Cub 90 head work

Bought tools, this’ll help with foul-strokes.

speaking of the buggers, dissembled the c70 head.

Lovely isn’t it?

ports not touch much, i wonldn’t have shaped it like that

scrub scrub

polish polish, why? bored i suppose, now i have a head that could be used in a pinch.

removed the flywheel and future supercharge bracket, it’s possible my previous issues might be coil related, as the coils were off a lifan, and this engine is a zongshen.

borrowed the c70 IRK

all stop, have to gather some tools and some courage to tap these. please don’t hole the cases!

can you tell what my next bike maybe?

i consider this head a minor upgrade, the stock head and very offset plug and bowl.

tired of four stokes, so back to the rg125! deep breath, measure once and cut!

Repeat after me, angle grinder is a precision tool.

Looks good from that angle.

Fit’s here too.

bit wide here, but nothing is perfect.

Rust is lighter than carbon fiber.

Prep? nope. Race? yep. Boom? YEP!

Got a three hour enduro race on at the local go-kart track, watergrasshill nifty fifty 2019  https://www.adventurepark.ie/

So a working bike is necessary! Need this to stop leaking, first attempt with carpet tak failed to no surprise.

JB-weld that fecker.

Special sauce also known as dihydrogen-monoxide, very important for re-magnetizing over heated inner rotor kits.

spent far too long making the side cover fit, and then ditched it in the end.

Ready to go? super light weight carbon end can fell off, so a rg125f end can was pressed into service. it was very very heavy.

Had a great race, all 27 minutes of it!

Some might say that taking on a 3 hour endurance race was too much for my old ass, and my only graceful way out was to select first while flat out in second at 10Krpm. Four times.

i think i just hadn’t got used to the new gear change setup

Took engine apart in the paddock, always wanted prove it was a 86cc in front of the other racers

Lovely destruction.

From last to sixth in the first lap, then i led for six laps before blowing up. proved i’m the best, just didn’t have to go the whole way to prove it.

Fastest laptime of the honda engines. Funkie Junkies have a YX of unknown CC with some honda cases slapped on the outside. Chicken Chasers were more open about it they have a YX120.

A Fish Called Honda (thats me!) is/was running an 86cc, next was Team Cider with a 107cc, then Classic bikes with their 114cc. All honda based, i’m the best

I’m stole the trophy because i’m also the sneakiest.

ok when i say stole i really mean traded my DNF prize of a Rolo easter egg. nice.

Divorce your bike?!

More throttle housing fixing, the cheapo epoxy didn’t set, probably not mixed right, so scrapped it all off and put some honest to god JBweld on it.

Then test painted it with all the colours i had.

the only good bit of paint was the cyan one, the red reacted and the yellow had a clogged nozzle, whatever, the guys in front will know i’m coming.

Investigating more front clonks, turned out this bush was melted from way back in 2013 when the bike was burnt out. Pic doesn’t show it great, but the metal sleeve is quite offset.

Where’d the rest of the packing go?

didn’t have any replacement bushings about the place.

So, a bit of floor mat (as seen in the background) shoved in under the sleeve and trim off the excess burnt bit’s, it’ll be grand.

could not get the other shock off, the bottom arm bolt was well stuck in there, no unnecessary movement of the shock so i left it..

In some major sad news the cbr6 is off back to the pile from which it came. 12 years and 10 months of service, touring, track days, pizza delivery, daily commute. I think the rear wheel is the only original part now.

It could be fixed again, but after near 13 years of continuous use it has to die now, you gotta move on. ‘still cried tho.

and it was fecking hard to look back over all the pictures, mostly of the cbr smashed up.

what to replace it with eh?

Nifty fifty 2019 went ahead without me, sick wife meant no fun for me, however it was hilarious hearing all about how the pro racers did in my absence.

dead last, crashed twice and jumped the start. first ever restart in nifty fifty history afaik.

also they stopped racing because it would not go forward. not sure how they could not see that the front sprocket fell off…

Anyway, my dads new engine worked well so the old stock 70 is now surplus, mine now!

Poor thing.

88cc head, never got it running right for the race and took it all out for 86cc the day before the race.

c70 head, same head e22 as on my 90, except for all the missing chunks, and the sealing surface. this is after i abused the fuck out of it with a plank of wood and some sandpaper.

note the exhaust valve, just a bit burned!

easy repairs first for the race bike, throttle housing snapped, looking closely it was cracked a long time ago and only let go now.

also found another old crack, load of epoxy glue lathered on and it’ll be grand

Next thing is the gear change, what i had worked great for the manual 4 speed, but the auto clutch in the three speed is quite banjaxxed, and needs a bit of force to change gear.

so the lever could be a little longer, easily done. but the rod also needed to be longer, not having the right tools i done a bang up good job with stuff i found on the floor, quite literally.

Slicks for our not very good pitbike we intend to race against some quite good pitbikes..  more on that later.

24mm cvk gy6 carb choke delete

So the new carb for the 88cc racer looks great but i don’t have a 12v supply to power the fuel enrichment circuit or choke. because race bike.

off it comes then! easy to bolt off, without power the needle is in the open position, you can see it here in the middle

pre cracked from the factory! probably happened on delivery, would be mad if i ever intended to use it.

the insides, it can be unscrewed, but it is glued in place so the housing will crack.

took the needle and it’s barrel, place it fully seated in the metal housing, covered the the holes on the side with some tape in case of leaks and globed in some two-part epoxy

Waiting for that to harden up now before i bolt it on and test.

88cc head porting part deux

So to start with this head is off a 107cc, it has a large angled squish band and more meat and length to the inlet, it also uses the longer cam here:

http://dratv.com/6licamwiaude.html

pic of the stock intake, horrible casting, spring seat protrudes really far into the throat. pretty much the same as a stock honda 90 head.

Valve seats first, much sand paper and course lapping compound. crap job, so i went back to taking lumps out of the intake.

raised the port roof, smoothed down the spring seat hump

i say smoothed…

back to vavles seats

after many many little bits of sandpaper and some help from a drill to spin the valve, the seats are good enough.

Porting is complete, spent more time opening the valve seat throats, they did not match the head very well at all, also widened the port where the stem sits, i could do better but i do i need to spend that much time and foul-stroke?

24mm carb fitted, note how close the bowl is to the head, i think it would not fit a stock 90 head, but it fits this one so i’m all ready!

Race bike needs both brakes, i don’t have a two foot long foot so to match my rear sets i gotta make a brake pedal. and i don’t have a lotta spare metal lying around so the original super tucked in pedal will have to be sacrificed.

scraps of metal found and half the day spent poking at stuff

original pin chopped down and welded to frame as pivot.

Discovers my nice inverter arc welder is actually a piece of shit. i thought it was damp rods, but no, it’s just shit. super cheap tiny AC buzz box welder worked flawlessly.

Nope! pushing the rod is not going to work, feck. problem for the next day.

you know them niggly problems that take years off your life? this wasn’t one thank feck it, converted the throttle cable from a tiny nib thats supposed to act on the carb slide, to a…

..Large round nipple, yeah suck it SEO.

 

things to do before race day on the 23rd:

lots, not gonna lie and attempt to make a list, i just have lots to do and tools to buy.

88cc head porting

Race is soon, need faster engine, orders parts asap!

24mm cvk carb and inlet manifold, a second hand 1980’s honda rs250 foot peg, rasps for the dremmel, better quality air filter (old one is barely hanging in there) and a 38 and 39 tooth rear sprocket.

Engine out! real pleased at how easy that has become.

head off, inspection, and i’m a happy bunny!

valves didn’t hit the piston and the piston didn’t hit the head.

chamber is really black due to me running so rich all day on the new years run, still no real damage.

valve seats are still fucked, who’s surprised?

got all prepped to flow things and i realise.. that i put the collet and nut in a safe place to avoid the smallie from taking it off (as he would occasionally run about the place with it) and choking on it. A really really safe place.

I did in the mean time get a loan of a dremmel and made a start on flowing the head, piccies next time!

cub90 test

Can you tell what it is yet?

Yep, stop ya stones getting in ya engine!

All set for the new years day test run

..and i ran out of fuel, twice, appears that setting the L needle really far out wasn’t a good idea, who’d have thunk it?

anyway after farting about all day, i set the L needle where it should be and it still didn’t run great, in 1-3 it would pull like it had a power band, but falls flat in fourth. got better as the day wore on, keep forgetting there is plenty of running still to do on this cylinder piston and rings.

couple of backfires/pops here and there too, indicating what i already knew, the valve seats needs fixing.

regarding the lack of up top power, the head isn’t ported so with that done it may help alot, or it could just plainly be the gearing, 24mm CVK carb on the way in case we need more breathing. it’s also much slower at 81kmh rather that 87kmh

Vibration! much reduced which is really a very handy thing for an endurance racer.

Saw this on the run, hydraulic drum brake mod,

interesting!

rg125 on hold

I like cooking alot, but my knifes selection left alot to be desired, so i made a better one!

polished up nicely with some 1200 grit, already feel the urge to get a 2000 whetstone from amazon.

Rg125 raditor, considering my options, do really want an upgrade.

Everything stops when the music isn’t right, poked the wires and we were back on track.

Beat that straight

this bit needed more finesse, less hammer

a selection of tidied painted and bought bits

Helper number one fitted it all up!

And now the rg is on hold because this cub90 is now in the shed, gotta run it in on the new years day run and lots of other bits need completing before race day.

the netbook, the 88cc and the rg125

So first a little update on the netbook situation, bought a dell 2120, super cheapo, didn’t realize they came in single core models..

upgrade time!

Whole motherboard upgrade,

*eyes wwan port* pci-e ssd?

failing purple msi wind gave up its ram and ssd to my new chunk top.

Anyways back to the fun stuff, clutch carb, and rev counter installed.

They don’t work, but they are installed..

Check out the rubbing from the carbon fiber pipe on the shock 🙂

new old pipe is the best pipe ever.

springs installed to keep choke from closing accidentally, and the throttle from accidentally staying open 😀

Ford bits installed!

These will be where i install the rear sets, next week probably, no mig wire!

Pump and switches for runner 180 water pump mod.

Onto the Rg125, gs500 37mm forks fitted up quite nicely,they are a ton lighter and 0.59kg/mm springs seem to suit it

lock stops, steering lock, everything perfect.

Top yoke is ugly, but what are you gonna do?

Whole thing is sitting a bit high, we’ll fix that.

gs500 wheel is drop in replacement, if you needed to keep the stock gsxr forks.

Disc is a 320mm vs 310 and the speedo drive is a smaller outer diameter

Replaced the lower bearings with ebay specials, no rubber seal, unlikely to do so many miles i’ll need that. Dogbones need extending to lower the back about 3cm according to my calculations

extended 6mm, or at least i planned to, actually got 5mm, best i could do with a angle grinder and a stick welder.

Dropped fork 50mm, threw on the clipons i bought, i bought 38mm clipons cause i’m an idiot, rushed to buy them, nothing an angle grinder and some filing couldn’t fix. I like the radial master cylinder.

Onto some plastics mock up.

Fitting the under tray and some of the electrical loom

Probably gonna have to tidy that, quite heavy too!

Big gaps, need to move tail piece forward 30mm

2T oil tank i don’t think will fit under the plastics, thinking of making a tank and putting where the batter lived.

Moved forward here,

Much tidier, gotta weld it up next time i’m out there.

And also my cbr was sick!, ran rough as feck, very close to happily dumping it in the spares pile (already on DoneDeal looking at other bikes) but then we found the blanking plug for number three vacuum port, fallen off an sitting in the vee behind the cylinders… pop’d  it back on and the cbr’s butt was saved again for another day.

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