Honda CBR250 Rear Sprocket HELL!

[Generalchaos]

I have spent today trying to fit a new chain and sprocket set to my 2012 CBR250. All was going well until we tried to remove the six bolts (stupidly fitted with Allen bolts) that hold the rear sprocket in place.

Two people involved, one holding a bracing bar on the casting, the second using a socket on the nuts to try and get some leverage to get them loose.

 

After a great deal of effort I eventually managed to "Crack" the nuts about 1/8 th of a turn but then the nuts began just turning the bolts at the same time.

 

The Allan key was not able to hold the torque required to loosen them without the possibility of rounding the heads.

 

I decided to be safe, to take the sprocket and casting it is bolted to, up to the local Honda service - Niyom Panich.

 

They first tried using their "Windy" gun impact driver - not a cat in hell's chance of loosening them using that so they took out a large lump hammer and an impact driver and proceeded to whack the living daylights out of it, to the point I was afraid they would smash the casting.

 

In the end, they gave up and told me they would have to destroy the Allen bolts or maybe the nuts to free the old sprocket. They did not have new bolts or nuts in stock and were a bit wary about carrying on. In the end I took the parts back home and tried heating them using the gas cooker but could not get them to budge.

 

Not sure if anyone knows for sure but... (Honda dealer didn't know either) do Honda use Loctite Blue Threadlock on these parts? I suspect that they do as I managed to crack the nut, but was unable to slacken them off.

 

Anyone managed to get these damn bolts out and if so.....what method? (Seems CRAZY to lock them in like this, they are specified as 55 Ft/Lbs torque - We must have been applying over 150 and could not get them free)

 

I had an issue with one of the Honda mirrors on the same bike, could not loosen it, and it turned out to have been splattered with Loctite at the factory. It was eventually loosened using the gas hob, but I still destroyed the Allan bolt head in the process.

 

Cheers!

[A1Str8]

They most probably use loctite if you are not able to remove it. It's still crazy that an impact driver and a hammer didn't help either. 

To some people, it seems to be easy though. 

 

 

[drift]

I had the same issue when I changed the rear sprocket on my CRF 250 L. 

I rounded 2 of the Allen head bolts. I took it to a motocross shop and I think they took a cutting torch to it. Maybe just melted the head of the bolt.a bit to pound it out.

I put the new bolts back in without the locktite.

 I would think maybe a motocross shop deals with this all the time. More so than the local Honda shop.

Edited January 6, 2017 by drift

[Generalchaos]

Glad, (but not really glad, if you know what I mean) To hear other people have the same problems.  Seriously, I had a 3 foot steel bar levered across the casting, lying down with my feet bracing the bar, a socket on a long bar with a 2 foot pipe as an extension on top of that, a 16 stone helper holding it together and we actually heard the nuts CRACK loose, but they are held with something else. Stupid to put these bolts on so tight. I think I need a gas / welding torch.

 

I have a fierce gas burner in the kitchen but I think it will cause more problems with the pressed in bearings. I need some direct heat, or drill them as per the YouTube video. The guy at Honda today told me they had exactly the same problem with the CRF 250 too.

Edited January 6, 2017 by Generalchaos

[Generalchaos]

54 minutes ago, drift said:

I had the same issue when I changed the rear sprocket on my CRF 250 L. 

I rounded 2 of the Allen head bolts. I took it to a motocross shop and I think they took a cutting torch to it. Maybe just melted the head of the bolt.a bit to pound it out.

I put the new bolts back in without the locktite.

 I would think maybe a motocross shop deals with this all the time. More so than the local Honda shop.

I think there is no need for Loctite, 55 ft/Lbs of torque is more than enough,  I have loosened cylinder head bolts that were torqued to 120Ft/Lbs in 20 year old cars easier than this junk. Probably half of the problem is due to the Honda service places, firstly no one uses a torque wrench, secondly no one knows what Loctite Blue Threadlock is, I assume Honda just play it safe so cannot be sued for bits dropping off. But why in God's name anyone would put stupid bloody Allen Bolts on an application like this is beyond me, it has to be cosmetic as the Honda Allen bolts are really shallow and will round off even with hand torque. (The timing cover and Crank cover being another PITA - I eventually got those out on an MSX using a sharp blow from a hammer. Trying to loosen them normally just rounds them off.

Edited January 6, 2017 by Generalchaos

[taninthai]

We spot welded a steel rod across a couple of the Allen head side and then unwound the nuts easy.

Allen heads bolts are the wish things to use,Honda have also used then on the bottom of the  fork leg on the crf again major mission to get it undone

[thaiguzzi]

7 minutes ago, taninthai said:

We spot welded a steel rod across a couple of the Allen head side and then unwound the nuts easy.

Allen heads bolts are the wish things to use,Honda have also used then on the bottom of the  fork leg on the crf again major mission to get it undone

Indeed.

 

Weld on something, anything, preferably a hex bolt, and you'll have plenty to grab hold of both sides. The original fasteners will obviously be toast. Replace with new, stock (high grade) fasteners, torqued to the correct figure BUT USING A THREAD LUBRICANT SUCH AS COPPER ANTI SEIZE.

[Neilly]

On 06/01/2017 at 6:56 PM, Generalchaos said:

Glad, (but not really glad, if you know what I mean) To hear other people have the same problems.  Seriously, I had a 3 foot steel bar levered across the casting, lying down with my feet bracing the bar, a socket on a long bar with a 2 foot pipe as an extension on top of that, a 16 stone helper holding it together and we actually heard the nuts CRACK loose, but they are held with something else. Stupid to put these bolts on so tight. I think I need a gas / welding torch.

 

I have a fierce gas burner in the kitchen but I think it will cause more problems with the pressed in bearings. I need some direct heat, or drill them as per the YouTube video. The guy at Honda today told me they had exactly the same problem with the CRF 250 too.

 

I had the same problem when I did my 250L the first time...the easiest way was to leave the wheel in the bike until you have got the bolts turning freely (there's no cush drive on the 250L so you have to use ring spanner doubled up). Once they're turning freely you can then put the allen key in the other side supported by a stand (I used some wooded blocks) to hold it level. If the Loctite still doesn't want to let go then a bit of heat on the bolt head ought to do it. I did manage to get five of mine out intact...one I had to drill out.