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UltimateJames

Overheating DT125R Help pls

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Hi im james from Wakefield and im new to the site and to the DTR but iv had mine a couple of months now after doin the cbt its roughly a 2000 - 2003 model (on a q plate due to being stolen recovered)

Firstly iv been reading all the threads about de-restricting the bike and i think mine has been done to a point in that it has a full DEP exhaust and snorkal removed and iv been told its been re jetted and has a new piston and rings fitted although im begining to wonder if thats true as im having some problems with it.

Iv taken out the reed switch from the speedo so im now getting 60mph + (iv had 75 on the clock) wich is nice lol.

The main problem is its loosing water from the expansion tank overflow (from the pipe that runs into the frame)causing it to overheat, more so if i give it full beans, iv since fitted a new head gasket but its not made any difference so not sure what to do now ??.

Also iv read a lot about earthing the wire to the speedo but cant find the plug with 4 wires going in and 3 coming out anyone got a pic ??

Changed chain n sprockets today £36 off ebay for powerlite cogs + DID chain only thing is the rear cog was 55 tooth and new one is 57 so looks like im gonna loose a bit of top end ? not sure how much difference its gonna make tho ?

any advice welcome, cheers James.

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Guest MaD.VeZ

Hi im james from Wakefield and im new to the site and to the DTR but iv had mine a couple of months now after doin the cbt its roughly a 2000 - 2003 model (on a q plate due to being stolen recovered)

Firstly iv been reading all the threads about de-restricting the bike and i think mine has been done to a point in that it has a full DEP exhaust and snorkal removed and iv been told its been re jetted and has a new piston and rings fitted although im begining to wonder if thats true as im having some problems with it.

Iv taken out the reed switch from the speedo so im now getting 60mph + (iv had 75 on the clock) wich is nice lol.

The main problem is its loosing water from the expansion tank overflow (from the pipe that runs into the frame)causing it to overheat, more so if i give it full beans, iv since fitted a new head gasket but its not made any difference so not sure what to do now ??.

Also iv read a lot about earthing the wire to the speedo but cant find the plug with 4 wires going in and 3 coming out anyone got a pic ??

Changed chain n sprockets today £36 off ebay for powerlite cogs + DID chain only thing is the rear cog was 55 tooth and new one is 57 so looks like im gonna loose a bit of top end ? not sure how much difference its gonna make tho ?

any advice welcome, cheers James.

Hi James. Welcome to the forum B)

75mph sounds very good for a DTR imo. Others may argue though.

First off i have to ask, You do have coolant in your radiator and not tap water? ( may sound daft, but i have seen it done, and it causes similar problems to what you have).

The cause of the overheating could be the a few different things, but most likely is probably the fact its been jetted and had the snorkel removed, the jet size may be incorrect and is too small. If this is the case then it will run hot and boil the coolant and cause it to expand out of the overflow. I think the coolant leak is a symptom and not the cause.

The earthing of the wire doesn't apply to your bike( its for the 2004> DT125RE/X models).

The 2 less teeth will make a difference, but you will gain in acceleration what you lose in top end (maybe 5mph or so), have you got the same size front cog with the kit as was on originally?.

On a CBT doing 75mph isn't a good thing imo, but there is no law against how fast you can accelerate B)

Out of interest, when you say you have taken the reed switch out, have you removed it completely or simply moved it away from the speedo face?

Also it isn't a pink DTR is it? I have a mate who had a pink DTR on an Q plate and he was from the Wakefield area.(he sold it a year or 2 back).

Vez.

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Hi James. Welcome to the forum  B)

75mph sounds very good for a DTR imo. Others may argue though.

First off i have to ask, You do have coolant in your radiator and not tap water? ( may sound daft, but i have seen it done, and it causes similar problems to what you have).

The cause of the overheating could be the a few different things, but most likely is probably the fact its been jetted and had the snorkel removed, the jet size may be incorrect and is too small. If this is the case then it will run hot and boil the coolant and cause it to expand out of the overflow. I think the coolant leak is a symptom and not the cause. 

The earthing of the wire doesn't apply to your bike( its for the 2004> DT125RE/X models).

The 2 less teeth will make a difference, but you will gain in acceleration what you lose in top end (maybe 5mph or so), have you got the same size front cog with the kit as was on originally?. 

On a CBT doing 75mph isn't a good thing imo, but there is no law against how fast you can accelerate  B)

Out of interest, when you say you have taken the reed switch out, have you removed it completely or simply moved it away from the speedo face?

Also it isn't a pink DTR is it? I have a mate who had a pink DTR on an Q plate and he was from the Wakefield area.(he sold it a year or 2 back).

Vez.

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Hi James. Welcome to the forum  B)

75mph sounds very good for a DTR imo. Others may argue though.

First off i have to ask, You do have coolant in your radiator and not tap water? ( may sound daft, but i have seen it done, and it causes similar problems to what you have).

The cause of the overheating could be the a few different things, but most likely is probably the fact its been jetted and had the snorkel removed, the jet size may be incorrect and is too small. If this is the case then it will run hot and boil the coolant and cause it to expand out of the overflow. I think the coolant leak is a symptom and not the cause. 

The earthing of the wire doesn't apply to your bike( its for the 2004> DT125RE/X models).

The 2 less teeth will make a difference, but you will gain in acceleration what you lose in top end (maybe 5mph or so), have you got the same size front cog with the kit as was on originally?. 

On a CBT doing 75mph isn't a good thing imo, but there is no law against how fast you can accelerate  B)

Out of interest, when you say you have taken the reed switch out, have you removed it completely or simply moved it away from the speedo face?

Also it isn't a pink DTR is it? I have a mate who had a pink DTR on an Q plate and he was from the Wakefield area.(he sold it a year or 2 back).

Vez.

Hi Vez cheers for the info mate, it is tap water thats in there yeh as im having to top up before each trip ? ill try getting some proper coolant in there see what happens, is it special coolant i need or is the stuff for cars the same asin antifreeze / summercoolant ?.

Im also thinking of checking the thermostat and could the water pump cause this and is there a way of checking it ?

I will try take the carb off and see what jet is in there, i was told it had been done but im not convinced am i right in thinking it should be a 240? if not where can i buy one the right size ??

the reed switch i removed it from where its fitted to the speedo and tucked it inside the speedo housing still wired up and its working fine with 60mph + easy now ( naughty yes i know but shhhhh lol )

Also its not pink one its blue with werx stickers

Im loving the bike and happy with the speed its got now just need to get the cooling sorted so i dont have to carry a bottle of water everywhere i go !

Does anyone notice the difference using super unleaded petrol as iv tryed it on both and i think it makes a massive difference to the power imo

Cheers James.

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Guest MaD.VeZ

Using tap water is a bad idea for any length of time. It boils and expands at lower temps than coolant, its ok for a temp fix to say get you home, but any length of time is bad. There are minerals in there that will clog the engine very quickly, especially when it boils. Look in the bottom of your kettle at the lime-scale, you don't want that in your engine. If you have to put water in there, use distilled water, like you would top a battery up with, its only cheap and available at most garages and doesn't contain the minerals like tap water.

I think you can use the coolant you put in cars, as long as it is for aluminum engines, can't say for sure though. I use rock oil Kool that requires mixing 50/50 with distilled water, but if you are a signed up member here you can get a discount at opieoils and they do some ready to use coolant from Motul that looks quite good http://www.opieoils....ing-liquid.aspx .

The standard jet for your Year/s of bike is a 240 iirc, so you would need to go up to a 250 or 260 , I can't remember when Yamaha changed from a 210 to a 240 but its was around about the time of your bike, so maybe someone else on here can remember exactly?

I agree about the super unleaded, BP's has a 97-98 RON (Research Octane Number) compared to standard unleaded that is 95 RON. BP are apparently stocking an ultimate unleaded with a 102 RON, but i haven't seen it locally yet.

That being said, some people say that the performance increase is a myth, as most vehicles only require around a 91 RON and anything above this is a negligible increase in performance. I know that my bike runs better with it, starts easier on cold days etc, so thats all that matters to me.

Vez.

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 Using tap water is a bad idea for any length of time. It boils and expands at lower temps than coolant, its ok for a temp fix to say get you home, but any length of time is bad. There are minerals in there that will clog the engine very quickly, especially when it boils. Look in the bottom of your kettle at the lime-scale, you don't want that in your engine. If you have to put water in there, use distilled water, like you would top a battery up with, its only cheap and available at most garages and doesn't contain the minerals like tap water.

I think you can use the coolant you put in cars, as long as it is for aluminum engines, can't say for sure though. I use rock oil Kool that requires mixing 50/50 with distilled water, but if you are a signed up member here you can get a discount at opieoils and they do some ready to use coolant from Motul that looks quite good http://www.opieoils....ing-liquid.aspx

The standard jet for your Year/s of bike is a 240 iirc, so you would need to go up to a 250 or 260 , I can't remember when Yamaha changed from a 210 to a 240 but its was around about the time of your bike, so maybe someone else on here can remember exactly?

I agree about the super unleaded, BP's has a 97-98 RON (Research Octane Number) compared to standard unleaded that is 95 RON. BP are apparently stocking an ultimate unleaded with a 102 RON, but i haven't seen it locally yet. 

That being said, some people say that the performance increase is a myth, as most vehicles only require around a 91 RON and anything above this is a negligible increase in performance. I know that my bike runs better with it, starts easier on cold days etc, so thats all that matters to me.

Vez.

Well iv been to Startrights in leeds and got some Putoline Organic readymixed coolant to try so ill see how that goes and find out what jet iv got.

Hope it dont throw it out tho cost £12 for 2 litres and it cant be mixed with water lol.

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I think your head gasket has gone, have you torqued down the head nuts or re-checked them. If it is this youll be pissed off when you lose your new coolant. :blink:

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Guest MaD.VeZ

I think your head gasket has gone, have you torqued down the head nuts or re-checked them. If it is this youll be pissed off when you lose your new coolant.  :blink:

Having two head gaskets leak the same is unlucky, or a warped head maybe.

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Having two head gaskets leak the same is unlucky, or a warped head maybe.

you are supposed to torque them down, then torque them again later i think..was this done ?

Could also be a faulty seal somewhere which stops the pressurisation, radiator cap seal possibly ?

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Guest MaD.VeZ

you are supposed to torque them down, then torque them again later i think..was this done ?

Could also be a faulty seal somewhere which stops the pressurisation, radiator cap seal possibly ?

I didn't think about the cap.

My money is still on the tap water though. 

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I think your head gasket has gone, have you torqued down the head nuts or re-checked them. If it is this youll be pissed off when you lose your new coolant. :blink:

I'm with OG here!

DTR's are very prone to blowing head gaskets, even new head gaskets!

It is very important to thoroughly clean the surfaces of the cylinder head and barrel before fitting the new gasket. I know some "amateur" mechanics who've taken up to 3 attempts to do the job properly!

Make sure there is no damage to the mating surfaces, and tighten the head nuts in a cris cross pattern so that you don't warp the head.

Sorry, but I reckon you've wasted your £12!

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i recently bought a dt125re,leaking aftermarket head gasket,total crap,yamaha £12 genuine gasket,job done,nearly 30 years of repairing bikes,most after market stuff is over priced and crap,your head could be warped,for £12 i would chance a genuine gasket,save your coolant,see what happens.

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I'm with OG here!

DTR's are very prone to blowing head gaskets, even new head gaskets!

It is very important to thoroughly clean the surfaces of the cylinder head and barrel before fitting the new gasket. I know some "amateur" mechanics who've taken up to 3 attempts to do the job properly!

Make sure there is no damage to the mating surfaces, and tighten the head nuts in a cris cross pattern so that you don't warp the head.

Sorry, but I reckon you've wasted your £12!

Ok i put the coolant in and guess what, yep by time i got the 17 miles home from work its all out again!!!!

The rad cap iv changed so its not that either and when i did the gasket i followed the haynes manual and used a piece of emmery paper on a glass chopping board to lightly smooth the head surface in a circular direction.

it was then tightned down and tightned again after a run out. in a diagnal

Looks to me like the head maybe warped a bit so im gonna get it skimmed to make sure then get a gen yamaha gasket ( where can i get one ) hopefully fingers crossed it will be ok and hope its not the barrel.

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Ok i put the coolant in and guess what, yep by time i got the 17 miles home from work its all out again!!!!

The rad cap iv changed so its not that either and when i did the gasket i followed the haynes manual and used a piece of emmery paper on a glass chopping board to lightly smooth the head surface in a circular direction.

it was then tightned down and tightned again after a run out. in a diagnal

Looks to me like the head maybe warped a bit so im gonna get it skimmed to make sure then get a gen yamaha gasket ( where can i get one ) hopefully fingers crossed it will be ok and hope its not the barrel.

When i have had head gaskets blow on my DTR they usually flood the cylinder with coolant, either when running or when left to stand overnight. But my DTR has a hard life off road which may be why the head gasket has never just leaked in one direction like yours could be doing.

A Yamaha dealer can order you a gasket. I think there is a ATV dealer in Leeds that is a Yamaha dealer, but you may find one closer.

Vez

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When i have had head gaskets blow on my DTR they usually flood the cylinder with coolant, either when running or when left to stand overnight. But my DTR has a hard life off road which may be why the head gasket has never just leaked in one direction like yours could be doing.

A Yamaha dealer can order you a gasket. I think there is a ATV dealer in Leeds that is a Yamaha dealer, but you may find one closer.

Vez

with mine you could see on the gasket where it had been leaking into the water jacket,also tell tale carbon track on cylinde head surface to small hole in barrel water jacket.

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with mine you could see on the gasket where it had been leaking into the water jacket,also tell tale carbon track on cylinde head surface to small hole in barrel water jacket.

Well it was definatly the head gasket !!! think the head is warped so its on its way to be skimmed as we speak, iv been to Padgets in dewsbury for a genuine gasket and its a bit thicker than the pattern one i had last so fingers crossed ....

Have some pics iv just uploaded to photobucket so once iv figured it out il post em up

cheers, James.

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DSC02115.jpg

This is the head the first time i removed it to change the gasket

DSC02127.jpg

This it today (blown again)

DSC02268.jpg

Head gasket you can see how bad it is from the carbon blown into the water ways

DSC02267.jpg

not bad on barrel side apart from one small bit but hopefully thats due to the other side going ?!!

DSC02270.jpg

marks in barrel ( should i be worried ? )

DSC02274.jpg

DSC02275.jpg

should there be a screw in this hole on the carb

DSC02276.jpg

DSC02278.jpg

anyone know where the jet is lol ??

DSC02282.jpg

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Good news i think iv fixed it, got the head back today from Neil`s Auto Service Centre in Ossett, really nice guys and the first time iv used them for anything.

Took the head in at 2pm tuesday and they rang me at 1030am this morning so massive thanks to the lads there for the fast work and only charged me £25 !!

Put it all back together this afternoon filled up with fresh coolant (again) and iv been out for an hour tonight n all seems well cant see any leaks at all and temp stayed down.

One problem is for the first 20mins i had a massive flat spot in the revs but it could be due to not having a thermostat in at the moment and its quite cold tonight plus iv had the carb off to have a look what jet was in but didnt find out yet. Will know for sure in the morning on way to work.

DSC02285.jpg

DSC02284.jpg

DSC02283.jpg

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Nice one James, The jet was that brass thing in the middle of the carb, it will have a number on it. I see your cylinder head is one of those weird ones with the convoluted squish band, mine has that one on too. has 3BN on the head iirc.

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Nice one James, The jet was that brass thing in the middle of the carb, it will have a number on it. I see your cylinder head is one of those weird ones with the convoluted squish band, mine has that one on too. has 3BN on the head iirc.

Hi mate yeh it is a 3BN and im gonna have a proper look at the carb another day, i did take that jet out and there was a number but didnt look like it said 2?? didnt have time to check it properly today tho ill save that job for later ill just be happy if it stays cool without blowing the coolant out for now lol

Cheers everyone for the advice.

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