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2010 FE390 Front Sprocket Replacement

F

fizz

Joined Jun 2010
139 Posts | 1+
Canberra Australia
I have just orderred a 12 tooth front sprocket for my FE390; can someone confirm that:
- it is 'turn clockwise' or 'anti-clockwise' to get the original one off, and,
- what torque do I tighten the new one up to in Nm; do I use loctite?
(my other bike a Husky 610 sprocket is held on with only a circlip)

Thanks in Advance
Fizz
 
Screw, engine sprocket
M10
60 Nm (44.3 lbf ft)
Loctite 243

Need someone else on UHE to tell you which way to turn the bolt. I can only guess Anti-Clockwise to loosen
 
Standard anti-clockwise like any other bolt. It is really on there tight - so you do need a long bar.

From the user's manual page 87:

Screw, engine sprocket 60 Nm (44.3 lbf ft) M10 Loctite® 243T
 
I know that the 12T is a factory option, but the smaller you make the front sprocket, the harder it is on the chain. If possible make the rear sprocket bigger.

Greg
 
Like CodeMonkey said you do indeed need a long bar, and to work out how you're going to stop the shaft turning! That sucker really was on there tight. I tried putting the bike up against a wall to stop it moving forward but it just made the rear wheel spin even with it standing on quite a grippy surface (maybe if someone else had sat on the seat it would have worked). I ended up wedging something between the wheel and swing arm to stop the wheel turning, but no doubt someone will pop up soon with a better way to do it.

The old Husky circlip is certainly easier, but I don't miss it as the splines on the shaft wore out on my TE450, probably at least partly because the sprocket is always a little loose on the shaft behind the circlip and moves about. Had to get the shaft replaced. :(
 
Impact gun.
Make sure you have the sprocket facing in the proper direction. It makes a difference.
 
I don't have an impact gun, but it sure might be worth getting one! What do you do to stop the shaft turning?
 
Bought an eletric impact from the hardware store just for doing countershaft and clutch hub nuts. About $100 USD. Comes in handy for other things as well.
Just put it in gear, you may even be able to remove it in Nuetral. It is all with the impact mechanism, it hits so hard and quick.
 
I wondered if it might be enough just with the shock of the impact and maybe being in gear - useful to know that for sure so I'll see about getting a gun as it would be a lot easier that way.

Of course it didn't work with a normal wrench by hand just relying on the engine to stop it turning - it turned the engine which triggered the fuel pump and that made me jump as I thought it was going to start up! Better to use an impact gun and have the shock applied to the nut rather than to me (though some would say it's hard to tell me from a nut anyway).
 
GregUK said:
I know that the 12T is a factory option, but the smaller you make the front sprocket, the harder it is on the chain. If possible make the rear sprocket bigger.

Greg
Click to expand...
You can't go bigger than 52 teeth with the stock chain guide. You have to get the TM Designs guide. Plus there are not a lot of 54 tooth sprockets out there.

I've been running the 12 on the front for about 1K miles now with no problems.
 
CodeMonkey said:
You can't go bigger than 52 teeth with the stock chain guide. You have to get the TM Designs guide. Plus there are not a lot of 54 tooth sprockets out there.

I've been running the 12 on the front for about 1K miles now with no problems.
Click to expand...
It's not a huge deal but there are two issues:
  1. The smaller the sprocket, the tighter the chain has to wrap around it and the more wear, therefore, on the sideplates of the chain[/*:m:18709qrz]
  2. The second issue is a bit more complex. Unlike a gear, a sprocket doesn't transmit force at a constant velocity. The smaller the sprocket, the more exacerbated the effect is. A 12T sprocket acts like a dodecagon (12-sided polygon) as the chain hooks over each tooth. This means that for one rotation of the sprocket, the chain is marginally accelerated and deccelerated a dozen times. That's no deal at low speed because the effect is quite small. But at higher speeds it can establish harmonics in the chain length that are often manifested as a visible whipping of the chain. Resultant wear on the drive train follows. [/*:m:18709qrz]

As I say, it's not a big deal, but , for trail bikes, going bigger on the rear is preferable. That said, for high speed road bikes, a large rear sprocket can also give problems!

Greg
 
Putting it in top gear improves your chances of not turning the engine over.

I usually use a tyre lever through the swingarm, resting on the rim and hard up against a spoke nipple. Can help to have a helper, but once its in place with a bit of load on it it works fine. A length of 2x1 will do too, just make sure it is right at the base of the nipple, against the rim.

Apart from the tighter radius of a smaller sprocket bending the chain further, the fewer teeth have to share the same load, so that also increases wear on each tooth. I'd be changing the 12t sprockets regularly so that its not the weakest link in the drivetrain.

With 1 Chaingang rear sprockets, I use 2 RK EXW chains and 6 15 t cs sprockets. Unfortunately, Chaingang don't do sprockets anymore :( .

Steve
 
Steve. I heard on the ADVRider site that the Chain Gang is back in business .
 
fizz said:
Steve. I heard on the ADVRider site that the Chain Gang is back in business .
Click to expand...

Excellent, if true. No mention on their website, http://chaingang.com.au/

I stocked up on Berg sprockets when I found out last year that they were stopping production, and I just got some sprockets for my DR, so won't be needing any for a little while. And my latest roadie has a shaft.

The problem Chaingang had was that they lasted too long, and the cheaper and lower quality alternates like Supersprox were better marketed. IMHO, their prices were justified, and good value, but people didn't always see it that way.

Steve
 
Hello all, new to this site
I changed my front sprocket on my 570 last week.I dont have air tools so I just put it in 1st and got my mate to use a big ballpain hamer and wedge the handle under the R/H footpeg and apply the rear brake while I undid the bolt, it worked fine. Use locktite on reinstall but dont go overboard ( you have to remove again), and i believe the washer behind the sprocket bolt applies pressure to the bolt as you tighten, My torque wrench was my right arm,i did 70 odd k's and rechecked, all good.
 
easyrider said:
...
I changed my front sprocket on my 570 last week...
Click to expand...

How many teeth on the new sprocket? If 12, whats your experience..

Regards
Fizz
 
I changed from a 13t to a 14t, I have the 52t on the rear, The 13 was to short and found i was shifting to much, The 14 created a whole new experience, and i love it :bounce3: (Remember changing 1 tooth on the front is equal to about 3 teeth on the rear), ive only had the bike a month and its my first berg, Im ex KTM. Good luck its hit and miss with sprockets cause everyone is different, fortunatly I got the 14 with the bike so i didnt have to outlay.
 
I have one of the electric impacts that works off the bikes battery, it works great for the counter shaft sprocket, also for the clutch hub. All you have to do is leave the bike in gear, it will do the rest. If you don't have one you might try having your wife or good friend hold it with a 1/2 drive socket and a breaker bar and then start your bike and go for a short spin, that should do the trick. Oh wait never mind, that would just tighten it further. :lol:
Righty tighty lefty loosy
 
Mark_Donovan said:
If you don't have one you might try having your wife or good friend hold it with a 1/2 drive socket and a breaker bar and then start your bike and go for a short spin, that should do the trick.
Click to expand...
With advice like that, it's just as well I ordered an electric impact wrench earlier today! :mrgreen:
 

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