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1979 DT250MX oil pump connection to carb?


roffster
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yeah mines a small bath but not as small as some, I can do a carb body with turning it over occasionally as its not completely submerged. Dont expect miracles they arent industrial ones after all! Mine is big enough to fit a CD into. This one in fact

http://ie.farnell.co...1-4l/dp/1316381

my bike is more of a rolling restoration than a full on one, it has been rough in the past...I owned her from new and used as a winter hack for many years.

yours looks really promising I must say, should come up really nice, If you decide to do her up nice why not show us in the projects forum...it would be good to follow and try to answer any questions you might have.

Let me know about the spigot...that carb body is at work. I dont want to pull it out for nothing. ;)

Oldgitonabike, I would like to take you up on that offer of the spigot if you don't mind. It seems Tony has unearthed proof not to be argued with.

You'll let me send you something to cover it and the postage please?

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PM me your name / address roff

I just had a look at Tonys pics, it seems that it was a banjo fitting so mine might be different, I'll send it anyway just in case, perhaps if its a close fit you can use rapid araldite to secure it?

all this assuming I can remove it OK ;)

One thing is clear though...thats the right place for it unlike the pic I found...wonder if he seized it :eusa_whistle:

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Try blowing or spraying some carb or contact cleaner down the hole 'B' in your photo and you should see it come out a small hole on the inside of the carb at the bottom on the inlet side as this is where the two stroke oil gets injected in. As I mentioned earlier it looks like you have the oil line connector / spigot missing which I think should look like the one in the link I sent you from pgm that should push into hole B which the oil line connects to.

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Well, I sprayed carb cleaner into the hole and sure enough it comes out of a tiny hole I hadn't even spotted on the base of the intake just as YPVS TONE had said, so this is the right hole!

Then delivered by armoured carrier, the spigot that oldgitonabike had very kindly removed from a spare 175 carb arrived this morning...........................Too big! What were Mikuni thinking? why isn't a common hole on many of their carbs not the same size??

Paul your spigot measures 4mm in diameter and the hole looks to be 2.5mm. Thanks anyway but it is back to the drawing board for me. If you pm me your address details I will send your spigot back for safe keeping.

I'll have to send a message to pgmyyamaha and see if the RD measures the same size and then persuade them to sell me one if it is.

I ordered the clutch centre boss yesterday, so if that arrives soon then I think I'll be trying to start her up with pre-mix. Not the end of the world, but dissapointing. I guess I'd better get used to dissapointment as I'm sure that this won't be the only setback I experience getting the old girl back on the road.

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YPVSTONE and oldgitonabike, I was just thinking I could drill the hole out to 4mm. There is plenty of meat on the casting, what are your thoughts? There doesn't seen to be a part specifically listed for it anywhere. Once in it's in I suppose, am I being stupid or is that a viable idea do you think?

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sounds good to me Ian, use a new drill that hasnt been sharpened by hand, then it will be dead on and some aradite rapid. Thats what i'd do with it, Oh and leave a shoulder at the bottom of the hole for the spigot to butt against, take care zinc is very soft and may tend to pull the drill in if drilling by hand, pillar drill would be better!

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Personally I would wait to see if the one from pgm is right. If you do decide to drill the carb just make sure that the hole is fully clear of swarf befrore you press in the spigot .

missed your link Tony, yes I would do the same before anything drastic like drilling, Ian can you make up you minimum order with other stuff?

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Yes I was a bit worried about leaving any debris in the hole. I have emailed pgm so i'll see what they come back with, I'd imagine the minimum is only because of the free postage but I don't mind paying that. If push comes to shove I could buy a few if it fits and then they be sold as compatible with DT250 carbs. I'll see what theirs measures up as and then make a decision on the drilling, I would definitely use a pillar drill. The hole it comes out of in the intake base is tiny, not much bigger than a pin hole, it seems hard to imagine enough oil getting through it. Thanks guys.

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Hmmmmm. pgm have come back and the brass spigot on their elbow is 3.3mm. I'll measure the hole again but I am pretty sure it is narrower than that. Looks like I'm drilling.

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I just checked by spraying carb cleaner through and a good strong jet comes out of the hole, it is fine but does this mean the pump will spray the oil through the small hole under pressure? It is definitely coming out of the hole I have a line pointing at the hole in the photos. in the second one you can just see it in the shadow.

oilfeed2.jpg

oilfeed1.jpg

It is small though isn't it?

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  • 2 weeks later...

So it's been a bit quiet on the DT250MX front the last two weeks. It was a busy weekend mountain biking in Wales last weekend which put paid to my planned work on the bike (I can't wait to get an engine to get me up the hills. Fat Old Git power wears a bit thin after about 10 mins)

Anyway the bike immediately ran into delays because of the Clutch centre boss which is what is stopping the engine going back together for a trial start up. Nothing on ebay, there was one on ebay USA but it turned out he wouldn't ship to UK even though the listing said differently. CMSNL had it listed and I ordered it with the one odd clutch spring screw and washer I needed, over 70 Euros with delivery but I didn't want to hang around for ever. As luck would have it they then rang to say they didn't have any left and couldn't get one, so it was back to the hunt. I tracked a NOS one down in Canada from www.MyOldYamaha.com and what is more it was on sale at only $39! I have to say Ken Broden from the site has been brilliant in sorting me out with the part, he even threw in the final clutch spring screw and washer he had for me.

All in with shipping and tax was $69 (£43) I think that is pretty good considering a good chunk of that is the shipping. It should arrive in the next week and then it should allow me to put the clutch in and get the case back together and give her a try (god I hope the clutch boss is the right one).

This weekend I'm going to drill out the oil inlet on the Carb body to allow me to fit the nozzle that Paul so kindly gave me. I'll post some pictures of the operation after the weekend.

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Sorry boys" i"v just seen this thread. , i have drilled the oil hole before,, A after_market carb i bought for one of my DT"s had a blank face, where your hole B" is

I had a nipple , so sized it up. and drilled clean thru to venturi,,,, It worked fine,,, watch & not drill hole too big,,, or you will be buggered,, :eusa_doh:

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