The International CBX Owners Association

I read through some of the posts concerning ignition timing and didn't find what I was looking for. I did use the book and advice here and checked the pulsar to make sure the tits.............can I say tits here...........make sure the TITS are lined up at TDC and they are right on. I even rotated the crank twice to make sure I had a TDC reading. The chain tension was adjusted several months ago and I tried different brands of fuel.
When cold it doesn't do it but at running temp I get some valve clatter if the rpm is too low, maybe 2500 to 3000 with the throttle 3/4 open pulling a grade. I'm not talking about going slow in 5th with the throttle wide open like you're not supposed to do. This occurs if I am moving along at a reasonable rpm and then open the throttle wide. It can also occur from a stop if I let the rpm drop to around 1100. Going at highway speeds there is no problem and it runs great. At idle I can snap the throttle and it idles right back. My 79 doesn't do this so I am comparing the 80's operation against it. This isn't causing any real problems but I don't want something minor to become something major.

twinegar wrote:I read through some of the posts concerning ignition timing and didn't find what I was looking for. I did use the book and advice here and checked the pulsar to make sure the tits.............can I say tits here...........make sure the TITS are lined up at TDC and they are right on. I even rotated the crank twice to make sure I had a TDC reading. The chain tension was adjusted several months ago and I tried different brands of fuel.
When cold it doesn't do it but at running temp I get some valve clatter if the rpm is too low, maybe 2500 to 3000 with the throttle 3/4 open pulling a grade. I'm not talking about going slow in 5th with the throttle wide open like you're not supposed to do. This occurs if I am moving along at a reasonable rpm and then open the throttle wide. It can also occur from a stop if I let the rpm drop to around 1100. Going at highway speeds there is no problem and it runs great. At idle I can snap the throttle and it idles right back. My 79 doesn't do this so I am comparing the 80's operation against it. This isn't causing any real problems but I don't want something minor to become something major.

Hmmmmm... Load related hey ??? Clatter.....First thing that would come to mind would be piston slap, second coming to mind would be wrist pins ??

OK... Mileage ?
Leak down test ?

Mileage is unknown, it had about 8K on the odometer but the speedo looked newer so I don't know. It now has 17K. It only does it at low rpm on a grade. I got cheated on the leak down tester off Ebay so I don't have one.

It is the same sound that you get with bad gas.

OK, If it's a genuine 17k bike I wouldn't think it's a carbon buildup problem....

Pinging sound like bad gas eh ? What temp plugs ??

I just yanked a plug and the number is DPR7EA, never heard of that size so I will go to the shop tomorrow and get the standard size.

Do some google research before you spend extra money Twine....

When I pulled the valve cover during the restore it looked untouched, no marks on any bolt heads or anything so would looking at the combustion chambers give an indication of mileage? I am not afraid to pull the head and cylinders so would it be a good idea to pull them and replace the valve seals, tensioner's and cam chain?

Pull the headers & look inside the exhaust ports/valves Twine. That will give you a good indication what's been going on....Kick the cams to open the valves, may be able to see more.

I had the pipes off when I pulled the engine and saw a thin layer of carbon in the exhaust ports. I only looked because I was trying to figure a rough mileage on the bike. I think if you drove the bike you would say it is valves clattering. Being sort of familiar as to what piston wear sounds like and having dealt with pre-ignition and noisy valves I am 99% sure it is valve related that might include carbon build-up. What do you think about the plug number I posted? Could the valve guides be worn and not smoke?

Try this Twine... http://www.gadgetjq.com/spark_plug_cros ... rcycle.htm

Valve related ?? but then it seems to be load related too ?? Thin layer is fine & is normal, your looking for encrustations of carbon to support the problem..

Valve guids could be worn & not smoke if valve guide seals have been recently fitted.. They won't last too long though.

Sounds like a winter project for Spooky Tom and as always I will have lots of pictures of the project posted at my site for others to look at.
ONE MORE QUESTION:
I mentioned several parts I would change while I have the top end off, what would you add to that list?

..............replace valve seals, tensioner's and cam chain? What else?

twinegar wrote:When I pulled the valve cover during the restore it looked untouched, no marks on any bolt heads or anything so would looking at the combustion chambers give an indication of mileage? I am not afraid to pull the head and cylinders so would it be a good idea to pull them and replace the valve seals, tensioner's and cam chain?

17000 isn't a lot of miles but old age has a habit of weakening the "rubber" on the tensioners & indeed valve seals. Wouldn't hurt to do a close inspection & then go from there....

OK, thanks!