Oil leak...

[mattlacey]

My list of issues with this bike (NH 350) is growing faster than I can fix them! Still, I guess that's part of it right? Anyway, in trying to rule out the battery as part of my electrical gremlins, I had the bike running on the drive, and after it was dripping more oil than usual, enough to create a puddle. At first I was concerned that there was a lot of metal in it, because it looked shiny, but on closer inspection it was tiny bubbles:

I looked for the source and quickly noticed that this nut is loose:

Still getting to know this bike, this us under the chain that links the engine to the gearbox, right? That'd explain the bubbles if so. Question is, should it be tight? I assume so but there appears to be no thread - I couldn't pull it straight off but I can move it back and forth a bit and twisting it does nothing.

[simon.holyfield]

Lets deal with the nut first - there's not enough leak there to worry me!

The nut actually retains the primary chain case to the frame - there should be a spacer between the case and the lug on the frame.

The bolt the nut is on is actually the gearbox bottom bolt whose head is on the other side of the bike under the gearbox. Give it a turn and make sure it's really tight into the frame lug. When you've done that, and you've made sure that the spacer is in place tighten the nut down onto the primary case.

The leak is probably not coming from that nut - it doesn't go into the oil space in the primary case. The leak is probably dripping from behind the clutch through the drain hole in the tin clutch cover above. They always do that because there's effectively no seal behind the clutch - the design just relies on the oil not being high enough in the case to come out. Of course once you run the machine and fling the oil around, guess what? - it comes out!

The key is to keep the oil level low enough so that it just touches the bottom of the chain but it doesn't come out. The level plug is much too high to be used for its intended purpose. It's very common to have a problem like this - so common that you might call it a feature.

[will_curry]

To add to Sime's suggestions, if the rear chain oiler is misadjusted or damaged so that the
oil feed is excessive you will get a nice puddle just there on tick-over. My recently acquired twin
had such damage and does exactly what you describe - along with positively lubricating the
back tyre once moving.

A word of caution over tightening the nut you indicated. There is very little clearance for the clutch inside
the chaincases. Too far one way or the other and the clutch will damage the sealing flanges which stop oil
running down the walls of the chaincase exiting via the large hole where the mainshaft passes through.
It's not uncommon to find the thread for the nut stripped as users forget to slacken it off prior to
adjusting the primary chain which involves slackening the gearbox pivot bolt.

[simon.holyfield]

A word of caution over tightening the nut you indicated. There is very little clearance for the clutch inside
the chaincases. Too far one way or the other and the clutch will damage the sealing flanges which stop oil
running down the walls of the chaincase exiting via the large hole where the mainshaft passes through.
It's not uncommon to find the thread for the nut stripped as users forget to slacken it off prior to
adjusting the primary chain which involves slackening the gearbox pivot bolt.

There's a note somewhere, possibly in Draganfly's List 15 which talks about the space between the primary case and the gearbox being of variable length. I've made a couple of these, and as Will says you don't want to tighten this nut against a spacer which is too short and bend the primary case...

[Simon.Gardiner]

The chaincases are actually disturbingly flexible (speaking from experience ) - but that bottom chaincase fixing stud set-up can be confusing and is a common cause of problems.

The lower gearbox pivot bolt that incorporates the chaincase stud is illustrated on Drags:
https://draganfly.co.uk/shop/60463/pivo ... r/#2382-55

SG

[mattlacey]

Ah those photos help a lot. I did top up the oil the other day to make up for the oil leaking from the exhaust valve cover, but I guess despite reading the manual I may have put in a bit much. Good to know these kinds of puddles aren't rare... even though I knew this bike was going to leak oil I'm not sure I realised quite how much!

It's not uncommon to find the thread for the nut stripped as users forget to slacken it off prior to
adjusting the primary chain which involves slackening the gearbox pivot bolt.

So they wind out the pivot on the other side and exert too much pressure on the nut which is flush already?

To add to Sime's suggestions, if the rear chain oiler is misadjusted or damaged so that the
oil feed is excessive you will get a nice puddle just there on tick-over. My recently acquired twin
had such damage and does exactly what you describe - along with positively lubricating the
back tyre once moving.

Sounds... exciting

[nevhunter]

Keep minimum oil in the chain case and spray good chain oil towards the Cush drive regularly with engine idling, does it for me. Close off the rear chain oiler and do that with chainlube too. Primary chains CAN last a LONG time. I prefer to NOT have a 1/2 link any where OR a Joining link either. Nev

[MarkO]

On the other hand - why have oil in the chaincase at all? Keep it well lubed as you would the drive chain - preferably with the modern waxy non flinging chain spray lube. Secondly, if there is any blow by from the crankcase via the crankshaft into the chaincase on this bike, then there is some lubrication going on there anyways....possibly too much perhaps!

[will_curry]

The chaincase oil lubricates the engine shaft shock absorber as well as the chain and to a lesser
extent the clutch freewheel bearing.

[MarkO]

Clutch bearing is packed full of grease and I also moly grease the spline of the shock absorber and a wee bit on the lobes - both also get coated with chain fling off or perhaps even blow by.