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ok I had recently rebuilt the top end on my 150f which my brother now rides. I ordered some new head bolts, valve cover bolts, and a new head gasket becasue it was slightly leaking oil on the timing chain side. So i get the engine off, get the valve cover off, everything looking good. I get the head off and there it was, a puddle of oil in the exhaust valve pocket on the piston. it was all black. look at the pics. notice the oil all over the head gasket, it was only leaking right below the cam cover.

It ran well. It didnt smoke. Why is there oil on everything? Since it was rebuilt me and my bro put about 6 hours on it. What could it be? Im pretty upset about it i thought i done well on my first thumper top end rebuild. Thanks to all input.

i had already wiped off some of the oil.

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wet oil on the piston..... hhmmm?? Maybe it dripped off the head during removal. I think you would see more signs of burned oil if it was leaking like that. Your piston looks pretty clean; what does the bottom of the head/ valves look like? If everything is clean and free of heavy carbon build-up, youre ok. Put your new parts and torque everything down properly!!!! Keep an eye on oil consumption too.

Jesse

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When i rebuilt it i replaced everything. The previous timing chain broke so i replaced these parts.

Timing Chain, Piston, Rings, Valves, Valve seals, top end gaskets, tensioner, timing chain guides.

And i wiped the top of the piston off i didnt think id take any pics then.

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Also there was tiny metal shavings below the cam in that little pool for oil. And i found little plastic pieces like from the guides. the guides are pretty worn down to.

and as for oil consumption, i check the oil before each ride and never had to add oil.

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Your timing chain broke??? while riding??

Did you remove the side covers and inspect everything?

Do you have the shop manual?

If you were leaking oil into the cylinder, you would see: blue smoke from the exhaust, heavier carbon deposits on the piston & valves/head, and you'd be having to add oil.......

based on how you describe and show "wet" oil on the piston.

As for metal shavings and bits o' plastic..... clean all that out and keep an eye on what comes out when you do oil changes. Those bits are probably from the rebuild.

So I am still kinda thinking that nothing is really wrong if you didnt see any of the "burning oil" signs listed above. Besides, if it was bad, you would probably be fouling the spark plug.

Jesse

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yeah it broke while riding. but i replaced everything i thought that might have been damaged just to be safe. but if you think its fine ill put it back together with the new parts and keep on riding. i was just concerned because oil was everywhere but i guess it was from head removal like you said. thanks

and for the timing mark on the flywheel is it the left or right one that is at TDC?

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Your freaking out over nothing. Put it back together and run it. Some oil got in there when you were disassembling. With that much oil, you'd see some serious score marks in the cyl. walls and the top of the piston would be full of carbon.

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Casper,

You will find it's easier to set the cam timing if you remove the entire flywheel cover. It's only a few more screws. The magnet will always try to pull the flywheel away from TDC.

Once the cover is removed you will be able to view the timing marks much easier while setting the timing. Make sure to put tension on the cam chain before settling on you final setting.

When looking at the engine from the flywheel side, engine rotation is counter clockwise. The first mark is the "F" or ignition mark. The second mark "T" is the TDC mark.

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Casper,

You will find it's easier to set the cam timing if you remove the entire flywheel cover. It's only a few more screws. The magnet will always try to pull the flywheel away from TDC.

Once the cover is removed you will be able to view the timing marks much easier while setting the timing. Make sure to put tension on the cam chain before settling on you final setting.

When looking at the engine from the flywheel side, engine rotation is counter clockwise. The first mark is the "F" or ignition mark. The second mark "T" is the TDC mark.

I noticed that. I had to rig up a way to keep the flywheel at TDC.

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