GSX 400 F Cylinder Head Retorque

[Guest]

Hi again,

Today I am wondering about one Maintenance job that is written in the service book. I have searched this forum for an answer I haven't found one that makes me calm about that or to stop thinking. I have on oil leak between the head and the fins of the cylinder. There is also a leak under the cylinder block on the left side on the engine. It isn't bad, motorcycle doesn't leave stains under itself. It just sweats a little. I have to go with a rag and wipe it off. Mileage of mine is now 83k kilo. I have no knowledge if anybody even retorqued the head. My questions are:

1. Should I retorque cylinder head? (manual says to inspect that every 5k kilo, seriously?)
2. Manual doesn't say the way either. There is specification but I don't know if I should loosen those twelve nuts and go within the diagram from the book or only check the torque with set value?

I have oncoming valve job anyway in the dead season and there is no way to go to those nuts I will need to take out cams anyway.

And she still has charging with that SH-572 R/R if you are curious. There is one more thing. Getting a new head gasket might be extremely hard job(in Poland).

[Nessism]

Do one nut at a time by cracking it loose first, just enough to get it moving, and then tightening it up to spec. You may want to hit the nuts with penetrating oil for a few days before doing this work. You should not have to remove the cams to reach the nuts.

[John Park]

Do one nut at a time by cracking it loose first, just enough to get it moving, and then tightening it up to spec. You may want to hit the nuts with penetrating oil for a few days before doing this work. You should not have to remove the cams to reach the nuts.

This is not the GSX400 you're probably thinking of, but the four cylinder model GSX400F - for four - that replaced it in Europe. All the head bolts are inside the head so they'll be well lubricated; I don't know if you can get to them without taking the cams out or not, but probably you can. For that matter, the GSX400 twin had all its nuts inside as well, whereas the GS 450s have four on display and the original GS 400 had all 8 on the outside - how convenient; so much for progress.

The head gasket is listed as available at cmsnl.com [Netherlands/Holland] for 39 euros.

This is a bike that even the Canadians didn't get, but it seems to have a reputation for bottom end problems, much like the plain bearing 750s have. But here's one with 83,000 kilometres on it and still going, so maybe you had to drive it flat out across Germany on the Autobahn to melt the rods. The Bandit 400s seem to be indestructible; well, legitimately.

[Himer]

Manual isn't straight about that. In the maintenance section there is no writing that I have to take off cams. But in disassembly section it is clearly written that I need to take the cams out to reach nuts with the socket. Japaneese I want your stuff too that you're taking

Mine is regurarily visiting circuit and most of the time engine hits redline. No problems yet. I do have one more question about valve clearance. One says that I should take value between from the book for both cams. And I came to a version where you do take highest value for the exhaust to prevent burning exhaust valves. I really don't know how to get those values properly.

And to be exact(that blue one, swedish version):

IMAG0070.jpg

I took a spin with GS500, roll from 60 kph. GS 500 stays way on the back even considering lack of engine capacity. For me this engine is just amazing and sounds very good. Only my Vmax after some time is less than GS 500 when it finally grinds in. I love this bike and that's why I am taking extreme care of it. So, very soon in the dead season she will get full service including carb adjustment because somebody didn't do that and there are problems with going higher from the slow system. On the needle and main jet everything is fine, there is a problem with rich mixture in slow system I need some colortune to straighten this out.

[Steve]

I have nothing to add concerning how to get to the bolts, but this is the method I use to re-torque:

Determine the final torque before starting. I don't know what units you will be using, likely Newton/meters or something like that. I don't know the conversion factor for pound/feet, but those are the units that I know, so will be referencing them. I also do not know what the spec is for your bike, so will just mention a general number for information.

Let's assume that the spec is for 25 pound/feet. Loosen a bolt (about 1/2 turn would be fine), re-torque it to about 20 pound/feet. Continue with all the bolts, loosening, then bringing them all up to 20. Finally, following the sequence in the manual, torque them all to 25.

Keep in mind these numbers are EXAMPLES, not specifics. The general principle is to loosen, then snug them up to a point below specification, then bring them all up to spec in sequence.

.

[Himer]

For mine it is 20Nm. About getting to nuts I will get the idea with the valve cover off. Photos on factory book aren't good and there is clearly misinformation in both sections. If it wil turn out that I will get to those nuts without taking out cams, then it will be better for me - less work. But to be honest. What idiot would put head nuts under the cams where retorque is main periodical maintenance job? Taking out cams after each 5000 km would be just stupid. And I never saw a head that has nuts unaccesible.

So I guess first torque seqence to 12-15Nm then going up to 20 within the book sequence.

[Steve]

So I guess first torque seqence to 12-15Nm then going up to 20 within the book sequence.

I would probably go just a bit higher, maybe 15-17Nm.

.

[Himer]

I diggged some photos in the internet. Nuts are good for reach without taking cams - less work Actually head is shaped to get access to them with socket as I thought. Okay then, what about valve clearances? Which limits I should set? Lower or higher ones? I am sorry to bother you for this but I had only 2 strokes in my life and they had windows in cylinder walls instead of valves.

[John Park]

Assuming that it's the same system as the other 4 valve per cylinder engines, you'll need a 9mm open end wrench for the locknuts and a square socket thing to hold the screw. If you get Robertson screws in Poland, the #2 size is the same and fits over the screw. Those were the sizes as I recall, but it's been a while. I just bent one of those screws at 90 degrees and screwed it into a small block of wood as a handle.

There's probably an official tool available somewhere, but all you have to do is hold the screw while you tighten the locknut. Maybe some one else has another solution.

The clearances always tighten with wear, so you want to be closer to the larger number. Probably the specs call for .08 - .13mm or .003 - .005". If they're close to the bigger number then leave them be; close to the smaller, I'd loosen them.

By the way, I used to have a Jawa 350 that I bought new, which is pretty similar to the CZ. It was the Californian model 1971 with upswept exhaust pipes. Red and chrome, and rather stylish. Totally reliable but just transportation.

[Johnny]

Himer, can't you order parts (gaskets) from the internet? I live in Estonia and I have ordered several times from www.partzilla.com, the stuff arrives quite quickly, within a two weeks time, the only downside is, that you have to pay taxes when it gets to your country. This adds a bit of paperwork and makes the final price higher than you started out with, but if you need a gasket or two, it is reasonable.

Also, there's this site: www.motorcyclespareparts.eu, ordering from there, you shouldn't pay any additional taxes I believe. I placed an order there just yesterday, but as I haven't received anything from them yet naturally, I am not going to say yet that are they good or not. But the stuff I've ordered from Partzilla is on my bike.

[Himer]

On partzilla there's no such a model as mine listed.

[Johnny]

Oh, but try searching parts by their number (manufacturer code), not by the model of your motorcycle. Often they don't list every make of the motorcycle although the part is still made and available. For the parts codes you have to find the parts catalogue first though... For my own bike, I found the catalogue from some Finnish internet auction sale, so you may have to hunt for it a bit. But it will be an invaluable tool once you get it. And someone may have it already scanned too and be willing to share!