Cagiva supercity problems please help

[rich16]

Hi all I bought a 1994 supercity off ebay for fairly cheap yesterday. I spent the whole day along with my old man and brother stripping and rebuilding everything but the motor. The motor had good compression so we left that. It was running like a bit of a dog so we wanted to check as much as we could.

It had NO airfilter
Carb was dirty (28mm carb)
reeds were good so cleaned and re fitted
new plug (br9es)
NO fuel filters in tank, they had snapped off
changed all fuses.
No breather pipes on carb so fitted decent second hand ones
Removed cleaned and replaced slider (throttle was stiff)

It started up great, sounded much better ticking over. It revved nice too. But, when riding its extremly slow. There is very little pull at all. At around 6-7000 rpm the powervalve will open which only slightly increases speed. Then as you reach the redline (it wont actually get as far as redlining), at around 8500 rpm it holds back and makes a choking noise, literaly like its coffing. It sort of jumps like its been starved if that makes sense??

Taken it on a duel carrigeway for 10 mins seeing if it maybe just needed a bit of a run, but it was no better. Also worth noting that there is a strange, almost like metal rubbing at higher revs. Like a fairly high pitched squeel.

one more thing, when ticking over on the stand, if u tilt the bike towards yourself then sit it back up again, the bike revs by its self to around 3500 rpm for about 20 seconds then goes back to normal idle speed

one last thing, the powervalve does click twice when you turn ignition on

I have a 34mm carb which im tempted to fit

piston is single ring i noticed, from looking through exhaust exit hole. also from this side and reed side the piston looked in good condition

Im at a loss what to do, please can someone help, i have a decent but limited knowledge on 2 strokes and mechanics in general and I really dont want send this off to the bike shop, mainly because of cost but also because of pride!!

thanks, andy

[N cee thirty]

well the pv noise at ignition should be it going back to normal for starting

if it has one ring than i'd say get a new piston with at least 2,single rings are usually for race outfits and don't last long

squeeling usually means bearings,all wheel bearings good ?

i don't know much, but thats abit of help for you
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[rich16]

thanks for your help, yeah wheel bearings are good.

Im lucky in the way my brother has a supercity too, 1996 model and between us we have a complete supercity minus a frame in boxes. So I managed to get a lot of spare parts. I have a spare engine which needs a new piston and a clean up, cranks good, piston was a twin ring too so may think of fitting this?

also fitting the 34mm carb, does anyone know standard jet settings/float height??

thanks again

[evoboy]

Just rebuild the top end on it.

If the bore looks scored, get it rebored and honed. Then get an oversize piston kit to match the bore, new top end gasket kit and a new small end bearing.

It doesnt cost much to buy all that and its not all that difficult to do the work.

If i buy a bike thats not been in proper working order, ill 9/10 rebuild the top end on a 2stroke motor, reguardless of if its 'been done 100mile ago' or not.

Its one less thing to worry about.
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[Kickstart]

[rich16]

thanks for the help guys. Going to have a go at the powervalve today but its a whore to get to, looks like I might have to actually remove the engine to get enough room to pull it out the cylinder. Also got a 34mm carb here I intend on fitting but theres a small circlip missing off the main jet, so need to try and track one of these down?

[stirlinggaz]

hi,
i wouldnt recommend fitting the bigger carb until you have identified the problem.
firstly, i'd get a copy of the wsm or if there isnt one specifically for the supercity, get a mito version, for the engine section, as it contains some usefull stuff about the pv & other things.
is the pv working as it should? does it re-set itself when you turn on the ignition? (if you look at either of the pulley wheels, you should see it turn 1 way & then the other.)
have you tested compression? clean fresh fuel? fully charged up battery? (this DOES make a difference, especially to the pv)
& as Keith says, the pv lade clearance/distance is vital. (or it collides with the piston)
have you tried taking the plade out & cleaning it? they get carbonned up quite quickly, which makes them stick.
try cleaning the blade with a soft wire brush & then polishing with autosol.
if you do decide to go for the 34mm, it should be the ES version rather than the LD version that is usually fitted to the aprilia rs & others.
the carb settings are as follows :
Main jet : 152
Starter jet : 60
Low speed jet: 40
Throttle piston : 50
Needle K43, clip on 1st position (though i hear a few people have it on the 2nd)
ATOMISER : 266 DQ (which is the important bit thats different on the LD version)
Float n^2 3.5g
air/mixture screw : 1 & 1/2 turns out.
oh, & fit a decent spark plug! (iirc, it should be B95EGV, if its the same as the mito)
good luck!
cheers,
GAZ
ps : you can get a replacement needle clip here https://www.dellorto.co.uk/merchandise/products.asp?CategoryID=2&PartsectionID=33

[rich16]

wow thanks Gaz for all that info, very kind of you. The poweralve does open and close properly when u turn ignition on but I believe it will need cleaning. It had fresh fuel as last sunday I went to clean fuel tap and filters and the filters wasnt there! Fortunatly we had a spare (got a complete spare bike minus frame)

I havent charged up battery! Never even crossed my mind as it starts up fine. Also couldnt get my tester on it as there isnt much clearence from the top of the head but the compression felt strong using my thumb. Today my old man has found a different tester that should fit.

Thanks again, hopefully today we will crack it

Andy

[rich16]

Hi everyone, if anyones interested, spent the whole day on bike today. Main thing I done in respect to the running problems is completly remove the powervalve and clean/rebuild. It was minging, very clogged up. After this it operated much smoother. Also ive had to remove the air filter, the foam was starting to break up. Anyone know where I can get a new one? I believe the mito one is different?

also fully recharged battery, as someone on another forum said this might be worth doing.

before the bike, at around 5500 - 6500 rpm, seemed to back off and 'choke' and refuse to rev anymore. Now it was much much better, but does the same at 9000 rpm. A couple of times I got it up to 10000 then it would back off and slow down to 9000. Also, it revs all by its self when sat still in neutral. The idle screw seems to make no difference?

Also I got and fitted the correct plug. One more fault which I didnt get chance to have a go at was the fuel tap wont turn off.

Anymore ideas or suggestions would be great, thanks very much

Andy

[Kickstart]

Hi

One point is to make sure you reset the power valve clearance after taking it out and cleaning it. The clearance is small enough that reusing the gasket compresses it enough to possibly cause allow the piston and power valve to touch.

All the best

Keith
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