Hi guys, Can anyone tell me what is a 'normal' amount of black carbon crusting on the top (inverted dome bit) of an inlet valve (the valves that sit beneath the throttle bodies) as I have the throttle bodies off my soon-to-be track bike at the moment and I can see they are crusty. They look dry and crusty rather than oily and the crust doesn't go into the chamber or up in to the throttle bodies, it is just around the valve end. Although I don't have a picture, I have found an image on Google which resembles the amount that is on all of the inlet valves - the bike is a 2008 bike with 4000 miles on it. Is this too much for a 4000 mile bike (which I think it probably is). My next question is, do you think the likelihood is that it is burning oil, like many 2008 bikes? Unfortunately I have only heard the bike running once, when I bought it, and it sounded good, no smoke etc. But I think this points to burning oil... thoughts?
any/all internal combustion engines, there comes a time during the RPM cycle where wave propogation moving through the intake/exhaust tracts will FORCE combustion gases back into the intake system, even if just for a fraction of a second. There are many factors that influence when in the RPM cyclethis is likely to occur, mainly camshaft-valve overlap, injector/ECM fuel enrichment cycles, and exhaustdesign determine this negative wave propogation back into the intake tract, but the point being it will happen over time so nothing really to worry about, just chemical clean them if there not titanium and whiz them back in... Job done
Thanks Dave really appreciate your input mate. Very useful indeed. So even on a 4000 mile old engine this is a normal amount of build up? My thinking is, if this bike lived to see 20000 miles for example, this would be 5 times as much which surely means we are going into ropey territory with regards to the valve efficiencies. Also, as we all know the 2008 blades have been known to burn excessive amounts of oil, I am concerned this is a contributing factor to the carbon build up? Are there any other ways to test / see if there are tell tale signs on excessive oil burning?
I've seen worse, There not fantastic for such low Mileage but there's a lot of different factors that come into play, difficult to work out how much oil it's burning without monitoring the consumption, or stripping engine down and checking bores pistons and ring tolerances! I wouldn't worry too much.....
Yo can also tell a lot by the plug condition .... http://www.onallcylinders.com/2012/12/20/reading-101-how-to-read-your-spark-plugs/
Plugs are coming out at the weekend so will check them out then... cheers again Dave, food for thought
Some more info here fella but doesn't paint such a good picture.... All valves in internal combustion engines will suffer the fate of carbon and combustion by-product build-up as your photos show. Clean all you like - they will be coated again in a few hundred miles. Use the appearance of what you have as a guide to engine condition and mixture accuracy - the light brown, dry, hard deposits on exhaust valves are usually indicative of a correct mixture and an oil-tight engine. Some of your valves (particularly inlets) showed signs of oil ingress making the deposits soft and black. Expect inlet valves to be darker and with hard carbon deposits. Soft and black = oil. If on the back only, then usually valve stem seals are letting oil by. On the face only (usually accompanied by softer oily deposits on the piston tops) indicates oil coming up past the rings. Fluffy black carbon deposits indicate a rich running engine. Bit like spark plug reading really...but more informative. Look carefully at the bevelled face and the matching seat in the head. Black spots show where combustion gas blow-by has started to burn the metal. In extreme cases (particularly on exhaust valves) this can lead to a V-shaped cut in the valve sealing face leading to loss of compression on that cylinder - normally this would have been recognised in the running engine as a misfire, particularly under load, e.g. accelerating up hills. This is not to say that inlets don't burn too - a small defect in the sealing can lead to hot combustion gases leaking back into the inlet plenum past the valve, burning the seat / valve as it roars past. Any black marks on valve sealing face or seat in the head which cannot be removed by mild engineering , i.e. minor refacing of valve and seat and subsequent lapping-in, indicates that the valve should be replaced, probably along with the seat insert. Some modern fuels claim to reduce deposition of material on the valve heads and stems due to increased detergent action and efficient complete combustion. Shell V-Power, for example, claims not only to minimise deposit formation, but to do the work that you just spent hours achieving - i.e. the removal of deposits left by less efficient fuels over the years!
Again much appreciated mate. This most definitely lends itself to my thoughts as to what's happening in there. I suspect it's oil working its way up there and being burned.
I do believe also the use of Shell Optimax/V-Power does help keep and infact clean the valves. I've done a lot in the car side of things, eg race car and engine building and only used that in all my cars and now Fireblade too. As a short story, good friend of mines Vectra kept running rough, going on 3 cylinders on idle, as he worked in a Tesco store he would fill up there with std pump fuel, told him to swap to Optimax as it was called and all back on 4 cylinders. Then after a while I hear the car again and back to 3 cylinders, and yes he had gone back to the Tesco std fuel again !!! Back to Optimax n yes all ok again. For the amount of miles we do on our bikes not work using cheap fuel. Even in the Porsche Cayenne Turbo S we have I only use it and that knows how to drink fuel, but still cheaper than engine problems !!!
Those valves aint from a 4000 mile engine Bash, i have one in the garage with 21000 on it and it's nowhere near as choked up as that. If the engine is a genuine 4000 miler suspect something is wrong or its lived its life doing 2 mile journeys.
could this also be a problem with the crank case ventilation perhaps? seems way to dirty to me ive seen less build up of shit on a 20k L200 with a blown head gasket
Can anyone help ? I have had my bike plugs changed and the mechanic said he has seen quite abit of carbon on the inlet and told me. He said it might be a problem because my bike is 2011 Honda Fireblade 1000rr, he said they had a problem with them leaking too much oil and blowing up?. The bike has 3000 miles on the clock and hasn’t been ridden for 6 months ? Can anyone help thanks
I had a 2011 repsol and did 50k on it....never had any issues it was rock solid other than the bastardo c-abs so not sure what he's banging on about
Copy that. My last bike was a 2011 repsol and never had a day's trouble - apart from the abs. The engine was perfect from day one.
I have noticed from various post that people tend (including my own valve check & adjustment) to find valve clearances too tight. My thinking is that they are so to allow for wear and running in during the forst 16k. In my case because of road use and maybe high quality oil, this wear did not take place! So if the valve clearances are too small, then they remain open into the cylinder a fraction longer. Adding valve ovelap to the equation then there is potential for increased carbon build up. I could be wrong about this so I don't mind fining out. Adding cleaner to the fuel (or buying super unleaded) could keep this in check. We are lucky we do not have GDI engine in our bikes
