Camshaft Top End Rattle

Not Happy

I took the bike out for it's first run this afternoon. Plenty of power, the motor is very willing, lots of low down punch, but alas when it warms up you can hear the knock. It is quiet enough when first started when the motor is cold. But as it warms up the knock becomes apparent. You cannot hear it while riding, so i don't know if it is happening at higher revs or maybe I just can't hear it. Apart from the noise I am extremely happy with the motor.

The only thing I did not do when the motor was apart both times was to check the backlash in the gears of the transmission, could it make a noise like this.

What about the backlash between the crank gear and the clutch gear, remembering that I have straight cut gears on my motor.

My next task is to synch the carbs to at least see how far out they are.

Here is the video:


http://s226.photobucket.com/albums/d...t=P1010042.mp4



Comments please.

Bill, glad my thread is of use to others. Sometimes I think I am posting too many pics and sometimes I think this thread is developing from a query about a noise in my motor to a thread on an engine rebuild project. But as long as I receive encouragement from people like you I will keep going.

Thanks Bill for your suggestion.

I've been keeping close tabs on this thread as well Don. I have a similar noise and have not had the time or $$ (mostly time) to really get into it. Thanks for such a detailed record. As far as too many pics etc, keep em coming, its the detailed posts like these that are priceless when it comes to figuring out this type of problem

Great work Don, she's a real beauty. Thanks for writing this all up, very educational. Ray

Thanks Ray, it's been a fair journey for me as well. It might not be all over yet though, until I get it out on the road and get a few miles on it I will not know if their is more tuning, carb synching , etc. to be done. Here's hoping it runs without any further problems.

[Ghostgs1]

Great work Don, she's a real beauty. Thanks for writing this all up, very educational. Ray

Thanks Coady, yes it's eventually coming together. A couple of years work, sometimes focussed, sometimes not. I am glad it's nearly finished and hope to get some miles on it now.

[Coady]

Thanks Pete, the new 550 badges belie to 700cc motor sitting in there.

Love this - reckon you'll give a few other riders a surprise with this one Don!

You must be almost 30kgs lighter than a 750 and only 50cc smaller (or 52cc...)

Looks sweet too.

Correct again. It does work out at 696. Sorry for that. I will need to rethink my gearing now. I might need a couple of extra teeth on the back sprocket to compensate for the drop in HP. haha

hehe. Yes, those 3cc's are at least 7/20ths of a horsepower!

Weird, I get 696 ccs from my math.

But that's cool, near 700cc's in a 550

Correct again. It does work out at 696. Sorry for that. I will need to rethink my gearing now. I might need a couple of extra teeth on the back sprocket to compensate for the drop in HP. haha

Weird, I get 696 ccs from my math.

But that's cool, near 700cc's in a 550

Dunno .

673 + 1mm o/s = 699cc

[tkent02]

Dunno .

Ah, had not read that.
About 63.25mm?

[tkent02]

I thought he just used a 650 top end?
Which is 675cc?

Yes, with very oversized pistons. 699.

I thought he just used a 650 top end?
Which is 675cc?

[tkent02]

He was rounding up from 675cc

The window of opportunity is pretty small.

When babied from the outset, the peaks of the hone are just rounded, leaving valleys in-tact. When under heavy acceleration (lots of load) the combustion causes the rings to expand more, and the early 'sharp' peaks are worn down more quickly and further. Eventually the heat cycles and such harden those and very little seating of rings is further possible. Getting them worn down and rings seated quickly before hardening (and a bit of carbon glaze that fills the valleys) is important for the best seating of rings.

I believe the over sized pistons he used makes it work out to 699cc. Should be a rocket.
That explanation sounds good to me, I certainly see no advantage to waiting at all, get the engine working hard immediately, on and off the throttle.