2009 EC 450F head bolt torque settings
 

Hi there fellow GasGas riders,

I have a 2009 EC450F, and am going through a top and bottom engine rebuild. I am slowly putting things back together but when it comes to the cylinder head bolt torque settings I am feeling a bit nervous.

I have searched here as best I can, and the torque table on this site lists 25Nm for cylinder head bolts, but I think this spec is for the 2 strokes?

The 2005 workshop manual lists 4.5kg (presumably kg/m which is 44Nm) as the torque, but there are many posts on this site saying the torque values in the manuals are not to be trusted.

So what settings do I use?

I looked at the DRZ400 specs as there are apparently some similarities between the motors (DRZ spec is 46Nm) but TT forum says the DRZ manual specs are not to be trusted either and to instead use 43 ft lbs (58Nm).

I also looked at older WR450 specs and they have a specific procedure for tightening the cylinder bolts (torque the cylinder head bolts to 20 ft lbs, then loosen and re-lube the bolt threads, then torque to 14 ft lbs, then turn each bolt 90 degrees, then another 90 degrees for a total of 180 degrees (one half turn)).

I could flip a coin and pic a spec, but I think I only get one chance at crushing the head gasket (which cost me close to $200 AUD - ouch).

Any helpful suggestions or GasGas wisdom from a guru would be greatly appreciated!

Thanks very much

Mike

Your engine looks like this?
https://img12.img-bcg.eu/auto24/560/079/41606079.jpg

In that case 45nm is correct. I have done mine in 2 steps - first pass to 25nm and then to 45nm.

I probably have reinstalled my head with the same head gasket for more than 10 times - just did a piston change and the same gasket is still working as intended. Not a single problem. But be careful with the cam bridge/holder bolts. In my opinion those are prone to stripping and one of mine stripped at 8nm. It was probably damaged before but it is still something to look out for.

Thanks very much for the reply.

First of all I must say... wow... Yes that is the same engine, but mine looks nowhere near as immaculately clean as that. You will have to share your cleaning tips with me!

Also stoked to see what the machined surface with the 2 bolt holes above the exhaust is good for, holding the clutch line! I assumed it was for an additional temp sensor, but mine has never had anything fitted to it. I am going to shamelessly copy that.

Very reassuring to know the torque settings are good, but also that you have managed to reuse the head gasket multiple times. I had trouble even sourcing a new head gasket, didn't want to risk reusing my old one, but perhaps I could have saved some $$$. Oh well...

I am possibly overthinking it, but did you grease or lube the head bolts and washers when torqueing? I read that torque values in the table on this site are for dry bolts, and lubricating the bolts can change the values by up to 30%.

Thanks for the tip about the cam bridge bolts too. That would been a proper tragedy stripping one of them.

This is a picture I found from the internet and it is of a brand new GasGas Quad bike. I am not sure if the motorcycles use that mounting for the clutch line or not(mine does not) but if it works for you then go for it. I think the torque values are meant for "dry" bolts unless specified otherwise. I cleaned my head bolt threads with brake clean but I did not clean the holes. This method has worked well for me.

I also cleaned the cam cap M6 bolts with brake clean as those were prone to stripping the threads in the head. On my bike, one of the cam holder bolts stripped the threads out of the head at ~10nm so this time I torqued them to 8nm. I have done ~100km since and so far the engine is working well.

Ok thanks very much Mekket.

You have been very helpful.

Much appreciated.

No worries, thats why we are here for :) Let us know when you get the bike running!

Hi again, bike is now up and running nicely, but not yet fully run in, just done a couple of temperature cycles. Hoping to do that maybe this weekend.

When I first went to start it after the rebuild I had issues with the starter clutch slipping and was initially not able to start my bike. Thankfully with a lot of digging on this forum I found some help and got it sorted!

Thanks again for your help!