| Author | Message | ||
     Valvesprung |
Have now worked through two tanks since I got my '97 S3 on the road. I seem to be getting 100-110 miles to the reserve. No other ridability symptoms. Seems to make good power, and pull smooth and consistently. No flat spots. No rich smoking, and no leaks. Also seems to diesel slightly on shut down. Not much, but does give a sputter/hiccup each time. I do have the idle adjusted down as well (heard that can be one of the issues for that). Seems odd based on what I read of the S3/S3T's. should be getting 38-50mpg, and it has a 5.4 gallon tank. Seems like most people get 180-220 miles before hitting reserve. The only other thing of note, was I'm pretty sure it only took about 3.6 gal when I filled up last time. I'll recheck that today when I fill up though, and will report back. Thanks for any help you can give!  | ||
| 2003xb9r |
There are so many variables that could be affecting this. Is the ignition timing correct? Is the VOES (vacuum operated electrical switch) connected and working? This will affect MPG under cruise. What type of carb is on it? Stock or aftermarket? Jet sizes, air cleaner type & condition, your elevation above sea level, riding style. Is it used mainly around town or on the highway etc. Have you done a plug reading etc? My 2000 S3T (converted to CV40 carb) runs like a champ and returns well over 50 (Imperial) MPG on a trip, even over mountainous roads, something my brother in law is jealous about. His 2015 Honda VFR1200 can't get anywhere like the MPG. (Message edited by 2003xb9r on May 03, 2017) (Message edited by 2003xb9r on May 03, 2017) | ||
| Two_seasons |
Dieseling at shutdown sounds like carbon build up on piston and head/valves. ^and what 2003xb9r said^ | ||
| Lake_bueller |
I've never tried this on a motorcycle for carbon buildup...but has worked on my Land Rovers. Run engine until hot. VERY slowly add seafoam into the intake. You need it to ingest but not flood the system. The engine will eventually stall out. Let sit for about 30 minutes. Restart engine and be mild horrified by the smoke coming from the exhaust. Not to worry, it will disappear after the carbon is cleaned from the engine. As I mentioned....I have NOT tried this in a motorcycle engine. | ||
| Lake_bueller |
and what 2003xb9r said! | ||
| Valvesprung |
I've used Seafoam on VW's in the past, and may give it a go. I had typed the original post up earlier and had to remake if after screwing up, but missed some details... I'll check the carb, but believe it's stock. I will verify. Also it has the carbon race intake and the SuperTrap exhaust currently. Plugs looked clean when I did them last week, but will do a plug chop. | ||
| Valvesprung |
Also, this last tank was a mix of riding. About 50-60 miles of it were spirited back roads, the rest in town. | ||
| Lake_bueller |
The last time that I only got 100 miles before hitting reserve was at the track. Even with 50% spirited riding, I get around 30 mpg. Otherwise with a standard mix of daily driving, it is about 48-50 mpg. I think the best was just around 65 mpg. That was riding north across Indiana on superslab with a brisk south wind. | ||
| Ocbueller |
On some old tubers the pickup tube on the petcock needed to be shortened. Shortening the main pickup allows it to run further before needing to switch to reserve. May or may not be your issue. SteveH | ||
| Valvesprung |
Would make sense, especially if it's only taking 3.6 gal. I'll check that in about an hour | ||
| K12pilot |
SEAFOAM IS THE CHIT!!!! | ||
| Valvesprung |
UPDATE! It only took 2.6 gallons to fill her up, and over 108 miles, that puts it at ~41-42mpg which seems right. So really it seems an issue of the fuel tap tube being too long? | ||
| Upthemaiden |
Despite the manta tanks being a lot bigger, how much that affects the amount of gas available in the ON position as opposed to RES would depend on how low down the extra gas is stored. The extra parts of the tank are pretty low near the bottom line of the tank, so I wouldn't be surprised if all of that extra gas you're holding, is only accessible with the petcock set to RES. Now that you've got that fancy new luggage rack, I'd say strap a small gas container on the back, and ride until you're empty. Then you'll know exactly how far you can get on both. I wish I had somewhere convenient on the bike to store the little 25oz gas bottle I have. It'd be nice to have as a backup, but it's bright red and would stick out like a sore thumb no matter where I put it. | ||
| Valvesprung |
That's a great idea, and I was wondering about the fuel storage in the tank. Even when I filled up last time it seemed to have a lot of fuel moving around still which surprised me. | ||
| Natexlh1000 |
That dieseling on shutdown thing make me nervous. Either clumps of hot carbon as mentioned before or running lean/hot. More likely the carbon thing though. | ||
| Valvesprung |
From what I've read it can be caused by improper idle setting. It's almost non-existent when it's allowed to idle all the way down and is set to 1100-1000 rpm (which is common from what I can find). It's really never that bad, just has one extra kick/sputter after the switch is hit. Never more than that. I'll probably still run some sea foam through it, as I know it's done some sitting in the last year. | ||
| 2003xb9r |
I only run my tubers in the "reserve" tap position. Got sick of trying to get the tap to reserve before the engine cut, not easy when it's lurching & bucking & the •••••• behind you is trying their best to run you off the road. I zero the trip meter when I fuel up & know to start looking for gas when 110 miles rolls by in the case of the small tank S1s by which time my ass is telling me to stop anyway. With the S3 & manta tank it just goes for what seems forever! I have been meaning to run them dry & carry spare fuel to see what they really will do but have never gotten around to it. | ||
| Valvesprung |
Another 110 miles and took 2.7 to top off (was on a very spirited ride). Kept on reserve and had no issue, just topped off at a stop and figured I'd check mileage again. Seems like it's within reason for MPG, and just a petcock tube issue. I'll do some seafoam for carbon clean up, and should be good! |
