My 2013 TR280i has started to smoke recently, any idea what might be the cause? 

Doesn't run so well as well and it doesn't seem to be the fuel mixture issue, I've tried with a different fresh fuel/oil mixture and still the same.

I figure it's maybe a gearbox oil leaking slowly into crankcase room, but where that leak might occur, a bad crakshaft seal in one side? Any ideas?

Bad crank seal on clutch side would be your most likely answer. 

Take the flywheel off and look for residue or loose or sheared bolts on the plate that holds and seals the crankshaft, gasket can go and lots of smoke is a sign of this. I would check this side first

Are you losing any gearbox oil?  

Measure what you put in, then what you take out when you next change the oil.

Edited August 6, 20188 yr by Andy

I think I could tell by the smell if the bikes using transmission oil imagine the exhaust would be a bit dribbly too.

About 3 years ago mine went right of song like a regular bike running with the choke on. Must have felt brave and adjusted the sensor by hand mind you I didn't totally slacken it just enough as move it a minute amount.

Just listening to the motor until it took throttle nice and clean and set it at that.

Can't even mind which way I moved it but it'll be obvious if you give it a go and mind to mark the original position.

Anyway I take no responsibility for this post if you destroy your motor all I'll say is mine's still perfect after all this time and it's done a load of work.

What could possibly go wrong! 

I’ve found I need to adjust and reset the TPS about every 100 hours to keep it in top running form.

Cheers guys for the great info!

Will check the TPS first, if OK then see if there's oil in the magneto side of the crank when I have time on the weekend.

OSSA people the best!

TPS was spot-on 600 mV, also no oil in magneto chamber. Wonder if it's the other side of the crank seal? If so then I'm fecked since it needs complete crank removal to get there...

I have worked on a couple of Ossa motors that smoked a lot, both had the following problem. On your motor on the crankshaft LHS, the needle roller main bearing runs on a thin steel sleeve which is a shrink fit on the 25 diameter crankshaft. The sleeve was under stress and ended up with a hairline crack, hard to see, that allowed gearbox oil to be drawn into the crank case. The sleeves are not available if yours is cracked, but you might be lucky and perhaps the oil seal has failed on the RHS of the crankshaft. If there is a hair crack on the sleeve, you can always fit the later model LHS inner plate with ball race, that runs on the 25 diameter crankshaft, so the sleeve needs to be extracted - easy if it is split. If the RHS seal has failed, which would be uncommon, then you have no option but to replace the main bearing and seal. Yes, it is a very lengthy job, and needs some setting up to put back together, but it is possible. Bye, Peter B.

Is your oil low? Were all the bolts on the mag side crank plate tight? I have seen the gasket fail, you cannot tell until you remove the plate, seeing as you have to go in from that side anyway I would remove the plate and check before pulling the crank. With the plate removed you may also be able to See if there is any excess oil in the crank case 

Edited August 15, 20188 yr by canada280i

On 15.8.2018 at 10:37 AM, peterb said:

I have worked on a couple of Ossa motors that smoked a lot, both had the following problem. On your motor on the crankshaft LHS, the needle roller main bearing runs on a thin steel sleeve which is a shrink fit on the 25 diameter crankshaft. The sleeve was under stress and ended up with a hairline crack, hard to see, that allowed gearbox oil to be drawn into the crank case. The sleeves are not available if yours is cracked, but you might be lucky and perhaps the oil seal has failed on the RHS of the crankshaft. If there is a hair crack on the sleeve, you can always fit the later model LHS inner plate with ball race, that runs on the 25 diameter crankshaft, so the sleeve needs to be extracted - easy if it is split. If the RHS seal has failed, which would be uncommon, then you have no option but to replace the main bearing and seal. Yes, it is a very lengthy job, and needs some setting up to put back together, but it is possible. Bye, Peter B.

I checked the LHS hasn't leaked into magneto chamber, but I remember there was an oiling channel for the LHS crank needle bearing when I did an overhaul last winter, so in theory it could leak from the oiling channel into crank chamber as explained by you w/o leaking into magneto chamber at the same time (leaks only to one side).

I guess I have to pull the LHS crank plate off to observe? 

Can't remember how I did it last time, but I remember it was a PITA to get it off w/o special tools. Any good tips on removing the LHS crank plate?

 

21 hours ago, canada280i said:

Is your oil low? Were all the bolts on the mag side crank plate tight? I have seen the gasket fail, you cannot tell until you remove the plate, seeing as you have to go in from that side anyway I would remove the plate and check before pulling the crank. With the plate removed you may also be able to See if there is any excess oil in the crank case 

 

Can't tell from the oil consumption since it tends to vary on mine (thick transmission oil get's stuck on gears etc). Will see if I can remove the crank plate, let me know if anyone has a good trick how to pull it with normal tools!

Edited August 16, 20188 yr by tsiklonaut

The 2013 motors have a tighter tolerance between the inner plate and crank case and need to be extracted reasonably squarely. To remove the inner plate, remove the 3 stator bolts and hang the stator out of the way, then all of the plate bolts too. You need 3 long M5 allen bolts and a steel plate with a centre bolt, and 3 holes that match the stator bolt circle diameter (BCD) Use this set up to carefully extract the plate. I'll have a look for my extractor set up and see if I can get a photo of it on here. Some measurements too. Bye, Peter B.

You mentioned thick transmission oil that get's stuck on gears. We always used ATF Dexron III on these (and many others) bikes, which is certainly not thick transmission oil. Bye, Peter B.

Here are a couple of photos of the inner plate puller. Originally made for a Scorpa (Yamaha motor) flywheel puller, then modified for the Ossa using the inner 3 holes. The BCD, not accurately measured, is 42.0mm, check your stator hole placement. M5 bolt length = 70mm. Hard to see the third inner hole on the photo. (Two sets of 3 holes) Plate is 6mm. Hope this helps. You should be able to get someone to make up one of these. With the centre screw puller, make sure it does not damage the M10 thread at the end of the crank, I use a nut in between. Bye, Peter B.

 

I used a piston from an old hydraulic foot pump with a few nuts and bolts.