Yamaha TT350 seizure? Please help

[Kingoftheswing]

Hi guys, any advice or help would be greatly appreciated. I don't think this is going to be an easy or cheap fix!

I have a 1987 Yamaha TT350. Been out on it for most of the afternoon today and was running perfectly. On my slow plod home the engine all of a sudden lost all power. I pulled over and tyres to kick the bike over, the kick start to my horror was rock solid. After leaving it for a few minutes it began to free up, however, the engine now has no compression and will not start.

It is possible that I got a bit of water into the cylinder, which I know can cause a seizure but I'm doubtful that this is the case.

I was thinking that it would more be the thinning of the oil as the engine heated up has caused a partial seizure.

Any thoughts or information? I have done some reading and believe my first port of call would be to check valve clearances, piston and rings.

Thanks in advance.

[Kwacky]

What oil you running and when was the last time you changed it?

[Kingoftheswing]

Silkolene semi synthetic. Changed it last Friday, along with oil filter and air filter.

[Kwacky]

Have you drained any of the oil out to have a look at it? It should (fingers crossed) still look fresh. That'll eliminate a couple of bigger problems.

[Kingoftheswing]

I can drain it, I haven't yet done so. I'm unsure what you mean by fresh, from my experience new oil that's been run around an engine is almost instantly a dirty colour? What exactly am I looking for?

[Kwacky]

You're looking for discolouration in the oil or any metal.

[Kwacky]

There are a load of off roaders on http://www.throttlemonkey.co.uk/forums/" onclick="window.open(this.href);return false; they might have someone on there with experience of your bike.

[Kingoftheswing]

Just drained the oil, it is no different to the colour that I would normally expect. There is however metal flakes in it. They are very small, look a bit like glitter.

[duke63]

From past (sad) experience that usually means either the big end has gone.

[Kwacky]

I might not be so with this bike. They do get some flakes in the oil. Its not a sure sign of failure provided they get regular maintenance.

Have you seen flakes in your oil before?

Before it cut out did you have any backfiring or smoking?

[Kingoftheswing]

I changed the oil on Friday, there were no flakes in it then, not that I noticed anyway. The only reason I noticed this time was due to the fact they were caught on the base of the sump plug.

There was no bang, backfire before it cut out and I didn't notice any smoking. However I have no mirrors so wouldn't have noticed it.

It was odd, immediately when I stopped I checked the fuel as it felt that it had run out. It was half full so I tried to kick it over and kick was solid.

[Kwacky]

From what you've said I think you were right in your first post. Piston and rings are next to investigate.

[Kingoftheswing]

In the case it doesn't seem all doom and gloom, maybe a top end rebuild should suffice.

I will attempt to get the engine removed and cylinder off tomorrow and report back with my findings. Thanks for your help.

[Kwacky]

Good luck.

[Deegee]

Might be worth asking around any engineer friends you have and see if you could borrow an Endoscope and have a look in the spark plug hole. Dead handy bits of kit even if you end up buying one, a cheap but reasonable one is a similar price to a head gasket set.