Why is there black crap in my crankcsae

[midlifecrisisrd]

Any body else had this? It's on my dt125 lc.

Bike running like crap, would not rev and stuttered all the time. Top end seems fine as piston and bore are standard with machine marks just visible so not worn out but crank case, crank and rod are all black and wet. You can wipe it off so looks like oily carbon deposit.

Bike had been stored a long time and engine had never been to bits before so no bodges. Only thing similar I have seen before was a bike that has been lying that I took the top end off and everything seemed fine but ran like crap. Turned out to be gunge in the ring grooves causing them to bind in when started but looked fine when in bits.

Bike starts and runs perfect cold but either goes off as it warms or warms up fine and as soon as you try and pull away it goes off then. LH crank bearing has play so stripping to change and unsure of crank seals ( not stripped that far yet ) as there is a his that comes and goes sometimes.

Also found a 13mm restrictor in the outlet of the front pipe that looks way small and Bill's bike does not have this but is identical year and model.

Anybody?

Never seen the black before

Steve

[steeley]

I have seen a similar restrictor recently and the customer asked me to cut it out.as for the black gunk have not seen one like that.i would say though replace both main bearings and seals.

[midlifecrisisrd]

Jun 30, 2013 12:12:40 GMT 1 steeley said:

I have seen a similar restrictor recently and the customer asked me to cut it out.as for the black gunk have not seen one like that.i would say though replace both main bearings and seals.

Wonder if it is something to do with the emissions as it is a swiss model. Are the 350 YPVS's not got different cylinders for the swiss market and a 352 capacity.

Got bearings and genuine seals for it. Just waiting for a puller to split the cases arriving.

No signs of overheating on the bottom end and crank side float measures 20 thou so in spec.

Steve

[steeley]

over the years I have made various tools for splitting these types of engine and reinstalling the cranks.good luck with your rebuild.

[billbott]

Black crap in your crank cases? Thats the least of your worries Steve!!!!! Ha ha!!!!!

[midlifecrisisrd]

Jul 1, 2013 13:01:54 GMT 1 billbott said:

Black crap in your crank cases? Thats the least of your worries Steve!!!!! Ha ha!!!!!

Tell me about it lol

still mystefied by the black crap. There is black blow by on the piston and the exhaust is really cruddy so can only think it has been blowing down the crank case rather than out the pipe.

It does look very rich, top of piston black too and a black ring round the top of the barrel where the rings stop.

Steve