pug speedfight & my other one...

[vvtr]

hi chaps..
bought myself another scoot
this one's a '00 peugeot speedfight ac



looks a bit dazzling atm lol finished in a bright orange urban camo
mods so far include leo vinci pipe, polini 70cc kit with new piston & rings, bearings just done, stage 6 induction kit with 19mm carb, better cdi & coil etc, malossi multivar variator, malossi +10% gear kit, full circle crank and nice new sports profile tyres

fuelling's ok but it's not quite revving out as good as i'd like... so after a few miles under the belt i stripped the covers off & measured the squish for starters & found it at 2.1mm which imo is a little on the high side!

so anyway, as ive some experience in 2 stoke porting from my race days ive been checking out your port maps with interest and will be having a play with this software before i make any major changes... mediafire.com/?w8em1enwwtcwwx8

im looking for a nice midrange to top end peaking as high as possible.... 12 - 14k rpm if the can will allow it!
appreciate your wisdom on this and will keep you updated as to what i find & what ive done!


my other scoot (on here somewhere) is a baotian bt50qt9 with the following - 80cc bbk, ported big valve head, high lift cam, 21mm slide carb, foam filter, 32kv coil, kamikaze cdi, naraku variator 6g, clutch (reds), naraku +10% gears, big bore header & home made carbon can... it's currently awaiting repair as i burnt out the stator on a 1000 mile run!

it runs surprisingly well though, pulls 45 uphill no problem and pulls 50 easy, topping out at 60mph!

i do miss the smell & noise of the 2T though which is why i got the pug!

[90GTVert]

2.1mm is pretty far off for a 70. I'd start by getting that somewhere closer to 1mm or at least 1.5mm and you should see a big improvement in power.

[jmkjr72]

if thats a polini sport kit it will take a lot of work to hit that many revs
heck to even get to the 12000 rpm range i wad to work my corsa kit over a bit
how many gaskets are in there to get 2.1mm squish
most of the polini kits the best you can hope for with no gaskets is .9mm
with the thinest base gasket i could find im running 1.1 to 1.2mm squish

[vvtr]

yeh cheers guys, i'll be aiming for 1mm (or less) - it's only got one thin head & base gasket atm as the problem seems to be the lip on the head which is a bit excessive to say the least.

ive started by taking the grinder to it & draw filing it flat to get it to a decent level then i'll lap it to the cyl.
thing is, i might end up jacking up the cylinder yet and taking a bit off the top so there's bo point getting excited about it yet lol.
plus it'll have to wait cos ive just been called out. who the hell works on nye lol

regarding the revs... i'd be happy with 12k, though i reckon it will go higher with a bit of work.
regardless what make of cylinder is on it, it's the porting that will dictate the rpm and its me that decides on the porting, though i won't be going mad with the files but i am looking for a sporty engine

[jmkjr72]

yeah the exhaust needs a lot of work on them its way undersized for a higher reving engine
at least when it comes to the hm bores

[stepthrutuner]

For the 12g range I would think a 21-24mm carb would be more appropriate. Cyl. timings will necessarily be in the area of high 190s exh/mid 130s xfer. Also I suggest going more for a cylinder compression in the 160-180 psi range regardless of the squish for that a/c job. Your 4t sounds really impressive.

[vvtr]

Dec 31, 2011 11:02:59 GMT -5 stepthrutuner said:

Your 4t sounds really impressive.

lol yeh... well it was til it failed!

the 1000 miler was a charity run visiting a load of uk racetracks, 12 riders on various peds from an 80s honda vision to a few pimp sr's
one tgb seized within 30 miles, a chopped baotian had the genny fail but as resident spannerman we got them running - the tbg was completely rebuilt overnight by the lad's dad.

one of the apes had a very annoying misfire which turned out to be the wrong reach plug lol!
the day before we set off he'd managed to fit a new piston with the arrow pointing upwards and suceeded in smashing the ends off the rings!!

then another tgb had seal failure but limped to the next stage for a refit... !

mine... ran brilliant and was setting the pace until i fuelled up just before mallory park... when i went to restart it it just span up.. i popped the cvt cover off to find the gear had milled a lovely groove in the splines so it got packed in the fail van til the next stop where i borrowed a mig and buzzed the gear onto the kickstart ratchet to give another 8mm of spline.

set off again and had great fun passing the aprillias and knocking their mirrors lol until i filled up again just outside brands hatch and it totally refused to start.

it had been losing power progressively over the last 50 mile or so but the plan was to strip it at the campsite and give it a refresh.
i spent 2 days on it and regardless what i did i could not get it to start.
tried 3 carbs, bypassed the vacuum tap, stripped the top end completely, changed al the gaskets, even took the valves out...
after trying to jump start it for over an hour the primary coils gave in... well, one of them, so i managed to pick the windings and get it to spark but it still wouldnt go.
i ended up using it for spares to fix 2 other peds.

on the saturday between us we rebuilt 4 scooters lol, 2 complete engines, then got very drunk!

the ride home was 14hrs in the saddle lol.

for 2012 we're riding through europe to the gp in mugello....
if anyone fancies it, have a look at our webby www.beastrun.com for more info.

some of the riders from this year's run:

for the 2012 euro run im hoping to have the pug running sweet & yes, i'll be taking plenty of spares lol! ;D

regarding the can thats on the pug atm... yes the header looks a little restrictive to me too... ive got a few bits n bobs lying around in the garage but i'll probably end up fabbing one up from scratch before im happy with it!

i just put it all back together to give it run with the higher compression and lighter rollers but can i find my keys anywhere???

[vvtr]

found my keys... in my boots lol!

took it for a quick spin with 1mm (ish) off the head...
runs a lot better.. in fact it runs better with the spark plug in tight lol!
but looking at it closer, first thing i noticed is a lot of bolts & screws missing and damage to the cooling cover..
the stage 6 reed block is a piss poor fit to the casing and there are so many sharp ill-fiting angles.
the piston stops 1.5mm short of the top of the cylinder which doesnt help the squish
there is no easy solution... it has to come out for a proper job.

didnt bother marking up the ports as i couldnt see properly - i'll leave it until the motor is out & on the bench in proper light, then get the dremel out
tbh i'd rather strip it anyway seeing as i didnt build it...

[aeroxbud]

Looks like you have your hands full for the new year. I have seen so many speedys with evo body work, i think the camo might grow on you after a while. Perhaps its last owner was doing those jewellery jobs and it was camo so he could dump in in a field to lose the police lol

[vvtr]

oh yesss! my new carb arrived today



just to compare... on the left is the 19mm adpter from the stage 6 induction kit thats currently on it


should be fun trying to jet this one properly lol :s

[vvtr]

after some thought ive made a decision....

ive done this before with good results so fk it im going to go for it.
as the cylinder im using is cast iron so it has no liner... i can afford to bore it out a bit further.
currently it is a 67.66cc polini corsa (?) big bore kit.
they dont do anything bigger without major mods including different crank, longer conrod for longer stroke and lots of milling to the crankcases.

yeh right

on my old suzi x1 i posted earlier about wrecking the cylinder then using a 49mm std piston off a suzuki fr80 which has the same size (12mm) gudgeon pin and same distance from pin to crown.
it meant boring my old cylinder out quite a lot but this doesnt really matter on a cast barrel apart from it makes the ports shallower (particularly the boost ports) and loses the chamfer, but the main thing is the skirt area under the piston, (which is not really doing anything apart from guiding the piston on its downstroke) is made thinner...

it was still ok & went like stink, but i had to drill the boost ports deeper (before i bored it out) and cut a bit off the new piston skirt as it was quite a bit longer than the original one etc etc...

anyway, ive decided i want more than 67cc on my scooter, without doing the other machining mods... and i want a massively oversquare bore/stroke for high rpm, so i plan on doing the same thing as before... sort of.

so, looking around, and knowing the dimensions of the suzuki piston will match the critical dimensions of the pug piston, i found these....
tbh i was really surprised you can still get these as the bike they're off is like 30 years old!!!

motorcycleproducts.co.uk/catalogue/piston-kit-suzuki-fr80-197587-250mm-p-133022.html
that's a +2.5mm fr80 piston, 51.50mm which means i will have to bore the cylinder a further 4.5mm but will make it 81.24cc

that extra 14cc is a world of difference lol.... the difference again from going from a 50 to a 65cc big bore kit, near enough.

i got my verniers out and had a measure...
4.5mm diameter is only 2.25mm off the radius, so i would only be reducing the cylinder walls by 2.25mm.

pffft.

then i found this....
motorcycleproducts.co.uk/catalogue/piston-kit-suzuki-fr80-197587-400mm-p-133023.html

MWAHAHAAHAHHhaaaaaaarrrrr

+4.00mm oversize fr80 piston = 53mm bore, which would mean opening my 47mm cylinder out another 6mm.
again, halving this to 3.0mm means there is still plenty of meat left in the cylinder but it increases the capacity to 86.04cc

anyway,guess what i just ordered lol


this is just a simulation & estimation using the software i posted earlier, but you get the idea...

i've limited this to power output with my new 26mm carb... really dont want to go any bigger or i'll be tanking up every 10 miles lol!

first - the 51.5mm 81.24cc mod - peak power 24.7bhp @ 11,356rpm
but that orange line is where i would get ring flutter @ 11.000rpm.


compared to the 53.0mm 86.04cc mod - peak power 25.4bhp @ 11,069rpm, just above the ring flutter speed of 11k.

as you can see, there isn't a great deal of difference in raw HP with the extra 5cc, but maybe a little more torque?

what the bigger piston does do is make it rev a little lower, which would probably be safer in terms of ring flutter (you dont want a ring breaking at 80mph on a ped lol) and also the 'mean piston speed' is lower in the number of feet per minute the piston travels, so possibly longer piston & ring life.

another difference is in the porting.... for optimum power / piston wear, at the moment the exhaust port is cut to 32mm, which is 66% of the bore size, but with the larger bores, i could possibly increase the width of the port further & wring a bit more power out of it lol.

but thinking about it...as there is not a lot of difference in power, less than 1hp, between the 2 oversize pistons, i think i'll change my order and go for the smaller 51.5mm bore so if i end up wrecking it i can still rebore it and go larger.... that's me being sensible, which is rare.

opinions are welcome. but i won't listen lol. i never do!

[90GTVert]

Should be an interesting endeavor. Keep us up to date on it.

I leave the BMEP all the way down when I use that prog. Seems like I get more reasonable estimates. Maybe all of my motors just suck though.

[vvtr]

yeh i know what you mean... using the 'tools' tab, it calculated bmep at 9.95, which is probably not far off....
the previousl owner got the fuelling set up on a dyno (with the 19mm carb) and was told it was producing 16hp....
now personally i think it's more like 8-9 lol which incidentally is what this app calculated it at with the porting & bore as-is, with a 19mm carb, peaking at 8500.

the main point of the simulation was to see whether it's worth boring another .75mm off the barrel to fit the 53mm piston, and what gains it'd give over the 51.5mm kit.
and also what the rpm difference would be with the oversquare set-up.
the ring flutter speed is alarming though... especially as the scooter has no tacho yet.... maybe it would be worth limiting the rpm with the zorst or cdi?

in real terms i'd like to see 9-10,000rpm and a nice 12-15hp with a good spread of power.
that's about what you can expect from an old stock japanese 80cc aircooled mx bike so it's not unrealistic, plus if you look at some of the dyno runs on youtube from the high end scoots from polini etc, theyre topping 30hp but need a rebuild every 8hrs running!!!

before i do this mod i want to put it back together with the 47mm piston, to see what difference the new porting, head mods & port matching has made (if any!)

as it is the ped goes quite well with the 47mm kit, accelerates ok up to 50mph with best ive seen on 'track my ride' at 63mph
i'd like it to rev a little higher but with 12" wheels im not really over concerned about going even faster lol, lets see what happens, and how long the crank lasts!!!

[190mech]

That must be a thick cylinder barrel!If you can punch it that much,be sure to widen the Ex port to 65% of the bore(if it doesnt get into the hold down studs..)

[vvtr]

yeh lol!!! it's already 47mm... the piston ive just ordered is 51mm which is +2.0mm oversize & will take it to 79.9cc.
thats 4mm bigger diameter than the current piston, so ill be reducing the wall thickness by 2mm, which isnt going to dent it tbh!! plenty of room left!

yeh, i'll see how i go with the port... will probably taper it out but it wont be by much - there is 9mm between the exhaust & transfer ports so i'll have to see where the ring stop is before i start grinding!

piston is on its way
works out if i keep the bmep at 7bar it should produce about 13hp which will be just right