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Discussion Starter · #1 ·
Doing a chain and sprocket replacement. Came up to the rear sprocket but the bolts are too tight to undo. Ive read somewhere that they had success with an impact wrench while in a youtube video they drilled the bolts off.

Any advice before i go purchase an impact wrench or new bolts.
 

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Doing a chain and sprocket replacement. Came up to the rear sprocket but the bolts are too tight to undo. Ive read somewhere that they had success with an impact wrench while in a youtube video they drilled the bolts off.

Any advice before i go purchase an impact wrench or new bolts.
Try heat; warm them up with a blow dryer or a heat gun and then try removing them.
 

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The first tool you ever get out when working on bikes is WD40 or similar.
It must be rusty if a 1/2" drive 375mm offset handle wont remove them.
 

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IIRC, the first time I tried to do a rear sprocket replacement, I tried to loosen the bolts rather than the nuts.

Loosening the nuts worked much better.:D
 

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As John said, loosen the nuts first... on the CBR these are U lock nuts, so the factory shouldn't have used any high strength Loctite on the threads. When I've done rear sprocket changes on other bikes in the past, I'll break the nuts loose before removing the wheel from the bike, and with the transmission in gear... that way you'll have good leverage on the wrench. Those nuts are torqued to 55 lbf.ft, so they shouldn't be too difficult to loosen.
 

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Discussion Starter · #6 ·
To get access to the nuts, your choice is either an open ended 17mm spanner, which generally ruins the nuts or to take the wheel off and use a 1/2 socket with an extension.

So far I've put all my force and might trying to turn the nuts with a 1/2 300mm socket wrench with absolutely no luck. So I went out and brought a 12volt impact driver which hasnt had any luck either.

The bolts dont look rusty at all, but I'll go out and buy some WD-40 anyway and try again. If that really doesnt work, then I'll assemble it with the old rear sprocket and in several weeks when I get the free time I'll take it too a workshop and have someone else give it a crack.
 

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To get access to the nuts, your choice is either an open ended 17mm spanner, which generally ruins the nuts or to take the wheel off and use a 1/2 socket with an extension.

So far I've put all my force and might trying to turn the nuts with a 1/2 300mm socket wrench with absolutely no luck. So I went out and brought a 12volt impact driver which hasnt had any luck either.

The bolts dont look rusty at all, but I'll go out and buy some WD-40 anyway and try again. If that really doesnt work, then I'll assemble it with the old rear sprocket and in several weeks when I get the free time I'll take it too a workshop and have someone else give it a crack.
300mm ratchet handle is nothing. Get a 1/2 in drive breaker bar.
 

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Had to cut mine off. I tried rattle gun, impact driver and break bar with 3 foot extension with no luck. When I went to the bolt shop they said the lock nuts used burr the thread so they can't be undone. Get some grinding wheels and get stuck into the Allen key side. Replace with standard nylock nuts and bolts.
 

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eh

Doing a chain and sprocket replacement. Came up to the rear sprocket but the bolts are too tight to undo. Ive read somewhere that they had success with an impact wrench while in a youtube video they drilled the bolts off.

Any advice before i go purchase an impact wrench or new bolts.

When I replaced my sprocket, I took a 3/8 cobalt drill bit, drilled the heads, and then I replaced the bolts with 12.9 steel nuts and bolts, torqued to proper settings, and had red locktite used to make them stay. 1000 miles later and still at proper torque settings.
 

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Discussion Starter · #12 ·
Get some grinding wheels and get stuck into the Allen key side. Replace with standard nylock nuts and bolts.
This is probabally the route I will go down, with some red locktite. For now I have reinstalled the old sprocket set, which honestly looks perfectly fine compared to the new one. In several weeks when I get some free time I'll take the sprocket assemebly to a workshop and get some more information about it, and pick up some new bolts and nuts if they cannot get it off either.

Thanks for the replies!
 

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This is probabally the route I will go down, with some red locktite. For now I have reinstalled the old sprocket set, which honestly looks perfectly fine compared to the new one. In several weeks when I get some free time I'll take the sprocket assemebly to a workshop and get some more information about it, and pick up some new bolts and nuts if they cannot get it off either.

Thanks for the replies!

I find locktite 242 works good, just takes a day to cure.


Sent from Motorcycle.com App
 

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Had to cut mine off. I tried rattle gun, impact driver and break bar with 3 foot extension with no luck. When I went to the bolt shop they said the lock nuts used burr the thread so they can't be undone. Get some grinding wheels and get stuck into the Allen key side. Replace with standard nylock nuts and bolts.
They are stupidly tight. Im changing my rear sprocket and its insane. There is no rust or dirt on the bolts. I used a good penetrating oil for 24 hours with the wheel on the side so it can seep in. Whacked it hard with a hammer many times. Used a propane torch to get it super hot. Used a breaker bar and a 17mm socket and rounded off the nut!!!

They are supposed to be 55lbft, i would guess closer to 120ftlb until the nut rounded. Im half way through cutting mine off and im very angry at the situation. If i had known it would have been this hard i would have just left it.
 

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Soak nuts overnight with PB-Blaster, works way, way better than any other penetrating oil. Be sure to only use 6-sided socket or you will round off nut on back side.



I prefer to use air-driven power-tools for this. Allows for precise centering of 6-sided socket without any off-centre rocking motions caused by trying to generate lots of torque by hand. Over 1000 lb*ft torque to bust difficult nuts loose. In severe cases, it's snapped shank of bolt when nuts were rusted on.



Use lightweight threadlocker like Loctite 242 (blue) when reassembling to keep corrosion out.
 

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Im half way through cutting mine off and im very angry at the situation.
I don't know a mechanic who hasn't rounded nuts or broken bolts. When you are a young mechanic it happens more times, then you gain all the experience in the world, and it still keeps happening:D:ROFLMAO::LOL:

A good mechanic got very angry at least once about a stuck screw (not even broken yet), and also got over the anger.

Overcome the anger is one of the most important skills for the veteran mechanic. Yes, a screw causing trouble means more work time, so obviously no mechanic invites himself to such a challenge, but when it comes the best remedy is to concentrate on the solution, because anger only causes more damage.
 

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If i had known it would have been this hard i would have just left it.
Everything is fine, when you overcome the problem you will feel much better, and I would love to hear what was the solution that helped to you.
 

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There is no rust or dirt on the bolts. I used a good penetrating oil for 24 hours with the wheel on the side so it can seep in. Whacked it hard with a hammer many times. Used a propane torch to get it super hot. Used a breaker bar and a 17mm socket and rounded off the nut!!!
You work very well(y)(y)(y)
Try this too:
  • I should have tried to open from the side of the screw T45 (NOT Allen), and just hold the round nut with pliers, maybe it's not too late yet. Try to loosen the screw (where the opening torque is smaller)
  • It is possible to weld a 17mm ring wrench to the nut (sacrifice the ring wrench for the purpose)
  • You can hit the sides of the nut with a chisel.

And yes, the fastest is to cut the nut, it's really not bad, you'll have to order a new:.
90128-KYJ-900 BOLT ???
90304-KGH-901 NUT
Note that these are not ordinary iron screws, these are reinforced steel.
 

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Everything is fine, when you overcome the problem you will feel much better, and I would love to hear what was the solution that helped to you.
I tried all the the nuts to see if I could get any to budge. I got a few to spin, but the bolt also spun. And when I put an Allen key on the bolt that just rounded off the bolt head. I ended up grinding the heads off. I wouldn't even recomend anyone try anything other than grinding off the heads, as its seems like a waste of time.



It was 4pm on a Friday and the the replacement bolts would be a special order item (maybe 4 business days wait). So I bought 8.8 steel structural m10 x30mm bolts with nylon locking nuts and red lock tight.($20) Both the nut and the bolt have 17mm heads and the nut doesn't have the metal locking plate that makes it impossible to get off. So in future it should be removable with out too much pain.



New Michelin street 2 tire
Cbr300r sprocket kit 14t/36t
X-ring chain
I'm midway through painting the lettering white with acrylic paint
 
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