I have been reading quite a bit about the apparant "run hot" issues with some of the later model bikes. The concensus seems to be that Harley has leaned them out so much that they are "overheating" I guess the first question in my mind is: on an air cooled engine what constitutes "overheating". In my 32 years experience as a mechanic for both cars and bikes and with race experience is that fuel mixture makes power. Power makes heat. The leaner you go (to a point)the more power UNTIL you scuff a piston or burn out an intake valve. Has anyone ever scuffed a piston or burned intake valves as a result of driving one of these "lean" Harleys? How hot are they getting? (not oil) I measured my head temp after a run with a laser thermometer and then measure the Yamaha Rodstar that did the same run right beside me. He was 30F hotter near the plug area of the head yet becuse my pipes we snapping (cooling) a bit he said "man, you bike is hot".

I haven't researched too deeply but I suspect what Harley is doing under the watchful eye of the EPA is moving all bikes to a stoichiometric (chemically correct). 14.6:1. air/fuel mixture. It isonly at this ratiothat the catalyst canboth oxidize the CO and UHC (to CO2 and H2O) and chemically reduce the NOx (to N2). (UHC = unburned hydrocarbons.) So on catalyst bikes like in California we can be pretty assured that the ratio quoted is close so If they can make them run for Cali why not the rest of the world?

I believe the bottom line is that there is not real damage being done to the engine with the factory setup. I belive it is more a "customer dissatisfier" which could be from a whole host of resasons of which include limited experince with your ***** hanging over a big cube "AIR COOLED" engine. We went through this when the automotive sector had to change over to catalyst eqipped vehicles. Remember 160 deg thermostats? Summer, winter stats? They are gone. Now it's just 195 deg stats in cars and trucks. I'm afraid if the complaints keep going in that Harley will have no choice but to consider Liquid Cooling on all of their models. For me personally that would be a catastrophe and the end of an era.

 

I agree.
One of the problems is keeping cylinders round as the heat goes up. one reason water cooled works so good. I think there are ways around this so we can keep our bikes like they are. Thicker, better made cylinders probably will help here. Some, from Axtell and Jims maybe some others,already have iron twice as thick as stock. And cast in. I don't knowhow stock does. Maybe new materials in this area are available.
Another thing they are going to have to do is oil cooling. They are availabe add on now but the factory will go here soon. Piston cooling jets are on the new BT engines now. Oil cooling can be very effective.
Just some thoughts on this. I, like you, would hate to see things change too much.

 

yes technically they are "leaned out" but only to the point that EVERY OTHER EFI SYSTEM in the world runs at! 14.7 to 1 AF ratio isnt too lean as to overheat / damage the engine. At thats only at cruise. 33% of riding RPM or something like that.

If the engine TRULY ran lean we would see holes in pistons by now.

The "run hot issue" is only a riders comfort issue. There are ZERO heat related failures that I have seen.

You can fatten your mixture up to be technically "too rich" which will cool down your thighs but all that will do is lower your MPG

There is a happy medium in a proper PERFORMANCE TUNE that runs slightly fatter than perfect (remember perfect is 14.7 to 1 which the bike is built to work at) and give you more power and good mileage.

 

Well, I'm glad to see some good ole knowledge and common snse thinking on this topic. This whole heat thing drives me crazy. I have actually been on a ride where someone pulls over. We go back to see what's wrong and they say "I think my bike is overheating". I ask them what the indicators were as far as driveability symptoms or what leads them to believe they are overheated. Most common response: "2007 and 2008's run hot didn't you know that? lol

 

Here in this high desert, 14:6/7:1 is too lean and I have seen the damage it causes($$$).
Look to get it somewhere around 13.3 to 13.6, no leaner.

 

BZZRD:

There's a Road Star Riders forum where I hang from time to time cause I used to own one a few years ago. One night I asked the question how hot do they run. I was concerned about my 07 Street Glide which on a 60 degree day was running 350 degrees on the rear cylinder. Temperature taken with an infrared thermometer about one inch to the left of the spark plug. At the time I had K&N 3909 AC, and Ruch Mufflers with 2 inch Baffles and was running a Terminal Velocity II fuel mngt system.

Amongts the answers I received was this very methodical answer from someone obviously concerned about temps. His answer relates to Road Stars only. Here is his reply:
"Back in july 05 I took my digital thermometer to star days in St Joseph, Missouri just to get a baseline on engine temp. The temp every day was 95 to 98 with plenty ofhumidity. As folks would pull in and shut down I would walk up and check the temp. I checked all at the head as close to the plug as possible. It freaked some guys out cause they had never seen one before. Anyway thehottest road star I tested was 265 degrees. His was the only on to exceed 240 degrees. I checked mine almost every time I shut it down and it never exceeded 230 degrees. At night it would run no more than 210 andI'm running High Compression pistons."

I have no reason to doubt his answer as he had collected the data long before I ever asked the question.

My 07 that ran 350 degrees on the rear with the TVII. The next day I took the TVII off and installed Nightriders O2 IED's. The $69 wires that alter the voltage coming from the O2 sensors. The outside temperature was close to the same. Ran the same course and stopped to measure temps. Now my rear cylinder was 250 degrees. Last test I did was returning my bike to bone stock. Stock AC and stock exhaust. Still running Nightriders O2 wires. The outside temp was about 70. Now my rear cylinder was running 300. Still a lot better than the original 350.

Hope this helps.

 

So what your saying Rider57 is that stoclk 07 and 08's are damaging engines and HD has a higher warranty repair for engine damage as a result in that area? If I chose to keep my my bikestock it would keep blowing up as a result? HD would just have to keep fixing it? I don't buy it for 1 second. Engines don't blow up running at stoichiometric correct AF ratio unless something else is wrong.

 

I did'nt say that at all, not even close.
If it breaks and is under warranty, your pretty much covered.
After warranty it will cost you something.
High heat in a air cooled engine will damage the engine as the oil breaks down from that heat.
Oil breakdown = poor lubrication = more heat from friction, make more sense this way?
Want to keep your bike running or in the shop getting repairs (warranty or not)?
You simply cant change physics, friction produces heat. Period!
Lower the heat to something the oil can live with and enjoy your ride.
Simple, but true.
The only other engine from the company that seem to show problems are the non-CVO 110's, they are dropping like flys.
60% that I have looked at have warped valves from heat, and seat damage from heat.
The CVO factory models do not show this problem to that level.
I have been a H-D tech for 20 years and a state emissions tech for 12.
If you still dont think it happens, drain your coolant from your car / truck and go for a nice ride. Dont worry about the cooling, it's air cooled now.

 

Well we can put an oil cooler on the engine. Here last week or so, 70 plus deg.F days, my oil temp is 220 deg.F without a cooler, running hard. After about 15-20 minutes. I have put in a better oil relief spring. That was to get more oil up to the heads. I have no venting problems with this. I figure this pickes up a lot of heat up there. A oil cooler added this summer will help.

Also to address the heat proplem at the source, assuming there is one, there are things the manufacture could do. Heat reflecting creramic coatings for the pistons and head chambers and exhaustpocket area,for one thing. Would be easy to do. Autos have done this for years. Just better flowing heads help. There are other things I bet. We might all go back to iron cylenders again, why not??, they stay round i believe.

 

Just thought I'd throw a couple things out there for discussion.

As far as heat making power, that's only true if that heat stays in the engine and goes out the exhaust. Kind of makes me wonder how that fuel mixture wouldwork if that extra heat couldn't escape through the cylinders/heads. All that heat you feel is energy wasted, but it's keeping the motor in one piece.

Also, in the past I always believed guys spending the extra money on synthetic oil were wasting money. That's mainly because conventional oil doesn't break down until about 400 degrees. Now I've been thinking about the 350 degree head temps, and sitting in traffic this august at sturgis. I'm thinking synthetics may become pretty important on these newer bikes.