Slight highway hesitation

[RaWarrior]

My Max has this intermittent, seemingly randomly issue. At highway speeds(anything over about 55 or so), a "lag" shows up in the throttle. Like you're holding steady at say 70mph, and start to slowly roll on the gas. I'll roll on a little, and nothing happens. Roll some more, nothing. A little more, and all of a sudden it comes to life and takes off with a burst of power. This problem comes and goes pretty randomly, and lasts a pretty random amount of time also. Sometimes for a tank or two, other times for only a minute. Then it may go several tanks and run perfectly. Setting the t-boost to 3k instead of 6k(opening it) always stops the hesitation instantly.

My Magna had this problem, but at all speeds and it turned out to be a bad(arcing) plug wire. The Max got new wires/caps/coils/plugs last winter so that can't be it, and leads me to think it must be a fuel issue.

Thinking it was maybe some water contaminated gas that's hanging around in the tank, I added some k-100(a cure-all type thing similar to sea foam) to the tank of regular 87 gas. The hesitation stopped and did not happen again for the remainder of the tank. I filled up again(87) and the problem returned. More watery gas? Added some sea-foam this time. Problem stopped. Since both K-100 and sea foam claim to raise octane, I thought maybe that was the issue. Filled up with 89, no additive. Ran great for the whole tank(and at least subjectively it ran smoother). I filled up with 87 next time and the problem returned just a couple minutes after filling up. Back to 89, ran great again.

The problem had not returned for 3-4 tanks, all 89 until I was forced to fill up at a dodgy, hole-in-the-wall gas station that still had mechanical "odometer" dials on the pumps. They were out of regular, so I had no choice but "super". Problem almost instantly returned and the bike seemed noticeably less powerful. I ran that tank through almost to fumes, and then just for the hell of it I put in 93 ultra at the local Sunoco. Problem vanished again, ran great, and now my idle was 200 rpm higher than before on the hi-test stuff.

Through all of this the bike is 100% rideable, idles fine, and once you get on it past the "dead spot", it takes off strong as always. It is annoying though when highway cruising, since it doesn't want to hold a steady speed.

Any thoughts on this? The randomness of the problem makes it difficult to tell if any of the additives/octane changes were affecting the problem, or were just coincidences. The engine is stock except for Stage 1 jetting, K&N filter, and holeshot slip-ons.

 

[gamorg02]

it sounds like bad fuel man. u've done a lot of testing and that sounds like a legit conclusion. keep with the good fuel, crap fuel wreaks havoc on bikes.

 

[RaWarrior]

Know of any compact water/fuel filters? I'd like to put one on the bike but they're all fairly large canister types, usually with an V8 oil filter sized spin on canister. Haven't had any luck finding a smaller one.

The other thought I had was that if ethanol content varies depending on what octane you get, which is maybe why the bike seems to run better on "premium" grades. I've heard around that some gas station chains put less or no ethanol in their hi-test grades, I have no idea if that's true or not. There's one station around that advertises ethanol-free gas, but it also charges a 20 cent premium over the current "going rate". It's kinda out of the way, and the extra price means I rarely ever fill up there.

But then again 87 is by far the most common grade, so it's a lot more likely the fuel in the tanks is fresher since it turns around a lot faster.

I've noticed that it seems the overall quality of fuels around here has gone down....I've gotten visibly cloudy fuel out of name-brand gas stations more than once when I fill up cans for the "toys". Every so often my truck runs like ass after filling up, and for the remainder of the tank. Quad carbs seem to be very temperamental....

 

[naughtyG]

I've had a very very similar issue and thought the bike was actually misfiring. I ran some SeaFoam in the next tank and the problem went away. Seems more than likely that it is bad fuel, and I think that the 87 we find here in FL may often contain more than 10% ethanol as the sticker says - it's a cheap way to make more profit for gas distributors and who's gonna find out unless the gas gets tested?

 

[RaWarrior]

I wish there was a easy way to test fuel to determine actual alcohol content, and get some hard data about which chains use more/less ethanol, and if the content varies by what grade you buy.

I know ethanol-free is available in large quantities....at the marina where I work we got ethanol-free fuel loads daily from a local family owned fuel company.

Naughty, what octane do you run? I'm not trying to start a "regular vs premium" debate again, but if you seem to get higher quality fuel with premium I'll get that just to avoid watery regular. I can't tell if the subjectively smoother operation with 89 was due to octane, or just a lack of water, or less ethanol, or a combination of all three.

Maybe I'll keep a small bottle of sea-foam in the sandwich-box tool kit to add when it acts up.

 

[naughtyG]

I've been running '87 constantly, from many different filling stations, but always E10 as I can't find a single one without here in Orlando (or in Trampa for that matter..)

I think my problem is a little more serious than just bad fuel though, see my other thread :bang head:

 

[BrianK]

Regarding fuel additives, I've had great success this past year with BG Products Fuel Supplement #203. It only needs to be used every 3000 to 5000 miles.

I just finished a year long test using the BG #203 fuel supplement in my 85' VMax after reading about it in the VMOA Magazine last summer. The bike has run great all year and the best part - No carb cleaning required all year now!

In the article the writer (a chemist) compared WD40, Sea Foam, BG #201 (super charge II) and other additives and noted that the only additive currently available that actually contain chemicals that cleans and maintains the CV carb systems are the BG Products fuel additives.

BG's #201 (super charge II) has to be added every tank full, but the BG #203 (CF5) is only added every 3K to 5K miles.

I had spoken with my local BG Products "tech guy" here in Houston, a rider himself and he guided me towards the BG #203 so I didn't have to put in in so often. He also said, that it was the same chemicals as the #201, but at a stronger ratio mix.

Good Luck,

Bdk2272-5125

 

[RaWarrior]

Sounds interesting, though when I called the 4 local "BG service centers", three didn't know what I was talking about(had never heard of BG), and one said that he didn't carry stock for reselling, only for his own shop use. I've heard of the "44K" stuff as being up there with sea-foam for "working miracles", though I've never seen it around here.

From their descriptions at least, it seems like all of their fuel additives claim to all do the same thing, so I'm not sure what the difference between them all is.