Ironhead Gas Cap problem?

[Chuckthebeatertruck]

You're correct -- the bendix from the factory did not come with an insulator.

The insulator is a -78 part number (29250-78). . .but many a person discovered adding an insulator can make a big difference on bendix in hot weather.


However, this is one of those times where you need to put on your thinking cap. With the M linkert, there was an insulating block; DC linkert; there were insulating gaskets. With the Tilly, there was a bit insulating block. With the bendix, there was nothing and with the original Keihin -- ditto. But, in 78 an insulator becomes available . . .

We don't too often hear about running issues with DC linkerts; we hear about starting issues with the Tilly, but not running issues; and no one really says anything about Keihin . . . but there's a whole lot of threads about Bendix and hot running problems.

There might be a cause and effect . . .or maybe not. That's up to you to decide. This particular post might put it into a different perspective: http://xlforum.net/forums/showpost.p...58&postcount=4


So, this might be one of the few times I'm suggesting you don't "do it like the factory" and instead "do it like the factory once did" before the Bendix came out. That said, if you're only experiencing this seasonally and you understand the parameters under which it happens . . .you may not wish to mess with an insulator. Conversely, most ironheads seems to show themselves a bit better with a longer intake tract.


Similarly, yes, your motor was "cooling down" but as it did so . . .the heat went somewhere. First law of thermodynamics -- heat always flows from hot to cold . . .and the carb is colder than the manifold and heads. So, it absorbs a lot more heat then we realize.

The vaporization is the effect -- the cause is the heat soak. So the heads may be cool when you come back out . . . but float bowl is still down.


In theory, yes, a higher flowing petcock should break the lock -- but theory and reality don't always coincide. It's one of those cases where only you can truly tell what it going on. The internet denziens, myself included, can only guess and share our personal experiences. I've personally never sprung for an "authentic" pingle so I can't comment. I've only had generic repos of a pingle or el cheapo no name single handle petcocks. I've not had issues with any of these -- only with oem or AM wing petcocks.


I leave it to others to debate over avgas. I assume not go out of my way for fuel or to store special fuel when I can adjust the bike as necessary.

[Ferrous Head]

I have most commonly seen needles sticking in seats on Amal equipped Big Bore Triumphs. If there's and engine that vibrates worse than Ironheads, it's them.

I think you'll find the biggest restrictor in your fuel path is the need;e/seat. Compare that orifice to your petcocks orifice and you'll see what I mean.

If the flow your getting into the float bowl is sufficient to run the engine at WOR (it is) there won't be a problem at lower rpm's.

So, something else is going on. You don't really need a new petcock.

Are you riding around with a "full to the brim" fuel tank ? If so, drain about 1/4 of it out and try again.
Some gas caps have a labyrinth vent and some use a one way valve. If your cap has a one way valve it's possible to pressurize the tank.

I think it was Ed Green (?) Cycle World editor who dropped an XLR engine into a KRTT and went to Willow Springs to "see what it would do".
The XLR engine had been "breathed on" and probably made good HP. In practice the bike was a rocket ship. (And just as maneuverable).

Come the start of race 1 the bike missed and stumbled so badly he pulled in on the 1st lap. Seems they wer worried about the length of the race and fuel consumption so wanted to make sure the tank was completely full. They might have even cooled the fuel. Don't know.
But the heat from the engine warmed the tank of gas which expanded. With no where else to go it pushed the needle open on the seat and flooded the carb. Race over.

If you haven't yet removed the filter from the equation I have to wonder why not. It's very simple thing to do.

[Ferrous Head]

I tried for about a year to get an electric fuel pump to work. Did actually race with it for a while.
The basic problem is motorcycle carburetors have a too small float bowl. That limits the size of the float. They work well on cars running big four barrel carbs with large fuel bowls.

There are pumps made for carbs. In their specs they will say 4 PSI. Don't believe it. They don't go down that low. Now you need to add a pressure regulator. I even tried running two.

What we need here is low pressure high volume.

To get the volume (I'm running Meth) you need to run an alcohol needle and seat. These are supposed to hold 4 PSI Don't believe them, they won't.

It becomes a very fine line between enough pressure to get the flow rate where it needs to be and exceeding the floats ability to close the valve. Seat pressure.

During this whole process I became fairly aware of how these things work. Flow rates, pressures, needles and seats and vibrations.


Yes, funnily enough, vibrations. When I had everything balanced correctly (an adjustable furl regulator) the fuel would just slightly dribble from the over flow at idle. Lift the revs just 200 rpm and the dribble stopped.

The guys running Mikuni's on the Big Honda Fours were having a problem with vibrations too. At the end of the straight on full noise the needles were bouncing on the seats and flooding their engines. Took a wjile to figure that out and come up with a fix.

But the long and short of it is, gravity works. I now use that exclusively.

I have never had a vapor lock on any of my sidecars. Even sitting on the dummy grid when the air temperature hit 107 F. That was on gas, not meth. The engine was HOT.

[ZTatZAU]

Originally Posted by Chuckthebeatertruck

You're correct -- the bendix from the factory did not come with an insulator... There might be a cause and effect . . .or maybe not. That's up to you to decide. This particular post might put it into a different perspective: http://xlforum.net/forums/showpost.p...58&postcount=4

Thanks for the link Chuck! I read that entire thread and, at least for now, will try to do without adding an insulator.

Originally Posted by Chuckthebeatertruck

In theory, yes, a higher flowing petcock should break the lock -- but theory and reality don't always coincide. It's one of those cases where only you can truly tell what it going on... The internet denziens, myself included, can only guess and share our personal experiences. I've personally never sprung for an "authentic" pingle so I can't comment. I've only had generic repos of a pingle or el cheapo no name single handle petcocks. I've not had issues with any of these -- only with oem or AM wing petcocks.

Well, I should know what works or doesn't work soon. My new Golan petcock should arrive today but, as you know, the weather in our neck of the woods will be somewhat cool and rather wet for a while.

Originally Posted by Chuckthebeatertruck

I leave it to others to debate over avgas. I assume not go out of my way for fuel or to store special fuel when I can adjust the bike as necessary.

I know AVGAS has been much discussed and debated here; but mainly in connection with octane, lead, and being ethanol free. But I do know that AVGAS is much less susceptible to vapor lock than MOGAS... which I thought might help with my situation and why I asked.

Originally Posted by Ferrous Head

I have most commonly seen...

I think you'll find the biggest restrictor in your fuel path is the need;e/seat. Compare that orifice to your petcocks orifice and you'll see what I mean...

So, something else is going on. You don't really need a new petcock....

Some gas caps have a labyrinth vent and some use a one way valve. If your cap has a one way valve it's possible to pressurize the tank...

I think it was Ed Green (?) Cycle World editor who dropped an XLR engine into a KRTT... But the heat from the engine warmed the tank of gas which expanded. With no where else to go it pushed the needle open on the seat and flooded the carb. Race over.

If you haven't yet removed the filter from the equation I have to wonder why not. It's very simple thing to do.

Your anecdotal information is all very interesting Gene! And I hope to have all this sorted out soon. Time will tell. And while you may have missed me mentioning in all the above, I've already eliminated the gas cap and the in-line filter issues from the equation.

I'm hoping the new Golan petcock will provide sufficient flow to "unstick" the needle valve if in fact, that is the problem.

ZT

[Chuckthebeatertruck]

I truly think you'll find the majority of the issue you're experiencing is temperature and fuel blend in our little corner of hell land.

Sadly, you may have noticed a recent price split that grew between 89 and 91 octane. Long story short; whiting (which refines for all sorts of companies, not just BP) pumped out a ton of 87 spring blend, a cut for 89 -- but our 91 is still WINTER blend. The concept being the higher end vehicles requiring 91 are much more able to adjust their fuel/air curves -- and a decent percentage are also direct injection motors now and really can handle crap fuel. For carburetor, this blend works tom terrific below 70F, but starts showing up its mess in our 85-90F crud. It vaporizes easy -- and it can also be a mofo to start if you're between hot and cold. Not consistently a mofo and certainly not if you have an auto advance, but for the rest of us . . .it can be "fun" when the fuel blend doesn't match the riding conditions.

As a "data point" -- bikes I rode the week before the hot weather needed completely different starting techniques than when I rode them the next week commuting to work on the same tank of fuel, fueling up again in Cook county -- but just outside the city. Same behavior all weekend on four different bikes. Starting Monday evening, temperatures dipped and two of the bikes were back to their "cold weather" starting characteristics. The only change in the equation -- weather and ambient temp. Electric start bikes a lot easier to get up and running than kick bikes.

This stuff wasn't as stark even 20 years ago. Our regional blends are hella different than what folks a bit further out get of the 5 county area. Because Cook County dominates our fuel blend -- and there's also particulate matter fights -- our fuel is getting weirder and weirder here each year. Again, this is something folks in BIG urban areas are experiencing; but not in smaller markets. You pretty much need to be in a city of 1M plus to be seeing this right now. So, for most folks reading this post -- everything we're writing does not fit their reality. They aren't wrong . . . and neither are you (or me) for looking into root causes and ways around them.

Hence why you have to be your own R&D. If AvGas does it for you -- cool. We all have our ways of skinning cats.

My goal with all my bikes is a totally hassle free ride. If I have to do ANYTHING special to a bike due to weather -- I consider that vehicle "unreliable" and it goes to the back row until it is dead reliable in all conditions.

The reason is that I use my bikes differently from many others with "old" bikes. All of my bikes are used for commuting and errands primarily; with pleasure riding being secondary. When at work, my bikes have to sit outside in full sun/rain. There's no shelter of any kind. More to the point, I can't afford to get stuck on my way to or from work as I cut through some pretty unfriendly parts of Chicago . . . for 30 miles. There's literally no where I want to be stuck on my commute or even stopped for any length of time. No where.

Therefore, the bike may not have issues, must not require anything special, must be able to idle away in dead stopped traffic on the Dan Ryan for minutes on end, and must be cool -- cause my boss is also a vintage rider and it won't due for my bikes to be cruddy and challenged to run correctly.

That's my long way of saying . . . you're on the right track. Keep juggling the parameters and YOUR answer will appear. There's no right or wrong here -- just what approach you take to eliminating the issue.

You've got plenty of data points; plenty of advice; and plenty of experience.

[trappnman]

" generic single handle petcocks. The advantage of the single handles is they are easily rebuilt if they leak or otherwise f up."

spot on

[ZTatZAU]

Thanks Chuck! I always appreciate your thoughtful posts!

Originally Posted by Chuckthebeatertruck

I truly think you'll find the majority of the issue you're experiencing is temperature and fuel blend in our little corner of hell land. Sadly, you may have noticed a recent price split that grew between 89 and 91 octane... Long story short; whiting (which refines for all sorts of companies, not just BP) pumped out a ton of 87 spring blend, a cut for 89 -- but our 91 is still WINTER blend... but for the rest of us . . .it can be "fun" when the fuel blend doesn't match the riding conditions.

I'm almost embarrassed to admit that I never buy the higher octane fuel but rather have always used the Unleaded Regular in all my bikes. Maybe I just don't ride so aggressively to require 90+ octane fuel but I've never experienced any pinging on my Sportster or my GL1500... if I'm in the right gear!

So, is it possible my recent issues could be as simple as the regular grade gas vaporizes easier than premium gas and I should be running premium in my Sportster for that reason alone?

Originally Posted by Chuckthebeatertruck

As a "data point" -- bikes I rode the week before the hot weather needed completely different starting techniques than when I rode them the next week commuting to work on the same tank of fuel... Our regional blends are hella different than what folks a bit further out get of the 5 county area. ... So, for most folks reading this post -- everything we're writing does not fit their reality. They aren't wrong . . . and neither are you (or me) for looking into root causes and ways around them.

Understood!

Originally Posted by Chuckthebeatertruck

Hence why you have to be your own R&D. If AvGas does it for you -- cool.

I don't know if AVGAS will do it now or not! I was running 100LL in it when I first put the XLH back together last fall and it ran great! But it was still quite cool outside back then.

Originally Posted by Chuckthebeatertruck

My goal with all my bikes is a totally hassle free ride... All of my bikes are used for commuting and errands primarily; with pleasure riding being secondary.... More to the point, I can't afford to get stuck on my way to or from work as I cut through some pretty unfriendly parts of Chicago . . . for 30 miles. There's literally no where I want to be stuck on my commute or even stopped for any length of time. No where.

I can certainly relate to that, having grown up on the South Side of Chicago and I wouldn't have traded that experience for anything. Things are much different now in my old stomping grounds. I came out to Dupage county to raise my own family in the 1970s.

Originally Posted by Chuckthebeatertruck

That's my long way of saying . . . you're on the right track. Keep juggling the parameters and YOUR answer will appear. There's no right or wrong here -- just what approach you take to eliminating the issue. ... You've got plenty of data points; plenty of advice; and plenty of experience.

Thanks again for your advice and for taking the time to share your knowledge and experience with others. I'll keep you posted!

Originally Posted by trappnman

" generic single handle petcocks. The advantage of the single handles is they are easily rebuilt if they leak or otherwise f up." spot on

Thanks for your reply Trappnman! But the Golan petcock I've ordered, while a bit pricey, appears to be easily rebuilt when (or if) necessary!

ZT

[Ferrous Head]

TarzAU.

Here am I thinking the AU on the end of Tatz is the country code for Australia.

It's easy to forget that not everyone lives here with me. In Oz. The fuel here still works.
And we don't really have Compton, El Paso or The South Side of Chicago.

And I haven't had to rely on my bikes for transport to work and back for years now.

And I think most of us here just really hate the annoying little things that makes us question the reliability of these poor old bikes.

I've used 3 of Pingal's products. Rear engine mount, petcock and engine cut out.

The rear mount is great. The petcock is great (Can't comment on the Golan) the cut out ? Not so great. (Cost me a race and I'll never buy/use another one.)

One of the great things about Avgas for me was that it was always a known quality. It came in sealed containers. The quality was assured. If I had a problem I never pondered the possibility that it was "bad" fuel.

If your buying at "Lazy Larry's Stop'N'Go" who knows what's in there.

[Chuckthebeatertruck]

Originally Posted by ZTatZAU

I'm almost embarrassed to admit that I never buy the higher octane fuel but rather have always used the Unleaded Regular in all my bikes. Maybe I just don't ride so aggressively to require 90+ octane fuel but I've never experienced any pinging on my Sportster or my GL1500... if I'm in the right gear!

ZT

Ah, you keep letting out all these little nuggets . . .

Let's cut right to the chase -- any octane will run and any octane will avoid spark knock under normal conditions.

There's more going on . . .


1) yes, octane is related to spark knock/ping -- however at 9:1 you won't be pinging your stock ironhead even on hot days unless you advance it well past 45 degrees (40 on your 1000).

2) a higher octane in an IRONHEAD is recommended because of the chamber shape, masked flame front, and longish stroke. Basically, too low an octane and it burns odd and too high an octane it keeps burning long after the maximum push has been achieved. Either condition, especially too much octane, actually makes your bike run hotter even if it isn't pinging.

3) Premium fuel is far less volatile than regular unleaded and yes, it does evaporate more slowly.

So, yeah, it could be as stupidly simple as you put in easier flashing fuel that was still blended for winter/spring at a time you needed low flashing fuel blended for late spring/early summer.


Like I said -- internet denziens don't have all your data points . . . .

[brucstoudt]

Originally Posted by Chuckthebeatertruck

3) Premium fuel is far less volatile than regular unleaded and yes, it does evaporate more slowly.

that's why i don't use it anymore in my kick start magneto motor,it's not high compression.