what to do with my bike and its gearbox

[Guest]

before i start id lake to say my bike made of cheese

anyway iv had numerous problems with changing gears on my bike. i have changed some many things now.

it had new clutch friction plates and a new gear shift rod and pins. changed the oil had new chain and sprockets and its still being a pain.

problems i having at the moment are.

when changing gear sometimes the gear lever sticks and wont come back down and then when i try to find the next gear i cant as the lever stuck in the air. it eventually drops and then i can change to the next gear.

Next problem

This mostly happens after iv giving it full throttle when needing to slow down i go down the gears and i hear a loud crunch/breakingclicking sound. loose power engine drops to idle. change down and i hear a big noise like from going from 2nd to 1st 9big clunk and then evreythings ok. its done this 4 times now.

sometimes its a pain to get into the next gear but iv read that you need to give it a lot of force when changing gears.

so apart from maybe change the oil for a more thicker type 10w40 from 10w30 i cant think of anything else to do with it besides stripping the engine down to the gearbox. i know i am going to get comments like pass your test and buy a big bike. as much as i want i cannot do that due to finances and my insurance doesent run out until august.

so something needs to be done as i cannot sell it in this mess when i can have a bigger bike. has anyone got any other ideas before i consider ripping the engine apart ?

just shouldnt happen though a gearbox gone at 11000 miles on a 08 bike so yeah any ideas would be appreciated

thanks

[Guest akey]

What bike mate???????????

The first problem sounds like the selector return spring is shot.

The second problem is difficult to diagnose over the internet mate sorry.

[Guest]

Its a Honda CBR 125R 2008

just looked new spring is only £1.70 just getting to it. do you know where abouts the gear shift drum is ? is it easy to get to or is it complete engine strip ?

to be honest it sounds as there a number of things in the gearbox that could have broke selector forks bent, bearings gone, teeth sheared i guess the only way to find out is to take a look at the gearbox

[RicKsTa]

You must be doing something seriously wrong to shear your teeth, or bearings gone at 11000 miles. Those engines/gearboxes are bulletproof. Try changing the selector return spring as Mark said then report back..

[Guest]

how easy is it to change the selector spring and where abouts is it ?

[RicKsTa]

Have you not got a haynes manual? Best £15 you will ever spend

[RicKsTa]

Oh btw you will need to get inside the gearbox just so you know

[eastanglianbiker]

if its inside the gearbox you will need a full gasket set as well as the cases are l/h and r/h sides instead of top and bottom so will mean cylinder head and barrel off as well

[Guest]

so bascially the whole thing has to come apart. really cant be arsed with all that to be honest but it needs to be sorted.

[eastanglianbiker]

yes the whole lot apart no other way of getting to the gearbox itself

[Guest]

how long would this take a (normal person) to do ?

it took me like 4 days to change a clutch lol

[Fozzie]

how long would this take a (normal person) to do ?

it took me like 4 days to change a clutch lol

 

A dinky little CBR125 engine causing you that much hassle!!

Id have the engine out, on a bench, in pieces, in an evening from work. Then a couple of evenings or a good rainy weekend day to get it totally apart and back together again! I do actually have a haynes manual for one of these bikes as well. Though its ranged in the 2004-2007 model.

I'll have a look in that and trouble shoot for you. Will report back laters

[Fozzie]

I shall now copy and paste what the Haynes manual says about your bike... On the specific problem etc, this is exactly how its laid out in the book minus the (see section 6) rubbish.

Doesn't go into gear of lever doesn't return

1. Clutch not disengaging

2. Selector fork(s) bent or seized. Often caused by dropping the machine or lack of lubrication. Overhaul the transmission.

3. Gear(s) stuck on shaft. Most often caused by lack of lubrication or excessive wear in transmission bearings and bushes. Overhaul the transmission.

4. Selector drum binding. Caused by lubrication failure or excessive wear. Replace the drum and bearing.

5. Gear change lever return spring weak or broken.

6. Gear changer lever broken. Splines stripped out of lever or shaft, caused by allowing the lever to get loose or from dropping the machine. Replace necessary parts.

7. Gear change mechanism stopper arm broken or worn. Full engagement and rotary movement of selector drum results. Replace the arm.

Jumps out of gear

1. Selector fork(s) worn. Overhaul the transmission

2. Gear groove(s) worn. Overhaul the transmission

3. Gear dogs or dog slots work or damaged. The gears should be inspected and replaced. No attempt should be made to service the worn parts.

Overselects

1. Stopper arm spring weak or broken

2. Gearchange shaft return spring post broken or distorted.

My educated guess on the matter would indeed be that you changed the clutch recently and herein lies the problem. Does the clutch bite very quickly as you let go of the clutch or is it immediate? I've seen gear changing problems occur before due to this simple thing.

[megawatt]

Not familiar with this engine, but gear selector shaft return spring is often located behind the clutch basket. So , not an engine strip, just a clutch strip!!!

[Guest]

wow fozzie a lot of info there thanks

iv messed with the clutch several times and its made no difference. it also did this before and after i changed the clutch plates

it jumps out of gear occasisonaly but the main problem is the lever sticking and loosing drive when going down gears

[Fozzie]

When you push the lever when its jammed up does it go back down easily? If so its the return spring.

If it jams then I would suggest dropping the gear box out and replacing all the bearings and make sure the drum isnt binding. Then it should run smoothly

Its a big job but it feels good once you've done it.

[Guest]

what happens is i change gear by lifting the lever with my foot then the lever stays up and wont come back down so when i try changing the next gear i cant find the lever

and when i press it back down it goes down as though i was going down a gear

[Fozzie]

So it takes a long travel back down and goes down a gear? Sounding more like that spring has gone!

[eastanglianbiker]

the return spring is pictured here as item number 11 it could also be the main selector shaft number 9 is bent and causing it to stick where it passes through the seal.when you took clutch out could you see the spring showing behind main clutch housing ? http://www.hondaofbournemouth.co.uk/pro ... -4242.aspx

[Guest]

Hi i havent taken the engine apart yet

went out before on the bike started the engine in neutrel as always and then went into first and the bike jumped forward and stalled. its done this 3 times now and yes i am pulling the clutch in.

It has always jumped forward in first since i changed the clutch plates. and it only jumps forward/sometimes stalling when the bike is first put into gear from starting the engine after that its fine.

whats this then clutch adjustment ? i have like a 1/3rd of the lever set so there is freeplay

[megawatt]

Adjust clutch cable at both ends to give about 1/8" free play at the lever. Try it and if still jumping forward, your clutch ain't workin properly mate. Take it to bits and rebuild it properly

[Guest]

i will give that a go and see if its any better so im guessing the freeplay only needs to be very small ?

[andyc]

Did you soak the clutch friction plates in oil before fitting them?

[Guest]

yeah they were left in brand new oil for nearly 24hrs. il adjust the cable this morning and see if it helps.

thanks