Knock at idle.

[yellowdatsun]

As the title says, my 2008 has a knock at idle. It seems to be only at idle as well. I have the stock exhaust, so It's not hard to hear the engine. When slowing the revs down it only appears as the engine gets right down to idle. Just a bit above it sounds fine. When riding it sounds fine. Ideas? Time for a piston and crank? I don't know the history, other than the bike has a lot of hours on it. Not sure what, if anything, has been done to it.

In addition, I checked for the "gold dust" in the oil filter, and have to really look hard to see anything in the oil. I would assume it would be more obvious than this.

Valves are within spec.

Edited January 10, 2013 by yellowdatsun

[FORMA MOTO]

The motors are extremely noisy.

You should compare to another X.

If it truly is a knock or tick sound, stop running the motor.

If you don't know the hours, and you think it's over 200, don't ride it anymore.

Just rebuild the head and top end and be done with it.

Killing a crank on these bikes is not easy to do, so I doubt very much that is the issue.

[yellowdatsun]

I don't have another one to compare to at the moment. I've read they are relatively noisy to begin with, but I don't notice that noise on the 450R's that I hear.

I was going to pull the head and top end to check the piston and cylinder, so I'll just proceeded with that. No idea on hours, I'd rather be safe than sorry. It does puff a small amount of smoke when revving the motor sometimes.

Good to hear the cranks are hard to kill, hopefully it's just piston slap. We shall see soon.

The cam chain feels tight, is there any advantage to the manual tensioners if my auto unit is working fine?

Edited January 10, 2013 by yellowdatsun

[bikenband]

Before you go digging into your motor, check the clutch basket. Pull the clutch cover off the right side of the motor, grab your clutch basket and rapidly move it back and forth (clockwise/counterclockwise). If it clicks or knocks it probably means the rubber dampers on the back are worn out. There are many ways to fix this but easiest is to order a new OEM clutch basket, or "clutch outer set" as they call it.

[yellowdatsun]

Too late, I already dug into it.

Crazy assumption here, but I'm guessing there's not supposed to be that much of a gap between the piston and cylinder. Obviously I pulled the rings for this shot, but still, the gap seems really big.

I will look into the clutch basket next time I have that side apart.

[FORMA MOTO]

Let's see the sides of the piston skirt for wear, and the inside of the cyl for cross-hatching.

Your service manual gives you measurement limits for every part, incl the piston.

[yellowdatsun]

I'll take a look at the piston and measure the tolerances in the morning, but I can say the crosshatching looks great. Someone has been in this motor before, as evidence by the wear on the bolts. So I assume the nice crosshatching is not original, for a bike with so many hours. I wonder if the cylinder was bored/honed, and then a stock piston put back in.

Edited January 10, 2013 by yellowdatsun

[FORMA MOTO]

I'll take a look at the piston and measure the tolerances in the morning, but I can say the crosshatching looks great. Someone has been in this motor before, as evidence by the wear on the bolts. So I assume the nice crosshatching is not original, for a bike with so many hours. I wonder if the cylinder was bored/honed, and then a stock piston put back in.

Honda cylinders are rock hard. My crosshatching looked brand new at 400 hours, 2nd piston.

[Qqqqqqqqqqqq]

The nikasil coating is VERY tough , have you ever seen any gold dust in the oil filter ?

[yellowdatsun]

Heres what the piston looks like:

[yellowdatsun]

The Honda manual lists the service limit of piston-to-cylinder clearance as .18mm, I have .70mm. I just went back out and measured it again to be sure, and got .69mm. That's almost 4 times the maximum serviceable limit. Sooo I think it's time for a new piston and cylinder set.

If you look at the piston pic, at the very bottom of the black area it appears to have some wear, indicative of slap maybe? Piston looks new on the underside, and a little rich on the top.

[crazybrother]

Just so you know, that is not an OEM piston. Here was mine right around 200 hours... And yes I did clean it off before the pic's.

[crazybrother]

And here was my Cylinder.

Old head.

And old piston before cleaning it off.

[yellowdatsun]

Thanks a LOT for those pics, and the piston info. I was actually digging online to see what a stock piston looked like because I was curious to know what was in the engine. I'm assuming the cylinder is stock, because it has the MEY markings like everything else.

Anyone have experience with the CylinderWorks kits? Or should I just go with Honda stuff? Not looking for a big bore kit, stock dimensions is fine.

[crazybrother]

I would stick to OEM all the way. No suprises.

[yellowdatsun]

I find mixed reviews about the aftermarket stuff, and nobody seems to complain about the factory parts, so I'll probably go this route.

[yellowdatsun]

Just ordered OEM Honda parts from my local dealer, should be here mid next week. We'll see how things are once it's re-assembled.

[FORMA MOTO]

Just ordered OEM Honda parts from my local dealer, should be here mid next week. We'll see how things are once it's re-assembled.

You should do the head with TRX intake valves while you are in there.......

[yellowdatsun]

I had thought about doing a few things "while I'm in there", but need to keep to some sort of budget. The valves are still in spec, so they can wait a bit.

[Qqqqqqqqqqqq]

The OEM gear is great , also , I have been using Cylinder works kits for years ... No problems .