a good clean out and pulled the petcock apart and cleaned it as well as it was full of crap.

Brand new fuel in and some carby cleaner additive just to make sure. Got her started and did a quick run up and down the driveway. Seems ok. Need to get a new air filter on Monday though as the old one fell apart.

Oil change and coolant change tomorrow.

Might also start pulling bolts and bits off and cleaning/polishing/painting and put them back on.

The PO has really opened up the airbox at some stage. All the road going gear has been pulled off it as well. Must have raced it.

[MalMember]

Good stuff mate. Keep us updated on the clean up and we’ll need some pics when she’s all shiny.

[Rod WalkerMember]

Oh Dear God what a saga. Chased all over the place yesterday for a new air-filter and oil filters. Only place that had the air filter in stock was BikeStop. Today I realised I had the wrong oil filter. Turns out there are two different types and mine is the one that is hard to get. Once again BikeStop to the rescue.

So haven’t had a chance to have a run on it as it is sitting in pieces waiting on the new filter to come in. Decided to start taking bits off whilst waiting and clean them up. Damn these bikes have a lot of alloy bits. Rather than just use a piece of steel for a bracket KTM has used alloy,,,, with KTM stamped into it Makes it easy for a clean up, polish alloy, replace.

The engine sump plug was beat to hell and I had a hell of a time getting it out, so need another one of those as well.

Hanging on the rims coming in as well so I can get them up to TB to be laced up. Brake pads to be replaced and might as well pull the linkages and swingarm and check the bearings while I’m at it.

Arghhhhh I just want to ride it.

Also spotted one of these at Beard Bros. today. For some reason I really like this helmet.

[Author]

Posts