Wanna upgrade from 50cc to 70cc jog rr lc

Hi all I wanna upgrade my 50cc jog rr lc to a 70cc it's got a polini exhaust and some upgraded rollers what if anything shouldn't i do and how technically hard is it to do said work

Thanks all who reply to the newbie

 

It's not hard but...

First of all get the whole process right in your head before you start. Make a step by step list of everything you will need to do and then check it. What have you forgotten ? Don't forget it. Even experienced mechanics fuck up and it's generally because of lack of concentration and arrogance mixed up with a good dose of impatience. Be diligent and methodical. And patient ! Don't start the job unless you've really done your homework. In this day and age of 'youtube' - there's no excuse. What follows are additions to the general advice on film etc that you will find. It's not an exhaustive list of what to do - but it is a list of little things which will help. Do your research ! Google is your friend. These bits are not in order - so get them in order ! If you have any questions about this I will answer.

Broadly -
Clean before disassembly
Disassemble head - remove barrel
Stuff the motor with kitchen roll
Remove piston
Clean gasket surfaces on the block

Prepare new piston
Prepare cylinder (if you feel up to chamfering ports)
Fit new piston (no clips or rings!)
Test squitch and adjust with base gaskets

Once you have the squitch set right -

Remove piston
Put piston rings on
Piston on
Piston clips in
Remove protective tissue in the entrance to the engine
Sealant applied to gaskets
Base gaskets on with the 4 rods
Slide the barrel on
'O' rings on
Tighten head

Let it dry.

Hints & tips :

Before you remove the existing kit clean everything as well as you can around the cylinder. It will be covered in crap and you don't want it falling in the engine. Turps, toothbrush around the base and compressed air are your friends. If you don't have compressed air - wash after the turps scrub with detergent & let it dry.

The more access you have - the easier this will be - so remove anything and everything that is in your way. By this I mean the bodywork ! Don't be lazy. Have it off. You'll be glad you did.

Light ! You are going to need it - so get some. Even in broad daylight you still can't see shit so get a lamp/anglepoise light - whatever.

Before removing the old piston - stuff the entrance to the case with kitchen roll. Piston clips are impossibly attracted to the dark places inside engines - so stuff the entrance around the con rod with tissue while you take the old piston off and while you put the new one on. If anything falls in there - stop everything and do whatever you have to do to get it out. If you've used kitchen roll - you won't have to.

Before assembly, clean up all gasket surfaces on the block with turps and tissue - then de-grease with acetone.The old gasket is probably going to stick so soften it up with the turps, use a scalpel/toothbrush/fingernails - whatever - but get it all off, clean and de-grease. Remove the four piston guides from the block - it makes this easier. I use a pipe wrench on the smooth middle bit for this - but a decent pair of pliers works. You can clean up the threads with turps & a toothbrush too - and run them through a die if you have the gear.

You need to set it up with a dry run to test the squitch - What does the kit want ? Get it right. This is the major factor in getting the performance you paid for - besides good assembly (sealant).

You will need calipers to measure the solder when you've 'squitched' it. Get some !

You need to get some decent piston clips as the stock ones (no tails) are a nightmare. Poiini clips have tails and you can put them in right with needle nosed pliers. Make sure they are properly seated. Rotate them in the grooves once they are in and make sure the curved tails are not hanging 'in mid air' (in the gap in the clip housing). In this pic you can see the piston clips with the tails:https://www.flickr.com/photos/116877957@N08/14328862853/ They're the 2 little things surrounded by the 'O' rings.

Replace your roller cage. They cost pence but if they go, everything goes. Put a blob of oil on it before putting it in the top end.

You need to use sealant on all the base gaskets (you may need more than one to get the squitch right) -so paste them all with your fingers before assembly. This is why you do a dry run to test the squitch)

I use sealant on the 'O' rings in the head too. Just a light film. It ensures that it's all air tight and it preserves the life of the 'O' rings too.

It's a good idea to prep the skirt of the piston with some emery paper and round off all the edges. It lets oil get up the barrel instead of being scraped off 'windowcleaner' style. D.o this before putting it on and wash that sucker. Dry it. Fit the ring(s) Go the full 360. They are chamfered on the top and bottom but not the sides. Rub out anything that is sharp. Do the same around the holes for the piston clips. If you are OCD like me - polish the top of the piston - 260 emery paper, 400 ish emery paper, 600 and then a go with some 'rouge' and a cotton wheel.

It's an even better idea to chamfer the ports of the cylinder - especially the exhaust port. This preserves ring life and reduces wear and tear while you're running it in.

Put your (sealant-dabbled) base gaskets on without the cylinder guides. Put one guide through the gasket(s) - screw it in - then do the other three. This will allow you to not plaster the piston with sealant as you try and put the gaskets on (if the four guides were in place).
Tighten the head progressively and opposite diagonally.

There are all sorts of guides hither and yon - do a search. Homework makes everything easier/better.

The hardest part (apart from the piston clips) is getting the barrel on when the rings are on. Put the rings on before you put the piston on the crank for final assembly ! When you do the dry run for the squich calibration you don't need the rings or the piston clips - so don't put them on for that bit (the first stage of the process).

When it comes to actually putting the barrel on - with clean hands - rotate the rings so the gaps are aligned with the pins in the piston and then pinch the the rings from underneath while simultaneously sliding the barrel on. A little oil inside the barrel with a finger helps this process. But it isn't easy. You have to jiggle the barrel while pinching like a bastard. This is where your light will help. Stay calm - pay attention to the rings and their little gaps (aligned with the pins in the piston) and if you don't get it first time - go for a brisk walk. Don't forget any 'O' rings before you put the head on ! And once it's done - leave the engine t settle so the sealant dries for 24 hrs.

Good luck.

 

Turbo, you need to become a tutor for wannabe scooter mechanics.
Thats a brilliant write-up

 

Thanks Steve - But it's just because I have made every fuck up known to man - and some I invented myself (facepalm)

 

A man who can admit to his mistakes can make ANYTHING