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CBF 125 Chain slack uneven


Khiss
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Hi guys,


I have a Honda CBF 125 that has around 1500 miles on it. I'm trying to sort out the slack in the chain for the first time since I bought it (300 miles ago ). cleaned the chain with a cloth and lubed it with castrol, but for some reason the slack is still very uneven. On one side it's less then an inch and the other is more like 3"


The sprockets look fine, and with such low mileage I don't believe the chain could have worn out.


What am I missing?

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Unfortunately chains do tend to ware out uneven. When adjusting you should always adjust from the tightest part of the chain at the bottom middle. A manual will say how much slack you should have but generally around 1.5 inch to 2.5 inch is common. If theres a huge difference your chain could have worn prematurely maybe if its not been greased or looked after. Generally though unless a new chains just snapped you should change both chain and sprocket as a set to avoid one wearing the other out.

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It should only have 1 inch or a bit more at 3cm of movement really... You adjust for the tight spot in the chain it. My old chain had a big tight spot and a big slack spot. The only way to fix it is to change the chain...


At 3 inches slack I'd say the chain ran dry and was buggered! That's 7.5cm!!!

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2.5k on cbf here just done the chain. I've got 5mm difference in the tight and loose spots. I'm guessing the chain hasn't been looked after by the previous owner.


my colleague at work has a 3 yr old wr125 from New has never greased the chain, in fact for the past year he has been riding around with a faulty float valve. spewing fuel everywhere he goes. I've offered to fix it for him for £50 :P

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Ok, so from what I read, I defenetly need to change the chain then. I would have two questions then:


1. I'm planing to keep the bike for only another 8-9 months and about 1000-1500 miles (gonna get a full licence), so I really don't want to spend money on an original honda chain. I saw unbranded chains for £15-20 on Ebay. Will these do? what should i go for to keep the budget low, but make sure it lasts me that 1000 miles.


2. If I'm at it, I'm also thinking about changing the sprockets size, so that it gives me more speed. Would that be worth it? What are the downsides?



Also, if i keep riding for another week or so, is it fairly safe with the chain being so uneven.

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it says at 5cm you risk damaging the frame. It might pop off the sprockets which happened to me on my old bike. I managed to get it back on at the road side. Just go easy on the throttle and don't use engine braking.


Changing the sprocket size to get more speed will reduce acceleration. I can easily keep up with traffic so don't know why you would want to go faster. it's safer having more acceleration. I doubt the sprockets need changing? Do the next owner a favour and use DID o ring :)

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With more top speed you lose acceleration!

But too big a sprocket and you lose more top speed as it becomes too much for the bike to handle!


It's an 11BHP bike, you would need a full exhaust system, and lighting it anyway possible to keep acceleration the same and support a 2 tooth increase on the front sprocket. All for an extra 10mph or so :lol:

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but for some reason the slack is still very uneven. On one side it's less then an inch and the other is more like 3"

OK, just ruling something (stupid) out here. Are you saying at the top of the chain you have 1inch slack and at the bottom you have 3inches of slack?

Have you raised the rear wheel when testing this??

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You only measure the bottom half of the chain? Rotate it round to measure the slack at different points. No taking the chain guard off mentioned in the manual.


And you measure the slack by gently pushing down. Measure from top of the link. Push up gently and it's however far the top of the link has moved. I watched a ton of videos first. My second time adjusting a chain :P


http://www.obairlann.net/reaper/motorcycle/beginner/chain-slack.jpg

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  • 8 months later...

I've had a CBF125 (MY13) since September. I brought it pre-registered with 4 miles on the clock.


I was experiencing the same uneven chain wear after the 2500 mile service; the mechanic said he could not adjust it out and I'd decided to have it replaced anyway, and in the mean time something went wrong with the rear brake a sudden clunking noise which was the brake bar moving forwards/backwards instead of just up/down.


So that's the back story;


Whist investigating the brake clunking noise, they found out that the rear sprocket hub was uneven (bigger on one side than the other), which they said is "causing uneven chain wear". They have approval from Honda to replace the sprocket hub, sprockets and chain under warranty.

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