BIG HELP REQUIRED PLZ yam dtr 125 head gasket problem

[befdelta7]

hi,
my dtr overheated a few weeks ago, i noticed coolant leaking out between the barrel and head also the radiator level dropped and the coolant in the rad was cloudy and smelt of exhaust gasses.

my question is.. after 3 barrels, 4 cylinder heads and 2 new head gaskets, why is it still blowing?

im seriously at my whitts end, and going to set fire to the bike. i have had the top-end apart/together 7 or 8 times in the last few weeks.. can even do it in the dark.. done it so many times.

this is the last time im going to try to sort this issue.. seriously, if it dont work check ebay!!

well....

i have a gasket sealant that the bloke in the shop assured me can be used on a cylinder head.. packet says: not reccomended for cylinder heads!
anyway will it work if i used it on the cylinder, then the cylinder head itself, with 2 gaskets in between?
or any other reccomendations i can try to get this seriously unreliable dtr to become reliable, any other sort of material i can use for a gasket ECT ... has cost me inexcess of £300 to get it going, should of bought a second hand engine really

THANK YOU !!!
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Dont do a wheelie in front of a traffic copper... it gets you 3pts and £220 fine.

[27cows]

I had the top end off my DTR a couple of times and never had a problem (I re-used the head gasket once). Golden Hermatite sealed things fine.

[finpos]

eh, have you actually tried to use a proper (manufacturer's) gasket, and no sealant at all, especially the stuff that says that it's not suitable on the packet?

f.

[befdelta7]

havent accually used any sealant yet.
bought two gasket sets from ebay, suposably 'genuine' yamaha gaskets...

but going to buy a proper gasket set for a yamaha dt125r maybe sometime next week but cant seem to find one on ebay or any proper yammy ones anywhere on google.. any ideas?

think im going to use the old gasket and some sealant for a temp fix untill i get hold of a genuine gasket.
____________________
Dont do a wheelie in front of a traffic copper... it gets you 3pts and £220 fine.

[befdelta7]

havent accually used any sealant yet.
bought two gasket sets from ebay, suposably 'genuine' yamaha gaskets...

but going to buy a proper gasket set for a yamaha dt125r maybe sometime next week but cant seem to find one on ebay or any proper yammy ones anywhere on google.. any ideas?

think im going to use the old gasket and some sealant for a temp fix untill i get hold of a genuine gasket.
____________________
Dont do a wheelie in front of a traffic copper... it gets you 3pts and £220 fine.

[27cows]

Not 100% sure (it's years since I owned my DT) but I think sealant may have been recommended.

But it seems to me that there must be an underlying issue here. Why did the bike overheat in the first place? Was damage done to anything? If the barrel and head have been changed, I'd be looking at something else being the problem. Could be something silly, like too much coolant.

[befdelta7]

** double post **
____________________
Dont do a wheelie in front of a traffic copper... it gets you 3pts and £220 fine.

[befdelta7]

[finpos]

I'd be tempted to test your head and barrel choice for straightness yourself - you just need a straight edge and a critical eye, and use a new, genuine gasket, (no sealant, no good will come of that). If you've re-used a gasket, it might not work second time, especially if it's got bits that crush or it's coated in something.

Mating surfaces spanking clean and correct torque on the head bolts, of course.

Have you looked to see if there's any cracks in the original barrel?

f.

[27cows]

On the plus side, you've now got plenty of top end spares for when you get this sorted

There's only a limited number of things that can be causing the problem, you just have to eliminate the things it definitely isn't. Pain in the arse when this sort of thing happens and it often turns out to be something really stupid like a blocked waterway channel.

[hmmmnz]

might be time to change your waterpump as well
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the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[befdelta7]

iv looked and dont see any cracks on the cylinder.

you see the engine runs for about 30/40mins the temp needle stays a quatre of the way up the scale and moves up and down very slightly with stopping and starting in traffic as usual.. but then all of a sudden bam its right in the red, turn it off for a cheeky fag brake top it up with water from a bottle and its gone back down to nearly where it was before it started to move to the red, and can be driven a few mins before the needle hits the red.

really confused as to why this is such a big issue for such a relativley straight forward single cylinder 2-stroke.
____________________
Dont do a wheelie in front of a traffic copper... it gets you 3pts and £220 fine.

[27cows]

[ms51ves3]

When you tighten the head up, you are tightening the nuts/bolts diagonally and progressively?

[finpos]

When you say top it up, do you mean the expansion bottle or the radiator? If you have a blowing head gasket, it can be slowly filling your cooling system with gas while blowing the water out of the bottle. Unfortunately gas doesn't transfer heat so well, so then the engine overheats. If you just put the water back into the expansion bottle, you are leaving yourself short of coolant and it'll overheat again straight away.

You can usually tell the difference between a head gasket problem and general overheating because the first will cause you to spill coolant constantly as it is displaced by gas, while the second tends to happen about a minute after you stop the bike - as the coolant stops circulating, it soaks up too much heat and boils out.

I'd dearly love to see an intermittent water pump fault, but I doubt you'll find one.

f.

[finpos]

...and as I yak on about quite a lot on here, it's really easy to test for a cylinder head gasket leak. Bodge some stuff together so you can attach a tyre valve to the neck of radiator where the pipe to the expansion bottle normally comes out. Put 15PSI into it with a footpump, go have a cup of tea. Come back, if the pressure is gone and you have a cylinder full of fluid, your head gasket is ferked.

f.

[sickpup]

You are aware that not all DT125 base gaskets are the same and that if you use an earlier one on a later bike it will block the cooling system and that most pattern gaskets are to the earlier spec and need a modification to work?

[serlant]

as for buying a head gasket, https://www.wemoto.com/ you didn't say what year your bike was, just put dt 125 r into the search for model then pick your year.

[Vincent]

[27cows]

The gasket situation doesn't explain why the bike had the problem to start with. Presumably the engine had been running along happily for some time up to the point it first overheated and hadn't recently been apart/had gaskets replaced. Which would suggest it's probably pump, thermostat or radiator related.

[rodeobob]

Water pump impeller slipping on the shaft when it gets warm maybe.


Has it had good coolant in it?? perhaps the radiator is a bit clagged up.



A new pattern part head gasket has to be a better deal than re-using an old one with goo on it.

You want to be thankfull you can get pattern gasket sets and the price they are.

Its over 60 quid here in Australia for a gasket set for a DT200R. You can not buy a top end set, they make you buy the Genuine Yamaha parts.



Bob.
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DT200R '91
DT175 '91
Various IT/DT175 engines for 'projects'

[cagiva gezzer]

As above really:

1) Check that the water pump is working / circulating.

2) Check that you have the right gaskets.

3) Check that the head / cylinder are straight:


Coat the top of the cylinder in valve paste / grease and place the head onto the cylinder and PRESS firmly down. Notice how there are high spots (where the paste is) and low spots (where there isn't any grease).
https://www.bikepics.com/pictures/402383/

If you have uneven distribution of grease / paste you want to lap the two surfaces together. Coat the cylinder head in valve paste. Use small circular motions to smooth down the high points. When you've finished you should have even distribution of paste as below:

https://www.bikepics.com/pictures/402384/
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"because one stroke isnt enough and four strokes waste two"

[Vincent]

If you're going to lap the head and cylinder, you need to do it on a piece of glass.

[ben350]

..or an eningeers plate, just dont tell the engineer
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Ducati 996 Biposto
Suzuki Goose 350
DT125R Supermoto (Project)

[element]

check your thermostat too.. take it off and put it in hot water and see if it opens.

dont ever buy pattern gaskets.. let that be a lesson! you can get away with em on the side casings but not on the topend.. Ive heard people get a little as 300 miles before blowing again..

gen yam head gasket is only £10 or so..

dont need to use gasket seal. My head gasket went at 12k miles.. slight drip of coolant on the barrel. lapped the head just to be safe and replaced gasket. not had a problem since and im on 27k miles now
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