Need advice for an odd CBR 125 sprocket issue

[Alpha9five]

Hi everyone. Just had an odd bike arrive today. Its a 2005 CBR 125 with a CBF 125 fuel injected engine. Sounds great for a 125 right? Engine is fitted correctly, bike runs (we aren't used to getting them arrive to us running) , nice new Michelin pilot tyres with loads of life left. But, there is always a but and its one I've not had much experience with before so hoping someone here can help or someone had the same conversion.
The front sprocket doesn't line up with the rear, I mean not at all. Previous owner has done a bit of a bodge by putting the front sprocket on, then a nut as a spacer, then bolted the second sprocket to the first one. I'm not sure what to do here, its riding like that and the second sprocket in front its just about on the splines, but its not exactly something I'd feel comfortable leaving there as this is for my girlfriends brothers first bike. I'm just wondering if there is a rear hub anyone knows of that will fit that has the rear sprocket in a bit more to line up with the front. I will take some pictures tomorrow as I may sound like I'm babbling a bit. Any help would be greatly appreciated.

[stinkwheel]

Yeah, I'm struggling to picture it. Compose your thoughts, lay it out a bit at a time, in paragraphs. Preferrably with photos. Hit preview, read it through to check it makes sense.

I'd suggest photos of the front sprocket area, the rear sprocket area and the rear wheel/swingarm from the side and directly behind.

From what I can garner from your post, I assume it possibly has the wrong rear wheel in. Or the rear wheel has been fitted incorrectly. Or it has a swingarm off another bike fitted so they can fit a wider tyre (common among kiddies who seem to think a wider tyre will somehow make their bike better when all it does is ruin the handling).

So the rear sprocket is too near the swingarm? They have the chain on the front sprocket furthest away from the engine?

Definitely want to get it sorted before giving it to someone you care about as a first bike in any case.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[P.addy]

Yeah, thats not going to work.

Replace the CBF with a CBR engine, they are cheap as.

[Alpha9five]

[Riejufixing]

[P.addy]

200-300 pounds. It'll be faster and will just work. What's been done there won't.

[Alpha9five]

So here are the pictures as promised. The front sprocket is spaced outwards using the old mounted sprocket. The rear hub sticks out. The problem can be solved if I can get a rear hub that fits that is further in. It was riding like this but I don't really like the idea at all of 2 front sprockets or having it spaced out like this

https://i.ibb.co/QrtPmYF/IMG-20190922-110912.jpg
https://i.ibb.co/cgjkq50/IMG-20190922-110859.jpg
photo hosting

[Nobby the Bastard]

[Alpha9five]

[P.addy]

It is still a bad idea and you should not continue down that route.

[Alpha9five]

[Riejufixing]

[Alpha9five]

[P.addy]

[P.addy]

The more I read. The more I cry. 3D print a custom sprocket cover because the current one is bodged beyond oblivion.

I bow out to this, you'll spend more trying to make this work that simply adding the correct engine, this bike is bodged to hell and that's coming from me..

[Riejufixing]

[stinkwheel]

Can't think of a good, structurally sound way of making that work AND keeping the sprocket on properly.

Currently it looks like all that's holding the sprocket on are those two M6 bolts acting in shear. I wouldn't be happy with that. However it's normally held on with a thrust washer and the shaft isn't long enough to have one outside an extended sprocket.

The only way I could think of doing it "properly" would be to turn down the teeth off two sprockets to make splined spacers and weld them (securely and well) to a third sprocket. This would give you a sprocket with a deep, splined spacer attached on the inside. This kind of thing is a reasonably common standaerd setup, albeit made in one piece. (I'd probably use screws in the threaded holes as "belt and braces" in case the torque on the weld didn't play well).

Having made that, you then need to hold it on, so you'd need to really accurately drill and tap the centre of the output shaft (no mean feat) and have a custom shoulder bolt turned up to hold the sprocket on with.

So as above. Put the right engine in. You'll probably sell the current motor for what the other would cost.

OR

Chalk it up to experience. You bought a lemon. Part it out on ebay, buy a complete motorbike.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

If a jobs worth doing it's worth doing well...

The front sprocket would be something way, way down on my list of things to bodge given the stress it has to handle

Engine or rear wheel swap: you know it makes sense
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Nobby the Bastard]

[stinkwheel]

I wonder how solid the sprocket carrier is? Looks as if it might be possible to turn it down a bit? Not sure if it would be by enough though. Also not sure if it would leave enough "meat" for the studs to get into.

https://www.totalparts.nl/picture/boonstra/000000189672-1.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

[garth]

Thread is pure lols.

Outrigger is the only way I can think of.
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You ain't a has been if you never was

[jimspeed]

I don't suppose you can move the engine across a bit ? Sometimes there are spacers in the mounts.
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Hyosung cruise 125(passed test on, sold) Kawasaki el 252 (better than expected but sold on) Kawasaki GPZ500S first "big"bike.(sold) ZZR600 E5..Z750 2007,ER5, currently on a 2008 Enfield bullet electra x and loving it..
,"Alpha-9: Is there any correlation between dyno rod and dyno kits?"

[steve the grease]

Instead of moving the gearbox sprocket out you could move the rear sprocket in. I can't say how much clearance there is between the tyre and the chain , but you could measure it with a bit of string . Measure against the front inner sprocket front face and inside of the rear sprocket. Does it hit the tyre? if so you are Donald .... however if there is room you could fit another sprocket to the inner face of the rear sprocket. Ok it would be some welding and turning but it would work. Sooner or later that front sprocket 'modification' is going to fail and make a mess of everything ( although an inventive attempt!)
Basically bore most of the middle of a rear sprocket out. Then get it welded concentrically to the inside of the existing sprocket (By the centre not the teeth!) then turn off enough of the old outer sprockets rim ( basically all the teeth and a bit more) to give enough clearance for the chain. Result an offset rear sprocket.
Our local machine shop would probably charge about £50.00


Donald = Donald Ducked, rhymes with ........

[Skudd]

WELDING SPROCKETS IS THE ONLY SOLUTION.

That reminds me, my winter project needs to be started.
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