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Latest updates on progress of the C70 commuter
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<blockquote data-quote="69ST" data-source="post: 174538" data-attributes="member: 5"><p>Owners of old cars face a number of fuel-related problems. Things like fuel pump diaphragms and inlet needles with neoprene tips become Dixie-cup-disposables. Two-stroke motors, such as those used in chain saws and commercial landscaping equipment, are a pain in the arse to keep running. In this area, landscapers and tree services all buy their fuel at marinas; not everyone has that option. </p><p></p><p>Viewing your plug photo on a real screen, I don't see any metallic artifacts...good news for you. I do wonder if those thick deposits on the side electrode start glowing, as in red-hot...literally. That could easily result in pre-ignition. I'd want to retest the bike using a new plug, or at least after giving this one a good cleaning. It's a simple test that could give you a definitive answer and point toward the real problem.</p><p></p><p>Funny you mention the wear & heat issue. On the wear side, ethanol has an insignificant impact...it's almost like LNG (methane/natural gas), or propane, clean & high octane. Methanol is a whole different story. Gasoline, itself, is a dirty fuel but it has its positive aspects, to which most engines have been adapted. IMO, other additives that have come into use (the "goat piss" in pump gas soup) are more worrisome. Back in the day, ~45 years ago, there were detergent gasoline formulas, to which chemical "scavengers" were added and they could result in fouled plugs with deposits resembling what your bike...and kirrbby's truck...have exhibited. Of course, electronic engine management has really cleaned-up combustion, from cold-startup to idle to WOT, rendering the pre-PC era "Mexican tuneup" mostly obsolete. One thing that hasn't changed is oil control and once that becomes an issue, nothing short of a mechanical correction can fix it; that doesn't necessarily mean a major overhaul. As for increased engine temps, that's largely a result of leaner mixtures...a major goal of "reformulated" pump gas, largely realized by the addition of oxygenates. Alcohols, including ethanol and methanol, are both oxygenates. And they do result in leaner mixtures.</p><p></p><p>When E10 first hit the pumps, it became necessary to upsize the main jet by one number in many, but not all, situations. A year, or two, later I started seeing leaky petcock assemblies and, for those with VM22 carbs, problems with the main jet well O-ring shriveling to the point where it would no longer seal. Our own kirrbby went through the proverbial meat grinder trying to jet one of these carbs, unaware of this underlying problem. I also noticed, during testing/tuning sessions, that engines would rev-out cleanly with A:F ratios that were significantly richer than the rich limit had been previously. With A:F ratios sorted, to compensate for the "revised" pump gas available in this area, things mostly returned to normal, minus a few mpg...until relatively recently. Going back at least 5 years, I've gotten the occasional tankful of lame fuel...manifesting as reduced power, higher oil temps and a ~5-15mpg+/- decrease. As of this year, that's almost become the "new normal" (ugh)...~5C increased oil temp and ~5mpg less. On the surface, one could easily and logically conclude that the engine is getting a little tired. That said, if this were true, the results would be more consistent than they are. When you ride, say, 350 miles in 3 days, there will be plenty of fuel stops along the way, each one a chance to check fuel consumption, while the numbers are still fresh in memory. With ~85 mile range (per tankful), I'm usually hitting "reserve" at 62miles...with a tank top-off verifying actual consumption. When that comes up at 52-58 miles, then returns to the expected 62 with the next tank...clearly it's something other than engine health causing this. Another clue, refilling the tank at home, from a 6-gallon container then topping-off the tank (same day), at a pump, after it's been run low, consistently shows mpg in the expected range. Consistent mpg when using known fuel, random variations over the road, refueling from unknown sources. IMHO, this is not the kind thing that most folks would even consider, let alone make a systematic effort to decipher. I mean, WGAF about ~1/2 gallon of fuel burned at the rate of, say, 87mpg vs 94mpg? That's not enough pennies to even impact the "sofa cushion piggybank"<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" /> That said, consistently topping-off the fuel tank and a little basic math can be an effective early warning system/diagnostic tool. When fuel consumption takes a sudden dive, that should tell you that something is amiss.</p></blockquote><p></p>
[QUOTE="69ST, post: 174538, member: 5"] Owners of old cars face a number of fuel-related problems. Things like fuel pump diaphragms and inlet needles with neoprene tips become Dixie-cup-disposables. Two-stroke motors, such as those used in chain saws and commercial landscaping equipment, are a pain in the arse to keep running. In this area, landscapers and tree services all buy their fuel at marinas; not everyone has that option. Viewing your plug photo on a real screen, I don't see any metallic artifacts...good news for you. I do wonder if those thick deposits on the side electrode start glowing, as in red-hot...literally. That could easily result in pre-ignition. I'd want to retest the bike using a new plug, or at least after giving this one a good cleaning. It's a simple test that could give you a definitive answer and point toward the real problem. Funny you mention the wear & heat issue. On the wear side, ethanol has an insignificant impact...it's almost like LNG (methane/natural gas), or propane, clean & high octane. Methanol is a whole different story. Gasoline, itself, is a dirty fuel but it has its positive aspects, to which most engines have been adapted. IMO, other additives that have come into use (the "goat piss" in pump gas soup) are more worrisome. Back in the day, ~45 years ago, there were detergent gasoline formulas, to which chemical "scavengers" were added and they could result in fouled plugs with deposits resembling what your bike...and kirrbby's truck...have exhibited. Of course, electronic engine management has really cleaned-up combustion, from cold-startup to idle to WOT, rendering the pre-PC era "Mexican tuneup" mostly obsolete. One thing that hasn't changed is oil control and once that becomes an issue, nothing short of a mechanical correction can fix it; that doesn't necessarily mean a major overhaul. As for increased engine temps, that's largely a result of leaner mixtures...a major goal of "reformulated" pump gas, largely realized by the addition of oxygenates. Alcohols, including ethanol and methanol, are both oxygenates. And they do result in leaner mixtures. When E10 first hit the pumps, it became necessary to upsize the main jet by one number in many, but not all, situations. A year, or two, later I started seeing leaky petcock assemblies and, for those with VM22 carbs, problems with the main jet well O-ring shriveling to the point where it would no longer seal. Our own kirrbby went through the proverbial meat grinder trying to jet one of these carbs, unaware of this underlying problem. I also noticed, during testing/tuning sessions, that engines would rev-out cleanly with A:F ratios that were significantly richer than the rich limit had been previously. With A:F ratios sorted, to compensate for the "revised" pump gas available in this area, things mostly returned to normal, minus a few mpg...until relatively recently. Going back at least 5 years, I've gotten the occasional tankful of lame fuel...manifesting as reduced power, higher oil temps and a ~5-15mpg+/- decrease. As of this year, that's almost become the "new normal" (ugh)...~5C increased oil temp and ~5mpg less. On the surface, one could easily and logically conclude that the engine is getting a little tired. That said, if this were true, the results would be more consistent than they are. When you ride, say, 350 miles in 3 days, there will be plenty of fuel stops along the way, each one a chance to check fuel consumption, while the numbers are still fresh in memory. With ~85 mile range (per tankful), I'm usually hitting "reserve" at 62miles...with a tank top-off verifying actual consumption. When that comes up at 52-58 miles, then returns to the expected 62 with the next tank...clearly it's something other than engine health causing this. Another clue, refilling the tank at home, from a 6-gallon container then topping-off the tank (same day), at a pump, after it's been run low, consistently shows mpg in the expected range. Consistent mpg when using known fuel, random variations over the road, refueling from unknown sources. IMHO, this is not the kind thing that most folks would even consider, let alone make a systematic effort to decipher. I mean, WGAF about ~1/2 gallon of fuel burned at the rate of, say, 87mpg vs 94mpg? That's not enough pennies to even impact the "sofa cushion piggybank";) That said, consistently topping-off the fuel tank and a little basic math can be an effective early warning system/diagnostic tool. When fuel consumption takes a sudden dive, that should tell you that something is amiss. [/QUOTE]
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