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FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 12:12 am
by raYzerman
Posted this in the tech section, because it is technical testicle after all, and I'll try to keep it fun so you aren't bored (a pun you'll get later on). There is a valuable lesson here, in addition to the one about picking a qualified mechanic. Actually there's several lessons..... hang in there. So you've all seen the pics of the basket case engine in the Project bike thread... as I shuffled stuff around to take the pics, I did some forensics, but did not have to dig very deep at all.

To refresh your memory, 2006 FJR with 90k miles, hot starting problem due to low compression in a cylinder or two. I never did get to speak to that mechanic to hear what he measured that was "below Yamaha specification" requiring an engine rebuild. What should have happened is the mechanic should have done a leakdown test to see if he had valve issues or piston ring issues. I mean, really, WE know an FJR engine is not worn out at 90k, puleeze!! And next, it would have been nice to stick a borescope camera down a spark plug hole or two... even dcarver knew how to do that, and showed us pics of nice clean piston tops. As you read, please do chime in if I'm missing something......

First up, a picture of the head, valve side. Exhaust valves are nice and clean, and on the back side, both the intake and exhaust valves had no residue buildup on them at all, which kinda surprised me given the ethanol fuel. My friend the owner (whose mechanical knowledge is non-existent) did use Yamaha Ring Free occasionally, he gave me a few of those little bottles once. But look at the intake valves, all crudded up on the combustion chamber side. That would be carbon, which apparently gets burned off on the hotter exhaust valves... I was not expecting them to be so clean.

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Next up, we need to look at the cylinders and do some fancy measurements. Just how worn out is this rig? Well lookie here, a close-up of the bores shows the factory cross-hatching is pretty much pristinely intact! Impressive to say the least.

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What you see also is a brownish band (combustion residue) at the top of the stroke where the piston does not touch the bore, but combustion does go down that bit until it gets to the next band which is the top compression ring. Next you have a space and the next band is the second compression ring. Next you have a space until the oil ring set. Engine fires at top of stroke and drives the piston down. What we do expect is a little wear on the cylinder wall and some build-up right at the top edge of the top compression ring, it's called ring ridge and usually you can feel it with your fingernail. I checked them all... no freaking ring ridge at all! Surprising!

Getting kinda obvious we don't have a wear problem, but a true forensic anal-ist would get out his fancy bore gauges and measure every which way to determine bore size, ovality, tapered bore.... FSM specs are Bore - 79.000-79.010 mm (3.1102-3.1106 in.), Taper/Out of Round 0.0020 mm. Now that's some pretty fine testicle measuring one would have to do and it would take quite a while. I have the bore gauges, but I used my top secret super precision measuring laser guided..... I mean..... it is easier just to measure all of them in one shot and divide by 4. In this case, this is way good enough!! Well, I know there are naysayers, but I went further, I only measured half of them and divided by 2. Looked in spec to me!!

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Well, now that you're BORED, let's move on, stay with me here. Pistons are important, can't be too sloppy in the holes..... 78.905-78.980... OK, never mind, I got impatient too. These ones I did measure all of them at once, never even bothered with the math. Check 'em out!!

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Lookie all the carbon...... and here's a coupla lessons. First lesson, figure shit out before you go tearing down an engine, you woulda caught this right away, and yes I am pissed how this went down. If your mechanic says I gotta tear it down, you say "Stop right there"... (Meatloaf - Paradise by the Dashboard Light, LOL). Get more answers..... FYB and I had this discussion when analyzing what went wrong with the '07. He figured it out without a teardown, and that bike is running great right now.

Lesson Two, very important...... You have a relatively high performance engine that develops max power around 7000 rpm. This basket case was all carboned up. Every time it left my shop there was this slow acceleration and upshifting before it got 200 yards up the small inclined road leaving here. I questioned my buddy further on how he rode generally on trips (I have never ridden with him). Basically, rides like Grandma, shifts at 3500 rpm, and you can guess cruising at highway speeds probably put it in the 4000 rpm range, passing the odd car might take him up to 4500. He told me it had not seen 6000, and he had never felt that great pull we know just starts to kick in around there. Fer chrissakes, take that engine to its happy place once in a while. You've heard "ride it like you stole it", well do it safely, you don't have to be an idiot, nor am I one to bounce the tach needle off the rev limiter, but get this baby into the power band!!! Ride the twisties in a lower gear, learn engine braking, whatever, but don't ride like Grandma. What's the use of having a high performance bike if you're not going to use it like it was designed to be used... I'll stop now.

Now I can't go putting dirty parts back together, so the next question is, how do I get all the carbon off these expensive little pieces of aluminum and titanium coated valves... the valves are easy enough to get out, but what dissolves carbon that won't eat the metal? So, I'm just gonna soak a piston in Ring Free and see what happens. If you got a magic potion, lemme know.... I'll try one with Simple Green as well, I heard it does magic sometimes.

If you have a running engine and want to clean the carbon out, there is an old old trick we used way back when. Engine running on fast idle plus, spray some water in each throttle body and watch the steam come out the exhaust. On the old 2 barrel carb cars, you could stall it out if you put too much water in, LOL. Carbon does not dissolve in water, so the steam action will flake it right off. There are commercial sprays for exactly this method, but they have other petrochemicals that could enhance the process.

When you're done, use one of these. This is a fancy one given to me as a birthday present, truthfully I've never used it, but it looks kool. You can buy cheapies from China that have a wee camera on the end of a USB cord, plug it into your laptop. I have one of those too, and have used it.

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Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 12:56 am
by CollingsBob
Vapour blasting will remove carbon build up, a broken piston ring can be used - carefully to clean out ring lands.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 7:38 am
by wheatonFJR
Good stuff Ray. I'm bored.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 7:38 am
by Hppants
That was entertaining. So the initial diagnosis is an engine that is carbon-ed up from lugging? And that could have been fixed by a competent mechanic and a water spray bottle? Oh brother!

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 9:49 am
by danh600
How can you not consistently take an FJR up above 4K.
That's where all the fun is.
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Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:13 am
by raYzerman
Hppants wrote: Fri Dec 21, 2018 7:38 am That was entertaining. So the initial diagnosis is an engine that is carbon-ed up from lugging? And that could have been fixed by a competent mechanic and a water spray bottle? Oh brother!
I wouldn't say he lugged it, he just never wound it up.... water is the universal solvent, or so they taught me in skool.
Bob, thanks for the suggestion, but I have another solution brewed up.
Dan, damned straight, Bro. How can you not go 4000 plus every time you ride! Budiculous.
Wheatie, I'll just say what Oface says.... "try to keep up, will ya"
:mrgreen: :geek: :ugeek:

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:14 am
by ionbeam
FWIW, my '04 engine looked exactly like that when it was taken apart at roughly 38k miles. The carbon looked like that in the combustion chambers, piston crowns and valve faces. I can absolutely guarantee the engine was never lugged and I can absolutely guarantee the engine saw the top end of the tach regularly. My engine also had periodic dosing with Tachron or equivalent yet it was still carboned up. And, the rings were stuck on 3 of 4 cylinders. I need to treat my '15 with some Yamaha Ring Free periodically so it don't be lookin' like that too.

The plain bearings were all fairly close to the center of spec and uniform from rod to rod. (Plastigauge is a fiddling PITA for such a simple task.) The piston/rod assemblies were very well weight matched; the imbalance was so small it wasn't worth fiddling with it. In spite of the hammering that went on as the pistons crushed the valves there was no scoring on the plain bearings or crank journals. Placing the crankshaft on V-blocks and turning it showed that the crankshaft was absolutely true and required a gauge that measured accurately to at least 4 decimal places. The finish on the crank was good enough that there would be no gain to polish it. Even the top of the cylinders walls showed no damage, wear or ridge, consistent with what Ray found. :twisted: The hotrod urge was beginning to bloom -- since it doesn't need balancing or blueprinting can it be stroked or bored? I needed cams, are there any aftermarket cams with a hot grind? Will bigger valves fit? :twisted: ---- :idea: LET BE. JUST LET IT BE :!:

The transmission gears, dogs and forks were all in essentially perfect shape. There was negligible wear on the edges and tip of the dogs. Now would be the time to really carefully inspect the gear stacks and forks. If possible, now would be the time to upgrade the transmission with updated gears. The lash of the middle gear was good so what I felt as a bit of slop wasn't in the engine. Ray's engine is far enough apart that he will need to check the middle gear.

Such fun!

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:17 am
by bungie4
2nd Gear FJR is like...

https://youtu.be/5WAKvswf3Fs?t=135

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:21 am
by raYzerman
Thanks Alan! Hmmm, interesting about carboning up in your case... I think we need more data, so I'll take the inspection cam to tech days and survey everybody's holes, but not the kind of survey that is done in Owosso. :bustinlove: I have looked at the tranny gears, all look excellent, in fact, this bike had a second gear problem early in its life and parts got replaced. Looked at the balancers... not closely, but noticed they come apart and can get 180 out of rotation, so I just carefully left it alone and packed it away. The other one is still in the engine block, haven't looked at it for extra 'dots'. Middle gear has a shim. Briefly looked at the parts diagram, do not see alternate size shims available, so will have to look more...

Meanwhile, got several projects on the go. Wheeled the rolling chassis onto the lift yesterday, reorganizing some things in the shop, got to start staging things for reassembly today and get at it. Still no helpers have showed (sigh), maybe I should set up streaming video system with two-way chat service.... but in truth, I'm likely best left to my own devices.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:35 am
by raYzerman
bungie4 wrote: Fri Dec 21, 2018 10:17 am 2nd Gear FJR is like...

https://youtu.be/5WAKvswf3Fs?t=135
No drag strip for me.. a nice second gear run through Hungry Mother State Park is good though :P
Another good one was me trying to keep up with you on NC80...

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:42 am
by Hppants
I suppose I've got another excuse in my arsenal for when the Popo stops me, although "Officer, I was just blowing the carbon out." is probably going to get tucked away pretty far down the list..... ;)

I took Patriot's grenaded gen 1 motor apart - that much I could do. Bike also had about 90K on it IIRC. I distinctly remember seeing the cross hatch marks on the cylinder walls and mill marks still on all of the gears except 5th. The tops of the cam lobes were just slightly shinier than the other parts. Barely noticeable.

BTW Ray, I've still got quite a few parts left over on that motor. I've given away anything that anybody has asked for. If you find you are missing something, by all means, give me a shout. If I have it, it's yours. I can ship just about any day from my house.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:58 am
by bungie4
Ray, I've got some sketchy video of you and fitter running down 215 (I think) that same day. It's not long but it was a good day for sure. Next time I stumble across it, I'll send it on to you.'

... well, look what I found. Sorry, I couldn't afford more pixels back then. This was shot pre-goPro. Resize the screen to get rid of the pixelation.


Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 10:59 am
by wheatonFJR
raYzerman wrote: Fri Dec 21, 2018 10:35 am
bungie4 wrote: Fri Dec 21, 2018 10:17 am 2nd Gear FJR is like...

https://youtu.be/5WAKvswf3Fs?t=135
No drag strip for me.. a nice second gear run through Hungry Mother State Park is good though :P
Another good one was me trying to keep up with you on NC80...
Hey, that sounds like fun...maybe I aughta go over by there and blow the carbon out and refresh the tire surfaces.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 11:02 am
by wheatonFJR
bungie4 wrote: Fri Dec 21, 2018 10:58 am Ray, I've got some sketchy video of you and fitter running down 215 (I think) that same day. It's not long but it was a good day for sure. Next time I stumble across it, I'll send it on to you.'

... well, look what I found. Sorry, I couldn't afford more pixels back then. This was shot pre-goPro. Resize the screen to get rid of the pixelation.

One of my favorite places to ride. When that time eventually comes, I want y'all to spread my ashes out on the trout stream next to said road. That way, I get one last ride...and y'all have fun, too...as I flow on down the mountain.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 11:22 am
by Bounce
Good stuff. Thanks.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 1:50 pm
by raYzerman
Collective Soul one of my favourite bands!! It was a good day. NC80 south of BRP is real tight, hairpinny and downhill. Funner coming back uphill. Almost too technical if there is such a thing. On 215 at least you can get up some speed. All in striking distance of EOM MV.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 2:17 pm
by bungie4
raYzerman wrote: Fri Dec 21, 2018 1:50 pm Collective Soul one of my favourite bands!! It was a good day. NC80 south of BRP is real tight, hairpinny and downhill. Funner coming back uphill. Almost too technical if there is such a thing. On 215 at least you can get up some speed. All in striking distance of EOM MV.
FItter has video of part of 80... remember all the Ferrari's, then the one that bounced off the guardrail... sec.. I have to go find it.. Dead Ferrari in the video.. I still can't get over how far he kept going after making contact with the armco.


Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 2:40 pm
by dcarver
Yep. Been there done that. Carbon buildup under valve seat.
https://candybuttorg.ipage.com/pix/moto ... Zy8/18.jpg
https://candybuttorg.ipage.com/cba/node/221

Used to be a pretty fart smeller on the other board who worked as 4th level GM troubleshooting doode. He eloquently wrote about what wonderful things with ring expansion, fuel/air turbulence, and carbon minimization when running in the 'fun' zone. Wish I could recall his handle.

Good work Ray!

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 2:57 pm
by ionbeam
More carbon buildup.

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The reason my engine had to be torn down -->
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Note the silver area on the valve stem where it moves up and down through the stem seal and valve guide.

Re: FJR Engine Forensic Analysis

Posted: Fri Dec 21, 2018 3:26 pm
by Hack
raYzerman wrote: Fri Dec 21, 2018 12:12 am Now I can't go putting dirty parts back together, so the next question is, how do I get all the carbon off these expensive little pieces of aluminum and titanium coated valves... the valves are easy enough to get out, but what dissolves carbon that won't eat the metal?

Don't laugh, but... I wonder if a wet/stainless tumble would be safe..?
I use the method to clean/polish all my carbon-ed up pitsol/rifle brass... I can guarantee they'll come out spotless, but... 'Not sure if it's appropriate for such high tolerance parts.