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Gearhead

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Everything posted by Gearhead

  1. Gearhead
    Yup, definitely the sending unit, not making proper contact at the full tank level. In case you don't know, the sender is just a float on an arm, and the arm moves along a variable resistor. The rest of your gage behavior is totally normal. Mine runs about the first 1/3 of the tank (mileage-wise) with the gage chock full on 6 bars. Then it drops like a rock from there, and yes, when the gage shows E there is about 1 gal left. Jeremy
  2. Gearhead
    I'd do the whole can of Seafoam.... If that doesn't do it...it's almost definitely in the carbs from sitting so long. Evaporated gas leaves this weird stuff behind called varnish. A couple other easy things are draining the tank as George recommended and cleaning out the fuel bowls, and it would be best to do these before the big Seafoam event. To clean the bowls, locate the bowl drain hoses right under the carbs. Hold a large, absorbent rag under one, open and open the drain for that bowl 2 or 3 turns. The fuel will come out. Now take a can of spray carb cleaner and, again holding the rag there, use the red spray tube and shoot that stuff up the drain hose, then let it drain back out. Do that several times and observe what sort of stuff comes out. After that and Seafoam, if the problem persists, the carbs need to be torn down to clean properly. The other thing that comes to mind is the slide diaphragms. They get cracked and holed with age. I'm not sure if the low miles and garage storage prolongs their life or not. They're easy to check with the carbs on the bike. Just remove the round-ish cover with stripes on it that faces outward on each carb. Watch for the large spring and tiny o-ring. The diaphragms are right under there. Your observations and description were very thorough and detailed, thanks. That helps. Also, I agree that these engines hit their stride between 3-4k rpm. However, they run nice and smoothly below that, too. You should not have hesitations, bucks or stumbles. Jeremy
  3. Gearhead
    Hi Y'all, Manual calls out these specs: Secondary coil winding resistance - 10-15 K-ohms Plug caps - 10 K-ohms My bike is running normally and I didn't check the coils, but I did check the caps while I was clipping 1/4" off the ends of the plug wires and re-attaching them (a little preventive maintenance). A PO has replaced at least the front caps. The two rears don't have a brand name on them and I don't know if they are original, but they each have about 8.5 K-ohms. The front caps are NGK and are each 5 K-ohms. I figure, given the wide range of acceptable resistance in the secondary windings, that the spark probably doesn't really care that the fronts and rears aren't exactly the same. But I was wondering if 5K-ohms in the front (compared to the spec of 10) could contribute to ignition noise in the radio - not enough resistance for proper noise suppression. I don't understand noise suppression, so this is a wild guess. Does anybody know? Thanks, Jeremy
  4. Gearhead
    Did you check for spark on those two cylinders so you KNOW it has no spark? If not, maybe the spark is OK but the carbs are gunked. If it's definitely electrical, I'd suspect the TCI of moisture or bad connections. It happens all the time. It's location under the battery means that anytime the batt oozes a little acid, it ends up on the TCI connector. Jeremy
  5. Gearhead
    Yeah, agreed, but the alternator should handle an extra 55W without dropping to 12V. My bike has a pair of 55W driving lights (extra 110W) and it just barely handles it. I'm not saying it's normal or good to run with both headlight elements lit, but that should not kill the voltage if the engine is running a few rpm's. Jeremy
  6. Gearhead
    George, I beg to differ here. Not about the synthetic, that I don't know about. But DOT4 is the same as DOT3 except with a higher temp rating. Both are supposedly equally hygroscopic (they absorb water). BTW, hygroscopic is a good thing! I've read that some brake fluids, DOT5 methinks, is not nearly so much so. This is often thought of as a good thing, but I've read otherwise. Moisture gets into the system, one way or another. Condensation from when the cap is off, whatever - it gets in there. If the fluid is hygroscopic, it absorbs the water and TO A POINT is does no harm. That's why we should flush the hydraulics from time-to-time, esp. when the fluid is brown. But if the fluid is NOT hygroscopic, the water can condense in the caliper, rusting the piston. Jeremy
  7. Gearhead
    I could be wrong, but I don't think funrider is referring to the pressure plate, but rather the diaphragm spring. He stacked two springs, doubling the pressure on the clutch. Jeremy
  8. Gearhead
    From my reading here and also personal experience, Yamaha clutches commonly start to slip in this mileage neighborhood. Both my 87 Virago and 87 VR did. In both cases I replaced only the friction discs and the problem was solved. The VR is now pushing 70k miles, no big deal (new Yammy factory discs). But the Virago has 135K miles, and I haven't had to touch the clutch since that one time in the 50k range (EBC aftermarket discs). The weird part is that they don't wear out. In both cases, my old friction discs measured right on the spec for NEW plates! So why did they slip? Dunno... Both bikes were purchased with 40-some K miles on them. Maybe PO's had added Slick 50 in both cases, or some "energy conserving" grade of oil with "friction modifiers". Jeremy
  9. Gearhead
    Great gas mileage??
  10. Gearhead
    Man, Greg, how long is your holiday??? That cartridge emulator stuff is very interesting. Is there a downside? Regarding the EANDS anti-dive: Does anyone know if it ever causes problems? Does it really do much of anything? Jeremy
  11. Gearhead
    87 VR - 37 mpg avg over two years. Low 24. High 42. Winter 38. Summer 35.5. Jeremy
  12. Gearhead
    Hehehe...
  13. Gearhead
    That's weird, engines will normally run with really bad sync (not well, but run none the less). You said it was running really rich. Sync won't help that. Have you checked your fuel levels in the carb bowls? That and pilot screw setting is critical and could account for trouble. It could be so rich that it fouled your new plugs already. Chris, my average mileage would have to go UP by about 2 points to get to 39. :-) When I got mine a couple years ago 'twas in need of many things and was getting something like 32. The tuneup stuff, repairing the boost sensor, etc got the mileage up to 37, but...when I synced the carbs, mine actually went down a point or two as well. Can't figure that one out. Jeremy
  14. Gearhead
    The fall may have done something to your clutch lever. There is a cut-out switch at the inside end of the lever to kill the cruise when you clutch. Jeremy
  15. Gearhead
    On the boost sensor: now, mine is an 87 and these comments apply to most models, but I know 83 and maybe 84 is a little different. Yes, the timing is controlled by a computer called the TCI. It has a RPM vs spark advance curve programmed into it. In addition, it does vacuum advance for economy, accomplished via the boost sensor. This part outputs voltage based on the amount of vacuum applied to it from the carb stub. When vacuum is high, it sends some voltage to the TCI that tells it to advance the curve for better economy under light loads. If the sensor (I would actually call it a "vacuum sensor" if it were up to me) is faulty (and many of them are), the timing won't advance under light load, but will stay on the more retarded "baseline" curve which is best for heavy throttle. This will not cause pinging, but will cause MPG to fall. Therefore, I wouldn't suspect the boost sensor if the bike pings. One more thing. I'm pretty sure that high vacuum will NOT increase the timing at idle. I think the TCI is programmed for the vacuum advance to kick in somewhere around 2k rpm. So to check it, you need to run your idle speed up to 2k with the thumb screw, THEN pull vacuum on the line to the sensor. Jeremy
  16. Gearhead
    Hmmm, what we need is for somebody out there with a head pulled off a VR engine to cc the chamber (and any piston dish, of course)! Time for a science experiment... Jeremy
  17. Gearhead
    Thanks, 5bikes, I'll give it a shot one of these days. The tuneup items I have covered, but never tried lowering the needles. Do you mean "thinner" washers to replace the stock spacer? Jeremy
  18. Gearhead
    Dude, it's on the website under History. F - 120-90-18 R - 140-90-16
  19. Gearhead
    I'm not sure I'd call 10.5:1 "low compression". Jeremy
  20. Gearhead
    Let me know how the noise filter works for you. Do you mean a factory one? Some people say that they are too old, that the caps go bad. If you want to try aftermarket filters, you need two. My noise, like yours, is dependent on exactly what's turned on and what levels are set where. Hey GeorgeS, did you ever try new caps on yours? Jeremy
  21. Gearhead
    I had to cut holes for the speakers and mic. The thing is, the thinner they make the speakers the harder it is for them to sound good, so there's a tradeoff. The J&M aren't as small as my old Chatterbox stuff, but they are WAY better. When you do the install, make sure the speakers and mic are AS CLOSE AS POSSIBLE to your ears and lips without pressing on them. It makes a big difference in performance. I actually went back in afterward to shim all three closer to my head. Your lips should just rub the mic foam, so mine sticks 3/8" out of my chin bar to accomplish this. Jeremy Jeremy
  22. Gearhead
    Hey 5bikes, So what's your secret? Most of us here would LOVE to get that mileage from a Venture. I've never beaten 42, and that's on slow rides; it's usually averaging 37. Did you have to change stock jetting or is it simpler than that? Jeremy
  23. Gearhead
    Well, EFI has certainly helped cars increase mileage in the last 20 years. They say a well-tuned carb will produce as much power, but not the mileage of EFI. That being said, my 91 3/4 ton Suburban gets 11-12 mpg from it's injected 350, while my old 77 3/4 ton Chevy pickup, carbureted, got, well, about the same. The Sub does weigh 1000 lb more. But I work with a guy that says his much newer 1/2 ton Suburban with a 5.3L gets close to 20 on the road. I've toured with a guy on a 1100 BMW sport-touring bike with EFI. His mileage was mid-50's IIRC. Can't argue with that. And that was one fast bike, too. I really like not working on carbs with my EFI cars. EFI problems are a pain, but rare. That alone is a wonderful thing. One more benefit. Anyone wonder why the average car engine used to wear out around 100k miles and now that's more like 200k? One trusted motor machinist told me it's primarily EFI which accounts for that. Most wear occurs at startup, and the CHOKE on a carb greatly exacerbates that. Carbs need a choke because the cold piston and combustion chamber aren't condusive to atomizing the stream of liquid fuel from the carb, so it doesn't burn very well. The choke compensates by dumping great excesses of fuel in, increasing the AFR (air fuel ratio) from 14:1 to around 7:1. As the engine warms, the fuel atomizes better and the choke is no longer needed. Since injectors spray a more atomized form of fuel into the chamber, it burns much better even when cold and all the extra that's needed is a quick squirt from the cold-start injector. Anyway, when the choke is on, all that excess fuel washes down the cylinder walls of their oil, and over time that's 100k miles worth of wear on the engine. Jeremy
  24. Gearhead
    I've got the low end J&M for full face. They cost around 60 bucks apiece at Wingstuff.com and other online stores. They work well. Jeremy
  25. Gearhead
    Junk in your carbs causing a repeat of the blockage. Try draining the bowls, spray carb cleaner up the drains and let it drain back out. Spray out the pilot screw hole again. Run a strong Seafoam mix thru it. If that doesn't get it, you're probably stuck removing the carbs. Jeremy
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