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DT125 stuttering at high revs? (Sound clips)


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Within the last couple of weeks my dt125 has started stuttering around when you reach the powerband. It also jerks forward  a bit while it stutters. I haven't changed anything on the bike recently so I don't know why this has stared happening. Just yesterday I took the carb off and cleaned it out as I thought the main jet might be getting blocked but that didn't solve the problem. I have also tried multiple spark plugs. Some things I have noticed: it doesn't do it nearly as bad if at all when the bike hasn't yet reached full temperature, so for the first minute after pulling away the bike feels so much better. I've got some sound clips where can hear the problem. Clip1  Clip2  Clip3. Anybody have any idea what the problem is? It's really annoying because you're unable to ride the bike at a decent speed as it wont rev past the point where it stutters.

Cheers

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Plug colour?

Good spark?

Mileage?

How long has the top end been on?

Checked ALL the electrical connections for the ig, including the kill switch on the bars and the engine earth as well as the mag outputs.

Filter clean

Reeds in place and good condition

Exhaust tight

 

 

 

 

 

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15 minutes ago, Cynic said:

Plug colour?

Good spark?

Mileage?

How long has the top end been on?

Checked ALL the electrical connections for the ig, including the kill switch on the bars and the engine earth as well as the mag outputs.

Filter clean

Reeds in place and good condition

Exhaust tight

 

 

 

 

 

I can answer some of these now. The plug is a light brown colour, I think it's okay. As far as I know the spark is decent but I'll check properly soon. The bike has just broke 10k miles but it's only done at most 2000 miles since the top end was rebuilt. I checked the filter fairly recently and it was clean but I'll check that again. I'm also pretty sure the reeds and exhaust are okay but I'll make sure.

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How long has it been doing it? Have you put fresh fuel in it since?

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1 hour ago, finnerz89 said:

How long has it been doing it? Have you put fresh fuel in it since?

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It started a few days after Christmas. I've gone through a few tanks worth of petrol since it started.

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What RPM does it start doing it? And what year is your bike?

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It sounds like fuel or spark problems, if you have already checked the carb then my next thing would be to check the HT lead and plug cap, it's usually the small things that go first and a new cap will only cost a couple of quid. Also make sure the HT lead is not trapped or rubbed through anywhere that it can spark across on the frame or something, does sound like a misfire to me tho.

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10 hours ago, finnerz89 said:

What RPM does it start doing it? And what year is your bike?

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It starts at around 7k rpm and its a 2007 dt125x.

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Is your bike derestricted? That's when the cdi starts to retard the powervalve to limit the power on restricted bikes

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5 hours ago, finnerz89 said:

Is your bike derestricted? That's when the cdi starts to retard the powervalve to limit the power on restricted bikes

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No Iv'e derestricted it and im pretty sure thats not the problem. I remember what it felt like riding it restricted and this is differrent. It wants to rev more but it just cant whereas when it was restricted the bike felt like it was redlining at 7k rpm.

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Just sounded similar to mine when it had the rev limiter on. Where did you earth the cable behind the clocks? I'd double check it's all good. I'm also assuming you have an aftermarket rev counter then?

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2 hours ago, finnerz89 said:

Just sounded similar to mine when it had the rev limiter on. Where did you earth the cable behind the clocks? I'd double check it's all good. I'm also assuming you have an aftermarket rev counter then?

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I did have but got rid of it about a month ago. Actually I'll make sure to check the connectors on the coil because that's where I connected the tacho. I earthed the cable directly to the frame under the bolt for the radiator bracket.

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I figured out what it was. It was the connector on the coil which I used as the feed for the tacho. The connector was loose so I just squashed it a bit and problem solved.

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Err, thought I said that? :shrug:

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"Cough, cough".

Post #2

B)

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  • 4 months later...

I have had a TZR250 refusing to run on both cylinders..replacing a plug cap sorted it

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