Sprocket sizes XJ600S 1998

[tommosan]

Morning all, new to Forum.
I have recently bought a Divvy XJ600S 1998 and have been doing a bit of work on it.
Fork seals, replace rear shock, replace oil cooler, I have looked at the rear sprocket and it doesn't look too bad but will need changing soon, as the chain is almost at full adjustment.
Does anyone know the correct size chain and sprockets to buy? I am confused as some say 46 tooth back and some say 48 tooth, 16 tooth on the front seems to be a common denominator.
One other thing, do all XJ600's make an awful rattling noise?

Tommosan.

[grumps]

Welcome.

Not sure about the sprockets but, yes, they do rattle.

Various fixes around. I'm in the middle of doing the clutch/oil gear fix right now so I can't tell if it will solve the problem.

There are several possible rattle causes and it seems to be a bit of a
game on here chasing them around

Here is a useful link


www.xjrider.com/viewtopic.php?f=10&t=5797

[tommosan]

Thanks, for the reply, the bike sounds like an old Talbot Sunbeam I used to own, rattled like hell but went well.
I hope that my rattle is not a serious one, it seems to be when the bike is on tickover, getting a knocking sound, dissapears when I rev it up.
Have not ridden the bike yet since I bought it, waiting for the weather to be a little kinder, so early days yet.

Cheers.

[grumps]

Sounds like mine did. Fair bet it's the drive pin

[m40man]

Feb 22, 2015 10:13:40 GMT tommosan said:

Does anyone know the correct size chain and sprockets to buy? I am confused as some say 46 tooth back and some say 48 tooth

The naked 600N takes the 48 tooth, the faired 600S takes the 46 tooth rear sprocket. (That is, if you want to use stock size, which personally I think is fine).

[tommosan]

Feb 22, 2015 18:59:42 GMT m40man said:

Feb 22, 2015 10:13:40 GMT tommosan said:

Does anyone know the correct size chain and sprockets to buy? I am confused as some say 46 tooth back and some say 48 tooth

The naked 600N takes the 48 tooth, the faired 600S takes the 46 tooth rear sprocket. (That is, if you want to use stock size, which personally I think is fine).


Thanks for that, have made a note, I think the one that is on it is a 48t, so it is the wrong one.

[bobh]

Feb 23, 2015 10:18:10 GMT tommosan said:

I think the one that is on it is a 48t, so it is the wrong one.

If it's the larger sprocket, a previous owner may have fitted a longer chain to go with it, which could account for the adjusters being at the end of their travel.  So don't assume that the chain and sprockets are worn out. Check the front one, which always shows hookiness first, and if that's fine you're probably OK for a while.

Other checks are to try lifting the chain away from the rear sprocket - it it lifts less than about 2-3 mm it is probably OK. And look for tight spots in the chain - if there aren't any noticeable ones, again, you're probably good to go. If there are, make sure it's not just due to a tight link (or two), which can be freed off with some oil - this is quite likely on a bike that's been standing for a while.  Another indication is whether the rollers spin easily but without obvious looseness - if they are very loose they will make a rustling noise (which is often more obvious to someone following than to the rider).

The manuals also give a method of measuring chain stretch to see if it's within acceptable limits, but personally I'm not convinced it can be done accurately enough, with the chain on the bike, to be very useful.

There are (at least) three main causes of rattles. The clutch has already been mentioned, but also the valves can be very noisy if the clearances are near the top of the allowable range, and a pinhole in the exhaust (often in the collector under the engine) can sound like a mechanical rattle at tickover.

[tommosan]

Thank's for that Bobh, I have not checked the front sprocket yet, you could well be right in what you say about the longer chain, because it looks in fair condition.
When it gets a little warmer I will check it out, I will also check for hole in exhaust (it had crossed my mind) as I can see tape has been wrapped around both sides.
I asked at the local Yamaha about Valve clearances and they told me that they go quieter rather than noisier, (first time I have ever heard that) They have quoted me £175.00 to do the clearances, but I am going to wait until I have had a good ride on it and get it proper warm and see what its like then.

Thanks for the advice.

[bobh]

Feb 23, 2015 20:03:09 GMT tommosan said:

I asked at the local Yamaha about Valve clearances and they told me that they go quieter rather than noisier, (first time I have ever heard that) They have quoted me £175.00 to do the clearances, but I am going to wait until I have had a good ride on it and get it proper warm and see what its like then.

Thanks for the advice.

Yes, generally valve clearances close up over time, due to valve/seat wear. It's unusual to get significant wear of the cams or the tappet shims unless there's been a lubrication failure. So the main reason for checking is to make sure the clearances haven't closed up to the point where a valve could be propped slightly open during combustion, which would lead to rapid burning of the valve and/or seat (as well as loss of performance).

They also close up as the engine, and the valve stems, warm up, so it should get quieter. Obviously the exhaust valves run hotter than the inlets, and wear of the seats will happen more rapidly because of the hot gases - for these reasons the cold clearances for the exhausts need to be more generous than for the inlets. Being air-cooled, there will be a greater variation of temperature than with water cooling, so the clearances need to allow for the worst case expansion (e.g. being thrashed through Death Valley). Haynes actually suggests you can reduce the exhaust clearances below Yamaha's official recommendation, and certainly to minimise rattles they need to be set close to minimum spec. Also with air cooling there isn't the same sound-deadening effect that you get with a water jacket round the cylinder head. But there's no real evidence that a fair bit of valve rattle when cold has any long-term detrimental effect on these engines.

For some reason, though, the 900 Diversion doesn't seem to suffer, even though its head design is basically just a scaled-up version of the 600.

If you do decide to check the clearances, and it's a very straightforward job, you'll need to remove the oil cooler (on the later models which have one fitted). The oil pipe connections on the cooler, which are large hexagonal bosses, are quite fragile and can become detached from the body of the cooler when loosening or tightening the banjo bolts. New coolers are silly money, and second-hand ones like rocking-horse poo, so it's essential to hold the bosses when spannering the banjos to avoid stress on the boss/cooler joints.

If you give the job to a garage, make sure they are aware of this, and that any subsequent leaks will be their responsibility! I mention this because a mate actually ended up scrapping his bike (a 900, which has the same issue) for spares because he entrusted a valve service to a well-known tyre shop, who also do servicing, and it came back with a leaky cooler.

[tommosan]

Thanks for the advice, weather is getting warmer now, I was almost tempted to go for a blast today.
I have already had to replace the oil cooler, there was a leak just under the left hand side banjo, a case in point the previous owner being heavy handed.
Can the clearances be done without taking the Carbs off? I watched a you tube video and this American guy took the Carbs off, I couldn't see the need.

Cheers.