Honda MTX Gear Selection Problems

[gwernybwch]

Hi,

I was wondering if anyone could help me?

I have a MTX125 which would not select 2nd gear (all the other gears were fine).
So I split the engine and the one gear fork selector was worn flat (a common problem on MTX's), so I replaced the gear fork selector along with new clutch friction plates and put all back together.
I had a quick look at the other parts and nothing else seem particularly worn or bent and the small shaft that the gear selector fork slides on was fine.
Put it all back together and it still won't select 2nd gear. Arghh!

When the engine / gearbox is cold, it will just about select 2nd gear, but easily jumps out. When hot it won't select 2nd gear at all and kinda has a 'jamming' feeling to it.
There is no problem selecting 2nd gear when the engine isn't running.

I think that there is the same problem of not being able to select 2nd gear by going up (i.e. trying up from 1st to 2nd) as there is from going down (i.e. trying to go down from 3rd to 2nd) - but can't be sure of it.

Any ideas why a bike won't select one particular gear when the others are fine?

Thanks in advance.

[frazer1981]

When i replaced my cltuch plates on my mtx i had a similar problem.
What is was, was the little tooth'd thing that had fell out when i took the clucth cover off. You have to make sure it is lined up properly other wise you cannot select gears. Took me ages to get it right including having to take it all apart again as i could not change up gears but down was ok.

https://i154.photobucket.com/albums/s241/VR_XRAY/Picture001-1.jpg

https://i154.photobucket.com/albums/s241/VR_XRAY/Picture002-1.jpg

top picture shows the shaft and the teeth that need lining up correctly.

2nd picture shows the tooth'd gear that was the main cause of my problem's.

I am sure somebody will be here with the correct names and stuff but from my past experance with this i think you should check this out???
____________________
1st bike - chunlan starway 50QF4 (SOLD) 2nd bike - 92 Honda mtx125RW-L ( In my garage awaiting some TLC)
05 Honda xl125v Varadero stolen and recovered but now a write off!
07 Hyosung GTR125R

[gwernybwch]

Thanks for the reply and uploading the pictures, it's greatly appreciated.

Can I just check that you had the same problem as me - that you couldn't only select one gear (2nd gear) - and not that you couldn't select any gears?
Also, did you have any problems selecting the gears when the bike was not running?

Thanks.

[frazer1981]

Yeah could only get 1st and no higer though the box than neutral, that was even with the bike running or not running. May be your problem but as you may or not know 2nd gear on the mtx was not the best and even an older field bike version i had @ 15 had 2nd gear replaced twice in the 8 months i had it.
____________________
1st bike - chunlan starway 50QF4 (SOLD) 2nd bike - 92 Honda mtx125RW-L ( In my garage awaiting some TLC)
05 Honda xl125v Varadero stolen and recovered but now a write off!
07 Hyosung GTR125R

[gwernybwch]

I’ve made sure that the ‘reduction gear’ is correctly aligned and still have the same problem

I think that it selects fine when the engine isn’t running and when cold, but jumps out after a couple of minutes must be the key to be problem.

Anyone else want to hazard a guess as to what might be wrong with it?
All suggestions gratefully received.

[sumpgard]

i had similar problems first problem was very difficult to change gears at all this was a burr on the selector drum just cleaned it up with a file and some wet and dry. the jumping out of gear was week springs dont know which one caused this i just changed them all this fixed all gear box problems

[Jello]

Hi gwernybwch,

Have you looked at the roller arm/ detent cam unit? You'll need to remove the clutch basket.

Edit:

This picture shows the gearchange shaft assembly and detent cam, with the claw arm assembly bridging the two.
https://www.ryaneffigy.com/images/IMG_3360.jpg

This shows the roller arm with the detent cam removed.
https://www.ryaneffigy.com/images/IMG_3370.jpg
____________________
Honda MTX 125

[gwernybwch]

OK, I've had another go at it this weekend by fitting a new claw arm (the spiked arm that pulls and pushes the selector cam), which seemed to do the trick for the first ten minutes as i was able to select the gear and it didn't jump out of the gear and then it went back to not being able to select the gear and / or jumping out of gear (whether hot or cold).

I've tried changing all the gear components (without splitting it) and clutch from from an old MTX that I've got lieing around (the roller arm and the selector cam both seem fine), with those components in it doesn't feel like there is any chance of selecting second gear.

There are no obvious signs of wear on any of the other parts.

Any possible solutions gratefully accepted!