Dooooogster

That's twice cynic has hit the nail on the head. A bit spookie really. 1st was spotting that my bike cutting out wasn't an electrical problem but the cylinder going tight around the barrel due to lack of oil (see my other post) and then suggesting that the oil drive should be compared on this post. 100% - Great forum, great folk. Many thanks.

Just as a footnote, the reason for all the trouble - started out an oil pump problem ended up a seized engine problem. Pretty self explanatory. Drive on the right is the correct oil pump drive for the DT125r, the drive on the left is the one that caused all the sheared cogs that led on and on and on........Not sure where it came from (tzr maybe?). Guess them are the risks when buyin 2nd hand bottom ends off the net. Bike now going great only prob now is a little too smokie, so will have to add? some shims to the oil pump to decrease the oil flow.

Thanks.

Thanks for all the help by the way, will hopefully give something back to the forum when I build up my expertise! The little ring in my photo isn't rubber, it is metal and is number 4 in vez's exploded diagram. Do I need more of them? Also the rubber ring doesn't appear in anything I have seen or vez's diagram. At the moment I am pre-mixing with confidence and enjoying riding the bike without walking it home for the first time. It's great! Replacement oil pump arrived yesterday, although I will need to test it as the inner cog isn't rotating easily like the broken two. Am tempted just to suffer the oil light warning light and hassle of pre-mixing. Have got a tank of two stroke petrol to use up anyway. Lovely seeing the faint puffs of smoke coming out the exhaust. Although the purest in me wants the bike back to its original oil functioning design!

Cheers vez.

2 wheels, here are the photos - couldn't find charger so had to use phone -hope they come out ok. You will see both oil pumps and their shredded oil pump cogs, the drive off the old engine - in same condition as drive shaft on bike, also the gasket, shim and rubber ring that came off the oil pump. Also included the bike -bought as a £200 basket case a year past April, now after about £1400 repairs (yes mental!) here it is.

Thanks for taking the time to look into this 2 Wheels, much appreciated! Took the side casing off tonight to look at the drive shaft - in case there was grim news within. Nothing untoward as far as I can see. There is in and out play, but this is the same as the engine casing I have on my workbench (I have 2 engines!) In addition the circlips (2 of) on the inside of the casing look like they are designed to have a bit of play on them (sounds strage I know). I was going to swap the casings over but as there was no difference and the drive shaft from the old engine looked in not as good condition, then I put the original back on with a new gasket. As for the shim there is a small washer on the end of the drive shaft. I also see that there is a rubber washer on the outer base of the drive shaft that doesn't seem to go too well with the oil pump gasket, so i will check if that should be there. I am guessing I shall be far more careful putting the oil pump back on. I'll also test the new oil pump out on the old worktop engine first to see if there is a knack to it (and how to get it to engage)! I'll look for the charger for my camera too (hopefully tomorrow!) Thanks again.

Yeah, sure I can try to take a macro photo, but might be tricky to get the detail you are after. Will post when I can. You will hopefully see a cog inside the oil pump with the sharp end of the teeth all flattened and damaged, and a drive shaft (screw design) with no visible damage.

This has been a year long saga, but am not going to re-write war and peace here! Oil Pump on DT has never worked. Took it off and found that the big cog inside the pump that connects to the drive shaft of the engine was burred and shredded. You could turn it by hand and the adjusting pump moves up and down fine. I have inspected the drive from the engine and it has no visible defects and when I turn the kick-start it turns fine - so no issue there. I put another oil pump on with a fresh cog, started the engine and that pump didn't work. Took it all off again only to find that cog stripped too (ruined another oil pump!). So - 2 screws, make sure it is seated ok, nothing wrong with the engine drive shaft - so what is causing this to happen? Is it a bad design? Has this happened to anyone else? Or what am I doing wrong? None of the manuals say what to watch out for, or special instructions to seat the oil pump onto the drive shaft - it is just gently pushed on and 2 screws? I have another drive shaft, but it looks no different than the one currently on the bike. Have sourced yet another oil pump - but what is to stop it happening to this one? Am I destined to premix two stroke in the tank from now on? Help!

Yes I replaced the tube with a transparent one. Ok did the above including turning the pulley by hand, but the oil spurts a bit (as if it is being sucked through rather than pumped!) then just sits about 2cm from the oil pump and does nothing after that - so ther other 6 cm of the tube is air. I take it on the oil pump, the adjusting plate with the nut should be pumping up and down 10 to the dozen? Mine is doing nothing - no movement what so ever. Is it likely that the drive from the engine is lost? How serious is that? Update I see from another thread that you have answered a similar question 'strange oil pump problem' - so no need to bother you further. thanks for all your help!

Ok, OG last few wee questions. Should the oil feeder tube be full of red 2 stroke oil with no air bubbles? Or should it just spit little droplets of oil up the pipe even when you pull hard on the oil cable to bleed the system? I am taking no risks with my newly bored cylinder so what is the best premix to use in thtle tank; 1:32 or 4% or more? Just have no confidence in oil pump. Thanks for all your assistance so far, advice has been top notch. Premix a short term solution only, hopefully.

Ahhh!. Thanks very much OG.

Just about to replace my piston on a rebored cylinder. With the piston rings came a very thin kinked washer than looks like it should fit under one of the piston rings?? in the past i have just discarded this as didn't see any purpose in it. Does anyone know what this is for? Should it be used under a piston ring? If so top or bottom ring? I think I discarded it last time cause it made the ring not fit into the cylinder. Any ideas?

Checked cog from engine, it rotates fine when I kick it over (phew!) But the wee nut and washers don't move up and down when I turn it over or twist the throttle. As a result no oil being pumped through the tube to the engine. Just put a clear one on so I don't fry another cylinder. Don't seem to find spare oil pumps anywhere though.

Cheers vez. Sent it away today, rebore, new piston, all the gaskets and delivered back for 100 sheets. now all I need is a new oil pump for my dt.. might end up having to just mix it in the tank like the good old days!

Anybody know the best place to go to get a cylinder head re-bored with new piston? Is it best to go to a local engineers / yam dealership (£££££?) or is there a reasonable company over the internet that I can send it to? What is the going rate for the work? What about a Cylinder Re-sleeving Service - any experience with that? I see there is a service for this on e-bay for £185? Worth it? The cylinder I have was reasonably new, but has suffered damage through oil starvation (2-stroke). Defo not past max on max oversize or anything like that. Any advice would be greatly appreciated.

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

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.

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.

Thanks for the suggestion. It would just be my luck that the same problem would happen in the replaced magneto that was happening in the old magneto (i replaced the whole engine). I'll solve this mystery (prob via a professional mechanic) and I'll post the answer here. Stay tuned! Cheers.

ok, bike still cuts out, has been lying in the garage for a good few months, so now going to try again! About to throw in the towel and take it to a mechanic, although at £50 per hour labour (ouch!) could well end up the most expensive 1989 DT125 in the UK! Think the Spark plug cuts out when the engine warms up, although questioning my own sanity at the mo. Although I have renewed the coil and ht lead, still same problem occurs as the old coil and ht lead. Biggest mystery - when it heats up the engine eventually bogs down and cuts out (usually going up a hill). Plenty of blue smoke when it starts up then disappears so not an oil problem (unless the exhaust is clogged up with oil but i doubt it) Anybody know what wires connect to the HT lead and where the current comes from - and what theproblem could be? When it does cut out, i pull the spark plug out and it seems like no spark for a few kicks, then the spark reappears. How the mechanics are going to test this without taking it for a 15 minute ride - i don't know. This must be the most annoying problem ... For a laugh here is what i have replaced with this problem since I bought the bike (yes i am mental - although the bike is a lot sweeter, but same problem!) -Engine - top and bottom, -carb (x3) -ht lead and coil - regulator - cdi unit - petrol tank & cap - spark plug - battery - leads from the battery so the prob is with none of them!

Ok, winkled out the ballbearing and punched a hole in the other sponge hole to make sure that it is not the fuel cap vent. Bike awaiting a test run with the wee electrical fixes and petrol cap mod! I'll let you know if the mystery has been solved.

Thanks for the fresh angles. When I say fires up straight away, not strictly true, I do have to give it a minute or two first. I have tried to start it immediately and it reacts like it is gassed, smell of fuel too. So far I have found that the negative wire to the battery had a screw in connector on it (clear plastic wire connector with the two counter-sunk screws on the top) which I have removed and soldered (please be that!). In addition I have removed the in-line fuse on the positive wire (maybe not such a great idea, but I need to find the problem!). Not tested it on the road yet, but the lights on the dash appear to be a lot brighter. I'll not get my hopes up, just in case........with this bike i'm cynical!

Replaced the coil and ht lead as well early on, so not that- but checked just incase i have been really unlucky. I am now working my way through the wire harness (the wires are 21 years old, so are black inside and hard to solder!). It is the last thing it can be. I'm not sure what other options i have got other than replace a few wires, as I doubt i would get a replacement 1989 dt wire harness. I'm guessing that the newer versions will be different anyway. Does anybody know if a newer (say 2004 DT) wire harness can be used for an older bike? - I accept some connection cutting and lots of soldering! Or have things changed beyond all recognition? I HATE electrics, would much prefer a mechanical problem......them I can solve!

Thanks for the tips. Forgot to mention that the 1st thing I did was replace the spark plug to one of these titanium plugs. Recon it must be one of the coils or an earth, or probably the worst of the lot a poor wire somewhere in the loom. I'll just have to work down the checklist. Thanks again.