cbr125 forum

Hi all, im having a crazy problem and wondering if anyone could help?

Basically im aware of the known dreaded gearbox in these and people seem to have issues,

I'm also aware of the 1st to second clunk and the 1 to natural rather then 2nd but there not my issue :(

My issue isn't when the bikes stopped but when I'm riding.

When I'm riding it's all fine hunky dory no problems but then suddenly I'll be coming down from high revs in like 5th? Maybe 4th and when I'm coming to slow down all normal, correct down shifting etc.

it's rare and has only happened three time to many to me now but it's when I'm down shifting from high rev and in like 4th or 5th gear going down 1 gear I'll suddenly get no drive itl so to speak free roll like my clutch is in still and not engaged in gear, I'm not sure if it's going from 5th to 4th or 4th to 3rd but it happens so quickly and sometimes due to the free role it can be dangerous.

Now I know about the gears sometimes being a bit iffy in general, and you sometimes need to release the clutch a little to engage but this isn't that.

The only way best I can describe it is (this is two occasions) i was on a very slight down hill and I mean slight, slowing down all as usual gearing etc ,
then it just happened, there was nothing no drive engine still revving etc, i had to then tap it down a gear and release clutch again and it was then fine for a few days then today, same exact place roughly same sort of speed, only this time (this being the third time) I lost all drive and I could hear a very quiet like tapping , tinging noise maybe a quiet clunky?

this all happened quick and I was in a line of traffic slowing Down, I quickly pulled the clutch in almost instant still slightly hearing this noise i then tapped it down all the way so i didnt try the down tap 1 gear as I couldn't it was to late as the freely roll effect made the bike pick up some speed due to the free rolling. I'm puzzled.

I did a oil changed the other day usual oil, castrol power 1 10w 40 4T.

No signs of oil leaks or chain being to slack or to tight, recently had a chain and sprocket set a couple months ago max.

It's a 2012 plate cbr125r, no known engine faults current or to this date apart from this which has all happened over the space of a week?

Can anyone shed any light please??

How much km on your bike ?
It appear that some gear dogs slots may be damaged. You may need to replace them or you may need a transmission overheal.

I also found this on the forum : viewtopic.php?f=18&t=54&start=10 , not sure if it can help.

Good luck with this,

Regards

The bike only has 12600 miles which is low for a 12 plate, y the sounds of it it's a trip to the garage, but then I ask myself is it just simpler and less cost effective to get a new second hand engine -_-

This turned out to be the cush drive and also poor chain, since sold to a family member and done over 4000 miles problem free