gilera runner sp50 not pulling off

hi and thanks for that. we have bought piston and rings as the engine is just standard. When we bought the bike as a none runner, the guy we bought off had a new cylinder fitted about 4 months before we bought it, The cylinder is very smooth no scores the piston has some scores on it but not too bad in my eyes but hey what do I know. I have a doppler 70cc cylinder and head I was given but this is scored I have thought about having it honed, Would this cost much? Cheers Gaz

 

please put a good step-by-step tutorial on your magic on pistons and barrels

 

Will do - when the 'pro' photographer gets back from her mission. Can't work on ports and take photos........
Gaz - 'engine is just standard' - all the more reason ! This is a reliability issue - not really a performance issue. And worse - standard cylinders are the worst offenders - since economy is at a premium - they don't chamfer the ports at all. If you buy a more expensive cylinder - port chamfering is one of the reasons you pay more !
Plus - you will have an old cylinder to practice on. Don't chuck it !

 

Okay mate so should I buy a new cylinder and head too or just try the new piston and rings first. Should I have the doppler honed? We could fit that at a later date once my son gets used to this scooter

 

I always hone any cylinder I take off -if it's going back on.With one of these and some WD40.
http://www.maxiscoot.com/motoforce-rodoir-de-cylindre-mf34-00010.html
This guy is clearly an amateur. I hold the cylinder in my hand - and the drill in the other - that way you can 'feel' what you're doing.
Not too fast - and not to slow. And back and forth - you want a diamond pattern inside.

 

I'll post a video soon - I have a Top perf 50 to recondition before it gets a new piston !

 

That's exactly the way i hone my barrels as well. You can get the tool and stones from draper. Cheap as well for what they do. You can also put the hone in a pillar drill set-up with the barrel supported on wood blocks, saves the stones catching your hands occasionally.

 

Oh yeah thats just how we like it not too fast and not too slow back and forth
Couldn't resist

 

'I never seen so much whackin'

 

still waiting for the piston and rings to arrive hopefully here tomorrow so we can sort this out. I feckin hope

 

I'll get on the case with a tutorial - with a bit of luck you'll get it at the same time as the kit.

 

Paraffin is also good for honing tools and cheaper than WD-40. If any of you do this, you have to make sure that the cylinder and ports are sterile and absolutely free from any grit when you've finished.

When I've needed to quickly hone a bore to take the shine off before a rebuild and I've not had ascess to a proper honing tool like this, I've cut a slot into a piece of wooden dowelling, folded a piece of 400 grit silicon carbide sandpaper then put it into the slot, secured it with an elastic band, cut it slightly oversize to the bore of the cylinder then used that in a drill to get the job done.

Necessity is the mother of invention...

 

just got home from work and still no piston kit How pissed off am I. I have emailed the supplier they have been posted so should be here tomorrow. Hows your projects? Turbo

 

Well the lady's scoot is getting an 82 jet and 32 g of rollers and then i take it out for a test. it should be near perfect - if a tad rich. Need to test to find out- but the weather is atrocious.
On saturday I am going to see a sand blaster man for the wheels & the kick case of the typhoon. then the tyres go back on amd all the plastic comes off.
Mine is just dandy, but I'm not going out in this!

 

nice one. I work for an engineering company mate we have a shot blasting and paint shop we also have a aqua bead blaster. Where you based? You have helped me out maybe I can help you at some point

 

me dumb messed up with the replies Right you have helped me out so if I can help you I work at an engineering company we have a shot blast and paint shop also an aquablast machine. where you based? mate

 

That's really kind. Alas, I live across the water in a place where the locals speak neither French or Spanish. Sometimes they get restless and blow something up. Geddit ?

 

They play a lot of pelota there, don't they, Turbo?

One thing about honing cylinder bores. Some cylinders (e.g. Peugeot) are Nikasil (Nickel - Silicon Carbide) coated and honing the bore will most likely remove the Silicon Carbide coating that gets left after the Nikasil process. The Silicon Carbide coating helps to resist wear caused by the piston rings and makes the cylinder last longer.

If you do hone the bore of a cylinder that was originally Nikasil coated, it will wear out faster after honing, unless you know a place where they can re-coat it. Some workshop manuals specifically warn against reboring or honing cylinders for this reason.

Replacement cylinders are cheap enough, but I thought it best to warn you all about this.

 

Yes they do !
Thanks merlin. I have 4 Nicasil cylinders here (five with my gal's sport pro). 2 metrakit pro race, One Malossi team 2 ( not cheap!) and a Stage6 Sport Pro 2. The nicasil coating varies in thickness, but it's hard as nails and i never do more than a quick hone to de-glase the cylinder.
With port chamfering it's a different issue. When you chamfer the ports on a nicasil bore, you need higher speeds with the dremel (using a file is completely out of the qusetion). they tend to delaminate. Not that this has ever happened to me, mind!

 

OK - here we go with the top perf 50 cylinder after god knows how many miles.
This is it:
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/1.jpg
See the exhaust port? I need to go and take a snap of a standard ovetto cylinder because the difference is staggering. This is why the top perf 50 goes like stink with a decent exhast. But i digress....
Little bit scratched. Not surprised since the oil pump was on the way out......
This is what you need (I paid 15 euros for mine). You need to lube up for this. You can even use grinding paste if you're trying to get rid of really big damage. I have seen miracles performed.......
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/2matos.jpg
Then you put it in like so - Gently - trying not to scratch anything - yet....
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/3honin2.jpg
I hold it like this:
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/4honin.jpg
you need to go back and forth fast, but not with the drill too fast. '1' is better than '2'.
Now the chamfering. Here's what I use. Dremel with standard bits. You need to hold everything tight, go up the barrel and place it like in the pic. The on medium speed (not too fast in a cast iron barrel) slide back & forth aling the window. Do not stop in one place. Keep moving. I use a second smaller bit to get the bottom corners nice & even on the admission ports - trying to go along & up the wall. The big bit you see here is great for the corners of the big exhaust port.
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/8windows.jpg
Here we are with the exhaust port:
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/7windows.jpg
This is how I hold the dremel - against the skirt using my thumb as a guide against the cylinder. Hold tight and make fluid back & forth movements. yes- there is a dremel in my hand here. but i'm holding it tight & braced agzinst the cylinder.
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/9windows3.jpg
This is the Honed cylinder.
http://i572.photobucket.com/albums/ss162/bloodyhell451/prepa/6honed.jpg
Like I said. Big exhaust port. I have heard people say, Top Perf 50 iron? Same as stock'. To them I have one thing to say. Port window area. Look at the thing!
Then you clean everything with turps and then detergent.The you put some oil in the barrel with your finger. Either to stop corrosion (if it's going to wait to be built up) or to help the new piston/rings on the first start up.

As the more observant will have noticed - I only honed the cylinder. The dremel was not running. This needs video !
I will get on it - Bit I hope this helps with your prep.

Chamfering the ports slides the ring(s) back into the housing in the piston instead of them hitting a 90° angle. Running in essentially does this (though not nearly so effectively). Since they are sprung against the cylinder - they tend to bow out into the ports (especially the exhaust port - it's big). This constant battering causes them to fail. Especially when they are cast iron and not ductile (i.e standard kits). Chamfering the ports makes it a more gradual process and preserves ring life.

Honing scores the barrel. Paradoxically - this helps because the scores hold the oil better than a sheer polished surface. Oil is the only thing preventing the engine dstroying itself.

There are other tricks with the skirt and the rings. Soon !