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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Oil leak
Post Info TOPIC: Oil leak
j180


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Oil leak
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Looks like the TTR is coming off the road earlier than expected, in the last couple of days I noticed a bit of oil under the bike, had time to get a proper look today. Looks like the base gasket has perished, not sure if it has been put on correctly as it is hanging out by the edge of the engine by a few mm. Looks like the list of parts is growing 😨



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mypobox


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How bad is it, cant u just ride it. oil is cheap.

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j180


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Could do mucker but there's a pool under the bike after a 5 mile commute. I was going to rip it apart and powder coat the frame anyway. At least I can check the valves etc. Will just put the Tuono earlier and use that instead

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peteBLUEttr


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I am looking forward to some rebuild pics!

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Pete. South Somerset, England.
TTRfan


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A "blown" and leaking base gasket is a bit of a mystery confuse

If you consider its surface are, it would take a significant amount of pressure to blow it out if the head bolts are properly torqued up.

A possibility to consider is that the crankcase breather is blocked. This however seems unlikely as the pressure build up in the crankcase would clear the breather rather than blow the base gasket as that would be the least line of resistance. Perhaps very worn or damaged piston/rings/barrel might allow this?

My favourite theory is that the engine has ingested water at some stage and a hydraulic lock in the combustion chamber would have sufficient force (it can bend conrods after all!) to stretch the head bolts leaving sufficient movement to blow the base gasket. However, the possible flaw in this theory is why the head gasket wouldn't also blow confuse

Any thoughts guys?

Brian



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j180


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Its weeping from the base as far as I can see, cleaned everywhere in that area then took it up and the road for a couple of minutes and the only place there was oil was in the centre of engine at the base. Will have a further go over the weekend

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TTRfan


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Is your "decompressor" seal leaking? Once they let go they can make a real mess and it can be difficult to recognise the source of the leak.



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j180


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I have no idea where the decompressor seal is but will search it and have a look. Thanks for the advice Brian.

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j180


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Just had a look in the search engine there is no oil coming from the top of the engine at all. Going to strip tank seat etc off the bike to get a better look tomorrow

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dern


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If you mean the base of the cylinder at the front then mine did the same. No blocked breathers or anything sinister. Just removed the barrel, put new gaskets in, put it all back together and back on the road.

Regards,

Mark


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j180


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Cleaned around the engine today then ran it for about ten minutes, it's definitely weeping front the base gasket. It does look like the gasket has been badly fitted as one side looks as though it is metal to metal. Think I will now start taking it to bits. Haven't done this in years 😱

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locky


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I've just done a top end rebuild on mine to fit new valve stem oil seals and piston rings. While it was all in bits I reseated the valves and reshimed.
Quite a straight forward job and very enjoyable. If you're just going to change the gaskets it will be a mornings work.

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2004 TTR250. White Brothers E series exhaust, modded airbox, rejetted, 13/48 c&s & many more mods..
j180


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Maybe a morning for you but a life time for me lol.

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locky


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Just follow the workshop manual and you'll be fine and use a torque wrench.

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2004 TTR250. White Brothers E series exhaust, modded airbox, rejetted, 13/48 c&s & many more mods..
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