OK guys, I've got a little challenge. I can't quite figure the solution. Bike ('08 ST1300) has been idling pretty rough since I got it with 23K miles on it 2 yrs ago. #2 and #3 plugs are running a lot colder than #1 & #4. 2 and 3 have carbon fouled to the point of making the engine miss a couple times, and it seems like it has gotten worse through the 2014 riding season. The bike has about 28k miles on it. I put the bike up end of last November intending to work on this over the winter. Well, shoulder surgery in mid-January sort of killed that notion. Swamped at work - just got to start looking at it this past week.
"Igofar" (and others) had suggested the MAP sensor vacuum lines could be clogged at the 5-way tee. Gave tips on how to adjust the hose length to prevent it from happening again. So, I had ordered the $24 5-way plastic tee, and a length of 3.5 mm vacuum hose. Got it all pulled apart, dug down in there, and pulled the hoses and tee. Unfortunately all hoses and the tee were spotless.
Hooked up my manometer (yes, one of those old units with - gasp! - Hg in it (Still the most accurate vacuum measuring device as far as I am concerned). I set everything up for the start valve sync per service manual, started and ran until 3 bars (normal running temp, fan was cycling on and off). The vacuum balance was definitely off, maybe ?6-8 mm Hg between all 4 cylinders, but not terrible. In accordance with the guide, I set the idle at 1000 rpm, and tweaked the start valve adjustments on 2, 3, & 4. I could get them all to stay within ?2 mm of the same at idle, increase rpm and come back down to idle, all looked OK. I think I had to adjust #4 maybe 4 or 5 clicks. 1 click on the adjusters chgs the vacuum by 1 to 1? mm Hg based on my adjustments. I lost track of where I ended up versus where I started while tweaking, but no drastic adjustments required. The idle did seem to smooth out some (the gas in the lower tank is from last Nov, but I put in Stabil Storage in it the last few riding days, so it shouldn't be too bad) after getting all TBs reading evenly (about 145 mm Hg if I recall).
>>>>> My issue now is the vacuum balance doesn't stay even at higher rpms. SM says nothing about tolerance on this. My best compromise was to set 2, 3, & 4 about 2 mm less vacuum at idle. At 4k - 6k rpm (no load obviously), #3 and #4 run about 3-4 mm Hg higher vacuum, and #2 comes up about even with #1. I first was thinking the butterfly sync was off between left and right banks, but it is the two rear cylinders that are behaving a little differently rather than 1-3 or 2-4. I realize the FI is running open loop for these tests since the MAP is disconnected (the FI light is blinking of course), and maybe connecting the MAP sensor and letting it run closed loop will correct it all???
It's a pain to get down this far, and I wanted to do whatever I can while in here to get things optimized.
I will run compression test on all cylinders tomorrow if I can find a 12 mm adapter that fits these heads. All I have are a selection of 14 and 18 mm automotive plug adapters. I would be very suprised at this mileage with routine oil and filter changes if there is any cylinder or rings problems.
I am planning to check valve clearances tomorrow. The original owner never had them chacked at 15k. I've been meaning to do this since I got it Aug 2013, Just haven't gotten to it. Tomorrow.
If the valve clearances are really different between cylinders, that could possibly show up this way and be more of a factror at higher rpms, so maybe that will tell a story. A good friend of many years is the owner and chief mechanic at a cycle and ATV repair shop. He has a full Honda shim set, and said I am welcome to borrow it if I need to do any adjustments.
All other hoses look good. PAIR valves are good. I ran some seafoam through it a couple times last summer, but it didn't seem to change anything. Can't see anything else obvious.
I am hoping one or several of you FI specialists or troubleshooting geniuses can point me some direction that will lead to a solution. I'd really like to get this fixed and buttoned up so I can get in a few miles before November weather shuts me down until March-April on street riding.
Thanks in advance,
Randy
"Igofar" (and others) had suggested the MAP sensor vacuum lines could be clogged at the 5-way tee. Gave tips on how to adjust the hose length to prevent it from happening again. So, I had ordered the $24 5-way plastic tee, and a length of 3.5 mm vacuum hose. Got it all pulled apart, dug down in there, and pulled the hoses and tee. Unfortunately all hoses and the tee were spotless.
Hooked up my manometer (yes, one of those old units with - gasp! - Hg in it (Still the most accurate vacuum measuring device as far as I am concerned). I set everything up for the start valve sync per service manual, started and ran until 3 bars (normal running temp, fan was cycling on and off). The vacuum balance was definitely off, maybe ?6-8 mm Hg between all 4 cylinders, but not terrible. In accordance with the guide, I set the idle at 1000 rpm, and tweaked the start valve adjustments on 2, 3, & 4. I could get them all to stay within ?2 mm of the same at idle, increase rpm and come back down to idle, all looked OK. I think I had to adjust #4 maybe 4 or 5 clicks. 1 click on the adjusters chgs the vacuum by 1 to 1? mm Hg based on my adjustments. I lost track of where I ended up versus where I started while tweaking, but no drastic adjustments required. The idle did seem to smooth out some (the gas in the lower tank is from last Nov, but I put in Stabil Storage in it the last few riding days, so it shouldn't be too bad) after getting all TBs reading evenly (about 145 mm Hg if I recall).
>>>>> My issue now is the vacuum balance doesn't stay even at higher rpms. SM says nothing about tolerance on this. My best compromise was to set 2, 3, & 4 about 2 mm less vacuum at idle. At 4k - 6k rpm (no load obviously), #3 and #4 run about 3-4 mm Hg higher vacuum, and #2 comes up about even with #1. I first was thinking the butterfly sync was off between left and right banks, but it is the two rear cylinders that are behaving a little differently rather than 1-3 or 2-4. I realize the FI is running open loop for these tests since the MAP is disconnected (the FI light is blinking of course), and maybe connecting the MAP sensor and letting it run closed loop will correct it all???
It's a pain to get down this far, and I wanted to do whatever I can while in here to get things optimized.
I will run compression test on all cylinders tomorrow if I can find a 12 mm adapter that fits these heads. All I have are a selection of 14 and 18 mm automotive plug adapters. I would be very suprised at this mileage with routine oil and filter changes if there is any cylinder or rings problems.
I am planning to check valve clearances tomorrow. The original owner never had them chacked at 15k. I've been meaning to do this since I got it Aug 2013, Just haven't gotten to it. Tomorrow.
If the valve clearances are really different between cylinders, that could possibly show up this way and be more of a factror at higher rpms, so maybe that will tell a story. A good friend of many years is the owner and chief mechanic at a cycle and ATV repair shop. He has a full Honda shim set, and said I am welcome to borrow it if I need to do any adjustments.
All other hoses look good. PAIR valves are good. I ran some seafoam through it a couple times last summer, but it didn't seem to change anything. Can't see anything else obvious.
I am hoping one or several of you FI specialists or troubleshooting geniuses can point me some direction that will lead to a solution. I'd really like to get this fixed and buttoned up so I can get in a few miles before November weather shuts me down until March-April on street riding.
Thanks in advance,
Randy
