engine shudder during idle

[R1150Rclean]

So when I first got my bike it idled kind of fast, so I slowed it down to just over 1k, and the problem I had was about every 4th to 5th ignition there was a noticeable engine shudder (could see tank shudder). Replaced the plugs, air filter, ran a can of seafoam through, balanced the TBs, and now the shudder is very subtle and only occurs about every 20th ignition (it is so subtle the tank does not shudder). What is the shudder due to? I remember when I first replaced the plugs the pistons looked like they were carboned up, am I getting pre-ignition due to that? If so, is there an easy way to clean off the pistons, besides using seafoam? Checked the fuel injectors and they looked clean. Once I get out of idle speed the shudder goes away and the engine is very smooth.
Thanks

[Twempie]

Have you upgraded the timing chain tensioner on your left cylinder?
http://rubberchickenracinggarage.com/chain.html

[CycleRob]

I had to look in your profile to get details on your bike.

2003 R1150R Single Spark Non-ABS

There's no mention of the odometer, valve adjustment or if you had the bike since new . . . confirming the bike's service history. Also, what tool was used to do the TB synch?

About the main odometer, a big number like 70,000 would add in TB throttle shaft wear that would introduce an air leak -and- as an example, wear or pitting on the exhaust valves, after 40,970 miles on my bike looked like this:
http://r1150r.smugmug.com/Motorcycles/O ... Le7g-O.jpg
Not exactly a 100,000 mile engine in that area, is it.

Prior history would rule out someone "adjusting" the blue painted idle stop screws instead of the BBAS (BigBrassAirScrews), which totally screws up a very important factory system calibration. Compensating that tiny misadjustment with the BBAS would mess up the fuel mixture flow path on one side enough to give you an intermittent shudder. Yes, the blue painted throttle stop screws can be reset by humans with patience, procedure and precision IF the paint is missing or crumbled away.

My vote goes to things that come about with age and normal use, like:
--An imperfect fuel injector spray pattern.
--Water heavy oxygenated fuel.
--Heavy deposits on the Intake Valves.
The rest of the engine cylinderhead apart pics are HERE.
.

[boxermania]

CycleRob has covered the mechanical aspects.....I will deal with your riding style in regards to shifting, rpms and general use of the bike.

If you short shift, take short trips and the riding is leisurely, I would say you need to "blow the carbon out" This is generally accomplished by finding a back road, keeping the engine in a lower gear, say 3erd gear and accelerating to 7K - 7.5K or so, once there close the throttle and let the bike slow down to 30 mph and repeat the process about 4 to 5 times. This process loads the engine, which translates into heat, this in turn softens the carbon deposits and the strong vacuum of the closed throttle pulls the deposits out of the combustion chamber. Put some Techron (concentrate) in the tank, as per the instructions on the bottle.

I know my friend CycleRob will probaly frown, but.......

[R1150Rclean]

Okay,
The bike has 6,900 miles, everything was done at the 6k tuneup that was supposed be done (+air filter), got the bike at 5,800 with the service records which are at "okay" intervals. Did not mess with the stop screws, and they are tight-did nto see any blue locktite on them, but is on the TPS nuts.

Boxermania; I rev it a lot 4-6k sometimes hit redline, keep it at 3k or higher rpm when cruising, run Shell premium and use fuel conditioner for the 10% ethanol. There have been times when it ran smooth at idle after a good run. Today I was running it with "old" fuel conditioner and 2oz seafoam/gal (had that mixture for the last 2 weeks). The low fuel light came on and I filled it up (nothing added to the fuel), came home and it idled fine. Maybe the just expired fuel conditioner (label said it was good for 1 year after opening, 3 months past that and it did look a little thick as I poured the last of it into the tank ) and the rich mixture of seafoam was causing the idle ignition problem?

Did not realize how easy it is to pull off the heads, thanks for the heads up CycleRob . Will think about doing that to clean up the carbon on the inside if the problem comes back.

[CycleRob]

"Did not realize how easy it is to pull off the heads, thanks for the heads up"

I would not say it was "easy". One scary thing for me was how tight the camshaft sprocket bolts were. They loosened easier after a few seconds of a propane torch on the bolt head. I say it was scary because the chain is all there is to keep it from turning and the 80+ ft-lbs required put a very heavy tensile load on that chain!!! If the chain broke or stretched out, the engine would have to come completely apart, as in split the crankcase halves, to replace the chains.

.

[boxermania]

Ahhhh.....with more info at hand things become a bit easier. Once again assuming the mechanicals are OK, I wouldn't worry about major carbon deposits at 6900 miles and removal of the heads for cleaning, at least fo now. I truly think it would be a waste of time and resources......

Once again regarding the idle issue, I think, based on your latest post, that part of the problem is all the stuff that you are mixing with the gas. Stay away from the additives for now, run two or three tanks of good gas and see what happens. Gasoline already has an additive package and the repeted use of aftermarket additives might conflict with those already in the gasoline, that's why I suggest to stay away from them.

Another question....how much oil are you using? I'm trying to find out if the engine is broken in.....you've had it for only 1100 miles.

[R1150Rclean]

Another question....how much oil are you using? I'm trying to find out if the engine is broken in.....you've had it for only 1100 miles.

Will be careful with the additives from now on (was using STA-BIL). As for oil, not sure right now. Initially it was always 1/4 down in the window after a long run, after a short ride it was always 1/2 down (holdup in oil coolers). Will have to check it after a long ride to see where it is now.

Should it be burning oil, and if so how much is normal for ~7k?

[boxermania]

R1150Rclean

In answer to your question....if the rings are seated hardly anything, if not a quart or more between oil cahnges.

Regarding the oil consumption, (short version). The cylinder coating is Nikasil, a very hard wearing surface and it takes a bit of time for the rings to seat. If one follows the OEM recommendations for the first 2000 miles and then rides using the full gamut of engine rpm the rings should be seated by 5000 miles only requiring a few cc' of oil between changes (assuming 3000 mile changes).

On the other hand if the engine is kept on the low rpm range along with short shifting to take advantage of the available engine torque the seating of the rings will take much longer, up to several thousand miles. The downside is that the oil is burned in the combustion chamber creating carbon deposits....not good and also coating the rings (the oil rings that is) with varnish reducing their functionality.

[R1150Rclean]

Boxermania,
Looks like I burned ~1/4 quart in 1,100 miles. I have been running it hard some times, but often shift keeping it between 3k-5k rpm. Using Mobil syn 15-50, which may increase the burning, but could not find synthetic in 20-50w. The Castrol GTX 20-50 may be fine if I change every 3k, which I will.

Just redid the TB balance (it was off only for the idle), the bike is running very smooth now. STA-BIL website says to use the additive only for fuel that will be sitting for more than 2 months, I go through a tank in 2 weeks, oh well live and learn.
Thanks for the input.