1980 XS1100SG slow start

[Azoroth]

Hey everyone. I just wondered if anybody out there has issues with starting. My bike sometimes has issues catching even though it's really warm out it just doesn't fire up quickly. It cranks just fine so it's not a battery issue. Does anybody know if putting a better spark plug in would help? My plugs look fine now but if some Iridium's would help it catch easier I'll upgrade to those. I know in my Honda Shadow I used to have (as well as my Dad's Shadow) Iridium plugs made a HUGE difference in ease of start and made it run much better. Not sure if these bikes would make a difference or not.

Any ideas would be great. Thanks

[SFerinTEXAS]

I will reply to your question with more questions. What is your history with the bike? How long has this been going on? When was the last time the carbs were pulled and cleaned? How does it run after it does start? How does it start when fully warmed up? I am a fan of iridium plugs but they will not fix problems. Good std plugs should not cause what you describe.

[DGXSER]

For the most part, if you give the bike the correct amount of choke/enrichment it should fire on about the first crank over or so. All of mine have. As SFER suggested, the carbs need to be cleaned and properly setup for this to happen though, as well as proper valve lash set.

Another item that greatly effects this though IS spark. There are many folks on here who have stated after upgrading their coils, and in some cases going to iridium plugs, that their bike NOW fires up on the first crank. Not sure the iridiums will work as well with the stock coils, but your not hurting anything to try it.

[natemoen]

I have said this before and will continue to say it. Iridium plugs stay cooler than stock plugs, because of this they do not self clean well causing them to foul much easier and not clean off. So putting iridium plugs in when you are having troubles is a waste is money. If your bike is running great and you want to switch fine, but iridiums will not fix problems.

[redbone]

mine does something like you explained as well. when it is cold and choked it fires up no prob. if it is hot, it fires no prob, it is when it is just warm that it gets a little tempramental. i just give it a little throttle and it will start. these are old machines that like things just so!

[Azoroth]

I will reply to your question with more questions. What is your history with the bike? How long has this been going on? When was the last time the carbs were pulled and cleaned? How does it run after it does start? How does it start when fully warmed up? I am a fan of iridium plugs but they will not fix problems. Good std plugs should not cause what you describe.

Well I haven't had this bike very long. I just bought it a few months ago. Everything else on the bike is very clean. I was actually really amazed how clean and well taken care of it is. So I would suspect that the carbs have been cleaned, but I am not 100% sure.

[Bonz]

That's the first time I've heard that Iridium plugs run cooler... Iridium plugs allow the spark to jump the gap at a lower voltage threshold which can lead to better and cleaner running.

Everything I've known about plugs for a lifetime says it isn't the style of plug (iridium, platinum, copper, whatever), but the length of the center ceramic insulator that ultimately determines how hot or cold a plug runs. I think I said that more or less correctly...

The inside of the engine is HOT, and iridium has no effect on how hot or cool the plug runs, it's the other factors like I mentioned above. I can't see how a correct Iridium plug chosen by the heat range called for by Yamaha and stated by the plug manufacturer for any XS will burn cooler.

I can say unequivocally from a 1025 mile run over the 4th of July in my 80 SG with stock coils, stock wires with iridium plugs, they were the cleanest looking plugs I've ever seen.

I'll be persauaded otherwise by empirical data that shows they run cooler, thus causing fouling. Seems like the exact issues we always talk about in terms of poor spark, poor internal engine condition, poorly tuned carbs are still the reasons plugs foul, not the type of material in the center electrode.

Seems if they DO burn cooler, DUH, go up one heat range!

[SFerinTEXAS]

That's the first time I've heard that Iridium plugs run cooler... Iridium plugs allow the spark to jump the gap at a lower voltage threshold which can lead to better and cleaner running.

Everything I've known about plugs for a lifetime says it isn't the style of plug (iridium, platinum, copper, whatever), but the length of the center ceramic insulator that ultimately determines how hot or cold a plug runs. I think I said that more or less correctly...

The inside of the engine is HOT, and iridium has no effect on how hot or cool the plug runs, it's the other factors like I mentioned above. I can't see how a correct Iridium plug chosen by the heat range called for by Yamaha and stated by the plug manufacturer for any XS will burn cooler.

I can say unequivocally from a 1025 mile run over the 4th of July in my 80 SG with stock coils, stock wires with iridium plugs, they were the cleanest looking plugs I've ever seen.

I'll be persauaded otherwise by empirical data that shows they run cooler, thus causing fouling. Seems like the exact issues we always talk about in terms of poor spark, poor internal engine condition, poorly tuned carbs are still the reasons plugs foul, not the type of material in the center electrode.

Seems if they DO burn cooler, DUH, go up one heat range!

Well said.

if they DO burn cooler

Nothing out there to suggest this is true

[James England]

I've never heard anywhere that iridium plugs run cooler. I put them in my bike with the OEM coils and also later on with Dyna coils. They run fine either way. Without doubt, swapping the coils and getting rid of the ballast resistor + using iridium plugs, made my bike even better on starting and they run a nice tan brown colour all the time. An irritating little misfire I used to get disappeared entirely and I certainly wouldn't let what looks like some kind of urban myth in the making re iridium plugs stop you from using them. A better spark=better combustion=better running. As for fouling up....what fouling up? Plugs tan brown.... inside of exhaust baffles light tan brown. Instant starting. Perfect running. No misfires ever... at all.

[ManagerMike]

The automotive industry adopted iridium plugs for duability puposes only, not for better spark or different heat ranges (that is a function of insulating ceramic).
Platinum was first selected for over copper as electrode material due to better durabilty characteristics when the U.S. EPA mandated that manufacturers must warranty the catalytic converters for 8 years/80,000 miles beginning in 1996.
Early on it was discovered that the real world does not always match simulations, and platinum plugs DON'T last 100.000 miles as advertised by the suppliers (some folks NEVER change plugs regardless). The OEMs were getting slammed with alot of warranty expense replacing converters damaged by worn plugs.
By 1998 almost all auto manufacturers had switched to irridium for OE plugs because they WILL last 100,000 miles, although they cost even more, it's cheaper than relplacing converters. Irriduim just flat out erodes slower than platinum which itself erodes slower than copper.

However, if you are looking for the best spark at the plug gap as a result of the plug material you would naturally want the best electrical conductor available...copper (actually gold would be far better but unaffordable and would wear out in no time). But frankly, true copper electrode plugs are increasingly hard to find as the price of copper has risen faster than gasoline and still suffers from low durability/high erosion issues.

I've personally seen a set of standard copper plugs go almost 70,000 miles before the customer's vehicle was undrivable, but the average best is 40,000 miles, on the flipside I've seen irriuims at 180,000+ miles before the plugs themselves were causing running issues.

[crazy steve]

...However, if you are looking for the best spark at the plug gap as a result of the plug material you would naturally want the best electrical conductor available...copper (actually gold would be far better but unaffordable and would wear out in no time)...

Gold is actually a rather mediocre conductor; among the common metals, the one that ranks better than copper is silver. You'll find silver contacts in a lot of heavy-duty relays and/or relays where contact failure would be bad. Gold became popular because of it's decent conductivity coupled with it's excellent corrosion resistance compared to copper or silver. Another metal is 'german silver', actually a copper/nickel/zinc alloy, that has been used because that while it corrodes like silver or copper, it's oxide is more conductive...

[BA80]

If the ambient temp is high (like it has been here in Oklahoma for about a month now...100º+ daily) he fuel in the carbs tends to evaporate and fill the airbox with fumes causing a flooding effect if the bike sits for a short but not to short period of time. Let it set for 20 or 30 minutes or just a very few minutes and it will start right up. But, in between there is where the problem occurs. If it's hot out just a little throttle when starting will take care of the problem.

These bikes are CARBURETED not fuel injected like most people here are used to. Carbs have thier flaws and us old timers know how to finess them under different circumstances.

Carburetion is just that way.

[Lamric]

+1 on the fuel in the float bowls being low when the engine has stood warm.

So, turn the petcocks on to Prime for a few seconds before warm starting.

Also, when cols and using choke do not twist the throttle until the engine catches, opening the throttle during cold starting reduces the vacuum needed to pull the richened mixture thru.

[ManagerMike]

Gold is actually a rather mediocre conductor; among the common metals, the one that ranks better than copper is silver. You'll find silver contacts in a lot of heavy-duty relays and/or relays where contact failure would be bad. Gold became popular because of it's decent conductivity coupled with it's excellent corrosion resistance compared to copper or silver. Another metal is 'german silver', actually a copper/nickel/zinc alloy, that has been used because that while it corrodes like silver or copper, it's oxide is more conductive...

Touche' Steve! However I was only trying to ease the testosterone levels surrounding irridium by using the "follow the dollar" logic, and not trying to instigate a thread on alchemy