Cagiva Planet 125cc 1999 ....Possible carb issues

[simon2012uk]

Hi All

Looking for some help with my Cagiva Planet.

Fancied some 2 stroke fun so picked up this bike just over a month ago.
Apparently all it needed was a new stator as the battery wasn't charging whilst riding.
As always..this wasn't the case

The bike starts ok and runs ok...but as soon as i drop it into gear and try to pull away it instantly bogs down and dies.

If i rev it very high then it will pull away and goes like a little rocket.
Its been in a motorcycle garage for the past month but the mechanic has literally given up on it lol.

Compression was low so its had a new top end, cylinder, piston, rings, con rod and bearings etc. Compression now sorted, it was only a naff ring but replaced the lot.
Also had new powervalve, servo and control box.
New rectifier.
As far as i can tell all electrics now good.

Had the carb off numerous times, all been cleaned numerous times and air blown with compressed air, checked to make sure all jets are the correct size 65,65 and 120.
However it still does the same bog and die when dropped into gear.

Doesnt seem to want to idle either and will just cut out after a few mins warming up. It does seem to run very slightly better on half choke hence assuming that my probz are carb related.

Really lost now aha as was my mechanic.
Any ideas guy/gals?

[Paulf]

Rev it high to pull away....it is dependent on what you call high I was brought up on 2 stroke my father who owned a vellocet venom called my bike a buzzing bee. Brand new 125 cc it needed revs to get away and was high revving 12000 revs redline. It would stall at 4 stroke rev pull off or bog down until it buzzed. But it used to idle ok all day long if I let it. So yes you may have a problem with your idle mixture screw.

[jaffa90]

Did you remove the jets and see through them?

[simon2012uk]

[Paulf]

Any air leaks it sounds like a Lean mix too much air or not enough fuel

[simon2012uk]

[P.]

How many revs are you pulling away with...

[simon2012uk]

[P.]

Have you checked the spark plug and replaced it at least. Make sure its running the right one for the engine.

My RS had to be really revved to pull away, more than I'd want.

[UnknownStuntm...]

It's not the clutch dragging is it? Sometimes when I've not had mine running (like, actually riding it somewhere) for some time, it doesn't like being knocked into gear. I put it down to syrup in the gearbox, as a few miles seem to sort it out for a while.

[neptune8]

Possibly worn crankshaft oil seals.
____________________
Enjoy yourself, its later than you think

[simon2012uk]

[simon2012uk]

[P.]

Buying a new carb is a rash decision, its not likely to be that if its clean and not leaking. Have you done basics like a compression test and seen when it was rebuilt last. If its been standing, its probably got shit seals, any movement on them now will make it worse and they'll fail.

In short, its probably due a rebuild, I'd rather spend a few hundred on that than go down the carb route. Costings etc.

[simon2012uk]

[stevo as b4]

It's pretty poor advice to say scream it to 12000rpm to pull away without stalling. In fact only a twat would not realise that no manufacturer would make a bike like this and think it acceptable to ride.

Adding to that it's alot lower geared than say a Mito/RS etc. Also having a fully working set up exhaust valve should mean it has a reasonable midrange for two stroke 125.

Certainly as an example on the dyno my KMX 125 at WOT is making 12bhp at just over 6500rpm, and nearly 10bhp at 6000.

If it's Carburation that's the issue, then it sounds too lean low down, but then too rich on the pilot jet can cause no idle too.

Last resort would be to put it on a dyno and see what the fueling is doing as you open the throttle under load to see which way you need to jet to get it right.

[simon2012uk]

[Paulf]

Sorry I was not suggesting rev it to 12000. Apologies but re reading it may seem that's what I was saying. Rev at take slightly higher than a 4 stroke approximately2000-3000 max.
____________________
Past bikes simsom mofa 1s, suzuki hustler 250 (£35 in 1973), suzuki ts125k, mz150, yamaha yb 100, honda pc50, honda vision 50, all 2 stroke - then cars - honda pcx 125 (sold) own honda fes 125 and Mrs 125 spares or repairs. Started 1972 all accidents walked away no insurAnce claims

[stevo as b4]

I think it didn't really need a tacho, with the way it's set up and geared, the same as trail bikes don't really need a tacho either. You soon get to feel where a two stroke bike likes to be in the Rev range and just keep your left foot moving accordingly.

On a highly tuned Mito or similar, then yeah the tacho is useful for getting every last bit of performance out of it or on track etc. But then all the 125 supermoto bikes those crazy Italians ride don't have tacho's, and some of them are full MX spec 36-40bhp machines, and they manage just fine as well as riding them like loonies everywhere.

I'll probably take the tacho and all instruments off my old KMX 200 when I build it back up, as I want a light off roader that I can play wannabe trials bike with.

[stirlinggaz]

[dansp1]

Has the power valve been set up correctly?
try disconnecting it to make sure it is fully shut and see if that turns it into a torque monster

[Kickstart]

[redeem ouzzer]