Is this a cam chain problem or something other.

I replaced my cam chain on the weekend. Drove the bike on sunday and it was nicely quiet.
Today the chain slap is back!!! It seems to only be there at idle.

However, I took the cover off and the chain seems looser than it was.

When I put the spring into the tensioner (on the weekend) it did not take up the slack immediately. I had to manually rotate the engine a bit. Then the chain was tight and there was no slap when i drove the bike.

I rotated the engine manually today but no luck. I dod not remove the tensioner springs ( should there be two?) because they were such a pain to reinstall the first time. I thought I would ask here first.

Is the spring too weak? What is the correct length and strength of the spring?

I read about a primary chain noise caused at low rpm but it was not there on Sunday.

 

With an automatic tensioner make sure you clean it out. Put plenty of fresh oil into it before reinstall. And since you didn't mention it here's the procedure;
remove the left point cover and rotate the engine with a 19mm wrench to align the pointer with the "C" mark. Not the T mark. You shouldn't rotate the engine to set the tensioner. Loosen the end plug and remove the tensioner body. Romove the end plug and springs. Push in the one way cam at the other end of the tensioner body so you can push the plunger all the way into the body. Install the body and tighten the retaining bolts to 7.2 ftlbs. Then insert the springs and end plug "making sure the timing pointer is at the "C" mark and tighten to 11 ftlbs. This will allow the correct tension to be set on the cam chain. Replace the timing cover and ride! It is also a good idea to add fresh oil to the springs when installing them. Just dip them in oil and install.

 

One other thing, since the chain was loose check your timing marks on the camshafts just to be safe.

 

Blue I removed and oiled the tensioner ( i had cleaned it before) I played with it a bit and it did seem to move more freely. However when I put the tensioner back in ( followed your directions which are identical to what I did the first time.) the chain still slapped noticably. I put a shim behind the spring to check if it had weakened but this had no effect. I went for a drive to see if anything would change and after warmup no slap! I'll have to wait till tomorrow to see if it comes back.

I have 2 questions.

1 The slapping was most noticable at startup and at idle speeds of 500-600rpm (see #2) and disappearde with a little throttle. Does this sound like a primary chain problem(I don't even know if my XJ700 has one) or am I experiencing some weird cam chain tension problem?


2 My bike idles very slowly when cold even with the choke (actually it stalls often when the choke is engaged) but idles around 1200rpm when warm. What tuneup steps do I need to perform and in what order? (I have sent for the xjcd and am awaiting it.)

 

My bike has cooled off and the chain slap is noticeable again.

Any suggestions

 

My first suggestion is to get or find someone with a mechanics stethoscope. This will isolate whether it is the cam chain or the primary chain, (which yours does have). The chain should make more noise when warm since the heat will make it stretch slightly through expansion. If you can get a stethoscope place it on the top center of the valvecover and listen for the slap. Then check the front center at the camchain tunnel where the front guide fits in. Lastly check at the tensioner. If you don't hear it at these places then it may very well be the primary chain. I have not had any problems with the primary so I'll let some else tell you the best places to listen for it. I just don't think it would be that since the problem started after the cam chain replacement. There are 2 springs in the tensioner on my bike. So if one is missing that is most likely the problem. Yamaha is good at changing things like that. Easy way to check is to see if a dealer will look it up for you. Their software should show the part with all it's parts.
BTW Harbor Freight has a stethoscope for $6 if there's one near you. I have it and it works quite well.
On the idle problem sounds like a lean mixture but not that bad a one. I would wait for the XJCD and study the carb section first. Fuel level is a likely culprit as well as mixture setting or sync. First thing I would do is a Seafoam treatment by running half a can in a tank of gas. Then I would check my plugs with a plug chop. This will tell you if the condition is present after the choke is off. If it is then you need to check the fuel levels. If it isn't then a cleaning of the choke circuit is needed.

 

From direct experience: the primary chain makes noises not unlike a rubber mallet blow from inside the crank/gearbox.. heavy intermittant clunks..unerving and difficult to ignore.. a lower frequency sound, presumably because that chain has significant mass to it, unlike the cam chain which as you know is surprisingly small in size.
Unbalanced carbs alegedly play a large part in getting the Primary to thrash about at idle speed... could the carbs at idle be a part of the cause?

 

From your discussions it sounds more and more like it is still the cam chain. The noise is definitely the same as before the chain was changed and is a high speed tat-tat-tat as compared to the rubber mallet analogy. The noise goes away once the engine is up to temp. If the front chain guide did not seat properly is it possible that this is causing a noise.

There was no noise the day I did the chain replacement. I had to remove one of the small cam caps on the intake. I did not have the rear chain guide out and it seems hard to push with a screwdriver.( Mind you I do not have the carbs off and it is a tight fit.)

All suggestions welcome.

 

Actually I was thinking about the front chain guide last night after I went to bed. I thought you may have pulled it and not have gotten the bottom tab in place. Although if it is like mine that is a little hard. Mine follows a channel down the head and case so it seats rather easily. Did you pull the cams or just feed the chain through the bottom end? You say that the noise is the same as before. I thought it started after the chain renewal. It is very possible that it is a header pipe. These headers have double walls and when the inside one breaks loose it sounds like the cam chain. A mechanics stethoscope will determine that. A cheap alternative is to place a metal or wooden rod such as a socket extension or cut off broom handle to the header pipes. Cup your hand around the other end and place your ear to it. You will hear the sound much better.

 

I originally swapped the chain because it was slapping. I removed the cams during the switch. All was fine after the switch ( I went for a short drive with no chain slap)but the next day I replaced a cam cap that I had welded and the bike made noise again. (The only thing I did was remove an intake cap leaving the other 3 in place and replace it the next day.)

My exhaust is new so that should not be a problem.

A mechanic friend mentioned the carb imbalance issue about the primary chain that mike mentioned since the noise dissapears with heat.

 

Which cam cap did you remove?

 

The small one on the left (clutch) side of the intake cam.

 

Well if that's the small one then there is no problem with what you did. The small one next to the sprocket is not a cam journal. Only things I have left are the rear guide may need to be adjusted. That is the bolt with a jam nut just below the tensioner. Procedure for it is to loosen the jam nut and turn the bolt until finger tight, then back 1/4 turn and while holding it there tighten the jam nut. Other thing is the possibility that there is one too many links in the chain. Very unlikely scenario. I am about ready to send you my extra tensioner just to see if that is it. Hope some other guys chime in with some fresh ideas. I am about stumped.