YBR 125 few problems ,rear brake and electric start

muz379 · Derestricted Danger Joined: 15 Jul 2013 Karma :

New biker on a very big mechanical learning curve off work for a few weeks waiting to start a new job in feb when the bike is going to get a hell of a lot more mileage put on it traveling , decided ill do some preemptive maintenance and service it now rather than in the middle of my rigorous training for a new job .

First Problem - Ive just changed the chain and sprockets , but When going to remove the rear whee I couldn't loosen or undo the bolt on the brake torque arm , No problem I thought ill just take the sprocket holder out of the back wheel and change the sprocket , put it all back together but now obviously the rear brake isnt working as it did before because the wheel is now further forward than it was with the worn chain .
Ive adjusted the nut on the brake rod as far as I can but thats not doing anything I still have to push the rear brake pedal right to the end of its travel to get any brake force on the rear wheel , Is this because the brake toque arm is still holding the rear brake mechanism in the same position or have I dont something else wrong ? .
If needs be can I use a dremel to cut the nut off and replace it with a new one , and is the bolt for the brake toque arm on this bike just a normal bolt if not where would I get hold of one .

Another problem ive had with the bike since ive got it is that It wont reliably start with the button , I dont mind kick starting it from cold and once ive gone a few miles it will start on the button but eventually I want to sell this and for that reason I wanna get it back to starting reliably on the button , Im gonna take the spark plug out in the next few days and look at it / potentially replace it and look at the air filter/potential replace it , is there anything else It could benefit from having looked at to make it start with the electric start from cold .

YBR Ric · Spanner Monkey Joined: 16 Jan 2012 Karma :

It's not a standard bolt and if damaged will require a like for like replacement part.
Once the nut is loose the brake plate can rotate allowing correct adjustment of the rear brake pedal (20mm minimum of downwards free play IIRC).
Any nut that will allow a split pin fitted once tightened should suffice.

Re starting on the button, assuming you have a good battery...
You could start by checking the handlebar switch contacts and the main feed to the starter motor - which is subject to water spray off the front wheel,
then the solenoid connections themselves.

muz379 · Derestricted Danger Joined: 15 Jul 2013 Karma :

do you know the exact specification of the bolt by any chance , just had a go today with the dremel but it looks likely that I might have to destry the bolt as well . Cut the nut off but the bolt is stuck solid had a good go at hammering it for 5-10 mins and no movement

zark · Trackday Trickster Joined: 18 Dec 2013 Karma :

Bloody hell... I've got exactly the same on my ybr... yours an 07 plate too?

I haven't cut the torque arm nut off yet, and I don't intend smashing the bolt through. wemoto.com quoted Yamaha part number is 90179-08X03-00 for the nut... though I've found an m6 nyloc seems like it'll fit.

The Yamaha parts list shows 90109-08847 for the bolt if you got a dealer nearby? Give wemoto a call, they can seemingly get hold of anything!

The last 2 days, mine only starts from cold on the kick start... I hoped it was weather related... but seems pretty common from a quick googling. I'll have a look at the wiring the weekend, but at least its got a kick start! When its warm... its fine. Weird? Would a wiring issue only manifest in the cold?

Mark65 · World Chat Champion Joined: 16 May 2008 Karma :

Never had a problem undoing my 07 YBR torque bolt when I had it, try some plus gas on it, the bolt is recessed but should not be that hard to undo as it has a split pin for safety, reassemble with waterproof grease on it.
Starter, try taking the starter motor off and cleaning the contacts, check the brushes.

Mark
____________________
07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

zark · Trackday Trickster Joined: 18 Dec 2013 Karma :

sheeeesh... shows what i know....

this morning - starts fine from cold on the button.

after 20 miles, stopped briefly and then it wouldn't start again... just turns on the starter... might fire once - then stalls and dies straight away.

on the kick-start - starts fine every time. had a wiggle of the wires next to the fuse, couldn't see or feel anything loose or broken. the battery is clearly fine as i usually only start it twice a day and then run it for 40 mins or so (25 miles ish) and it happily churns over on the starter - just no firey goodness...

i presume if the spark plug was gone it'd affect the running all the time - so that leaves.... what... just the starter motor?? i'll whip it out and have a clean

What does pressing the button do that the kick-start doesn't that means it'll start (or not)

(sorry for the hijack!)

qarka · Spanner Monkey Joined: 10 Mar 2009 Karma :

zark · Trackday Trickster Joined: 18 Dec 2013 Karma :

Ah... since getting all "sodding bike won't start" it's repaid me by starting on the button first time every time... Rolling Eyes

my cable and connector wiggling must be spot on...

in other news - took the bike to a nearby mechanic and asked him to help remove my torque arm nut... His lad mucked about hammering sockets onto it for ages with no luck - and eventually cut through it with a grinder Shocked

he's obviously a knob - and cut through the whole bolt, rather than cutting half the nut away and breaking it off (which is what i was thinking he'd do) then replaced it with a standard bolt and locking washer type thing. i'm not too happy that there's no place to fit a retaining cotterpin in the new bolt - so i'll probably replace that back to OEM spec as soon as i can. I'm thinking adding a second lock-nut in the meantime... i can't see it falling off anytime soon - but yamaha must fit them for a reason, yeah?

YBR Ric · Spanner Monkey Joined: 16 Jan 2012 Karma :

The shaft of the Yamaha bolt where it runs through and makes contact the alloy brake plate is smooth and not threaded (VERY important).

zark · Trackday Trickster Joined: 18 Dec 2013 Karma :

Cheers for that - OEM parts ordered!!

muz379 · Derestricted Danger Joined: 15 Jul 2013 Karma :

zark · Trackday Trickster Joined: 18 Dec 2013 Karma :

Ordered from wemoto.com

Came in little Yamaha plastic bags, so the proper stuff.
The bolt is indeed smooth across part of it... I got the whole lot (bolt, washer, nut and cotter pin for about £5 delivered. The nut, washer and pin are fairly standard if you've got any laying around...

Great service from the wemoto guys though...