I have a new Montesa Repsol which is losing 100ml of transmission oil per ride from the clutch/gearbox into the engine oil. I’ve drained and measured the oil levels to confirm this is happening. 
I know it’s a warranty issue but I live hours away from the dealer and I’m looking for a fix to keep riding. 
Does anyone have experience with this? I’m thinking it’s a faulty crankshaft seal?

What year. They just had a deal where the outside left cover was bad. The details are in this thread. 

 Out of curiosity, just how did you figure that out with so low hours?

Look under Montesa 4 ride oil filtration issues. It even has models and serial numbers.

 The side cover waz defective, which could also cause a blown seal. The oil has to go somewhere.

Strange 🤔 the engine has the ability to pressurize or create a vacuum condition in the bottom end, but the transmission does not.  The engine typically creates greater positive pressure during operation from blow by gasses,  I would inspect the crankcase ventilation hose, because that pipe needs to vent in both directions and you don't need to take much apart to get to it.

It’s not a filtration issue - I’ve changed filters and the filter is coming out with oil.

It’s a 2024, bought in October 24 and not part of the recall.

i realised insufficient gear/clutch oil was coming out during oil changes and started measuring the oil I was taking out. 

 You are crazy not to take it back to the dealer and let them warranty it. I don`t care how long of drive you think it is.

On 2/18/2025 at 5:14 PM, lemur said:

Strange 🤔 the engine has the ability to pressurize or create a vacuum condition in the bottom end, but the transmission does not.  The engine typically creates greater positive pressure during operation from blow by gasses,  I would inspect the crankcase ventilation hose, because that pipe needs to vent in both directions and you don't need to take much apart to get to it.

 That`s a great idea. But a 301 that`s new needs to get a paper trail of issues before they refuse the warranty. The 4rt`s are competition machines, honoring any warranty is optional at best.

I’ve found the dealer more than difficult to engage with. After several phone calls without any response and a number of emails, I’ve eventually been informed they’ll ’contact Honda’ to seek advice. I’m not holding my breath.

To be honest, I just want the bike repaired and I’d pay or do it myself. They are competition machines and they do breakdown.

It’s worth measuring your oil levels during a change. There are a number of threads now about the crankshaft clutch seal failing. 
I changed my clutch plates to a Mitanni pack (which cost £££) after a couple of months owning the bike because of poor gear change, struggling to find neutral and problems starting in gear. I’m now thinking I was just running with low gear/clutch oil.

Curious on the subject of warranty; did the dealer sell you the complete motorcycle in the crate as a competition only race bike, or did they charge you additional for some kind of pre-delivery setup service?  At the very least a dealer should warranty their own service work if they charged coin for it.

"problems starting in gear." That will always be an issue, the kickstart needs to bring the engine up to the high idle speed to start because you do not have a battery and the auto-decompressor needs to operate at the correct time or the bike simply will not fire up easy.

Edited February 20, 20251 yr by lemur

As an update, the right crankshaft seal was changed which stopped the transmission oil leak into the engine oil.