RXC 620

Joined
Apr 18, 2001
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#1
I recently got a 95 KTM RXC 620. While I do like the bike and suspension, I am having some doubts about the engine.

When riding at a steady throttle opening (about 1/3 to 1/2) the bike seems to surge like it is running out of gas or something. On the low end RPM wise, it seems to knock when it's really trying to torque...it also does it when I'm on the highway doing about 50 or 60 and let the rpms get down.

I haven't checked the carb (DellOrto) yet but I suspect that it is either running lean or the timing is advanced too far...or both.

I'm running 100 Octane pump gas from the 76 station (Racing gas ya know..lol) and have seen a definate improvement over the premium I had in it before.

I'm waiting for a repair manual (hurry up Dual-Star) before I start wrenching on it (I've only rode it about 110 miles).

Any thoughts on this matter would be greatly appreciated.

JBB

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Joined
Apr 18, 2001
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#2
I forgot to mention that when I go up hills that it likes to DIE (as in: just quits vs stalling). Especially if they are rough. Float level???

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Joined
Jan 5, 2001
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#3
The del-orto carb on the RXC was one of KTM's better choices for air/fuel metering, anyone with an Edlebrock will know what I'm talking about. If it has been sitting for some time either at the dealership or a private owner I would check that the carb jets, air and fuel are clean. The RXC's ran pretty good right out of the box with only minor changes for climate.

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Joined
Apr 18, 2001
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#4
That's exactly what I have heard in the past and it was a major deciding factor in going with the 95 620 over a 96 RXC 400 with the Quicksilver on it.

I will definately take the carb off and give it a good cleaning but if the exterior of the bike is any example of what the innards look like, it will probably be spotless. The bike had to be sitting a bit though because it only has 5000 miles on it.

I've never worked on a Dellorto carb but I have looked at some different diagrams for them. I have seen some that have an internal fuel filter on the fuel inlet. I wonder if it might be clogged up and affecting fuel flow.

Thanks for the response,

JBB