Top end rattle

[andyb]

Probably the biggest problem with winding a motor up hard without a load is overshooting the target revs.  I've heard a racer say that there's a danger to the camchain during high rpm/no load use, but I don't know what the rationale was.  He compared doing this with exactly what you describe: rolling out of the throttle at the end of a land speed run instead of pulling the clutch and using the brakes to bring the speed back down.

Dunno, I use my engines to redline frequently on the dragstrip.  Making sure the engine is warm first is key, both to ensure lubrication and to make it carbuerate cleanly at light throttle openings so you can accurately hold your stage rpm where you want it without creeping.

Though I also am a fan of measuring compression and leakdown on used motors when I buy something, along with an oil analysis on the second oil change, so other than metal fatigue and maybe bearing wear... I'd say that they're not unknown anymore after that?

[Pat Conlon]

Andy, you would know this.....In the past I have heard that in certain high rpm racing situations the oem cam chain tensioner can fail....the reason the racers use the APE manual chain adjuster.

Can you explain?  TIA. Pat

[andyb]

I think mostly it's a problem of the aftermarket tensioners being a fairly cheap "performance" mod, honestly.

Maybe Randy can chime in a bit with more specific FJ information on it.

The only real crap stock CCT's that I know of are limited to a handful of engines.  The early Hayabusa went through what, 3 revisions on them? I think they final settled on one that is somehow linked to oil pressure. and I understand they're a bastard to work around.  I don't know much about the older KZ/GS stuff, but understand they're popular on those engines; they may or may not be actually necessary.  Honda had a reputation for camchain issues with high miles on a number of their motors, but I thought it was the chain itself rather than the tensioner.  Dunno, don't see more than a couple machines at the track that aren't Kaw or Suzuki these days.

I'm still surprised that I haven't seen a Ti (or some other exotic material) camchain for popular bikes.  Seems like it'd be a natural fit for people trying to reduce rotating mass a bit.

Personally, I prefer having the OEM automatic adjustment to yet another thing that can get screwed up during a major service. 

[Ront]

Hi I posted about my '86 fj1200 top end rattle last week-checked the cam chain tensioner, put the carbs back on and started it, ran well, no noise at idle but rattle still there starts at 1500rpm and now oil pouring out between cylinders 2 and 3 front of motor about a half inch above cylinder block base in recesses in cylinder block so looks like major problems. Can you pull head and cylinder block with engine in bike? Also does anyone know the cost to re-ring or would I have to bore cylinders and go to to oversize pistons. Thanks

[racerrad8]

Did you replace the tensioner gasket after removal?

Where you able to install the tensioner in the proper direction with the one-way cam downward?

Randy - RPM

[Ront]

Bonehead move  forgot the tensioner gasket  but was able to install with cam down    thanks    still have the rattle

[Capn Ron]

Also does anyone know the cost to re-ring or would I have to bore cylinders and go to to oversize pistons. Thanks

Hey Ron,

I did a full engine rebuild on my '92 that included new rings.  You first have to measure the cylinder bores properly with a cylinder bore gauge in six places in *each* cylinder.  You then do a bunch of math with these 24 measurements.  This will determine if the cylinder is still within wear specs for bore size and out of round condition.  If they are still within spec, you can get away with a "freshening hone" on the cylinder walls (about $80 at my local machine shop) and a new set of standard sized piston rings (about $42 each set x4).  If you find the cylinders out of spec, you'll have to consider your oversize boring options.

[ribbert]

Remotely diagnosing "noises" is difficult at the best of times. Is it a rattle, a tick, a knock, a light knock, a deep knock, is consistent, does it change with load or temperature, where it coming from and so on.

Contemplating rings and / or re-bore because your running out of ideas is an expensive and not necessarily guaranteed cure. It would cost you about $1300 to re-bore it with machining and piston kit if you did the job yourself. While it is not uncommon for members here to do this job themselves, it would be foolish and asking for more trouble if you under estimate the finesse, dexterity and basic knowledge required for a satisfactory outcome. Leaving out the cam chain tensioner gasket and turning your motor over backwards does not bode well for doing this yourself.

I had a car brought to me many years ago that had just had a top to bottom engine rebuild, at enormous expense (V8), to rid it of a serious engine rattle, THAT WAS STILL THERE! It turned out to be a broken spring in a $2.00 PCV valve. Pull it out of the rocker cover and it was a light "tick", put it back in and it sounded like a serious knock. The owner was standing next to me when I demonstrated this, he was near purple with rage as the motor was not high mileage and had shown no other signs of wear before the rebuild other than the engine knock.

The assumption that if you just replace everything, the rattle must disappear is not always correct.

IMO your best bet at this point would be to try and find an 'old school mechanic' with an experienced ear to have a listen to it. He could probably tell you with about 90%+ accuracy, exactly what it is from listening to it.
Most of the likely causes seem to have been suggested and worked through to no avail, but just throwing parts at it hoping it will disappear is not the answer.

Noel

[Bminder]

Before you tear into it too much, you might give Randy at RPM a week or two for things to calm down a bit with his family situation, then call him and ask him about it.
The guy is an FJ Whisperer!  With his vast experience with this motor, it's amazing what he can figure out over the phone. And it might end up being something as simple as Noah's situation.

[JMR]

I have seen those morons on youtube revving their bikes stationary to the rev limiter or valve bounce or when it can't suck and blow any more, whatever, and leave it there. Idiots. Do it on a cold motor and they should be shot.

God....there would have been a lot of dead bodies around Loudon back in the 80's and 90's.

[Ront]

Remotely diagnosing "noises" is difficult at the best of times. Is it a rattle, a tick, a knock, a light knock, a deep knock, is consistent, does it change with load or temperature, where it coming from and so on.

Contemplating rings and / or re-bore because your running out of ideas is an expensive and not necessarily guaranteed cure. It would cost you about $1300 to re-bore it with machining and piston kit if you did the job yourself. While it is not uncommon for members here to do this job themselves, it would be foolish and asking for more trouble if you under estimate the finesse, dexterity and basic knowledge required for a satisfactory outcome. Leaving out the cam chain tensioner gasket and turning your motor over backwards does not bode well for doing this yourself.

I had a car brought to me many years ago that had just had a top to bottom engine rebuild, at enormous expense (V8), to rid it of a serious engine rattle, THAT WAS STILL THERE! It turned out to be a broken spring in a $2.00 PCV valve. Pull it out of the rocker cover and it was a light "tick", put it back in and it sounded like a serious knock. The owner was standing next to me when I demonstrated this, he was near purple with rage as the motor was not high mileage and had shown no other signs of wear before the rebuild other than the engine knock.

The assumption that if you just replace everything, the rattle must disappear is not always correct.

IMO your best bet at this point would be to try and find an 'old school mechanic' with an experienced ear to have a listen to it. He could probably tell you with about 90%+ accuracy, exactly what it is from listening to it.
Most of the likely causes seem to have been suggested and worked through to no avail, but just throwing parts at it hoping it will disappear is not the answer.

Noel

I don't think you can make a blanket assesment of my mechanical ability just because i left the gasket out-the gasket was missing when I removed the tensioner -I got one at the dealer-Thanks for the advice

[Pat Conlon]

Ron, this is the forth time you posted a new thread on the same subject.
Stop it.

[ribbert]

I don't think you can make a blanket assesment of my mechanical ability........

You're right, I can't. I can only form a view from what you have posted to date.

Noel

[Ront]

I don't think you can make a blanket assesment of my mechanical ability........

You're right, I can't. I can only form a view from what you have posted to date.

Noel
[/quote

People stop replying to threads after a few days so posting new ones might get some additional input, what the hell is wrong with that?

[Capn Ron]

People stop replying to threads after a few days so posting new ones might get some additional input, what the hell is wrong with that?

Ron...We're all trying to be helpful here and get your bike sorted out.  If you just post an update to your first thread, it bumps it to the top and everyone sees it again and will have a chance to comment...IF they have something constructive to add.  I'll be the first one to admit...I wondered why so many people were having a "top end rattle" issue all at the same time.

I replied to your question about a fresh set of rings as a completely different topic.  I assume you're looking to do this *after* you get the rattle figured out?