Hi! I've got a question about poor fuel economy for a (new-to-me) 1999 Thunderbird Sport.
I have been getting 27.5 MPG on average on my TBS. The majority by far of my driving is highway. Like 60-70 mph. I read that I should be getting 31-42 MPG, with an average of 38.
No visible leaks from the fuel system. A relative suggested checking the spark plugs and replacing the fuel lines and crimps. Not a bad idea, I suppose. But is there anything else I should be looking at?
I'd run some Seafoam through it to see if that might help improve the mileage before tearing into anything. You did not mention how the bike was set up (i.e. windscreen/flyscreen/naked, heavy/bulky accessories, rider/passenger weight, tire inflation, type of fuel used, etc.) but anything that causes extra weight and/or airdrag should be addressed if the mileage doesn't improve after cleaning out the carbs. I weigh about 260 lbs and get about 40 mpg with my T-bird most of the time. If I add my wife or daughter, or some luggage, my mileage drops to around 30-35 mpg. I also use non-ethanol unleaded fuel (only available at 3 gas stations in my area) in my bike and my 2006 Nissan Frontier because I get better mileage and performance than with ethanol-mixed fuels. If/when the non-ethanol fuel becomes unavailable, I'm going to be in trouble.
Sorry, it's naked with no accessories. I weigh 185 lbs. Tire inflation is whatever the manual says, checked weekly. I use brand-name 89 octane gasoline. I frequently add a little Sea Foam to the gas tank. The carbs were cleaned and synced by a [mediocre] mechanic two months ago.
From what you wrote, it seems like something is wrong with my bike. I will try more Sea Foam in the meantime.
I used to fill up with name-brand 89 octane gas (with ethanol) in my Nissan and I was only getting 15-18 mpg. I ran 2 bottles of seafoam through it and switched over to the non-ethanol 89 octane fuel and now I get 19-21 mpg. Not a stellar improvement in mileage but I found that performance is noticeably improved. Same story with my T-bird. Non-ethanol fuel is hard to find and usually cost 10-20 cents more per gallon, but I am convinced that it makes a big difference. Perhaps going to a higher octane fuel will help?
The bike is stock, so yes I have the stock airbox. I should've mentioned that it only has 6500 miles, but it had been sitting in a garage for a while when I bought it.
That is odd as mine with ignition advance, green cams, pods and 160 main jets gets 40-45mpg on the highway and I'm 220 lbs. My dads 97 with accessories and windshield gets 37mpg.
Have you pulled the plugs to see if you are running rich?
So these are all good tips. I will check the plugs in the next day or two.
The air filter, from what I've read, is really hard to get at. It's only got 6500 miles on it, and I can't imagine it would have disintegrated from sitting. But maybe you're right, and I don't mind checking it out if it's not an all-day event.
While the fuel system sounds like an obvious place to look, there are several other possible causes. One thing often overlooked is the cooling system. If the bike is running too cold it will put a real dent in the fuel mileage. Likewise plugs in the wrong heat range. Oil that is too heavy can also reduce mileage, but not as dramatically. Finally, a sticking caliper can cause brake drag, and this can be intermittent, so having checked it doesn't mean it won't stick again. Of couse, wheel bearings and chain need to be moving freely, but I am sure you have probably already checked those.
running right/in tune you should/could easily get 50 miles pg cruising at 60-65..I do and I weigh 210.....the stock foam air filter will be completely degraded by now, it must be replaced immediatley, if it has'nt already been......put a k and n in it..as said b4 , pull the plugs for a look too...
So I pulled only the plug leads from the spark plugs. I didn't realize that I wouldn't be able to remove the plugs themselves without some special-a$$ tools. But it it gets really "interesting" anyway.
Cylinder 1 (left): nothing fishy.
Cylinder 3 (right): I put the plug socket wrench in there and was surprised to see (what I believe to be) engine oil on the wrench when I extract it.
Cylinder 2 (center): I pull the lead, and it is soaked with (what I believe to be) engine oil. I think the chamber is flooded with oil, but who can see anything in there due to it's position directly under the frame.
Unless someone convinces me otherwise, I am going to bring this thing to a dealer for repair. I can't believe I've been driving it, but then again, I guess I'll have to drive it to the dealer.
Installing the cam cover gasket requires quite a bit of care and finesse.
the part that seals around the plug sockets is especially challenging.
If you are a patient person and like wrenching on your own stuff, it's not so difficult.
If you are going to pay a Dealer to do that, get the valves adjusted while they are in there. And make sure to check their work. A sloppy mechanic could leave it with the same problem.
I just had the valves adjusted a month ago by the [mediocre] mechanic I mentioned in my first post. I suspect that this may be his doing. Thank you very much for the info.
lol...guess I could if I were in the motorcycle repair business. Just do what I did. Get the Haynes manual and do it yourself. It's not that difficult and it's good to know your way around your own bike.
I'm getting 52 mpg so something is up with yours-mind you, UK petrol is higher octane. I regularly clean the carbs with fuel additive and pull them once in a while to make sure they're clean-they always are.
I have Mikunis on mine and I guess you have Keihins on yours. Keihins are meant to produce better mpg.
Cam cover gasket replaced. New plugs because the old ones were fouled from the oil. They also figured out that one of the ignition coils was faulty, so they replaced that. Some other small tweaks to tune it right and ...
It's running fantastic now. Sounds totally different. Power is much more consistent in lower gears. I had nothing to compare to before since the bike is new to me, and I never rode a Triumph triple before. Before I was quietly wondering why anyone liked this motorcycle at all, but now I get it.
I will check fuel economy and report back to wrap up this thread.
Same thing happened to me when I got mine (sort of). It wasn't jetted correctly, running too lean and couldn't hardly get it past 85. It had no top end.
All of that is fixed now and I can't imagine having a bike other than this one.
Anyway, I'm going riding tomorrow. I might go down to Rosharon or even Galveston if the weather is nice. Have not been to Angleton in a while for an Anaheim burger in a while....I'm over due for one.
Beaumont is just a hop, skip, and a jump away. ANDDDDDD... Wait for it..... My igniter finally arrived today from the UK so HOPEFULLY my bike will be back running tomorrow afternoon.. *Fingers crossed*
lol....I only ride crazy when I'm by myself. In a group I like to keep it at the speed limit or 5-10 mph over.
Anyway, looks like we've hijacked this thread so I started a new one for an April Fools Day ride this Sunday here: April Fools Day Ride 01 April 2012
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Triumph Rat Motorcycle Forums
3.9M posts
167.7K members
Since 2002
A forum community dedicated to Triumph Motorcycle owners and enthusiasts. Come join the discussion about performance, racing, cafe racers, bobbers, riding, modifications, troubleshooting, maintenance, and more!