bad mileage, bad t-stat?

So I'm only getting in the 20's for MPG. I have been making shorter trips, and I'm a big guy (6-5, 230), but c'mon. Should be near 40 I'd think.

Noticed today that the bike doesn't heat up all the way to work. The temp gauge never goes over the very bottom line of the temp range on the gauge. I assume that's too low and I'm going to need to look at the thermostat. It also would make sense that the bike isn't getting hot so my mileage is staying low.

Can someone confirm, and if you've done it, how many hours? I bought this bike for mileage, so this isn't helping!

Thanks.

 

Joel,
We are the same size and I get about 39 mpg commuting. Here is a write up I did on changing a T-Stat LINK

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As info, most 3-4G bikes don't seem to get very far above the first hash line on the temp gauge unless subjected to stop and go traffic or temperatures in the 90+ degree range.

I would look elsewhere for your poor fuel mileage problem... Plugs? Bad gas? Really dirty air filter? Check the obvious mileage suckers before tearing into the bike...

 

I'm with VT. I have a 97, I'm 6'6" and 240 and I get in the 40's. Also my bike stays cool like you say unless it's in the 90's out. Fortunately I moved to the sicks so stop and go isn't an issue unless I venture into the city.

 

hmm

Thanks for the info guys.

The plugs were replaced this spring (May), carbs were cleaned as well. K&N filter was put in last year and cleaned this spring. Oil is clean, tires are at about 36 front and 40 rear psi.

The only other variable on this bike is that the carbs were jetted to match the 2 Brothers pipe before I got it. But that's a little much for a jet difference.

The bike is sitting at the low bar on the temp gauge within 3-4 miles in the mornings, so maybe the t-stat isn't all the way stuck open. I would hate to tear it down without having to (I bought this bike to replace my 86 VFR for the summer as it gets torn down).

Open to ideas. One other thought - my commute is only 6 miles each way, and I have to get on it at least once each way to merge into traffic, sometimes more. Perhaps it's the riding style? I'm not beating it though, I'm a newer rider and I'm incredibly cautious overall.

 

I had a simular problem on my 04. The bike would run as low as 145 F on cool nights/mornings. I replaced the t-stat and now the coldest the bike runs is 170. Warms up much quicker and runs smoother. My gas milage went up 5 mpg! I was getting 38, but now about 45 on the freeway. I'm 5'7", 150 lbs. When it runs too cold, it's on the warm up program, and runs richer. Like many said check other areas of the bike too. But sounds like the t-stat.

 

its not ur size...im 6'6 245lbs and im getting and avg of 44 mpg

 

Answer has been provided by OP:

"carbs were jetted to match the 2 Brothers pipe".

That, plus the ultra-short commute will not ever allow the bike to "fully" warm up = poor fuel mileage.

I have a 2 Bros pipe on mine, and it was not re-jetted. For the most part this is not necessary with just a pipe. A full exhaust, maybe, but not a slip-on.

Changing the t-stat is relatively easy and straightforward, so if you want to try this, by all means, do it. It might even help.

But I am of a mind to think that you will not see the benefits that you are seeking.

 

Joel
VT may be on the right track. It didn't register with me this morning that you had a 3/4 gen bike.

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Well, I filled up last night. 28.8 mpg. That seems awful. My '97 Prelude does 25 if I just locally commute and it's got almost 200 hp and a lot more weight. I'm OK with less than 40, but less than 30?

 

I haven't needed to choke for a start in the past 2 weeks (since summer started feeling like summer). That's a good thing to check - thanks for the tip (although when I pull the lever down, it does work and the engine dies quickly).

Brakes are very low and I'm putting on new pads this week. I'll check those. I can hear a slight drag on them occasionally, but it's faint, and the bike rolls fine.

The bike is a 96.

I'll clean the air filter again when I check the choke assembly.

I really appreciate the help on this, everyone!

Only other variable is my clutch is starting to get tired (late in the lever release I get the interaction), but it's certainly not bad yet.

 

Are you running stock gearing? If you have gone up on the number of teethon the rear or down on the number of teeth on the front, that will have an affect on MPG. Having to "get on it" will also not help any at all.When I had my 93, I got terrible mpg on short commutes, but I got in the 40's on longer trips as longs as I didn't hammer on it and I was +2 on the rear sprocket. Before my sprocket change, I was getting about 50 mpg on anything other than in-town riding.

 

Hmm, I do have 1 tooth difference on the front sprocket per the previous owner. He gave me the stock front gear. That's an easy change, and something I will try. This thing is quick enough for me without the mods.

 

Wow - all sorts of stuff keeps coming up!

My bike always needs the choke to start, no matter the temperature. After about 15-30 seconds, she's ready to run.

Sounds like a stuck/sticky choke slider, in addition to the gearing change (stock is 16/43) in addition to the non-stock jetting.

My '96 returns about 45 mpg all the time, and has no mods other than the slip-on (which by itself should slightly increase efficiency, hence better fuel economy).

BTW - the front brake pads take about 15 minutes to change out. Be sure to pull the cover off the reservoir first (and surround it with a rag or towel), and push the pistons back in by forcing the caliper against the rotor. A C-clamp is not necessary. Pay attention that you do not overfill the reservoir when retracting the pistons!!!