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What is the explanation for carbon build-up, engine meltdown, burned valves, scored cylinders, etc, especially when ridden gently then?

I can't see how running a strong fuel system cleaner can be blamed for numerous tanks of poor fuel economy.

Try Techron next time (if there is a next time).
What is the explanation for my non engine meltdown?:)
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The only engine meltdowns I've seen on here happened shortly after botched valve adjustments that nobody wants to admit to. Or running engine mods such as complete exhaust systems with a poor fuel mixture retune.
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Fuel cleaner has no/ poor energy density compared to actual fuel and I don't run my tank dry every time so it took a few fill ups to get rid of it all.
 

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Discussion Starter #22
Any recent mods or service work. Valve adjustment?
I used a small amount of fuel additive once and it decreased my fuel economy for three tanks. Never again.
Last mod was installing a Delkevic slip on last fall, but I have quite a few trouble-free miles on the bike since then and have only recently noticed the issues, which came on quite suddenly and were immediately noticeable.
And I was having the hesitation and increase in gas consumption for at least a couple of weeks before I added any additive to the gas.
The fact that it hasn't made any difference at all so far is what's leading me to think it might be some kind of sensor problem, like the O2 sensor or the throttle position sensor rather than a fuel issue.
If I run more B-12 through it this weekend with still no noticeable change, I'll pull and check the spark plug and start turning my attention to the myriad of mechanical possibilities that could be causing it, but I'm hoping I just haven't run ENOUGH B-12 through the injectors yet and it's just stubborn deposits of some kind.
 

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What is the explanation for my non engine meltdown?:)
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The only engine meltdowns I've seen on here happened shortly after botched valve adjustments that nobody wants to admit to. Or running engine mods such as complete exhaust systems with a poor fuel mixture retune.
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Fuel cleaner has no/ poor energy density compared to actual fuel and I don't run my tank dry every time so it took a few fill ups to get rid of it all.
Not sure about your good fortune, but there are more than a few instances here where there was some type of unexplained meltdown. Carbon build-up and burned valves have been found upon disassembly.

At a 128:1 ration (1oz per gal) I can't see it taking 3 tanks to clear the system. If you really want the full benefit - run the entire tank without diluting it.

You do what works for you, but I can't see the downside to removing deposits from the intake valves and combustion chamber once per season with a strong fuel system cleaner like Techron Concentrate.
 

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Discussion Starter #24
Depending on how you ride, running a strong fuel system cleaner in the CBR may prevent some serious issues.

The CBR appears to have unusual engine problems when ridden lightly and not revved. Deposits build-up in the combustion chamber and intake valves and lead to detonation, burned valves, and engine damage.

None of this has been proven absolutely, but everything I've encountered here over the last few years suggests that deposits could be the cause.

I can't say I've ever noticed any mileage drop from running Techron, but it could be possible. Not sure how it could continue after the treated gas had been consumed though.
You could be onto something there jkv357. For the first few years of ownership I was anything but aggressive with the RPMs. As I've become more familiar with the bike over time I've been pushing the engine a lot more and spending most of my time up in the "sweet spot" from 8000RPM to just short of redline. It could be that years of deposit build-up are only now becoming noticed because I'm wringing the engine out a lot more in all gears. Perhaps the hesitation has been present for a while now and I was mistaking it for lugging at lower RPMs.
If that's the case it may take more than a couple of tanks of treated gas to eliminate it all.
I don't think the unusual increase in gas consumption can be blamed entirely on riding more aggressively in higher RPMs though. It's so pronounced and noticeable from the good mileage I've always had that something else must be the cause.
My valves were well within spec at the 600 mile check and the bike has been absolutely trouble-free since I drove it home from the dealer, so this sudden onset of weirdness is a real head-scratcher.
 

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Not sure about your good fortune, but there are more than a few instances here where there was some type of unexplained meltdown. Carbon build-up and burned valves have been found upon disassembly.
Incorrect valve measurement and adjustment left them way too tight. This engine is very tricky even for Honda dealer techs that don't see them often or are doing their first one because of the fingers that reach down inside of the bucket to the shim.
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We also see a vast number of users running aftermarket exhausts with no dyno tune that have no idea how far off the map they are.
 

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I can attest that general light riding does not harm these bikes, as long as they aren't lugged. I generally accelerate/shift/cruise in the 4-5k range, and my bike is trouble free. I also have a slip-on exhaust without a fuel controller and have had no issues. My pistons and valves are squeaky clean (I also run 2 ounces of B12 through a full tank every 3k miles or so), I consume no oil, and my valves are always in spec. I will also say that the occasional spirited ride is good for the bike and the soul. :)

But, if a noticeable drop in mileage is seen as a direct result of a fuel additive, either the additive was total crap, or you added way too much. So much you diluted the fuel and are now reducing your combustable power. (an ounce or two of less explosive cleaner in 2.5-3 gallons is hardly noticeable)
 

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^I can confirm the above. My bike never sees the rev limiter and I also shift as early as possible in city traffic and so far no problems with the bike in 33,000km (apart from the spark plug and I still think changing it was unnecessary and they ripped me off with that...). Over here people very rarely use fuel cleaners (actually I had never even heard of that stuff before joining this forum) and it's generally considered to be useless and more of a money grab than anything. However we might have different fuel and a different climate here.
 

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Discussion Starter #28
Well, I think a lot of new owners pamper their bikes way too much if this forum is any indication. I'd never heard of Seafoam before joining this forum and the frequent debates about regular gas vs premium in a bike that's clearly designed to use regular gas have always perplexed me. It also constantly amazes me how many people with brand new bikes are chomping at the bit to add numerous performance "mods" before they've even logged their first 1000 miles. I mean jeez, if you wanted the performance of a 650cc motorcycle why didn't you just buy one in the first place?
My previous bike was a Ninja250R that was purchased after a laundry list of performance mods were done to it by a local gearhead who was basically attempting to wring every last ounce of performance out of it's 250cc twin cylinder engine possible, he spent hundreds of dollars on pod filters, full exhaust replacement, carb refinements and dyno tuning after every mod performed. While it was quite the little screamer of a bike, I found that all those mods increased maintenance duties tenfold and only made any small variation in performance a cause for concern. The darn thing was just too much work to maintain for it's comparatively small increase in overall performance.
The CBR250R, on the other hand, has always struck me as a bike that was designed about as well as a 250 could be from the get-go. I vowed to keep things as stock as possible and not succumb to trying to make it something it's not. It's about as "bulletproof" and maintenence-free as a small displacement bike can be. From day one it has met or exceeded my expectations and perfectly suits my riding style much better than the heavily modded Ninja250R that was trying to be something it wasn't really designed to be. After a particularly close call with an errant deer in the road that left me with deer snot on my jacket sleeve (it was REALLY close) I added a louder slip-on exhaust to help announce my presence to the animal world, but that's been the extent of my mods to the bike.
It's been so incredibly reliable and predictable since I purchased it in 2011 that this sudden onset of something being a bit "off" in the throttle response and MPG was instantly noticeable, but it also leads me to believe that once it's found the cause will be inexpensive and simple to rectify. Still hoping it's just a case of allowing the additive to work fully, but I certainly appreciate all your input on the matter. Joining this forum was the second best decision I've made after dumping the Ninja and buying my CBR250R.
 

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ive also never used fuel additives/cleaners etc
[7 road hondas] which all ran 'perfectly'..
then again all were ridden year-round..

cbr250r/cbr300r's ethanol free 91ron [86pon]..
with or without lv carbon slip-ons

all enjoyed a good clean out occasionally
once warmed up, thru gears to high revs
then back down engine braking..
motorcycles are made for the road,
not just, putting along with the cars..
these hondas have 10krpm + rev limiters,
meaning a designed in expectation to use
carefully selected gear ratios with available revs..

the 'middle way' works here..
riding sensibly according to conditions etc,
but including the occasional strong 'clean out'..
for riders natural secretion of adrenaline,
endorphins and dopamine can/should be
another addition to riding pleasure,,
not an excuse for addiction..
[to each their own, or course]
 

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Discussion Starter #30
I think I'm finally starting to see some results from the fuel treatment. The weather has been abysmal here the last 3 days, with rain and temps only in the 50s, but today was more seasonable and I was able to take the bike out for a "spirited" 3-hour ride. By the end of the ride I was starting to notice a lessening of the hesitation in all gears, but I still seem to have flat spots in the throttle response at certain RPMs. Mostly 5000 to 7000, but it's definitely improved at higher revs.
My mileage has dramatically improved. I barely lost a bar on the gas gauge in an hour of hard riding, so gas usage seems to be returning to something much closer to normal.
Almost time for another fill-up, so perhaps a 3rd treated tank of gas (I think I'll throw in some Techron this time) will be all that's needed to clean out any deposits that remain. Keeping my fingers crossed.
 

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Are you running ethanol-free 87 octane?

Ethanol will drop mileage, and some companies use more than others. Higher octane than needed will cost mileage as well.

If you get gas the same place every time you may want to try another brand to see if there is any change.
 

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Discussion Starter #32
Are you running ethanol-free 87 octane?

Ethanol will drop mileage, and some companies use more than others. Higher octane than needed will cost mileage as well.

If you get gas the same place every time you may want to try another brand to see if there is any change.
I'm running regular 87 octane, but ethanol-free is really hard to find around here.
I generally gas up at the same place in the car, but because of the not-so-accurate gas gauge in the CBR, I find myself filling up with whatever brand is available when that last bar starts flashing and it's usually far from my usual places. I do try to stick to major brands like Mobil or Shell for the bike whenever possible though.
I remember having to fill up with premium gas once when I first got the bike and the bike went through it like there was a hole in the tank. I don't know why there are still people who argue that Premium is somehow better than the 87 octane the owner's manual recommends. One tank is all it takes to disprove that misguided notion.
Since this is the first time I've ever run any kind of fuel system cleaner since I got the bike in 2011, I'm really starting to think that it's just years of residue in the EFI and possibly some moisture in the fuel system that's been the cause of the symptoms I've been experiencing and all it needed was a good cleaning. Or perhaps I just got a really bad tank of gas recently. At least at the moment the lessening severity of the symptoms seem to be indicating that.
 

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basically, 'premium' means 'paying extra'..
high octane rating means slower burning fuel..
slower burning fuel is used in high performance
engines to prevent pre-ignition [engine damage]..

our engines combustion chamber conditions
incl 10.7:1 cr etc, are designed for fast burning petrol,
ie lower octane 'regular' 91ron/87pon..

if opting for a non catalytic converter slip-on
'premium' additives are even less relevant..
 

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I don't know why there are still people who argue that Premium is somehow better than the 87 octane the owner's manual recommends. One tank is all it takes to disprove that misguided notion.
Because the add campaigns have deeply implanted the feeling that premium fuel gives more POWAAAA. There is a ton of 125 rider kiddies out here who put premium in their tiny engines because it gives them at least one extra HP.:wink2:
If you tell them that this fuel is rather decreasing performance and does only make sense in racing engines with high compression they don't believe it or outright tell you they don't care. Premium it has to be because more expensive means better!
Isn't propaganda, er I mean advertisement great?:grin2:
 

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Discussion Starter #35
Because the add campaigns have deeply implanted the feeling that premium fuel gives more POWAAAA. There is a ton of 125 rider kiddies out here who put premium in their tiny engines because it gives them at least one extra HP.:wink2:
If you tell them that this fuel is rather decreasing performance and does only make sense in racing engines with high compression they don't believe it or outright tell you they don't care. Premium it has to be because more expensive means better!
Isn't propaganda, er I mean advertisement great?:grin2:
It is pretty incredible that advertisements from the 1960s that promised a "tiger in your tank" (with free fuzzy "tiger tails" you could hang on your filler spout) still live on in the consciousness of the new millennium and can still influence the thinking of kids who hadn't even been born for decades yet...LOL.
 

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Discussion Starter #38
does the issue got fixed? i got same problem
Yeah, pretty much. 3 tanks of gas with additive either cleaned a build-up of gunk in the fuel system or helped whatever water may have been in there dry up finally.
Run a few tanks of gas with Seafoam, B-12 Chemtool or some other additive added and see if it doesn't clear things up before you start taking anything apart.
 
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