Setting up for pre-mix on 1975 DT250B

[threeputt]

The oil induction/injection still works on this bike but I'm having a hard time adjusting the oil pump mixture rate to get the marks to line up per the manual. The cable is old and stretched and there simply isn't any adjustment room left. Trying to find a replacement has been tough. I thought to better control things I may just go to pre-mixing my fuel and 2-stroke oil. What do I need to do to make this change? Is it as simple as - stop filling the oil tank and fill up the gas tank with pre-mix - or is there something I need to plug off or close up with the oil tank/line/pump etc? Thanks!

Jeff

[blackhat250]

Yeh jeff you can empty the system, and blank the oil feed nipple on carb, so it cant suck air thru,

Best on pump tho, see if you can get a cable .

[drewpy]

I'm sure you can get a cable made up.

loads in the UK but don't know any in the US.

have you tried yamahatopdog they stock everything

loads on eBay, unless your too tight

http://www.ebay.com/sch/sis.html?_nkw=YAMAHA+LOWER+THROTTLE+CABLE+DT250+DT+250+1975+1976+&_itemId=251084103421

[Airhead]

it's possibly an after market cable, they are often the wrong size. I'd re solder the nipple or make up a new section of cable myself

[Cynic]

Same here, keep the pump pre mix is nothing but hassle.

[threeputt]

THANKS for the replies! I will keep looking for a cable. I even went to a local Yamaha dealer here - their parts lady is very good - and she found 4 cables at various North American dealers. Well, at least according to they computer inventory. Alas, none were had. I found one on eBay about a week ago, NOS, but the fella knew what he had and wanted $140(US)! If I have to, I'll bite the bullet and pony up I suppose. Motion Pro, a company here in the US, says they can fab a new one if I send them the old one, so that's always an option.

One more related question... A friend of mine, small engine guru, 2-stroke whiz, and he had a Hodaka dealership back in the 70's, says the oil induction system introduces more oil than is needed today due to forty years on improvements in oils. He suggests that the alignment marks should be lightened a bit. I use Yamalube 2S. Any thoughts would be appreciated.

Jeff

[Airhead]

Hes probably right, oils have got better over the years. I wouldnt bother with it though theres no harm in using a little too much. If you'd have gone down the premix route you would have been using even more oil.

[Cynic]

Something for you to consider.

On one of the earlier squires meets I rode up with a couple of other forum members in spirited fashion. Enough that (to blackhats eternal hilarity I ran out of 2stroke. ie emptied the full on board tank and an extra litre I had for top up.

Last year I rode with a 125, never even used the top up. To the point even when I got home it wouldnt all fit.

So riding fast I used getting on for 2 litres. Steady I used a quater of that. Thats why you want the pump. Oil used to be better for 2strokes as emmision rules were easier so some more noxious elements could be used, also do you buy the very best oil? Let the pump do its thing as its set.

[threeputt]

Good points about the pump. Best oil? I don't know, I just buy the Yamalube 2S. I'm open to suggestions for a better 2 stroke oil...

Jeff

[blackhat250]

Jeff" there all good nowadays , we ran to France on triples, i was on cheapo 5 bucks a litre semi- ,] and my Edinburgh friend on Fully synthetic,[ halfrauds] .

We did 1800 miles . i used 5 litres of 2T, he used 3 litres. half way to France , he pulled his top end off ,as there was a rattle .

Turned out his Rings were gummed in, And he took them off when home , and were gummed in again, .

This prompted me to inspect mine ,,the pistons and bores are as clean as a whistle, ,

So " its not just quality of oil , its settup, = jetting -air screws etc, , Hes ditched the Fully synthetic now, But i think it was running too rich & not hot enuff,