I recently bought a 1995 KLR 250 and it had a weak battery. I replaced it and ever since then my bike has had trouble getting going.
As I put it into first gear and am accelerating, as soon as I let go of the clutch, even a little bit, the RPMs drop from 4-5 thousand to 0.
After revving the engine for 30 seconds or so, the bike will then take off.

Also, once I get going, the bike hits a certain point (8,000 RPMs and loses all power and stalls. I have to redline to get it going again, and it only works 60% of the time. If it stalls like this I pullover and have to do the engine revving for 30 seconds to get it going again.

I'll charge the battery and it will work for 2-3 uses, then the problem continues.

Could it be an electrical problem, a clutch problem, a fluid problem, ETC...

Help please

 

First of all keep it simple.
1. How did you know the old battery was bad. Did you test it w/ a voltmeter? When you replaced it, did you properly charge the new battery before using it? It should read 12 volts when charged w/ the engine off.
2. I doubt it is a clutch/fluid problem, doesn't sound like it fits the bill for that.
3. How many miles on the bike?
4. You mentioned you just bought the bike. Has it run like this from the first time you rode it? If not, did you poke around it any other than the battery? If so, was the bike stored for any period of time before you purchased it? If it sat any, even as little as a couple of weeks, the culprit could be some junk in the fuel system. Most likely a partially clogged jet.

A bit more info may help find the issue.

 

The bike has 5,000 miles on it
The previous owner only took it on a 50 mile desert ride. The first week I had the bike it ran great, but I did put the tail light fender, turn signals, horn, etc back on because the previous owner turned it into a dirt only bike.

I don't believe it sat for very long, and the problem seemed to be noticeable after I put a new battery that I bought from a motor sports store. I had them charge it as well.

 

Another forum replier thought that what's happening is that the clutch isn't fully disengaging when Idepress the lever completely, and that all I need to do is adjust the tension on the clutch cable. Try loosening up the cable.

"The other problem sounds like a carb issue. Your main jet might be clogged. Again, a simple fix. Just clean out the carb, paying special attention to the jets."

What does anyone else think?

 

I have a similar problem. I'm thinking of buying my buddies 2004 klr250. It has 6xxx miles. hasn't beeen started for around 9 months. I took apart the carb and cleaned everything out. changed the fuel, spark plug, oil and filter. I finally got it all back together and crossed my fingers. It took awhile to finally start, with choke on. it seemed to run ok with the choke on. as soon as I turned the choke off, it idled ok. as soon as I tried to give it a little throttle it would die instantly. drained the float and tried to start again. did this all day and she still won't go past idle. any ideas. sounds kind of like what's going on with your bike too. I also bought a new battery. thanks!

 

I got the bike fixed! I went to the dealer to get some jets. all they had was a 42 pilot for a harley, picked up a 120 main. drained all the fuel again from the tank and filled her up with fresh gas. drained the float bowl. installed new jets. added a washer under the needle. buttoned things up and crossed my fingers. 1st kick, no go. 2nd kick... fired right up with a beautiful purring sound. idle was great and smooth, revved great. took her for a spin around the block and she ran perfect! problem solved. dirty old gas in tank, clogged jets, dirty oil, old plug, been negleted. now happy klr jr! now my buddy says maybe price should be higher