2 stroke Gearbox Issues

[Djaniero]

My aprilia mx died yesterday evening enroute home. No weird engine noises or anything before hand..just a clunky gearbox then the bike lost all engine power.

So i took the exhaust off today to have a look at the piston and barel, all looked ok, but then i realised my gearbox was bone dry!.

I ve had a chat with a couple of mechanics today, and one suggested putting some gearbox oil in and pray that it solves my issue. But then another mechanic told me not to do this, and strip the engine/box to see what damage has been done. Reason being, if the gearbox bearings are ruined, and i haven't chewed the gearbox, then putting oil in and starting it up could destroy the perfectly fine cogs.

So a bit unsure what to do??

[wristjob]

so does the engine run normaly and when you try to egage a gear it struggles/stalls/wont engage.
for a gearbox to be dry you must have seen drips.or its been dry for ever.
neglect is a good way to kill mechanical things

[MCN.]

[hazza]

As said, Id bet it's the crank seal. You would have noticed 1.5 litres of oil where you park up. Has it been smokey as hell?
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3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[Djaniero]

No drips, or leaks whatsoever lads and not smoking excessively. I think the young lad, who I bought it of wasnt the best at maintenance as he thought he was

I can't kick start the bike at all at the moment.

Shall I chance putting some oil in and trying to start her up, or stripping the box down to see what the damage is?

[Pete.]

Don't listen to the first mechanic. Putting oil in something that's failed due to lack of oil is not going to produce a magical repair.

Your bike lost drive and now you cannot kick the engine over? Time to remove the right hand cover. Some bikes transmit kick-start drive through the clutch so it might be a simple clutch issue.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Djaniero]

Yeah mate. Just lost all power and cut out and now i cant kick the engine over.

Point taken. So i need to remove the engine and box and split the crank case to get to the clutch? I have never done this before but have a haynes manual and an array of tools!

[Pete.]

I never saw a clutch inside the crank cases. Usually it's behind the right hand engine cover.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Djaniero]

Sorry, my bad. You re right. Just had a look at this video.

https://youtu.be/VIP9onucTM8

Can i do this while the engine is still bolted to the bike or would i be better off to remove it?

[devojunior]

if it was me id go get some gear oil and get that in the box leave it stood over night then try get it going through the gears see how it goes.

my cars gear boxxes drive shaft seal faild and i lost all gearbox oil without knowing and drove for a few week until gearbox seized up so filled it up got gears back but eventually the bearings died.

moral of the story is.. well there isnt one just fix it properly once not half do it 3 4 times

[Djaniero]

Well going off the selector, I can still get through the gears, but I'm guessing something has definitely damaged inside, as to why it stopped working.

I'll take the cover off this evening and have a closer inspection. If I do need to repair the gearbox, can I do this with the engine still bolted in place, or will I have to remove the whole unit?

The haynes manual (for the rs 125..same rotax engine) says you can leave the engine bolted in while working on the gearbox, but all the gearbox tutorials online I've seen have taken the whole engine out to work on the box.

[andy_uk]

You need to separate the crank case so yes, it will need to be out of the bike.

Here's a link to the Rotax 122 engine manual (assuming yours is the 122, not the 123)
https://www.carlsalter.com/pdfs/Aprilia_Rotax_Engine_Manual_122.pdf
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Aprilia Classic 125, GS500E, ER5-A1, ER5-C4, ER6 & an XJ6 project frame...

[Djaniero]

Thanks Andy. Is that manual pretty much the same as the haynes?

I assume mine is the 122 engine (2004 mx) as the 123 was the earlier engine I think?