Cleaning Intake Valves...

[GreginDenver 125]

I've got my '99 5th Gen off the road for a while, it's partially apart for maintenance.

 

I've installed the new header and I've removed the fuel injectors and sent them out to be professionally cleaned and tested.  I couldn't help noticing how much carbon buildup there was on the backsides of the intake valves so I decided to do something about it.

 

And as you're viewing these pictures bear in mind the fact that this mess has managed to accumulate in only 20,000 miles (the current total miles on this bike).  I believe that motorcycles (and maybe the VFR in particular) recirculate a lot of engine oil vapor into the intake.  This means they (motorcycles) probably build up carbon deposits on the intake valves at a higher rate than it does on a car.

 

Here's a "before" pic of the Right Intake Valve of Cylinder #3

 

Here's an "after" pic of the Right Intake Valve of Cylinder #3

 

Here's a "before" pic of the Left Intake Valve of Cylinder #3

 

Here's an "after" pic of the Left Intake Valve of Cylinder #3

[rangemaster 80]

Curious as to the "something you did about it." I put a filter on the on the outlet from the valve cover and plugged the inlet to the airbox for this very reason. One of the small aftermarket tapered filters will fit under the tank.

 

rm

[GreginDenver 125]

12 minutes ago, rangemaster said:

Curious as to the "something you did about it." I put a filter on the on the outlet from the valve cover and plugged the inlet to the airbag for this very reason. One of the small aftermarket tapered breaker filters will fit under the tank.

 

rm

Didn't mean to cause confusion.  When I said that I decided to do something about the situation I was talking about doing the cleaning of my intake valves that I was documenting in this post.

 

I understand what you're saying about putting on a filter on the bike's crankcase breather lines (or doing other things that might prevent or help to reduce the oil vapor from depositing on the intake valves).  I've thought about doing some research and testing to see if I could mount a small automotive Oil Catch Can on my VFR.  I've got an oil catch can installed on my car and it does a really good job.

[GreginDenver 125]

Here's a "before" pic of the Right Intake Valve of Cylinder #2

 

Here's an "after" pic of the Right Intake Valve of Cylinder #2

 

Here's a "before" pic of the Left Intake Valve of Cylinder #2

 

Here's an "after" pic of the Left Intake Valve of Cylinder #2

[Grum 383]

Wow, that's really interesting to see. I never thought that this could be an issue on the VFR as the intake valves are washed with intake fuel. Had that amount of build up effected its performance? Hard to believe in just 20,000miles. The longest mileage VFR I had did 94,000kms when sold, it's performance and fuel economy was superb!

 

Could it be an issue with the type of oil used? Has it ever been overfilled with oil? Is the engine fumey or burning oil? Has the bike done a lot of short runs?

 

I've just recently purchased a 2018 Mazda 3 with a 2.5ltr Direct Injection engine. From the day I purchased it I've been concerned for the Intake Valves carbon build up, as they have NO fuel wash. I can only hope that running fully synthetic oil, regular oil changes, and hopefully that Mazda may have designed into it some form of clever oil separation before the crankcase is vented back into the intake! Time will tell.

 

[GreginDenver 125]

25 minutes ago, Grum said:

Wow, that's really interesting to see. I never thought that this could be an issue on the VFR as the intake valves are washed with intake fuel. Had that amount of build up effected its performance? Hard to believe in just 20,000miles. The longest mileage VFR I had did 94,000kms when sold, it's performance and fuel economy was superb!

 

Could it be an issue with the type of oil used? Has it ever been overfilled with oil? Is the engine fumey or burning oil? Has the bike done a lot of short runs?

 

I've just recently purchased a 2018 Mazda 3 with a 2.5ltr Direct Injection engine. From the day I purchased it I've been concerned for the Intake Valves carbon build up, as they have NO fuel wash. I can only hope that running fully synthetic oil, regular oil changes, and hopefully that Mazda may have designed into it some form of clever oil separation before the crankcase is vented back into the intake! Time will tell.

 

All Direct Injection engines require periodic cleaning procedures to de-carbon the intake valves (removal of the intake manifold and air-powered media blasting of the intake valves, usually with walnut shell media).  Dealers don't want to talk about this but if you Google search the subject you'll find out the truth (the YouTube videos of guys doing their own walnut shell media blasting are actually pretty entertaining).  There's nothing you can do to prevent this from happening.  After about 30,000 to 40,000 miles (from new) your Mazda 3 intake valves will look like cancerous black death.

 

The truth of gasoline internal combustion engines: the intake valves do not run hot enough to burn off carbon, the exhaust valves do run hot enough to burn off carbon.

 

With regard to motorcycles, like my VFR: I'm pretty sure that motorcycles generate a greater amount of crankcase gases than cars due to their high-revving nature.  As long as you're running a VFR with all the factory OEM crankcase ventilation plumbing still connected there will be a lot of oil-heavy crankcase gas entering the airbox and going through the intake valves.  You're going to get some carbon buildup on the backsides of the intake valves.  Yes, an engine with port injection does benefit from the fuel washing the intake valves but this won't completely prevent carbon buildup.

[FJ12Ryder 291]

I think this is one of those things that will just have to happen. Maybe if you compared dyno readings

periodically so you could demonstrate that the carbon buildup is more than a superficial problem then

I would be more interested. Until then it is just one of the side effects of owning an ICE, although it does

make you wonder how those engines with 80,000 or 100,000 miles are even still running if it's a major

problem.

[GreginDenver 125]

19 minutes ago, FJ12Ryder said:

I think this is one of those things that will just have to happen. Maybe if you compared dyno readings

periodically so you could demonstrate that the carbon buildup is more than a superficial problem then

I would be more interested. Until then it is just one of the side effects of owning an ICE, although it does

make you wonder how those engines with 80,000 or 100,000 miles are even still running if it's a major

problem.

My guess is that over the lifetime of a (port injected) vehicle (like the VFR) the intake valves probably build up a certain amount of carbon and once it reaches a certain level of fouling the accumulation stops (or at least slows to almost nothing).   There's probably a balance of opposing forces that asserts itself at some point (injector wash vs. oily crankcase gases) and the amount of carbon on the backside of the valves stabilizes (or perhaps it's a better description to say that after the accumulation reaches a certain level the accumulation will then yo-yo back and forth over time between a minimum and maximum).

 

So, yes, I completely agree with you that the 80,000 or 100,000 mile VFR engines are very healthy.  I just wanted to experiment with bringing my intake valves back to "as new" clean to feel what that's like (I've also sent the injectors out to be professionally cleaned and evaluated).

 

But as I was discussing with Grum, this "balance of opposing forces" does not occur on Direct Injected engines.  It appears that these engines just continue to get worse and worse until their performance drops to a point where the owner can't stand it.

Edited May 11 by GreginDenver

[FJ12Ryder 291]

It's always interesting to see the results of people experimenting. Wasn't trying to denigrate your work at all.

But I just wondered if it wasn't more cosmetic than actually detrimental to engine performance. But it does

seem like the engine would perform better with the valves clean, they sure look like they would.

[Marvelicious 59]

So... on the subject of carbon fouling:

There is a fuel additive called polyetheramine or PEA. This is the stuff that is required in a certain concentration for qualification as "Top Tier Gasoline" and it's the active ingredient in Techron. This compound is one of the few things that will actually clean carbon fouling in a running engine. Seafoam is great against varnish and it's a pretty good fuel stabilizer, but it doesn't do much against carbon fouling.

 

This sort of runs down a number of PEA based fuel system cleaners...

https://shedheads.net/best-fuel-injector-cleaner

 

TLDR: Lucas Fuel Treatment is pretty good bang for your buck on fuel treatments, and it's packaged in sizes intended for commercial vehicles... Buy a gallon jug for under $25 and it's 400 gallons worth. Cheap enough to use it all the time.

 

[GreginDenver 125]

13 minutes ago, Marvelicious said:

So... on the subject of carbon fouling:

There is a fuel additive called polyetheramine or PEA. This is the stuff that is required in a certain concentration for qualification as "Top Tier Gasoline" and it's the active ingredient in Techron. This compound is one of the few things that will actually clean carbon fouling in a running engine.

Yes, agree completely, PEA is great stuff.  I'm using it to do the cleaning pictured above in this forum thread.  When you're applying it (PEA) directly, as I am in this case, you can see it reacting with the carbon buildup, it instantly foams and bubbles when it contacts the carbon.

[Marvelicious 59]

Ha! I'd never thought to apply it directly. I've got a long dormant project bike sitting with the heads off... I'll have to do a little experimenting just out of curiosity...

[rangemaster 80]

Having a 4th Gen means pulling the carbs occasionally. When the carbs are off it's easy to see down the intakes to the back side of the valves. It used to look like the photos above.  Ever since I plugged the airbox intake and put the small filter on the breather there's been no build up on the intake valves. They look almost identical to the exhaust. 

[BuzznerSuntrusts 485]

2 hours ago, rangemaster said:

Having a 4th Gen means pulling the carbs occasionally. When the carbs are off it's easy to see down the intakes to the back side of the valves. It used to look like the photos above.  Ever since I plugged the airbox intake and put the small filter on the breather there's been no build up on the intake valves. They look almost identical to the exhaust. 

That’s great to hear! That’s one thing I did last year, put a filter on the breather and block the air box. I also use Costco gas whenever I can cause its top tier. I haven’t ever taken a look at my ‘99 104,000 mile intake valves. 

[squirrelman 90]

10 hours ago, GreginDenver said:

Yes, agree completely, PEA is great stuff.  I'm using it to do the cleaning pictured above in this forum thread.  When you're applying it (PEA) directly, as I am in this case, you can see it reacting with the carbon buildup, it instantly foams and bubbles when it contacts the carbon.

suggest reading the MSDS on this (or any) product before using.

[GreginDenver 125]

1 hour ago, squirrelman said:

suggest reading the MSDS on this (or any) product before using.

And never, ever drive a car or motorcycle on public roads... average 35,000 deaths per year out there (U.S.).

[GreginDenver 125]

Here's a "before" pic of the Right Intake Valve of Cylinder #1

 

Here's an "after" pic of the Right Intake Valve of Cylinder #1

 

Here's a "before" pic of the Left Intake Valve of Cylinder #1

 

Here's an "after" pic of the Left Intake Valve of Cylinder #1

 

Here's a "before" pic of the Right Intake Valve of Cylinder #4

 

Here's an "after" pic of the Right Intake Valve of Cylinder #4

 

Here's a "before" pic of the Left Intake Valve of Cylinder #4

 

Here's an "after" pic of the Left Intake Valve of Cylinder #4

[GreginDenver 125]

Now that I've posted up the condition pictures of all 8 intake valves here are some evaluation/thoughts…

(I think that people who have a lot of experience wrenching on engines might find this interesting so hang in there, I'm going somewhere with this...)

 

First, my main reason for tearing into what I think of as "The Stack" (fuel tank/airbox/throttle body) again was to gain access to the fuel injectors (just saying that cleaning the intake valves wasn't my primary purpose in the tear-down).

 

Backstory: I've owned this bike (a '99 5th Gen) for 2 and 1/2 years now.   When I purchased the bike I treated it to a pretty thorough refurbishment because I was really excited about finally owning a 5th Gen VFR and wanted my experience of the bike as be as close to "like-new condition" as I could get.  But for some reason (and I can't remember why) I didn't send the injectors out to be professionally cleaned and evaluated.  I've been kicking myself about this for a while now.

 

Not long after I posted up this forum thread Grum brought up the intake valve "fuel-washing" effect of the VFR's port injection which should help to keep some of the carbon buildup off of the backside of the intake valves.   When Grum reminded me about this effect I realized that the amount of carbon buildup I was observing on the backside of my intake valves was actually telling me good bit of information about the performance of each cylinder's fuel injector.

 

Here are my findings: if you look back up in this thread at the individual intake valve pictures I posted of Cylinder #3 and Cylinder #2 you'll notice these intake valves are very dirty.  Then when you look at the pictures of Cylinder #1 and Cylinder #4 you'll notice that these intake valves are pretty clean. 

 

Having seen this I'm predicting that when the injector cleaning report comes back to me from the injector specialist later this week it will say that the fuel injectors for #3 and #4 were not spraying very well, and the fuel injectors for #1 and #4 were spraying normally.

 

We'll see how that prediction turns out, but I'm reasoning that the intake valve fuel-washing effect will only protect your VFR's intake valves from carbon buildup if the fuel injectors are spraying the correct amount of fuel with the correct/proper spray pattern.  Poor output or a messed up spray pattern will probably result in more carbon buildup.

[squirrelman 90]

alot of great stuff miracle-working chemicals cause cancer, if you care. MEK for example.

[FJ12Ryder 291]

I simply don't know about this "intake fuel washing effect" with misting/fogging injectors.

 

Seems to me that the people talking about all the carbon buildup on the valves, are also the ones

selling "stuff" to clean all that nasty buildup off.

 

[GreginDenver 125]

14 minutes ago, FJ12Ryder said:

I simply don't know about this "intake fuel washing effect" with misting/fogging injectors.

 

Seems to me that the people talking about all the carbon buildup on the valves, are also the ones

selling "stuff" to clean all that nasty buildup off.

 

You're saying that carbon buildup belongs in the same category as Flat Earth and Sasquatch?

[FJ12Ryder 291]

Dunno, kind of leaning towards Douglas Adams' "Mostly Harmless". Bikes and cars run lots more miles than

you would think likely if it was a really bad thing. And seems like diesel engines would grind to a halt with the

direct injection in their engines.

 

Not saying it doesn't happen, and not having it is good, but not sure whether the issue isn't mostly cosmetic.

[jeremyr62 25]

Those valves in the before condition look fine to me.  Seen much worse. Riding a bike in the manner it was intended will keep valves pretty clear of crap in my experience.