smc buzz 50 gearbox removal help

[burge]

Hi guys just wondering if anyone of you has removed gearbox from engine on one of these quads as my daughters appears to have blown a seal/gasket as engine is pressurising gearbox and engine also sucking g/box oil , I,m currently away from home and just looking for any tips before I get home and strip it down cheers

[FLASHLIGHTBOY]

Hello.... you can buy a whole motor ( if it is a 50 cc ) VERY CHEAP... let me know.. as for the parts to buy & repair it.. $$$ for what it is worth.. get a new one .. and then learn & play with the old one for a winter project

[Weldangrind]

Please tell us more.

Are you saying that an excessive amount of crankcase pressure has popped a seal out or just made it leak? Inspect the breather hose that exits the top of the engine; it should have a smooth path towards the back of the engine, and then point at the ground. If it is pinched or plugged, it will allow pressure to build.

When you say it is sucking gearbox oil, does that mean blue smoke out of the muffler? More info about the symptoms you see would be helpful.

[burge]

G,day weld and guys , have had the buzz since new 10 years old now but still like new. So I know its history , youngest daughter was riding it when I was home and it started to blow puffs of blue smoke and down low in revs seemed to be fouling up plus the smell was nothing like the normal 2 stroke smell , got it home and chocked up rear axle and put some revs on was fouling up down low and almost dieing high up in the revs , was very fumey ,oil was spitting out the exhaust onto the floor plus noticed underneath a decent pool of oil from the breather so I am suspecting a crank seal but can't understand why it was dieing high up in the revs , it was like someone was shutting the fuel off ,unless the plug was fouling up with excess oil , what do you think , I,ve googled and can't seem to find anyone who has split one of these apart' cheers

[FLASHLIGHTBOY]

so this is a 2 stroke?? can you send a pic?

[burge]

If u look at my other thread on this page ( ATV identification please) its the red one in the pictures cheers

[humanbeing]

Ref to Honda PA50 materials. The engine is based on it http://www.motorfans.com.cn/bbs/view...originator=yes

[Weldangrind]

Does the PA50 use a reed valve?

[burge]

Thanks for the reply guys ,not sure if the buzz has a reed valve weld , but I can't remember seeing one when I pulled the carb and removed the restricted a few years ago

[Weldangrind]

Does the gearbox use a dipstick, or do you simply pour a measured amount of oil in?

[burge]

Yes gearbox has a dipstick attached to the oil filler , I reckon I lost about 100 mil out of the breather when I ran it in the shed

[Weldangrind]

Then I'm with you on the crank seal. I only have experience splitting the cases on old Suzuki TS two-smokes, and in that case it's the right side seal that fails. The left side seal only keeps compression inside, because the stator side is dry.

All that said, I'm surprised that the engine even has gearbox oil. Most of the two-smoke scooter / moped engines I've seen have only mixed fuel, with no crankcase oil at all (like the later model Aprilia).

Have you found a parts diagram?

[burge]

No weld I don't seem to be able to find a decent diagram

[Weldangrind]

HB, can you point to a decent shop manual for the PA50?

[burge]

Cheers weld ,hopefully HB will have something ,cause I can find nothing ,
I have no hesitations pulling it apart ,but some prior advice is always good to point out those hidden bolts or studs