Crankshaft seals...

spoggster · Post by **spoggster** » Tue May 26, 2009 2:35 pm

Hi,

Got me a kr1 which i bought as a non runner for a project. The non running was rectified by a top end overhaul and eventually,new carbs. Anyway,i was forced to leave it a while(even tried getting rid) but recently was hit with a sudden attack of enthusiasm and spare time!

The engine,whilst seeming to run ok(though i couldnt check that on the road due not havin MOT etc) started blowing smoke through the left exhaust. I figured that the crankshaft oil seals were on the way out. Deep joy! So what im wondering is,can you tell just by lookin at the seals whether they goosed or not? I'd hate to blow stacks of dosh sending the crankshaft away for no reason...

Also,whilst strippin the bike down(its completely in bits now with frame and swingarm at the sandblasters) i noticed that there was oil in the airbox. Ive never seen that before,could the two be related somehow?

Thanks in advance....

the-elf · Post by **the-elf** » Tue May 26, 2009 6:02 pm

Oil in the airbox could be blow back from the carbs so as long as its two stroke oil its fine.

spoggster · Post by **spoggster** » Wed May 27, 2009 10:30 am

Im pretty sure its gearbox oil....

Im guessing that doesnt bode well

the-elf · Post by **the-elf** » Wed May 27, 2009 10:41 am

I've not seen gearbox oil get that far back in the system before ( the reeds should stop it for one) its generally sucked into the cylinders past the leaking seal and burnt or the oil is blown though the gearbox and out the overflow during the piston down stroke (generally its a mixture of the two).

If your unsure of the condition of the crank, then IMHO its best to get new seals fitted (about £50 last time I checked) by someone like BDK, who can also inspect the various parts, bearings etc. and can advise on what is needed to restore the crank back to original condition. Depending on how bad the crank is expect to pay anything from £50 to £300. They will ring you with a quote before proceding though. Its worth it for peace of mind, For an extra £100 you can fit a new top end while your at it as well.

spoggster · Post by **spoggster** » Wed May 27, 2009 5:12 pm

Is a dodgy seal not usualy associated with running rough?

Either way,Im gona whip that bad boy out tomorro and get it sent off for some new seals!

Cheers!

the-elf · Post by **the-elf** » Wed May 27, 2009 5:53 pm

spoggster wrote:Is a dodgy seal not usualy associated with running rough?

Yes, sympotms can vary though, mainly its a loss of gearbox oil (being burnt or blown out of the air vent), and/or running lean (LHS outer seal seals to atmoshpere and not the gearbox). Also a loss of power, and generally poor running can also result.

Generally rough running, can be caused by either fuelling problems or electrical gremlins.

spoggster · Post by **spoggster** » Thu May 28, 2009 9:14 pm

Crankshaft on its way to BDK.....

Sheik Yerbouti · Post by **Sheik Yerbouti** » Fri May 29, 2009 11:03 am

not sure what kind of filter you're running there, but normally I oil air filters with gear oil. So seeing it in the airbox is not such bad thing.

spoggster · Post by **spoggster** » Fri May 29, 2009 6:50 pm

Now you mention it,i did get a new air filter and as per instructions i soaked it in oil and squeezed out the excess. That probably does explain the oil in the airbox! D'oh

Incidentally,when i got the crankshaft out,the oil seals were clearly buggered!

Once again,thanks for the input folks