DT 125 R cutting out problem

[Airhead]

Have you checked the fuel flow into a container...fuel tap filter?

[Vez]

Have you checked the fuel flow into a container...fuel tap filter?  

Other than the wiring loom, the tank and filters are the only things left.

[Airhead]

Other than the wiring loom, the tank and filters are the only things left.

Tank has been done Vez, well at least the venting cap.

[Vez]

Tank has been done Vez, well at least the venting cap.

I was thinking the " in tank" filters, easy one to miss.

[Dooooogster]

And the winner is.....Cynic (above post).

The loser is .....me.

Ok, after all the hassle the answer has been found, unfortunately and embarrassingly for me it is the worst possible one (and in hindsight most obvious). Solved it the day before it was due to go into the mechanics (£50 per hour)

To recap: The engine was replaced in two parts. Bought a refurbed bottom end and then replace the cylinder and piston with a mint tight fitting and power valved version. It purred nicely. Anyway. Put 2 stroke oil direct into the engine to protect it initially (it spilled a bit so quite a bit went in) when I bled the oil pump. So assumed that everything was ok on account of the plumes of white smoke. In hindsight the oily smoke from doing this just disguised the real problem.

As time has gone on the engine has got noisier and rougher sounding and becoming more difficult to start. Now very little compression and no start. Checked the operation of the oil pump and guess what? Has never worked. Should have replaced the black feeder tube with a clear one for assurance that the oil was flowing. Looked up the exhaust port to see a well scrapped piston with fused and melted piston rings. Gutted. What an idiot. Solved the mystery (should have listened to Cynic!) finally albeit 10 miles too late.

What are the chances that I can just replace the oil pump, piston and piston rings? (have already replaced the oil feeder with a clear tube - horse, gate, shut, bolted!)

Will the cylinder need a rebore? If yes how would I go about getting that done? Any good value, recommended reborers?

#1 Golden rule for all engines - check there is oil! And then check again.

Cynic - Many apologies. Thanks to everyone with their suggestions.

[Airhead]

Hmmm, funny thing is though...sit down to read this.

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There MIGHT be nothing wrong with your pump, it MIGHT only need bleeding and priming. To bleed just undo the screw at the top until oil runs out.

To prime, run motor on idle and hold pulley to full open position. if you use clear tube (yambits) you will see if its working ok.

lets hope the bearings are ok after this

[Dooooogster]

Thanks OG. Definitely the pump. On this one the pump doesn't move up and down when you twist the throttle. On the old engine it does. So am going to swap them over. Will replace piston and rings and inspect barrel, hopefully not done too much damage to that! As for other damage, perhaps my luck can change...Though it was leaking gearbox oil on the last few weeks.

[Dooooogster]

Not sure I could replace the engine for a 2nd time....

[Airhead]

ok any work done on oil pumps needs to be followed by what i said in last post.