Help!! 650 seca engine rattle big end???

Can anyone help? I have a 650 seca and has developed an engine rattle Wichita seems to be coming from the right side of the engine. It is barely noticeable when cold but very loud when hot. I know it's not timing chain or cam shaft and it has plenty of oil.
Could this be the big end bearings on there way out? It still runs perfectly well.
Any advice would be much appreciated, thought I'd try the forums before taking it to the garage (and paying £30 an hour!)

 

Is the knock engine speed or half engine speed . My guess is its a rod bearing mains are rollers takes a lot to take one of those out. Make sure you have no gas in your oil

 

If it's a rod bearing it might show up in a compression test.

Also, use the "screwdriver stethoscope" trick and see if you can nail it down. Could be clutch related, or ???

(Take your longest screwdriver; stick the end of the handle in your ear, and use the tip to "probe" about on the motor while it's running. You'll find it, betcha.)

 

Could it be the exhaust collector? I've seen them go bad and make a loud racket.

 

Rattle?

Rattle means you got something "Loose".
You have to Probe and Flag.

A wooden or fiberglass rod placed on the Block and your fist wrapped aroung the end with your thumb on the end applying pressure to the rod.

"Listen to your Thumb".
Put your ear right down and listen to the noises your thumb will pick-up from the probe.

Rotational and knocks will be distinct.

Flag;

Tape a bit of Tissue to the end of the probe.
Watch the FLAG for Exhaust and Air leaks.

Connecting Rod Bearings Live Test;

With the Engine running, ... Pull-of the Spark Plug wire of 1, 2, 3 & 4
One at a time.
If the Knock "Goes away" while the Plug Wire is off, ... that is a good indication that the Big End Bearing has SPUN.

You've "Spun a bearing" ... they say.

Thats where one half-shell of the two Rod Bearings gets loose and moves out of position.
The Bearing Knocks every time the Hole fires.
Not so much when the Wire's pulled=off.

 

Good idea. I thought my collector box had started "breaking up" last summer; turned out I had ONE headpipe loose at the collector, and only loose enough to make me thing the whole thing was disintegrating.

I could be a lot of things. Could be the clutch hub is loose. Assuming only does one thing. Assume=Ass+u+me.

Thus my admonition to not make assumptions, diagnose.

 

hopefully i am wrong but after 30 years classic signs of a rod bearing. Usually if its an exhaust leak it will get better as it heats up. If it was the clutch should stay the same .Try the stick method. Drain the oil thru a coffee filter. Not trying to disagree with rick but if you spun a bearing you would loose all your oil pressure and it would not get worse when it gets hot would be banging all the time. You might have flatend it out and the rod is moving sideways smacking off the crank. You need to get a video so we can hear it hard to diagnose a problem in writing

 

I was only suggesting he test and probe for noises.

I had guys come-by who thought that they spun a bearing and we've found some silly stuff that makes foreboding noises.

Burned-through Exhaust Port Flange Donuts will make you think the Engine is about to suffer a catastrophic failure.

The "Doink" that a bad U-Joint makes carries all through the Middle Gear and right-up to the bridge of your nose.

Probe.
Nail-down where the noise is originating from.

 

My collector box is shot and is blowing from all headers (crappy motad) so it's hard to pinpoint sounds!, but I used the old 'screwdriver probe' as suggested and it seems to be coming from the clutch area and also the very lowest part of the engine (next to the clutch) could it be 2 rattles or one that is traveling?
Also does anyone know if marving exhausts are any good for the 650 seca

 

"rattle"- clutch

"Knock"- big end

you still have some research to do....does the noise change when you hold in the clutch?

That kind of stuff....like Rick said, you've got to start nailing it down.

I'm going the bet on it being clutch related though<LOL>

jeff

 

Could even have something to do with the silly-ass miniature chain that drives the oil pump. Also located in the clutch area.

 

LOL, first time I cracked the manual and saw that chain I laughed. Then, I asked one of the engineers at work and he began to run calcs based on our best guess on the size and it actually came out to be much stronger then necessary since it carries basically very little load....but it still reminds me of one of those chains in the toy cars we had as kids Fitz.

jeff

 

If rattle was coming from the clutch could this cause the bike to drop down gears?? it does so usually under hard acceleration. Could loose springs cause both the rattle and gear drops?

 

I was hoping to open this thread and read that you had solved the mystery of the noise....but this sure isn't a good thing.

To answer your question in a single word......NO

No matter what was going on within the clutch, it would not cause downshifting into other gears. I'd suggest that you open the manual and look at the transmission pictures.....there are shift forks that slide the gearsets together resulting in different output ratios(gears). When the engagement dogs fail to interlock, usually caused by bent forks, the result will be gnashing of gears and/or false neutrals. The clearances are close so if the shifter was stomped on too hard, well, that can cause grief after repeated stomping. You've no doubt heard guys talk about a bike "popping out of gear"? That's caused by those engagement dogs failing to lock....sometimes, as will other famous Yamaha's, there is a production problem and there is too much space between the respecitve engagement dogs or the selector forks(shift forks) don't slide them to full engagement causing them to lose their hardened surface over time then they wear very quickly. I'm sure someone here will pop up and tell us about their xs11 or other bike with that issue.

The clutches relationship to all this is simply to connect the engine to the tranny....if it fails, it will fail to connect and it will slip. It can fail in a whole variety of ways but ultimately, it won't connect the engine to the tranny anymore, it won't turn your bike into an automatic and downshift it for you.

How's your starter working? Sometimes, the starter clutch can jam or break but it still wouldn't cause the transmission to downshift to a lower gear.....

Hopefully, someone here that's a lot smarter then I am will offer some words of wisdom or has seen your issue with your bike before, I haven't so that's about all I can offer.

good luck,

jeff

 

madmorgan93 if at all possible post a video with sound of your bike. How many miles on the bike, how long have you had it ?

 

Unfortunately I don't have a video camera, the bike has 5500 on the clock as it was sat for a long time but I doubt this is genuine now, the bike only downshifts under hard acceleration and never out of 5th, starter motor is fine starts on the button with no funny noises. The cluth made a 'knock' noise when released from 1st gear
The funny thing is with the bike it rides very well as if whatever the rattle is it doesn't affect the engine