drew_c14

If the dyno showed timing was ok I'm assuming that meant the power and tq were where they are supposed to be. If that is the case were you able to see these other issues on the dyno?

Hawkrider

Maybe the APEs are too tight?

Jaytee

Thanks everybody for the feedback. The carb sync sounds like a distinct possibility. She doesn't like idling and when she does stay idle for more than 20 seconds, the revs fluctuate quite bit. The suggestion about CCTs being too tight also sounds right. I was struck by the absence of chain rattle when I got the bike back (for a while I thought that was why it sounded odd, cause the noise had gone) I had asked the mechanic what technique he used to get the tension right with manual CCTs. He answered that he checked the chains with valve covers off and tightened until there was no more play. I wondered at the time if that might be a bit of overkill.
The dyno chart showed power only, and it indicated a pretty smooth line until about 130kph-140kph where it got a bit ragged. The mechanic suggested that the carbs might need cleaning (I was a bit disappointed to hear that, 'cos I'd cleaned them a short while ago, and thought I'd done a bloody good job of it)
Now I've got some ammunition to go with, I'll head back to the shop and see what I can get done.
Once again, thanks to all.

inderocker

If the exhaust note has changed it is possible that they did not get the exhaust cam(s) timed right.

SlowHAWK

If the CCT's are too tight you should notice the motor will sound sluggish when trying to start it. I had mine a tick too tight the first time I installed them... when I cranked it with the starter to make sure everything was cool, it sounded as if my battery was half dead... I backed the CCT's off a bit, and everything has been perfect since...

J.

kai ju

Replacing bent valves should not affect the way the engine runs, unless it was done incorrectly.
Carb synch is mainly an issue at idle and just of idle. Once the butterlies open the engine doesn't really care if you are off even by 6-8 inches of mercury.
Also, if the camchain is run too tight it will damage your cam bearings, which are not replaceable........without replacing the head. Basing adjustment on lack of play in the chain is incorrect, most manufacturers of engines with manual tensioners will specify adjustment at engine operating temp since parts grow at different rates.
You should be able to loosen the Manual tensioner ( carefull, just enough to see if it makes a difference ) and see if your idle speed increases.
If it does they were too tight.
A loose camchain is most obvious on the overrun, i.e. the rpm coming down after you blip the throttle. If it rattles, it's too loose. You should be able to turn the adjuster bolt by hand until the rattle stops and lock it into place.

Good luck.

Kai Ju

Jaytee

Well, it's been a while since I've been able to do much of anything, but finally getting back re your helpful suggestions on my rough-running problem.
The tip about too-tight CCT making the starter labour was spot-on. I backed my CCTs off a 1/4 turn and the starter spins more freely and the "mwah mwah " resonance at 3500rpms was silenced. Still didn't want to idle and was displaying all of the classic symptoms of carbs out of synch.....Rough idle, bad mileage, running a little hotter, vibrating. It was due for its 40,000 km service so I asked for it be dyno'd and for carbs to be checked and synched.
The dyno shows a fairly smooth line up to 6500rpm and then it breaks up quite badly. Power peaks at 80hp- should be closer to 90. The mechanic says that it goes "off-the-scale" rich at 6500 and above, and that it needs smaller main jets. What I don't understand is that the bike is just about stock standard. The only engine mods have been: adjusted TPS, and longer velocity stack. It has stock exhaust and air filter. How could my main jets be too large????
I am still wondering if the timing is out of whack after my failed manual CCT attempt. If the timing is out, would the dyno still read a smooth line up to 6500rpm? I assumed it would show up as a problem right across the rev range, not just at the top end. On the other hand, I can't see how the timing being out would cause it to run rich.
Bottom line is that it still doesn't feel right. I would swear it vibrates more than it used to and it won't pull from anything below 3000. To soon to see what the mileage is like.
Thanks to everybody for the suggestions last time, they were all a huge help.

vtrider

my friend had a FJR with bent valves and the bike was never right afterwards. Vibrated like crazy just as you describe and loss of power. He had to replace the head. The mechanic that replaced the valves said the head was cool but after taking it to an engine machinist something was warped or bad. I can't remember the exact details but you may want to have the head inspected