Runner engine strip down and re-build

ok as you all know i bought a Runner 50 engine off e-bay nearly a month ago.

The plan is to strip it down...clean it up...and rebuild it as a 70cc to replace the very tired engine that currently powers my Runner...

Anyway as since i bought the engine nothing has been mentioned again, i thought i would add a few piccys to show the progress or lack of imp:


This is the engine as delivered to my house from a breaker off e-bay..
the back wheel will come in handy for project pig-fight 70cc...but thats for another project imp:




A bit of spannering later and were pretty much down to the bare bones!!





The ever growing parts for the engine build!!!



Heres a quick update, I thought I best take some pictures after seeing wobbly's progress on his engine imp:

Heres a cheeky little shot of the auxillary exhaust ports on the rep cylinder, They will look small compared to the evo cylinder eh wobbly



The next pic is the rep cylinder on one side of the case showing the mismatch between the auxillary transfer feed / case. As you can see the barrel feeds need a slight bit of opening up to match the case.



This shot shows the unmodified case.



Here it is after some flowing work...still in rough of course!!



Had another little session today with the grinder starting to make some progress, im nearly at the stage now where it starts to get scary... and breaking through the case and reaching for the chemical metal!!!

still quite a way to go...long process this case flowing lark!!!



Heres the main bearings and BGM evo crank in the freezer, in air tight freezer bags and soaked in WD40 to stop them rusting.



A bit of a stealth modification going on here





just a couple of coats of black VHT paint needed now for that stock look
to keep the rozzers or mot testers happy



The main bearings, water pump and crank fitted into the cases.
Sorry I didnt get any photos of me fitting the crank... but its hard juggling a frozen crank and two hot engine cases and a camera at the same time.


The stator and flywheel fitted...


The water pump / oil pump belt and pulleys now in place and the oil pump bolted into place... (although I havent decided if I am going to use the oil pump or run with pre-mix yet).



Heres the barrel all masked up and waiting for a coat of stealth black VHT paint.


First coat on, a couple more to follow.


Whilst the barrel was drying I turned my attention to changing the rear axle bearing. Here I am driving the old bearing out of the case with a large socket and extension bar and hammer (out of shot).


The old bearing is out, here I am heating the case up with a hot air gun ready to fit the new bearing which is in the freezer.


Once the case was nice and hot the frozen bearing slipped into place with only a couple of taps needed from the hammer.


Heres a picture of the engine so far, as you can see its starting to take shape.


The old engine removed from the scooter


The old and new engines side by side.


The new engine bolted into place




I was talking with minor confusion on msn, and he let slip another one of his tuning secrets to me...he told me that the laser x-pro is an excellent pipe as we all know, but it can be improved by cutting the end can down by 20%!!
The theory is that the can is very long to keep the noise levels down,at the expense of retaining heat in the pipe, I had noticed that x-pro"s go brown around the downpipe area quickly through heat...of course if the pipe runs cooler then the cylinder runs cooler too...as we all know heat is the enemy of the 2 stroke engine...and cooler running can also help power!!!

I knew i had an old end can in my shed so i found it out and did some measuring...it was the same bolt pattern as the x-pro but 30mm shorter!!!
which is 12% shorter...I thought i"ll bolt it on and do some testing, that way if it dont work i can just bolt the x-pro can back on and no harm done...

This shows the difference between the laser inner baffle and the new 30mm shorter can...



Video of engine running...with shorter end can on x-pro..


ok i guess your all wondering if it actually made any difference...
yes it did...power and torque was improved, noise was up slightly too, but
it sounded deeper, which is good!!!
so now i was sure it worked...(why did i even question scooter shacks resident tuning guru) i chopped the shiny x-pro outer can down by 30mm on the circular saw at work...
I actually think the x-pro looks better with a slightly shorter can too...

And heres the laser outer can re-fitted cut down by 30mm with shortened tail pipe as well...



I hope minor didnt mind me sharing this little tuning secret!!!
wonder if i should chop it down another 8% to make the 20% or leave it at 12% shortened....mmm i wonder!!!!!


My stage 6 tranny bits came from scooter attack today, thought i would give stage6 a try...The europeans love the brand, and as everyone knows they are several years in front of us scooter tuning wise :lol:



The stage 6 CNC racing drive is fooking light...must be half the weight of the piaggio frt outer pulley



The adjustable race clutch...i havent fitted this yet as i want to cure the belt slip before i start messing around setting this little beauty up



My stage 6 wing cooler clutch bell that came last week...








been messing around all evening testing different roller weights and a stiffer contra spring with these new stage 6 parts...found a pretty good compromise, belt slip seems to have gone so happy days...

yes at last my gear up kit has arrived from S.A !!!

hopefully be fitted this week end



click on here to see me fitting my gear up kit
http://capridave.piczo.com/gearkit?cr=6&linkvar=000044

 

ok my good man...sounds good to me

i"ll drop you a p.m soon

 

This looks interesting.
I will watch this tread

 

nice 1 dave i never spilt an engine befor it dont look to hard is they time on these engine or r they self timeing i might have a go to fit my new crank on my 125 is it the same as the 50 nice work dave

 

and is it hard to take the old crank bearings out and pu the new ones in i fault that u needed a press but i have heard of sum sort of ice spray witch shrinks the beraing or sum think like that

 

Bookmarked :w00t:


Good luck with the project

 

Goodluck dave

 

cheers lads

 

Looking good Dave keep up the good work

 

did you have any trouble with bolts or screw rounded off ive had a few on the few engines ive done moast of the time i just drill them and tap them out bigger or use a nut on other side anyways im looking forward to seeing the finished product

 

Sounds good Dave good luck
i've got that spanner set

 

heat, patience and WD-40 is your problem.

looks good dave, nice to see you making a start on it.

 

no problems so far with nuts/bolts etc...

use good spanners and sockets...and dont rush is my only advice

when undoing/tightening you develop a feel for it over the years..

Dont forget ive been messing around with tools since i was 16...and im in my 30"s now (mainly with old school ford engines though)

And i would like to thank minor for some very valuable advise before i started this project

 

maybe the fact mine rounded off was they were verry old engines and the screws were basicly rust i got them out in the end anyway. if your going to go with a powerfull setup i have a few malossi parts doing nothing pm me or add me on msn if you want to know what ive got.

 

minor confustion have u got any tips on rebuilding a engine i am not to bad with my tool kit i no how and engine works and i can do every think to and egine but i have never tryed to and spilt and engine but i fink i could do it and i now that when u put it all back together coat everthink in 2t oil i have been playing around with bikes sinse i was about 9 with my dad so i fink should be able to do it wat u think cheers

 

if you ask you will never know? no offence minor its part of the learning curve if you dont ask you wont know, really gets me because how did you learn?

anyways i got plenty of 2 stroke books and changing a crank isnt impossible and can be done first time just take it easy and do not rush.

whats the worst that can happen? buy a second hand engine on fleabay and if you do fuck it its not your bike youve fucked its just the engine.

its not top secret and im going to do a guide with pictures next time im splitting the cases and doing a new crank step by step.

darren.

 

minors right if you have to ask dont do it ive mainly learnt alot of the internet and striping them myself i should be doing my first crank soon enough oh and if you realy want add me on msn i have a brilliant guide tweak sent me a while ago.