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DT125X won't rev past 8000rpm!


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Before I had my 2007 dt125x, I had a 2000 dt125r and I remember that it used to love to rev and that it redlined at 10.5k and went to 12k. I have recently fitted a tachometer to my dt125x as it doesn't come with one and I noticed that when I'm riding, it doesn't want to rev past 8000rpm. I know the tacho is accurate because it reads 1.5k when idling. When I reach 8000rpm, the bike is screaming. It was derestricted behind the speedo when I got it but I earthed the green/black cable to a different place on the frame to make sure, it made no difference. I'm assuming that the x and re models redline at 10.5 as well. Also, the bike runs fine, it pulls pretty well up to 50mph but after that it's gutless. It takes ages to reach 70 and the most I've got from it was 72 off the speedo. I've seen some people say they get nearly 90. So is the bike still restricted somehow or do the newer model dt's only rev to 8k. Also I forgot to mention that the bike has a full dep system.

Cheers :icon_smile:

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On here we have had some ludicrous claims for speeds from 125s, one muppet even claimed he had 100+ out of his, needless to say he got laughed at a lot. You have to remember it is only a little bike and has a lump (no disrespect intended) sat on it plus wind resistance all of which gangs up on the bike to make it struggle up to 70mph, which by the way is bloody fantastic when you think about it, don't know why it won't rev past 8K but bet it's so that the engine does not self destruct. Some lads on here have similar bikes to you and they really like this little bike and use it to learn how to ride before they go on to take their test and buy a bigger CC bike, the point I'm trying to make is that you can throw loads of cash at these little bikes and maybe add 10 or 15MPH to the top end but they are designed to go only so fast, if you reach the point where your doing more than the design was intended for you going to be buying a new engine every few weeks. Save your money and pass the test, buy a bigger bike and pass yours on (in the original condition) to the next guy to do the same.

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I went to go for a ride today and I noticed that where I had re-earthed it to the frame, the bolt had snapped. After fannying about a getting the broken bit of thread out of the frame, I tightened the bolt over the wire again and went for a ride to see if it made a difference. It felt light a different bike, It had much better acceleration, I actually manage to travel some distance before having to change up to 2nd gear and the bike was much more comfortable going at speed where before it would have been buzzing and vibrating like anything. So where the person earthed it in the first place was crap and where I earthed it after that, the bolt broke. But it's great now, I only went for a little ride but it reached 9k rpm :icon_biggrin:

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In stock condition the Powervalve shuts off at 7.5k and stops you revving further. Earthing that cable to the frame prevents this :) just a reminder that if you don't have a full license it's now illegal to ride your bike.

Stay safe!

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In stock condition the Powervalve shuts off at 7.5k and stops you revving further. Earthing that cable to the frame prevents this :) just a reminder that if you don't have a full license it's now illegal to ride your bike.

Stay safe!

Would the authorities be able to tell though, how would I get done for it?

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Realistically no, not without testing it.

Just giving you all the facts!

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Not sure to be honest, there's a thread on here somewhere with dyno results.

You could probably have it tested yourself to find out for sure

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So if from what I'm reading you are over the stock and legal HP for your bike then you also have NO INSURANCE cos if you ride outside the legal limits then your insurance will be invalid.

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So if from what I'm reading you are over the stock and legal HP for your bike then you also have NO INSURANCE cos if you ride outside the legal limits then your insurance will be invalid.

I was under the impression that everyone does this to their dt125's. It must be quite popular if the 2 that I have had were both derestricted when I got them.

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Not saying it doesn't happen just you must be aware that if the Insurance companies do test your bike after an incident then your up the creek. I used to ride to school when I was 14 and never even had a licence let alone insurance so who am I to throw stones? Just making a comment on what was being said not trying to be a smart arse, thought it was best to have out out there.

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Not saying it doesn't happen just you must be aware that if the Insurance companies do test your bike after an incident then your up the creek. I used to ride to school when I was 14 and never even had a licence let alone insurance so who am I to throw stones? Just making a comment on what was being said not trying to be a smart arse, thought it was best to have out out there.

I want the bike to be legal, but it's so much easier with it de-restricted. The thing is, what's to stop you just pulling the wire from the frame if you had an accident, as soon as that wire looses contact with the frame, it's restricted again.

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Its what it starts.

I gave my 50 a few tweaks.

Ended up with porting so severely it would barely run below 4k. Flat out was over, well whatever a stock rxs100 would do plus a bit as i was quicker.

Next you will fit a pipe, then reeds, then....

None of us are saints but in this day and age we have to give the proper advice. Following it is up to you. Same as it was for me in 87.

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I'm thinking about installing a rocker switch where you can switch between restricted and derestricted modes. Where does that leave me with insurance, If I had an accident but just switched it to restricted mode, there is no proof that the bike was derestricted at the time of the accident.

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If you do this then what makes you think that they won't look? Plus any mods on your bike will be particularly scrutinised by the Ins company if you have to make a claim, for instance if you bin it and it's a write off they take the bike away and have it independently checked by an approved repairer, they will spot it cos it's what they do all day every day, then when they tell the company what they have found your claim is not only refused but they will come after you for fraud and the cops will come and visit all for the sake of getting to 70 a bit faster, it's a no brainer really, ride your bike as is, take your test and get a bigger one. Or ignore this and take a chance. We don't think your wrong, after all most of us mod our bikes in one way or another, but the difference is we have a full licence and don't try to do wheelies down the high street anymore, well not often anyway. Plus even if your in the right (running with restriction on) and someone knocks you off the fact you have the mod on your bike means your NOT insured as your licence is invalid due to the mod.

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That's quite worrying, the amount of learners that have illegal dt's but probably don't even know it because they don't know the bike is derestricted. Also, how does the mod invalidate my license?

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Your not riding within the terms of your licence ie your bike has more than the permitted Horse Power, so that makes your insurance invalid due to it being more than the permitted amount. If your uncertain phone your Insurance company and ask them, they will tell you what your allowed to do and what your not allowed, DON'T say your have done this, otherwise look it up on the net, what does your licence say your allowed to ride (probably best really) if your in any doubt then come back and paste the blurb on here and someone will be able to decipher it for you, pretty complicated most of these things and sometimes they can contradict each other.

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