Ravies Posted September 15, 2015 Posted September 15, 2015 Hello!I'm thinking of ditching the Autolube oil delivery system from my '81 DT250MX/I suspect that the previous owner has already done that for me but I haven't got around to making 100% sure. Basically I'm going for the 'oil in the petrol tank' approach. Does anyone know the oil/fuel ratio for doing this. I've never owned a 2-stroke so I'm used to just sticking it all in the bottom end and being done with it.Cheers.
blackhat250 Posted September 15, 2015 Posted September 15, 2015 Aye ravie" the pumps are reliable , the ratio is 32/1 . . pre mix is a P.I.T.A. esp on long runs,,
up.yours Posted September 16, 2015 Posted September 16, 2015 oh no , here we go again !!!Go for it ravies , pre mix is more reliable Why do you think all the racing bikes do it.lots of two strokes are in the grave yards due to pump failure . If you pre mix you know it's in !!! Don't you.Mine has never had a rebuild and is still going strong on a 19 year old set of pistons.
YPVSTony Posted September 17, 2015 Posted September 17, 2015 oh no , here we go again !!!Go for it ravies , pre mix is more reliable Why do you think all the racing bikes do it.lots of two strokes are in the grave yards due to pump failure . If you pre mix you know it's in !!! Don't you.Mine has never had a rebuild and is still going strong on a 19 year old set of pistons. When I worked for a Yamaha dealer back in the 80's I can never recall any 2 stroke model having an engine failure due to the autolube pump failing. The biggest problem was the owners forgetting to top up the oil tank even though Yamaha fitted sight glasses or oil warning lights and sometimes both!! When we sold a new or s/h 2 stroke model we always made it clear to the new owner to regularly check the level in the oil tank and top up when needed as if they ran out it would get expensive. Yamaha first started fitting the autolube system on their 2 strokes back in 1964 and if it proved to be unreliable they wouldn,t have continued to use the system. A reason why racing bikes use premix is that having a pump and oil tank fitted would only add weight to the machine and even using premix they could still seize due to lubrication failure. 2
Ravies Posted September 17, 2015 Author Posted September 17, 2015 Well I'm hearing good reasons for and against the oil pump. But what I'm taking away from this is that pre-mixing isn't necessarily a BAD idea - and that's kind of what I wanted to hear. I'm not worried about practicality because this isn't going to be a daily, it will be for when I finish work early in the summer. So is the drill pretty much to ride around with a little vile of 2-stroke oil around your neck?
blackhat250 Posted September 17, 2015 Posted September 17, 2015 Yeh " I know what you mean , but I do big miles on my DT. 200+mls to the tank of oil, saves a lot of spilling and shaking at the forecourt,
up.yours Posted September 17, 2015 Posted September 17, 2015 first off , respect YPVSTony. good response.but with respect I stand by pre-mix ,I have heard of pipe blockages, pipes falling off and diaphragm failure all leading to engine seizure.I don't know of any other rdlc using the oil pump with nineteen year old pistons, still in good condition as are mine.as far as practical goes , I have a 350ml pop bottle under the seat with silkolen comp 2 off road t2 oil in it,this is my routine1. run tank to reserve ,look for garage.2. enter garage, empty pop bottle into tank3. put fuel into tank (about 10-13 litres )4. once you have paid for your fuel the speed hump on the way out of the garage mixes the fuel/oil for you.job done , totally practical
YPVSTony Posted September 18, 2015 Posted September 18, 2015 And with all due respect I will stand by using the pump system. One of the problems with premix is that it uses the same oil ratio throughout the rev range so the engine is given the same amount of oil pottering around town as it is running flat out on the open road. I remember my first road bike which was an FS1E which you had to premix at 20:1 and I remember it was a regular job to remove the cylinder head and barrel to decoke the piston and rings and to remove the exhaust and baffle to clean out the oilly buildup. I expect things aren't quite as bad these days with the availability of semi and fully synthetic 2 stroke oils, but I know on my 1983 RD350LC2 when I remove the exhaust baffles after several thousand miles there is hardly any oil or carbon buildup on them and that is with using a mineral based oil. What diaphragm are you refering too ? The oil is gravity fed down from the oil tank to a mechanical pump where it is metered out via the throttle position and engine RPM and then pumped into the inlet tract. Apart from a couple of oil seals in the pump there is no diaphragm in the pump to fail. Regarding pipe blockages the only time I have heard of this happening is when the bike has been sat for many years and the oil has gone bad. The oil lines all have retaining clips on them to keep them on so I expect where you've heard of the pipes falling off is where people have not put the retaining clips back on the pipes.
blackhat250 Posted September 18, 2015 Posted September 18, 2015 Amazing longivty of them pistons kev,,,, ,,,as long as there smoke all is good,, Amazing longivty of them pistons kev,,,, ,,,as long as there smoke all is good,,
up.yours Posted September 18, 2015 Posted September 18, 2015 (edited) yes john ,amazing in the fact it has been pulling my bulk (19-20 stone) around for the past 7 years . tony , I was almost swayed into switching back to my pump by your comments. so today as it is my day off I set about removing the oil tank and pipe work to give a good clean before re-filling with oil (EXOL fully synthetic racing oil) started the bike up but no oil came out so I gave it a good blow job to see if that would force some through , no joy there so I changed the pipes for some fresh pipe and replaced the O rings just in case it was sucking in air. still no joy , so then I decided to inject oil manually through the system then kick her up , but still no oil other than the what I had pumped up there myself. so then I left the bike running on tick over for fifteen mins to see if that would work . then decided bugger it I must be right. Edited September 18, 2015 by up.yours
Moderator Cynic Posted September 18, 2015 Moderator Posted September 18, 2015 Nope kev, I have been riding 2 stroke yams for nearly 30years and in that time I have never had a pump fail. I have had seizures but not because of the pump.Plungers can stick on bikes that get stood for a LONG time, but normally oil seizures are caused by idiots adjusting the pump or forgetting to fill it. Embarrassingly in my 28 years of 2 strokes I have done both on occasion.I have checked the oil flow, on long motorway runs my oil consumption is less than half the figure for full power riding. That is a big reason for not premixing. Your mixing for worst case, max attack oil quantity. Running oil in the fuel means you are running lean due to there being oil in the fuel, you have to increase the size of all your jets to allow for it. As well as having really bad mixture at lower rpm.Lastly its messy and inconvenient to carry all that oil. I filled up with fuel 8 times over the squires meet and topped up the oil once in 600miles. around 700mls went in.That's an oil ratio of 64-1.Pump every single time. 2
up.yours Posted September 18, 2015 Posted September 18, 2015 (edited) I have also ridden two strokes along time (im older than you) back in my youth I road a jawa 350 for 19,000 miles on the same piston and bore quite often with a side car on it ,over a four year period, and sold the bike on to a mate who had it for a further two years on the same pistons before he planted it into the side of a Cortina and wrote it off. this was pre mix only as it didn't come with a pump. , the only difference with the jawa was I used to mix the correct amount of oil to fuel ratio as laid down in the owners manual. surely if this bike was getting the wrong amount of fuel the engine would have collapsed either on the motor way down to brighton or on it's merry way with fully loaded side car on it's way to the kent custom show. I even tracked it a couple of times (total humiliation) that was fun . anyway cleaver dick, next year when we go to squires you can take a look at my pump and tell me why it's "FAILING" to pump oil into the carbs. could you just imagine what would have happened if I had just filled the tank and rode off relying on these ultra reliable oil pumps im not having a go "honest" Edited September 18, 2015 by up.yours 1
Moderator Cynic Posted September 18, 2015 Moderator Posted September 18, 2015 Your asking why a pump that has been running WITHOUT any lubricating oil in it for seven years doesn't work.......? Its not lubricated by the gearbox, but by the 2 stroke running through it.With a good pump bled correctly it will be fine. You could rebuild yours. 1
up.yours Posted September 19, 2015 Posted September 19, 2015 Your asking why a pump that has been running WITHOUT any lubricating oil in it for seven years doesn't work.......? Its not lubricated by the gearbox, but by the 2 stroke running through it.With a good pump bled correctly it will be fine. You could rebuild yours. I thought replacing the o rings would have been considered a rebuild. I can pump oil through the whole system using a syringe .
Moderator Cynic Posted September 19, 2015 Moderator Posted September 19, 2015 Did you check the plunger is opperating properly.By eye it does appear to move little or no oil at idle with the throttle shut.It is only a couple of mls per pump stroke even flat out.Did you fit clear pipe?
up.yours Posted September 19, 2015 Posted September 19, 2015 Yes and yes. I'm right about this pump , it would have been unreliable.See what you started ravies , I hope you have your answer now.
Ravies Posted September 22, 2015 Author Posted September 22, 2015 Haha! I had my answer about 10 posts ago but all this bickering has given me an even clearer plan. I think I'm going to go without the pump initially for aesthetic and (to a lesser extent) weight saving purposes. But then see how I get on and consider introducing the pump later on. So there you have it. You're all right!!And thanks again for your assistance with this matter.
blackhat250 Posted September 22, 2015 Posted September 22, 2015 Kev ,that's amazing milage wi the Jawa,,,,proof that 2 strokes are durable ,, I"l see if I can find a picky of you on her,,, yeh here ,,,,
up.yours Posted September 23, 2015 Posted September 23, 2015 Kev ,that's amazing milage wi the Jawa,,,,proof that 2 strokes are durable ,, I"l see if I can find a picky of you on her,,, yeh here ,,,, FUCK OFF
Moderator Cynic Posted September 23, 2015 Moderator Posted September 23, 2015 Haha! I had my answer about 10 posts ago but all this bickering has given me an even clearer plan. I think I'm going to go without the pump initially for aesthetic and (to a lesser extent) weight saving purposes. But then see how I get on and consider introducing the pump later on. So there you have it. You're all right!!And thanks again for your assistance with this matter.Weight saving, go for a good sh1t before your ride and you will save a lot more weight and whatever you blank the manifold with will look no better than the original pipe. Work for work sake.....
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