Ive just done this on my 125. p*** easy! Just hook it out with a flat blade screw driver. Dont go in too deep because there is a bearing behind it! But nice and easy it just flops out.
Cheers mate, managed to do it as you said...leak cured
I need to change the output shaft seal (sits in the gearbox casing and around the shaft which the small sprocket fastens to) but I can't see any way of getting hold of it to remove it...any suggestions?
You may need to completely remove it and clean the backside of the bore best possible with solvent, then after removing the snapring, use air pressure backwards through the pressure hose connection to blow the piston out. Careful to do this against the workbench or something as crap is going to fly everywhere when it moves! Cover with a shop rag or something to catch the fluid and pieces!
Success
Took 80psi air pressure to blow the piston to within 1/8" (3mm) of the circlip then wouldn't budge any further. Finally removed it using a stud extractor!
Piston, seals and spring all in perfect condition. Apparently you can't buy service kits for this particular M/C now so had a guy in the toolroom at work turn me a new nylon insert/bush. Pressed that in, replaced the 'O' ring and re-assembled with the original piston, seal and spring and worked smooth as silk.
Put it back on the bike and force fed fluid from each end to the banjo coupling with a syringe and hey presto, we have a good back brake again with proper lever travel
Usually if you pressurize the system and no fluid is forced back into the reservoir, that's a sign that the piston has not retracted back (or down in this case) to the stop at the circlip, and the bleed hole from the line to the reservoir is not opened (the system is not able to equalize itself).
Generally there are two causes for this (1) the rod at the back of the brake lever is adjusted too far up and/or (2) the piston return spring (in front of the seal) has sacked or broken (usually caused by rust in the system as water collects in the M/C bore or by wear on the sides of the spring, which gradually thins it to the point of breakage). You might want to pull off the rubber boot on the M/C and be sure the piston rod is back against the circlip.
Jon
Mmm, the MC piston only returns to within about 12mm (1/2") of the circlip. Total 'travel' from rest to fully compressed is probably only about 10mm (3/8"). Would appear that the piston is jammed at the top of its bore/stroke. Removed the circlip but can't get anything into the bore to 'grab' the piston to remove it.
put the long piece of silicone pipe from model shop on your syringe put into bottle of fluid and draw syringe and tube full of new brake fluid then connect to bleed nipple on rear caliper open the nipple and back fill the reservoir with the cap off and make sure that you are NOT pressing the brake leaver down, only crack the bleed nipple open 1/4 to 1/2 turn when syringe and pipe empty shut the nipple.
Tried it but the fluid just seems to squeeze out from around the threads on the bleed nipple (1/4 to 1/2 turned out), no fluid is being forced back into the reservoir
Well, got a syringe from the local chemist but damned if I can bleed it . Pressing the pedal gets fluid coming out of the bleed nipple but can't get any decent pressure
Tried bleeding it but from what you're all saying, perhaps a bit more perseverence is needed. Will try it again tomorrow. The fluid level was low which led me to believe there was a leak somewhere, strangely, I couldn't find any signs?
Think my rear brake master cylinder is shot, can't get any pressure to build up, although the pads move very slightly when the brake lever is pressed, the lever 'bottoms out' on the frame.
How much am I looking at for a replacement...or can you get a refurb kit? Where's the best place to source one?
Have you cleaned the carb and checked the pilot jet?
Right, gonna have a go at this tonight. Excuse my ignorance, but which jet is the pilot jet? Downloaded a service manual but the details are vague and nothing has any detailed labelling
Have you cleaned the carb and checked the pilot jet? The knock could just be a lean condition from a blocked or too small of jet. It will also fix your idle problem.
I haven't no but that might be a good suggestion, tried a couple of steep inclines recently and it felt choked up so that might be the culprit
Been out on it a few times now (had it about a month) and I'm not sure if the motor is knocking in some way or it's just a normal noise. It starts and runs OK (but doesn't like ticking over, despite altering that).
What are the classic symptoms of big end/little end bearing wear, how do you identify which it is and how big a job are they to change?
I'm pretty confident at having a go DIY but don't want to do a bottom end strip down if it's only a top end problem.....or should I just leave it until running is affected?
My 9 year old son is able to set off OK but lets the clutch slip from his grasp at the last moment because he can't reach the full travel of the lever.
This is obviously a problem when it comes to covering the clutch lever for slow speed feathering.
I've adjusted the allen screw/lock nut on the inside of the lever together with the sprung screw on the lever body but the bite point doesn't appear to alter significantly. Any suggestions?
Hi, just got hold of an '03 Beta 80 for my son, what a cracking bike
Just a couple of minor niggles:
1) It appears to seep oil from the seal around the output shaft (the one the gearbox sprocket is fixed to). Any ideas how big a job it is to fix and where to get a replacement seal from?
2) One of the fork seals is leaking slightly, how big a job is that to change?
My 9 year old is taking an interest in trials and I'd like to get him started on a reasonably priced, geared bike. Any recommendations would be appreciated.
Beta 80 - Output Shaft Seal
in Beta
Posted
Cheers mate, managed to do it as you said...leak cured