1978 dt250mx oil problem

[G Digger]

Hi.

I have just split my casings and replaced all bearings, I have rebuilt the casings and all the bottom end.

I have started filling gearbox with oil and after 1/2 litre it reads the correct level on the dipstick, the manual says the capacity is 1.1 litres.

Any ideas on what ive done wrong would be greatly appreciated.

Thanks in advance. Graham

[finnerz89]

Have you tried turning it over a few times and re-checked the level?

[G Digger]

No it’s still on engine stand waiting for top end to be finished. Added oil early to see if any leaks so if I needed to strip it would be easier. I have levelled  engine to replicate it in the frame and put in gear and rotated crank .so far not made any difference.

4 hours ago, finnerz89 said:

Have you tried turning it over a few times and re-checked the 

[finnerz89]

Strange one that!

I wouldn't let it stop you carrying on with the build, just keep an eye on it once the bike is on the road.

I had a similar thing once before after I'd stripped my clutch etc to fit a kick-start. I just filled with the amount stamped on the case, then it spat a load out of the breather once I'd ridden it so I had to drain some.

[NE0]

Hi Graham

Quote

Any ideas on what ive done wrong would be greatly appreciated.

There may be nothing wrong. the Simplest reason might be that although you have it on the engine stand , it may not be replicating the angle when on the bike. If its front end is  elevated then the dipstick will be in the oil prematurely as its pools in the corner so to speak.

Having said that, there are a couple of things to consider, bear in mind the engine is merely two boxes, in one box is the gears in the other box is the clutch. The same oil sits in both boxes. The oil will fill both sides via the open bearings.

How much oil did you drain out? Is the dipstick the right one length wise? When you replaced the bearings, were they identical replacements,? i.e open type not sealed bearings. Did you remove the side casing of any new bearing to make them open? (just thinking what might stop the oil getting from one side to the other). Was it all cleaned thoroughly? (sludge oil stopping the new oil from crossing over). Did you soak the new clutch in oil? I appreciate new cork plates won't absorb the missing half litre, but has the level now dropped as the clutch soaks up.

I'm not for one minute suggesting you haven't done any of the above, but you said any ideas on what might be wrong.

Hope this is of some help. Keep us informed.

 

 

[G Digger]

1 hour ago, NE0 said:

Hi Graham

There may be nothing wrong. the Simplest reason might be that although you have it on the engine stand , it may not be replicating the angle when on the bike. If its front end is  elevated then the dipstick will be in the oil prematurely as its pools in the corner so to speak.

Having said that, there are a couple of things to consider, bear in mind the engine is merely two boxes, in one box is the gears in the other box is the clutch. The same oil sits in both boxes. The oil will fill both sides via the open bearings.

How much oil did you drain out? Is the dipstick the right one length wise? When you replaced the bearings, were they identical replacements,? i.e open type not sealed bearings. Did you remove the side casing of any new bearing to make them open? (just thinking what might stop the oil getting from one side to the other). Was it all cleaned thoroughly? (sludge oil stopping the new oil from crossing over). Did you soak the new clutch in oil? I appreciate new cork plates won't absorb the missing half litre, but has the level now dropped as the clutch soaks up.

I'm not for one minute suggesting you haven't done any of the above, but you said any ideas on what might be wrong.

Hope this is of some help. Keep us informed.

 

 

Thanks for that Neo.

i think you’ve hit the nail on the head with the closed bearings. It’s my first engine rebuild and obviously didn’t think it through, 

I will check the bearings and open them up if necessary.

Thank you for your tactful answer and not insulting my lack of knowledge.

will let you know 

[NE0]

I took photos of all of my rebuild of my DT175MX, similiar to your larger 250. Here's some photos which may help.

Above: The New Bearing being offered into position needs its internal cover removing prior to fitting.

Above and Next: Prising the cover off the bearing with a small screwdriver. Not difficult.

Not sure I removed both sides of the bearing though, I just followed my photos of what it looked like before removal, so they matched. This above Photo shows ALL the New bearings in place.

This last photo shows the inside of the DT175MX Clutch side with the bearing side casing in place. So I did only remove the one side. The Internal side which can be seen in the two open cases photo above.

Edited January 10, 2021 by NE0
Additional photos.

[G Digger]

I’m pretty sure that’s my problem. It makes sense now, I assumed the oil found its way through oil passageways. Will drain and check it out tomorrow. Thanks again for your help as the photos.

i remember when I joined this club, you were helpful then. Cheers Graham 

[NE0]

You're welcome Graham, I've added another photo above for you.

[G Digger]

Hi Neo 

would both sides need to be removed?

[NE0]

I didn't remove the cover on the clutch side as you can see in the last photo (This was the photo of the strip down) So i only removed the gearbox side as seen in the photos above. I only had to do this with one bearing. The other bearings were purchased as open. I referred to my strip down photos and the Haynes manual which also detailed the procedure if I recall correctly.

Edited January 10, 2021 by NE0
Clarity

[G Digger]