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Post Info TOPIC: OVERHEATING PROBLEM??


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OVERHEATING PROBLEM??
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Not been out much since buying the bike,it had a few problems overheating and loads of smoke all of which pointed at the head gasket.
I have replaced this 2 weeks ago and been on a few short rides since but tonight was my first proper ride out of about 20 mile.
And i leathered it topping out at about 70mph.
Then the red light came on,so i stopped and the header was whistleing and the cap had blown off also the radiator had boiled dry.
I refilled the radiator with water and it was circulaing ok round the rad neck so pump and stat seemed to be ok
Has anybody any ideas as to why this has starting again??

Any help appreciated.



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DTR Respected Member

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Did you change the head gasket yourself? official gasket?
Sounds like it has blown again, i had this happen a few times.

Best bet is to get a garage to do it for you then when then problem starts again you can get them to fix it

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DTR Senior Member

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get the head skimmed(because they tend to warp) and put a new head gasket in and all should be fine.

Just make sure to bleed the system properly etc afterwords.

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DTR Senior Member

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Yep i thought so,you have said what i didnt want to hearno

Is there a diy way of checking if the head is warped??

I tried to find a quality gasket and ended up with a top end kit off ebay for around £17 so not a cheap inferior part.

I need to buy an expansion tank cap as i realised the pressure had blown mine off somewhere before it started whistleing tunes but i cant understand why there is no smoke which was the reason along with overheating i changed the last gasket.
Any other suggestions or things to check before i start taking it to bits again.
oh,,something else i noticed when i changed the last gasket it will still get the red temperature light coming on if it is left idleing for a long time then it goes out when i start riding as air flows over the engine.
Anyone come across this???

Carl



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Top end kits are cheap crap.
Official head gaskets come on their own and cost between £10-15

I used several cheap gaskets in a row to fix a head gasket that kept blowing, and even an official one that blew.
The problem was that i was not cleaning the mating surfaces of the head/barrel enough, i didn't have the tools for it.
It has to be COMPLETELY clean, no dirt, no grime, no previous gasket crud.

I took it to be done by a mechanic who did it properly but used a cheap gasket, it blew again, then i was told that it might be the head is warped, i gave him an official gasket to try instead and the bike has been fine since. (7k miles)

Moral of the story:
Clean mating surfaces properly
Cheapo gaskets are ****e

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DTR Senior Member

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Cheers for that,
I was told when i was looking for a gasket that there are cheap ones so i went or a slightly more expensive kit but obviously still crap.
Im going to get the head skimmed and try again with a genuine gasket i had trouble tying to locate one last time,where did you get yours from??
Does anybody know where i can get a genuine gasket from for a DT125R 2005??

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Any yamaha dealership that is near you, or even a small bike shop that is capable of doing engine repairs should be able to order them in.

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DTR Senior Member

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started  taking the head off tonight and noticed there is no thermostat fitted.
Also cant get the power valve cables to work the valve properly.
Can you adjust the valve on the end where the cables go by undoing the 10mm bolt and turning the bracket slightly??



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Having no thermostat wouldn't matter that much, just would be a pain when cold starting

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DTR Senior Member

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seems like somebody else has been having problems and took the stat out.
What else could it be if it turns out not to be the head gasket,the pressure has to  be coming from somewhere.
Is the head gasket a dry gasket or after skimming has anybody used hylamar or similar gasket sealant for extra help with sealing.

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It will be the head gasket, or very unlikely the base gasket

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DTR Senior Member

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if there is compression leaking into the cooling system, then it would cause overheating.

but yeah top gasket would be the one. no gasket sealents. Just make sure both mating surfaces are dead clean and flat. PLUS evenly torqued down

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im making enquires about getting the head skimmed tommorrow and trying to locate a genuine head gasket.Ive also noticed a small score in the barrel tonight so i might even get it rebored with a new piston.

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are you experienced with rebuilding bikes?
It would be terrible for you to go through doing all this yourself and then the head gasket blows again.

If your not experienced it might save you money in the long run by taking it to a garage

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DTR Senior Member

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We used to strip these dts down for fun about 20 years as scramler bikes when leaks and knocks didnt really matter before the days of the internet and public forums,we just used to go to bike shops and pay the ridiculous prices they decide on the day,but now im a bit older and wiser and in the middle of a mid life crisis i have bought a newer one and have chosen to mess about a bit again.The bike runs ok just that something not quite right will annoy me,i could just put water in every day but i think thats not  the way to go.

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