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Dnper Engine breather - help needed


dorttega
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Hi to All. A couple of weeks ago I became the owner of a Barn find project 1985 Dnepr Mt11 which I bought off the net from Latvia. I was pleasantly suprised when the bike arrived as it was complete as advertised and although rather shoddy looking, after a bit of spannering and ditching the stock coil, I managed to get it to run.

My plan is to now strip out the motor and transmission for a rebuild and get all the chassis and tinware powder coated, but as I looked around the bike I noticed that It seems to have a breather modification that is puzzling me.

On the right hand side of the timing chest, above the cylinder, just near to the hole for the coil wire, there is a pipe fitted into a hole which runs down into the engine at an angle. This pipe exits the hole and u bends downwards and has a length of plastic hose attached, the hose is open ended and just sits at level at the base of the engine.

The standard breather pipe exits the engine at the back of the timing chest and is connected to the airbox as it should.

Can anybody tell me why the front pipe has been added, the timing casing is definately made to have something fitted to the hole, but I cannot see any mention of this in any manual or see this pipe fitted in pictures of other dnepr engines. see atttached photos

Any expert help would be gratefully received

Cheers - Dave

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None of the Dnepr engines have a hole there.

No clue what use it would have in the coil and points area.

 

Edit, went and looked at the engines there is a plugged hole

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Hi, Dave

As far as I know, that hole is left over from the manufacturing process, when the hole was drilled

in the casting for the breather. I would plug it with something and forget it. My engine (mt10/36) has the same hole plugged with a slug of alu.

I can't see why anyone would run a pipe from it.

Good luck

Jim

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Hi Dave

Went into the garage and looked at front casing, that is cross drilling connecting to the crankcase breather on the right side near the generator.

The hole on the side should be plugged. Pics from my phone are always to large to post.

Thanks Iuca

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Hi Dave

Went into the garage and looked at front casing, that is cross drilling connecting to the crankcase breather on the right side near the generator.

The hole on the side should be plugged. Pics from my phone are always to large to post.

 

www.picresize.com to resize pictures.

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Thanks for your replies Guys, Yes I can see on the pics that the hole in the casting should be plugged as the actual breather path comes up the cast in oriface and turn through 90 degrees to the exit at the rear of the timing chest.

For some strange reason, a previous owner / bodger has drilled out the plug and fitted the tube in my photos, when the tube is inserted fully it must block off the 90 degree drilling and air must have been drawn in or expelled from the modified pipe and hose. I am now wondering if there was a previous breather fault and this modification was someone's solution to that

Since I am intending to pull out the motor and strip it for a look n see, I will be investigating further and I intend to put the motor back to factory spec anyway.

Thanks again for you help

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Perhaps the engine has excessive blow by the rings. And last owner didnt want it filling the filter area with oil vapor.Can get messy for the carbs.

 

Thats the same conclusion that I have come to as when I took off the air filter box top, there was a metal housing containing a ball of nylon string type material, this was covered in a black oily gunge.

It seems that sometime previously, the engine has been expelling excessive oil into the airbox, as you state this could be becasuse the rings are goosed.

Seems like someone made the bodge "fix" rather than find out what the cause of the problem was.

It's going to be taken apart anyway, so I'll find out when it's in bits.

Cheers once again for your input.

Dave

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