New cam chain & now I don't like it

Hello forum - get ready for a story.

The bike - 97 model turned streetfighter, airbox mod & after market can but everything else is standard. Ran great from tick-over to redline and as most of my riding is in traffic, I do most mileage under 4k revs. Loved it all except a very loud cam chain.
The chain was replaced by a family friend who has been a bike mechanic for ever, I trust him. As the engine cannot be removed from the frame (exhaust studs corroded lots) it was all done in the frame, he had to remove one or both cams to get enough clearance to fit the new chain. The carbs were not removed but an amount of wiring did have to get moved out the way.
Anyway ......................
Sounds great and runs great but only after you get it above about 3k. It does not want to rev cleanly off idle ..... exactly where I would normally be letting the clutch out. Also, the choke does not act like it used to. On a cold day the choke would help it start and raise the revs, now I have to turn the choke full off almost straight away or I cannot keep it running.

I have spoke about this to the mechanic who told me that he made sure the cams are all timed correctly and the carbs never came off.
I know that the carb settings are famous for bad running but this happened overnight so I cant help thinking that something has got missed somewhere.

Any ideas?

It sounds to me that the cam timing is slightly out.

Paul

Is it burning any oil? Run it for around 10 mins turn off and take out oil fill cap. Is there any smoke coming from there? If so cct wasn't reset when new chain fitted. Take out centre bolt of cct, remove both springs, take out two mounting bolts, push plunger all the way in, remount cct, replace both springs then slowly replace centre bolt. That will reset the cct for the new chain.

If that doesn't work then I am guessing either timing is a tooth off or a pipe is still disconnected or wire caught up. Even when you line cams up when tightening down they do move unless done carefully. Was the chain slack on the cct side?

yamahamad wrote:It sounds to me that the cam timing is slightly out.

Paul

I must admit that I have never experienced having a cam out of time. I don't know if I would notice straight away. The engine feels like it is pulling just the same once I get the revs up.
As much as I do not want to, I might have to open it up and have a look.

The White One wrote:Is it burning any oil? Run it for around 10 mins turn off and take out oil fill cap. Is there any smoke coming from there? If so cct wasn't reset when new chain fitted. Take out centre bolt of cct, remove both springs, take out two mounting bolts, push plunger all the way in, remount cct, replace both springs then slowly replace centre bolt. That will reset the cct for the new chain.

If that doesn't work then I am guessing either timing is a tooth off or a pipe is still disconnected or wire caught up. Even when you line cams up when tightening down they do move unless done carefully. Was the chain slack on the cct side?

He suggested that if the chain was to be replaced, it would be wise to sort out the CCT so he fitted a manual type. I will check the oil cap for smoke but I am not sure how that might be giving the flat spot.


Cheers both of you for the suggestions.

If your cct is too tight it causes excess friction on the cams and head making the engine work harder to spin and puts extra strain on the cam chain. This then causes the oil to burn as well which you will see if you have smoke out the oil fill hole.

Why was the cct changed? I have had 4 cats and after a total of around 80,000 miles on them never had an issue with a failed cct. Other members might disagree but I don't believe the cct is an issue on these bikes.

If it's running at higher revs I suspect that the cam timing is ok, and I would have thought that if it's out at high revs your valves would have hit the pistons. I would check all electrical connections starting at the battery and working your way through all the plugs connectors ( it's worth doing as at some point you'll find a corroded plug some were, been there, done that, type of problem ) also check the plug leads and the ends. It sounds more like some pipe/connection has not been refitted correctly or the dreaded muck has moved in the carbs and blocked a jet or a float jet is stuck and the bike is flooding. You could try fitting drain pipes to the carb drain tubes, draining the carbs and then turning on the ignition to flush the floats, then turn off the ignition and turn off the drain valves.
I have one question though, did the new cam chain come with a split link?

I know it can be done in the frame but it's hard work and by the sounds of it he accessed through the front and not the top or carbs, coil packs, cables and air pipes all need moving. Check that all air pipes are connected properly and maybe lift tank and airbox to check choke cable route also.

If it's a endless Cam chain the crank has to come out which is a complete strip!!! The chain's driven from the middle of the crank.

past-it wrote:If it's a endless Cam chain the crank has to come out which is a complete strip!!! The chain's driven from the middle of the crank.

He said his friend did it while engine was in bike so should be one with a master link. Would it make a lot of difference if the cams went on the wrong side? in to ex and ex to in? I'm assuming it would mess up the total engine and not just have a little issue? Never done it myself and don't really fancy trying so don't know the answer myself.

man_in_uk wrote:The chain was replaced by a family friend who has been a bike mechanic for ever, I trust him. As the engine cannot be removed from the frame (exhaust studs corroded lots) it was all done in the frame .........................

Any ideas?

Rather than an endless faultfinding guessing game chasing a 'ghost-like' gremlin, I'd be tempted to drill the exhaust bolts out and replace them. (After all, if they re corroded in, how long before they shear and fail anyhow ?)
Then, I'd ask 'the family friend' mechanic to redo the whole job again from there. Seems obvious something has gone amiss, so perhaps a re-start doing the job in the correct sequence 'may' resolve the issue naturally . . . .    

Cheers
0c

0ldcat wrote:
Then, I'd ask 'the family friend' mechanic to redo the whole job again

0c

I know what you mean but when someone does you a favor for nothing, it would be a bit rude.

I know the studs will need doing one day but its an old bike. If I had to pay a garage the right price for replacing the studs, it would cost more than the value of the bike.

I have since realized that as I do not have the standard clocks fitted .... I will not be shown any error codes on the rev counter. Not sure if the throttle position sensor would cause such a symptom but its worth a look.