'85 LTD Missing and Losing Power

[Rednaxs60]

Out yesterday for a trip to a local coffee shop for coffee and coconut cream pie. Felt a miss when on the highway, then when I hit town, the bike started to miss and lose power and eventually quit. No error codes on the ECU. Let it sit for a bit. Had a few people come by to assist with a push into the parking lot if needed - very nice to see. After about 20 minutes, started, idled well and I continued to the coffee shop. Had the coconut cream pie - moral imperative.

Went to come home, bike started right up. About a Km down the road, started to miss, then quit. Pulled into a parking lot, started then quit. Did this a few times. Called the local towing and while waiting I started the bike and let it idle for some 40 minutes, all was well. Didn't tempt the fates so bike was trailered to the house. Started and drove into the garage.

The bike idled well, but since it was not under load, expect that whatever was wrong did not get hot enough to fail.

Checked fuel pressure and was in spec. Thinking it's the coils. Will start and let warm up today then take around the block. Hopefully it will duplicate what happened yesterday. Coils are 34 years old.

Last year when I was having the electrical issue that resulted in my changed back to the OEM coils and wires, I noticed that the engine temp would be hotter than normal, and would get to operating temp and to the temp where the rad fan would come on quicker. I noticed this in the last week. Seems these engines are sensitive to a weak or lack of spark to a plug.

Will replace the plug wires first, have the wire. New boots, wires and coils cannot hurt.

Since there were no error codes, do not expect the sensors to be out of spec.

Ns sensor was replaced last year and should be good. TPS was as well.

Checked the Gr/Gl sensors as well last year, in spec.

Will recheck the sensors, but still leaning towards the coils.

More to follow.

Cheers

[ct1500]

Checking fuel pressure when engine is not acting up is an invalid assumption that all is well there. Ride the bike with gauge connected until it acts up for a definitive answer of fuel pump health. A heat related issue with coils would be more likely with MC stationary, going down the road provides a great deal of air passing over them not allowing heat to build up when the problem occurs. As far as plug wires they would all have to fail at the same time to stop the engine from running which is very unlikely.

I would be investigating the fuel filter which if restricted would allow the engine to idle all day long but not pass the required amount of fuel when under power. Remove the filter and blow through it in the same direction as the fuel would flow, if very difficult replace it.

[WingAdmin]

These are classic symptoms of a clogged fuel vent in the fuel cap - a very common problem. Unlock the fuel filler flap, go out riding, preferably on the highway until the engine starts to miss again. Reach down and unscrew the fuel filler cap. If the engine comes back to life, then you have found your culprit. If that's the case, soaking the cap overnight in Seafoam will often fix the problem.

[Rednaxs60]

Thanks for the info. So far 4 people hit fuel first off. Will be looking into the fuel pump inlet and look at the small filter screen for debris. I have also wanted to replace the fuel lines as these are probably the original. Tomorrow is a work/investigation day.

Fuel filter will get changed, been almost 1 1/2 years. Know that this is a key element in maintaining a good fuel system, especially for an FI bike.

Thanks for the input.

[Rednaxs60]

Out having breakfast on the bike. Don't know if I have the issue in hand. Soaked the gas cap in WD40 degreaser overnight (biodegradable stuff).

Work done this morning:

Compressed air through the gas cap, confirmed lots of spring tension left as well.
Cleaned the fuel pump inlet filter/screen. Not enough to keep the engine from operating, but did get some fibres out of the screen, indicates fuel lines are breaking down - time to change. Will wait until second bike is here.
New fuel filter - blew through the old one, no issues - better safe then sorry, good for another two years.

Just need a good ride to confirm the system is working properly, if not onto the next possibility.

Cheers

[Rednaxs60]

Last update. Did a 20 Km run first thing after doing the above maintenance. No issues with the engine misfire or dying so to speak. Remembered I have this nice ultrasonic cleaning machine, so I returned to the garage and used the ultrasonic on the gas cap, cleaned it up nicely. Put another 20 Kms on the bike at highway speeds and no issues.

Thanks to all for steering me towards a fuel issue. Could have gone down the rabbit hole as well. Still intend to upgrade the coils, wires and plug boots, but that can now wait for another day. First will be the fuel lines.

Cheers

[Rednaxs60]

Was out on the bike this morning at 0530 and 0 deg C - heated liner on and working well. Bike is operating very well. The little stumble I used to get when accelerating on an on ramp or when I was accelerating in the lower gears is gone now. Very aware of how it has been running.

Got to thinking about my engine issues last June/July where I spent quite a few hours trying to fix the misfire/stumble issue up to 3000 RPM. My final solution back then was to reinstall the original coils and wires in place of the new coils and wires that I had installed. My thread on this issue is: viewtopic.php?f=5&t=38911 I mention above that I had a little stumble when accelerating, and this has been there since I went back to the original coils/wires.

Now that I have had this issue present itself, I'm now curious as to whether the real issue was a venting issue back then as well. I have taken the coils I bought and have done a coil check and the coils are extremely close to spec as per the OEM service manual. When I get the second bike out here I'm thinking I will install the new coils, wires and new plug boots as well to test my theory.

Time for a new thread on this issue.

Cheers

[Rusty Bike]

Hi Buddy, been a while. I get the impression that your crank angle sensor is acting up. The one under the timing cover. I can never remember Honda's goofy names for sensors! From all I've read, your symptoms sound classic. Stock plug wires were real bad on mine. I used 7mm solid core wires from NAPA. They werre for a Satoh tractor, I cut to size. I also bought some neopreme tubing on Ebay and slid that over the wires for double coverage, like the OEM ones are. 7MM solid copper core wires are hard to find. Another thing, I don't think out gas caps are vented, if thay are, mine has been pluged since I bought the bike! When i open the tank, there is always a pressure bleed off. PPppssssss. Good luck with her.....................>>

[Rednaxs60]

Thanks Rusty. There is apparently a very small vent hole in the cap. Once I soaked, ultrasonically cleaned the cap, engine operated well, even got rid of a pesky miss when accelerating in the lower gears. There has to be a small vent because every know and then when I turn the engine off there is a gas smell and the only place that can come from is the tank.

Replaced the Ns sensor last year with new. Ruled this out real quick.

Last year as you know, I had issues with the bike missing coughing, sputtering, call it what you want, dying then restating. The issue was the new coils and wires I installed. Going back to the OEM original coils and wires fixed the issue.

Time to renew and decided to replace the coils with the new ones I purchased last year, new copper core wires and plug boots. Kept the OEM coils because these were closer to spec than the new coils - go figure. Replaced the wires, and boots. There are two sizes of plug boots - XD05FP and XB05FP. The LTD uses the XD05FP. The difference is the size, the XB is for larger applications. My parts guy had to look up the difference.

Did a road test and the bike missed, chugged, whatever adjectives you would like to use and died, but would start again. Got me to thinking of last year when I had my issues. The only common part was the copper core wires.

Had three options. One - install old wires again, the ones that are harder than the hubs of hell. Two - remove copper core and install the Beldon metallic steel core 7 mm wire. Three - order new from Honda at $25.00 CDN each.

Went with number two, option one would be last resort and didn't want to pay mother Honda. Took the bike apart and replaced with the Beldon metallic 7 mm wire. Did road test, and all is well. The '85 LTD does not like copper core, why - don't know. Will be checking wire resistance today.

Were the wires you used steel or copper core? Glad you used steel core wires and not copper, you would have been on the forum with another issue. The OEM plug wires are steel core as well, not copper.

As an aside, almost ready to travel back east and get the other bike on the road. Have two parts boxes ready to go.

Cheers

[Rednaxs60]

Done a bit more investigating. The OEM, Beldon and the copper core wires all had the same continuity. So went further. Looked at the core itself. They all appear to be tinned copper; however when I tried scraping off the tinning, it did not remove very well but a copper sheen seemed to appear. So I accept this.

Next I wanted to see how many strands of wire were in each. The OEM plug wire had 7 strands, the Beldon metallic had 7 strands, the copper core had 18 strands. The difference in the number of strands between the OEM, Beldon and the other copper core wire may be the issue, and it is the only difference.

Here are some pictures of each:

OEM Plug Wire showing heavy gauge wire strands

OEM Plug Wire showing heavy gauge wire strands

Beldon Metallic Plug Wire

Beldon Metallic Plug Wire showing heavy gauge wire strands

Copper core plug wire showing multi light duty wire strands

[Rednaxs60]

Always something. Clear up one issue, if it was the issue, and another will show up.

Bike is testing my resolve. Replaced the fuel pump with a newer one I had from last year. The older style, identical to the OEM original, was making noises I did not like. Will be making a special inlet elbow to take out the hose bend, good idea from Rusty Bike. Can always improve on the design a bit.

Bike worked well then decided to quit. Noticed that the alternator light was out when the key was turned on. Alternator gets field power from the auxiliary fuse block through a relay. Waited a few minutes, turned on the key, alt light came on, engine started. The power to the coils also comes from the auxiliary fuse block directly, better power supply to the coils. No error codes on the ECU.

Got the old girl back in the garage, replaced the relay, went for a 150 Km ride with a friend for coffee. Bike operated well.

Next morning went to go out and the engine started to miss. Turned around straight away and back to the garage. Now I have a TPS error code. Okay, older TPS, nothing lasts forever.

Checked the plugs as well. Did some research and dry soot on the plugs is indicative of a fuel issue. Have dry soot build up on the right side plugs. Replaced the plugs.

Replaced the TPS and got rid of the error code. Went to balance the right and left cylinder banks and only the left bank draws a vacuum of any sort. The right side does not do anything. Checked the cylinder pressure on both sides and down around 75-90 PSI. Last time I checked it was 125 PSI. I'm hating the worst in that a valve job is going to be required. Not going into the engine because it does not burn oil so the rings should be good.

Having no vacuum on the right bank also affects the PB sensor on that side, and could also be the reason the TPS error code is in play. Reading the supplement and looking at the description of TPS error code leads me to this conclusion.

To confirm everything this morning, went out and took the TPS units I have and bench tested them. Two out of three were within spec and worked correctly. Checked the wiring from the TPS back to the ECU plug and all is well.

Checked the ohm readings for the Ns and Gr/Gl sensors as well. Within spec.

Time to order a couple of head gaskets and some lapping compound. Been a long time since I have taken an engine apart, let alone a motorcycle engine.

Also looking at my schedule and 1 May is fast approaching. Don't want to take things apart and then leave for 6 weeks.

If anyone has some ideas, all accepted. Cheers

[Rednaxs60]

Another day and a good sleep can make a huge difference. Came up with a game plan for this morning.

Decided to prove the TPS wiring. Confirmed that the wiring was correct and supplying 5 VDC to the TPS and that the TPS was operating as it should. Next I hooked up my make shift power supply ( 3 AA batteries) and made sure I had a voltage signal to the ECU connector. All went as expected.

Next I put the TPS in and calibrated it according to the OEM supplement. Got the 0.475 VDC on the TPS with my make shift filed nut to get the 0.110 spec spacer between the throttle stop and linkage, hooked everything back up. The TPS code went away - think I had it calibrated wrong.

I also hooked the right PB sensor in parallel with the left PB sensor and hooked a vacuum gauge into the right vacuum lines because I could not get a draw on the right side with the manometer.

Started the engine and it operated terribly, but I had also backed the throttle linkage off as well.

Put the alternator back on and connected into the system - can only operate the engine and bike systems on the battery for so long.

Stared the engine and commenced balancing the right and left cylinder banks with my heat gun. I did not expect the manometer to work that well so I went a different route. Used 1/4 turn increments to get the cylinders balanced. Once I got close I started using 1/8 turn increments, then to very small less than 1/16 turns - more like a little bump.

After each incremental change, let it steady out then took a heat reading. Using this adjusted the RPM and balance screws to adjust the heat signature on each side. Takes a bit more time, but this procedure does work and takes me back to the good times I had in my Dad's garage in the '60s.

Letting the engine cool down for a bit then I will reset if required the TPS voltage, and check the cylinder temps again.

I'm just happy that there are no error codes on the ECU - for now.

More to follow, and thanks to those who have read my rant, good to think these issues through.

Cheers

[Rusty Bike]

I used copper plug wires. Engine is running great. I also had fuel pump issues. SOB would not always prime. I removed the chrome cover and taped it with a stick...got me home. Bought the 86 Prelude...Denso 9513003 pump from Rock Auto. That pump is longer so i attempted to make the Denso 3/8 hose barb on the inlet into a 90 deg. Dam thing is some kind of zink crap. Can't weld or braze to it. Ended up trying to seal it with JB weld...it's still weeping but not enough to drip. The pump i should have bought was the 86 Prelude pump by Carter #P70199. That one looks the same as OEM but then you still have the fuel line kink issue. I replaced my TPS with the BEI Duncan unit. Really made no difference I feel. The OE one tested good but I replaxced it anyhow. My big problem was the plug wires. BTW, if you lean out the TPS to much, the ECU will definatly throw a code. I think i had mine down around .468 VDC and code was now and then. At about .475 now I think. :Like i said, bike is running GREAT. No rich smell, no miss nothing but smooth strong power, bottom to top. Now I had the sticky clutch thing yesterday. See my other post. I do have master and slave rebuild kits on hand but I don't think it was a hydrulic issue. Like you said, these bikes can be trying at times but....Later Brother, ride safe.

[Rusty Bike]

I used copper plug wires. Engine is running great. I also had fuel pump issues. SOB would not always prime. I removed the chrome cover and taped it with a stick...got me home. Bought the 86 Prelude...Denso 9513003 pump from Rock Auto. That pump is longer so i attempted to make the Denso 3/8 hose barb on the inlet into a 90 deg. Dam thing is some kind of zink crap. Can't weld or braze to it. Ended up trying to seal it with JB weld...it's still weeping but not enough to drip. The pump i should have bought was the 86 Prelude pump by Carter #P70199. That one looks the same as OEM but then you still have the fuel line kink issue. I replaced my TPS with the BEI Duncan unit. Really made no difference I feel. The OE one tested good but I replaxced it anyhow. My big problem was the plug wires. BTW, if you lean out the TPS to much, the ECU will definatly throw a code. I think i had mine down around .468 VDC and code was now and then. At about .475 now I think. :Like i said, bike is running GREAT. No rich smell, no miss nothing but smooth strong power, bottom to top. Now I had the sticky clutch thing yesterday. See my other post. I do have master and slave rebuild kits on hand but I don't think it was a hydrulic issue. Like you said, these bikes can be trying at times but....Later Brother, ride safe.

[Rednaxs60]

Plug wires and new boots are good. TPS adjusted to 0.475 VDC. Adjusted it quite a bit because of balance/RPM adjustment. Any time you adjust the balance/RPM you should adjust the TPS to suit. It does make a difference with the exhaust smell.

I changed out the old OEM style fuel pump from a VW I think. Put in the Spectra SP1186, it's also a bit long as well but has the proper end to match the supply hose to the fuel system. I did change check the fuel hoses and the lines are all clear. From the shut off valve to the fuel pump I put in two 90 deg elbows. The elbows I could find to do this were PEX 90 deg brass elbows that are used in water systems. I shortened the fuel pump inlet barb and one of the PEX 90 elbows to fit. Used Green Line fuel hose, doesn't bend very well, looking for another alternative.

Found some new oil to try, European formula full synthetic 5W40, no friction additives. Seems friction additives are a North American requirement. $6.50 CDN a quart. Went for a good ride today and no clutch slippage so all is well. Purchased this at Bumper to Bumper here in Victoria. Will be buying some for the bike in Ontario. Costs less than standard mineral motor oil. I check the API donut for the spec. It is an API SN standard oil and the bottom half of the donut is blank, no specific additives or friction modifiers.

Did have some electrical wiring connection issues, tightened these.

Put the alt that I had purchased last fall for the LA trip back on. The one that was on was a $30.00 special from a wrecker. Took it apart and quite rusty all through, won't be putting it back on.

151 Km (just shy of 100 miles) road stress test today and all is well.

These are wonderful bikes if you don't weaken.

Cheers

[Rusty Bike]

I was running Rotella T6. I recently called Shell USA and talked to a product usage specialest concerning T6 vs T4, in our bikes. T6 has 1000 PPM zink, Rotella T4 is non synthetic and has 1200 PPM zink. This makes T4 superior for transmission gears due to improved shear factor. Also T4 is way cheeper. Both conform to JASO standards for wet clutch usage. I just put T4 in the Wing and will run T4 in my 98 Valkyrie also. Will be rideing the Wing for a while as I install some upgrades on the Valkyrie. Fun Fun Fun.............

[Rusty Bike]

Ernest, where is the fuel shut off located on your LTD? My SEi does not have one! I see it in the parts fich but it's not on the bike. I don't even see a place it would fit. I replaced the fuel line comming from the tank and that thing is a SOB to get in there. My fuel shutoff is a pair of 6" needle nose Vise Grips that I may start carying in the tool kit. BTW, my bike turned over 50,000 miles today. Just broken in nicely............................................>>

[Rednaxs60]

Fuel shut off valve is on the right side just above the passenger foot board. Here are two pics of location:

I worked on the fuel lines last week as well - it is not a work friendly area. You can also see the 90 deg brass elbows I used in the fuel line.

Here is a picture of the valve:

Turned over 151,000 Kms about 93,000 miles and doesn't burn oil, not bad for an old girl.

Cheers

[Rednaxs60]

I was running Rotella T6. I recently called Shell USA and talked to a product usage specialest concerning T6 vs T4, in our bikes. T6 has 1000 PPM zink, Rotella T4 is non synthetic and has 1200 PPM zink. This makes T4 superior for transmission gears due to improved shear factor. Also T4 is way cheeper. Both conform to JASO standards for wet clutch usage. I just put T4 in the Wing and will run T4 in my 98 Valkyrie also. Will be rideing the Wing for a while as I install some upgrades on the Valkyrie. Fun Fun Fun.............

Got the specs for the new oil I found. It's a Euro full synthetic 5W40 API SN spec oil. The data sheet indicates it is JASO MA2 certified so it has no friction modifiers and can be used in bikes with a catalytic converter like the CDN 1800s.

has a zinc content ranging from 0.089 to 0.109 ppm similar to Rotella T6. Like you mention, this oil that I have found is less expensive than T4/T6 up here. Have done an oil change and using this Euro formula. Working well. I'm a frugal/economical CDN. All being equal I can use this in my car and bikes. Win-win all round.

Cheers

[Rusty Bike]

Thanks for the pics Ernest. Nope, mine is not there, or anywhere else. Probably just as well off without it. One less thing to leak! That 90 just made it in there, looks good.