| Author | Message | ||
     Duanelr |
My coolant temperature has become stuck at 216F. Bike has over 40,000 miles on the odometer. To replace the coolant temperature sensor, the throttle bodies needed to be removed. This is my first time removing these. What a mess.. everything was coated with a sheen of oil. I can only assume this is oil from the K&N air filter? It's everywhere on the inside of the airbox and intake ports. Small sand and pebbles that were not visible before, fell into the intake tracks as I pulled the boots off. DAMN I've burned through dozens of q-tips with mineral spirits, and clear vinyl hose on a vacuum to clean out the tops of the intake valves. Still they are caked with black-crud. Questions: Do I need to worry about this carbon or black crud on the valves? Is there any kind of fuel additive that could get rid of this? Is it possible the baked-on black-crud is red K&N filter oil?  | ||
| Fresnobuell |
I doubt even a heavily oiled K&N filter would leave that residue. I looked down my throttle bodies when I cleaned the air filter a few weeks ago. Clean valves with no residue. Bike is pushing 30K miles and gets run hard. | ||
| Stevel |
That burnt carbon has come from exhaust reversion. It is normal. The intake air stream is not one way. Intake air and exhaust gasses shuttle back and forth in their respective tracks. You can feel this if you place your hand over either the exhaust pipe or throttle body. The normal way of cleaning is disassembly and soda blasting. This occurs in an overhaul. | ||
| Two_seasons |
If your airbox is full of oil, it may be from overfilling with engine oil during an oil change. | ||
| Fresnobuell |
Steve, this is normal? My bike has 75% of the OPs and the valves look nearly new. I can't believe this is normal. | ||
| Fresnobuell |
I decided to rotate to a clean filter today so I took a pic of my valves. I did have a very thin layer of oil on the walls of the intact tract.. I don't see the same on the OPs intake tract and I don't remember this being there previously. I am just wondering if this might be from the small amount of 2-stroke oil I am adding to the gasoline? I'll try to get a pic.  | ||
| Fresnobuell |
Couldn't get a good shot of the intake tract but here is a Q=tip that I ran accross the intact tract for about 1 inch. It would be GREAT if anyone is willing to take a peek down the intake tract ( good time for an air filter change)? You got any of this going on?  (Message edited by fresnobuell on August 07, 2019) (Message edited by fresnobuell on August 07, 2019) | ||
| Duanelr |
Thanks for the replies, guys. Update, I have cleaned the shit out of the air box, throttle bodies, boots, injectors, everything, (I can eat out of that air box). I've bought an additive that is suppose to clean this stuff up. I'll let you know what happens. | ||
| Stimbrell |
The crankcase gasses from these motors, blowby, is routed to the air box, it is not a tight system, very easy to accidentally route the breather to atmosphere. The thought does occur that if the crankcase breather was accidentally routed to atmosphere the intake would remain much cleaner, sure no one would do this to get by EPA shit that strangles performance of course. | ||
| Fresnobuell |
Duane, Stimbrell brings up a great point. What did the sponge look like at the end of your crankcase breather tube? Saturated? Is it possible that the dirty valve situation was caused by actual oil being sucked into the airbox? Any negatives about re-routing the crankcase breather tube to the atmosphere and plugging the hole in the airbox? This seems like it would keep the intact tract cleaner and provide for a better fuel mixture. Very interesting idea. Popular mod on the XBs. I can't remember if there was a reason it didn't catch on with the 1125s. From my personal situation, I am not crazy about the ring of crud on the outer edge of my valves, so I am discontinuing the addition of the 2-stoke oil and going to add a bottle of Sea Foam to my next full tank. I will pull the air filter to see if there is any difference. But now I am thinking it just might be gasses from the crank case causing my oily intact tract and crud on the edge of the valves. Hmmm. (Message edited by fresnobuell on August 08, 2019) | ||
| Stevel |
Harlan, Yes it is normal if the engine is consuming oil. Those deposits are burnt oil. The oil could be coming from blowby, valve guide seal or overfilling....who knows without diagnostics. I suspect the combustion chambers look the same. | ||
| Fresnobuell |
Steve, What is your opinion on re-routing the crankcase breath tube from the airbox to the atmosphere? Positive or negative. | ||
| Shoggin |
You won't get 'positive' ventilation that way (LOL see what I DID there??) The vacuum in the airbox helps pull the crankcase fumes from the crankcase and valve covers. The benefits of re-routing the breather outweigh that IMO. | ||
| Fresnobuell |
So Shoggin, you are thinking it's a good or bad idea to re-route the breather tube? Getting those gases out from the crankcase seems important from the research I did. I wonder how much the airbox pressure drives the system? It does make sense that the higher the RPM, the higher the airbox vacuum to deal with the greater amount of blowby being created.... (Message edited by fresnobuell on August 09, 2019) | ||
| Stevel |
Harlan, Do you think you know more than the engineer that designed the bike? I'm not being a smart ass, but the question is relevant. Effectively, you are asking if you should redesign the bike to correct a fault and that is absurd, of course not. The correct answer is to do some testing to figure out the cause of the fouling. Only at that time can we have the discussion on the best most economical way to correct it. We could I guess, have a discussion on what tests to run and what the results would mean. | ||
| Stimbrell |
The only thing I want going in to my air box is air and routing the blowby to your exhaust via a one way valve like a Krankvent would provide a partial vacuum that removes blowby, just saying of course since doing that would be illegal on a road bike. Sportsters since 2004 actually restrict the exit of blowby to the intake in order to create positive pressure in the crankcase to assist oil scavaging in their dry sump system. | ||
| Fresnobuell |
Steve, SO we should put the Noid back in because the engineers thought it was a good idea to put it in the 1125s? I understand what you are saying, but there are compromises all the time when dealing with EPA restrictions. The crankcase breather is obviously more complex decision than removing the Noid, but it's an interesting idea to remove it from the airbox. I did it on the XB in conjunction with the catch can, so why was this readily accepted? Because of the air-cooled Sportster motor in the XB? The only "test" I am doing on my situation (light fouling on the edge of the intake valves and light oily substance covering the intake tract) is stopping the 2-stroke oil in the fuel and dumping a can or two of Seafoam into the gas tank. The OP obviously has a more dire situation. (Message edited by fresnobuell on August 09, 2019) | ||
| Fresnobuell |
Stimbrell, Wouldn't putting the blowby gases in the exhaust cause major issues as it is still combustible? And doing so would obviously add complexity to the modification as well versus just venting to the atmosphere. | ||
| Fresnobuell |
Seems like higher pressure in the crankcase inhibits the movement of parts, ie performance robbing....so this would be a reason to keep the airbox vacuum as part of the breather system. Also, it's beneficial to the engine seals/gaskets to have lower crankcase pressure. | ||
| Stimbrell |
Putting the blowby gases in to the exhaust is a none issue, it is way too lean to be anywhere near combustible by a massive margin. If I was doing anything to my road bikes I would just allow my 1125 to breath to atmosphere, to be honest the fitting on the bottom of the air box is so loose it may as well vent to atmosphere anyway, on the Sportster unless you have wet sumping issues you want to create partial vacuum for performance gains. Just sayin' | ||
| Shoggin |
Taking the breather tube out of the airbox is a far cry from 're-engineering' the whole bike  I would do it. | ||
| Stevel |
Please explain to this crowd why taking a corrective action without knowing the cause is the smart way to go. | ||
| Shoggin |
Normally I would agree with you Steve. I am not saying this is what caused his dirty valves, but it does. So, In the instance of his breather system, if it isn't the problem he is having, it is a problem he can correct. You mentioned yourself "those deposits are burnt oil". Yep. Your turn. Please explain to this crowd, that (damn the EPA...) Why it is {ibetter} to add oily fumes of uncertain combustibility into an intake tract?} | ||
| Shoggin |
The negative 'crankcase pressure for performance and seals' discussion is accurate but is about a Positive Crankcase Ventilation (PCV) type system. Yes, you can see big HP gains in a big HP situation. Doesn't apply to us  Buells are 100hp and have a breather, simply a open hole in the case. The slight negative airbox pressure is not considered a PCV system. Besides, any gain below 1.5% (1.5hp) difference is outside dyno accuracy and considered immeasurable. | ||
| Fresnobuell |
Interesting discussion. Granted it's a given that sucking wet, hot, oily fumes from the crankcase into the intake is detrimental to both producing HP and keeping a clean intake tract. In this regard pulling the breather tube from the airbox would be a positive. However, the unknown factor is how much does the airbox assists the breather system in evacuating those fumes? And if there are any consequences to removing the negative pressure provided by the airbox. Will the crankcase "push" the fumes out? Will there be more of tendency for oil leaks without the airbox assistance? How about the development of sludge? Will there be HP-robbing resistance to movement if the crankcase pressure is higher? Too bad we don't have a Buell engineer to help us out! | ||
| Shoggin |
The answer is "Yes", but in theory because the difference in this example is immeasurable. The crankcase is under pressure from the combustion that blows-by the rings. Any positive pressure in the crankcase will evacuate through the hole in the case that currently leads to the air box. A open vent would be the same. The negative pressure in the airbox will draw some fumes through, but not nearly like a PCV system does. In an extreme example, Karls 447cu/in turbo motor for his Mile car (Shockwave Challenger) picked up over 140hp with an evacuation pump system. Granted its a boosted application but it's still more HP than any XB I know of, lol. https://www.youtube.com/watch?v=W7Qu9-SFcD0&t=2s | ||
| Fresnobuell |
Is the effectiveness of an actual PCV system better because of the additional ventilation provided by a separate breather tube in a addition to the PCV tube (as opposed to the single breather tube on our bikes?) Or is there another reason? | ||
| Shoggin |
Because it's Positive Crankcase Ventilation. Most commonly using restricted engine manifold vacuum (PCV valve) to create airflow through the case. It's super simple and cheap (most cars use this since 1961-ish) but works exactly backwards. High vacuum at low throttle and zero vacuum at full throttle when cylinder pressures are greatest. In extreme examples like racing engines, a separate vacuum pump is used to evacuate pressure from the engine block. Lowering pressure behind the pistons (for power) and removing gas soaked blow-by from contaminating the oil and risking an explosion hazard. | ||
| Fresnobuell |
So the PCV system is evacuating the most gas at low RPM (when blowby is at a minimum) and evacuating the least amount of blowby at high RPM (when blowby and pressure is at its highest)? Seems like this is opposite of what it should be. Am I missing something? The simpler system on the 1125r using Airbox vacuum makes more sense since it's pulling more gas out as RPM increase. | ||
| Stimbrell |
As does routing to the exhaust which is why I do this on my Sportster, on the 1125 I seriously do not think you would be able to measure the difference in power between venting to air and venting to the intake or exhaust. |
