Alright guys I need some help... I was on the way home from work last night on my trusty 2001 Yamaha R1 and it suddenly completely lost power, but only low down. I had to keep it at about 1/3 throttle at junctions and traffic lights just to keep it from stalling, and even then it was barely revving over idle with 30 percent throttle.

In order to accelerate at all, I had to have it the throttle pinned in first and second gear or it would again stall. Bizarrely once it got clear of about 4,000rpm, which was difficult, it returned to its normal creamy self.

Even weirder is it seemed to clear up literally as I pulled into my moobaan and now seems to run fine. Any ideas, I could do without getting stranded if it does it again?

The first thing to do is drain the fuel tank and then clean the carburetors. The most likely cause of your problem is some kind of contaminant in the fuel. Did you use a different fuel or petrol station lately? It probably blocked a jet but eventually got passed through as performance returned to normal.

However it is possible the motorcycle has an electrical misfire on one cylinder. Check your spark plugs boots, leads and even for a fouled or dirty plug. Happy hunting and good luck, let us know if you find something.

I investigated the carburetors as you instructed and found that the carburetor floats are covered with a sticky gel-like substance, what could that be?

...what could that be?

It is highly likey a fuel residue, by-product / contamination...I feel a Benzine/Gasahol "fuel war debate" about to start up again... :-)

Could you tell us what fuel/s you use and if you "mix" 95/91 Benzine and/or 95 Gasahol and for how long.

Depends also if you use a regular fuel station and it's "location and size" - some of the older fuel stations that do not get the volume turn-over of their storage fuels and they do have examples of more "contaminates and water" in the tanks

Your 2001 R1 is an older model and carb fed so If I had her I would give her a full fuel system clean out and syncro the carbs again, get a proper dyno tune and only run her only on Benzine (but that is just my opinion as she is a "supebike" so best to run her on the good stuff) regardless of the fact that she can digest the new Gasahol.

What difference will the odd circa 200 baht difference per tank make when your trying to run an R1 at her optimum = F all.

I run my 2011 Ninja on 95 Gasahol the majority of the time and throw the odd tank of 95/91 Benzine in her from time to time (if I pass a fuel station that has it)...but she is Fuel Injected and less prone to the fuel variables that the carb bikes experience. No problems to date...

Good luck and ride safe

SD

The sticky gel-like substance on your carburetor floats is likely the result of using gasohol, but I never seen a float that had sticky-gel like substance... Did you fill up your motorcycle with E20 or E85? With that I can understand the fast reaction to the ethanol... but with regular E10 fuel it should take months before a float gets damaged...

Anyway repair is possible, Mikuni who actually makes the BST36 carburetor in Thailand has a float replacement that is ethanol resistant...

I don't want to start a discussion about the gasohol, but believe THAT is the PROBLEM and nothing else.

Very likely, the source of the problem, is the ethanol in the fuel – but with an E10 fuel your motorcycle probably needs to be stored for months to generate something what could look like a sticky-gel like substance.

But read the posts, first Simpleme says that last night he had the problem, then Thaidesign, told him to clean the carburetor...the next day Simpleme tells us that he found that the carburetor float was covered with sticky-gel substance.... That is 3 or 4 days, if I put some simple plastic non-automotive part of plastic (say a plastic cap of a 1.25L. Coke bottle) in a liter of E10 gasohol fuel and see what happens I maybe get effects I can see with the naked eye after two-weeks...

If the OP told us that he by mistake fill-up E20 or E85 (respectively 20% and 85% Ethanol) I could understand the sticky-gel much easier...