Aprilia Supermotard problems.

[Brit_27]

Before I continue with my first post I just want to say hi and will appreciate any help you guys can offer, I haven't had a bike for years now when we used to blat around on 250's ! I've been involved with racing karts for years, so have a little bit of 2-stroke engine knowledge.

My son recently bought a used Aprilia 125 supermoto (06) and has been happily riding around on it although it had an awful flat spot when cold and at low revs, I did telll him that it needs looking at and setting up properly but he just said ok, contnuing to live with it.
Last week however he stupidly ran low on 2-stroke oil and managed to seize the bike while doing around 40mph. He then dropped it off at my house (he lives with his mum) to have a look at.
I couldn't get the exhaust off the front of the barrel as the Torx bolts have rusted on and I don't have any drivers that fit, allen keys drivers simply wouldn't hack it. I did take the carb and noted that it had a 120 jet fitted, the airscew was out 4 turns, everything seemed to be in order. The plug was black/grey ,albeit very dry after the seize.
The piston had freed itself once the motor had cooled down, so today we filled it with two stroke oil, made sure it was bled into the oil pump and then kicked it over a few times to get the bore wet. Once started we left it on tick over for around five minutes, I set the airscrew to 3 turns out (I've read it should be set 1.5-2 turns on one forum and 3.5 turns on another !) before I asked him to gingerly drive it around the block before coming back, doing a plug chop on the way. I was concerned that there wasn't any blue smoke but thought this was just from where the carb had been stripped and the settings ahd been altered.
Well it nipped up again once he hit 2nd gear, so it's not getting any oil .
After reading through old posts on here I am going to check the oil pump is working, there was air in the smaller pipe that feeds the carb, but it appeared to be moving.
Is there a technique for bleeding the oil pump ? We've always premixed our fuel/oil with karts, so the pump is new to me.
Now that it has seized twice I'll probably have to have the top end off and inspect the piston and barrel , should I have another attempt at running it first ?
Does anyone have the correct airscrew settings ?
Cheers Paul.

[Brit_27]

Well I had another crack at sorting the bike today.
I had the front of the exhaust off (I didn't need to undo the bolts after all ), just by removing the springs and then shone a torch up inside the port. The front of the piston is obviously scored, but the ring didn't look too bad, it looks like it is still free.
I brushed some 2/ oil around the visible bit of the piston and around the back of the bore that I could reach (there wasn't any score marks on the rear of the bore).
I then bled the oil pump by using a drill on the back of the pump that I had removed, I pumped the air out that must have been trapped within the pump from yesterday and then placed the pipe back onto the carb.
After a few kicks the bike sprang into life, I had plenty of smoke from the oil that I had put into the bore and let it idle for around ten minutes, at this point I noticed that any traces of blue smoke had disappeared from the exhaust. With this worrying me I took the plug out and noticed it was bone dry, no trace of oil at all. I looked at the small oil pipe and there one or two very small air bubbles running back up to the carb, so I repeated the drill on pump sequence again.
On restarting there appeared to be smoke emitting whe reving the bike at a stand still, so I'm hoping that the pump has now been bled properly. I set the airscrew to 2 1/4 turns and adjusted the idle with the black plastic screw. The bike will still bog down when the throttle is twisted hard or fast, applying a bit of choke cures this, so I'm not sure what is wrong there ? When riding it up and down my drive it pulled nice using a bit of clutch slip.
It's just down to waiting for my son to take it back out on the road to test, doing a plug chop on his way back, if we are happy with the plug we can decide on where to go from there.

[Brit_27]

Well day three and still having problems.
My son did a five minute gentle spin around the block to see how things were, the engine was still bogging at low revs, probably due to air being sucked in through a tired looking carb rubber, although the exhaust hasn't sealed brilliantly even with gasket seal on it.
I removed the plug to find it very dry and grey, which wasn't what I had hoped for. So we decided to drain the fuel off and pre-mix it, we used a 50:1 mix after which he rode the bike back home (to his mums) which is around 15 mins away, he said that the bike started losing power on the way .
I'm not sure if it's the damage to the piston that is causing this or perhaps the oil pump is giving up ? I'll get him back to mine tomorrow to do another plug inspection, as I think the last check was after to short a journey to colour the plug up.

[1cyl]

Def sounds like oil pump. Can you disconnect/expose discharge from oil pump and see if its pumping? (while running the premix for engine). Or how about a clear bit of 1/4" tube full of oil feeding the pump. And see if level drops in it when engine is running.
____________________
Chase my Witch up, Catch my Snitch up.
The SMC | The Pit | Stable

[Brit_27]

[Brit_27]

Day 4 and after a decent ride on the bike the plug is looking black, so at least it's getting some oil now. I did check the oil pump as per the YouTube video and all seems well with it.

Now I need to replace the carb inlet rubber, does anyone have a link to somebody who deals with Aprilia spares, I've not had much luck looking for an angled 28mm carb inlet rubber so far ?

[SQL]

Bowden Moto's are great.

https://www.bowenmoto.co.uk/

[Brit_27]