Mailmans XS2 , the rebuild.......again

Exact symptoms to look at the coil. Good job.

I sure hope that "new" coil fixes this for you. Many of us have started using these Honda MP08 coils and I've seen no complaints yet.

Thanks guys, that’s the first time I’ve had a coil fail. These MP08 coils are plentiful and inexpensive , used on eBay.
 
I’m still trying to get my carbs adjusted right and it’s making me a little crazy. After installing the used Honda coil it cured a whole bunch of missing, popping and backfiring. I last rode my bike about two weeks ago. On that day when I left the house the carburetors were set right on factory settings, my bike used to run really well right there.
When I started the bike it fired right up, idled smooth and when I rode off it ran great, when the motor got hot my idle climbed up too high and I backed both carburetors idle screws off 3/4 of a turn which brought the idle down to 1500. Still higher than I wanted but the bike was running good so I didn’t mess with it any more. That day was just a short shakedown ride.

Fast forward to today. I had been thinking about how my bike ran last time and I’m aware that a lean mixture can cause a fast idle, so I thought that I would try opening up the air screws before today’s ride. I backed both screws out 1/2 turn. Hit the starter and it fired right off and idled steady right at 1300 rpm. Hmmm…seems like progress.
No popping, good throttle blips, comes right back down to idle, so far so good.
Today I was going to ride further , and faster and it was already turning into a warm morning. I headed for a nearby divided highway , on the way there the bike ran wonderfully, smooth and strong. I hit the highway and opened er up, 60 to 70 mph steady for about 15 miles and then I pulled into this community and rode around slow with a hot motor, no problems, it was happy to just putt around. So I stopped for a bit.
915C6CEA-817A-4260-AAD8-4C01834F97E8.jpeg
And this is where it starts to get weird. After a few minutes I go to start the bike , and it did start, but I felt like it took too much cranking to fire. It didn’t hit right off. And now it’s idling really fast at about 1700-1800 rpm. I rode it a little more and stopped again.
98D2CDFF-303E-414D-9368-8448850317A0.jpeg
Now I’ve got an audience, an old guy came up to admire my bike. ( shit I’m expecting it to give me trouble starting )
and it did :confused: too much cranking and a pop before it started and a racing idle when it started. I head back out to the highway and another hard ride back home. Once I’m moving the bike runs great, pulls hard, no weirdness. Come to a stop light and the idle is still 1700.
When I got back home I let my bike sit for a while, still hot though, and I returned all my screws to factory setting. Hit the starter and vroom! Back in business, but still idling fast. I backed the idle stop screws back off 1/2 turn and my idle is where it should be.

So in case I lost you in all that. Right now the air screws are at factory settings. The idle screws are backed off 1/2 turn from factory.

I just can’t figure out why I can get it running so nice in my garage, then when I go for a ride and it gets hot, everything goes out the window and it starts idling too fast and becomes difficult to start.

For the record, my timing is spot on. My compression is 148 lbs both cylinders. Spark plugs are brand new with my rebuild, maybe 200 miles on them. My air filters are homemade , 1 layer of 1/2 inch foam wrapped around stock filter cages. Pamco ignition with E advance.
 
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I’m still trying to get my carbs adjusted right and it’s making me a little crazy. After installing the used Honda coil it cured a whole bunch of missing, popping and backfiring. I last rode my bike about two weeks ago. On that day when I left the house the carburetors were set right on factory settings, my bike used to run really well right there.
When I started the bike it fired right up, idled smooth and when I rode off it ran great, when the motor got hot my idle climbed up too high and I backed both carburetors idle screws off 3/4 of a turn which brought the idle down to 1500. Still higher than I wanted but the bike was running good so I didn’t mess with it any more. That day was just a short shakedown ride.

Fast forward to today. I had been thinking about how my bike ran last time and I’m aware that a lean mixture can cause a fast idle, so I thought that I would try opening up the air screws before today’s ride. I backed both screws out 1/2 turn. Hit the starter and it fired right off and idled steady right at 1300 rpm. Hmmm…seems like progress.
No popping, good throttle blips, comes right back down to idle, so far so good.
Today I was going to ride further , and faster and it was already turning into a warm morning. I headed for a nearby divided highway , on the way there the bike ran wonderfully, smooth and strong. I hit the highway and opened er up, 60 to 70 mph steady for about 15 miles and then I pulled into this community and rode around slow with a hot motor, no problems, it was happy to just putt around. So I stopped for a bit.
View attachment 192957
And this is where it starts to get weird. After a few minutes I go to start the bike , and it did start, but I felt like it took too much cranking to fire. It didn’t hit right off. And now it’s idling really fast at about 1700-1800 rpm. I rode it a little more and stopped again.
View attachment 192958
Now I’ve got an audience, an old guy came up to admire my bike. ( shit I’m expecting it to give me trouble starting )
and it did :confused: too much cranking and a pop before it started and a racing idle when it started. I head back out to the highway and another hard ride back home. Once I’m moving the bike runs great, pulls hard, no weirdness. Come to a stop light and the idle is still 1700.
When I got back home I let my bike sit for a while, still hot though, and I returned all my screws to factory setting. Hit the starter and vroom! Back in business, but still idling fast. I backed the idle stop screws back off 1/2 turn and my idle is where it should be.

So in case I lost you in all that. Right now the air screws are at factory settings. The idle screws are backed off 1/2 turn from factory.

I just can’t figure out why I can get it running so nice in my garage, then when I go for a ride and it gets hot, everything goes out the window and it starts idling too fast and becomes difficult to start.

For the record, my timing is spot on. My compression is 148 lbs both cylinders. Spark plugs are brand new with my rebuild, maybe 200 miles on them. My air filters are homemade , 1 layer of 1/2 inch foam wrapped around stock filter cages. Pamco ignition with E advance.
I'm not familiar with the Pamco stuff, but is it possible the E-Advance unit is staying advanced at idle when it get hot? Would explain both the high idle and pops when trying to start.
 
If I get this right you have a different new coil. And Coils are affected by heat
I had massive starting problems when hot with stock coils and kick start.
Weak charging. many years ago.
Had to take a walk sometimes. letting it cool off.
So the starting problems hot can be that please google " hot coils difficult to start "
there are plenty on that
You being in Arizona it is not unlikely you are at high temperatures climate wise and if the coil is on top of the engine it can get hot there.
Electrical properties can vary with temperature and perhaps ignition timing if the range is 10 C to 40 outdoors
it can be 50 -60 on coils ( Just guessing )
Idle I also have varying . I have come to get used to it . Hot days after hard rides it climbs
I just adjust a little by hand and come colder weather I adjust again.
I now have 1200 -1700 rpm at times with Boyer ignition.
I don't think it is possible to get it even at all weather .
Without lot of work And it runs smooth and even out on the road I don't want to mess that up.
 
I'm not familiar with the Pamco stuff, but is it possible the E-Advance unit is staying advanced at idle when it get hot? Would explain both the high idle and pops when trying to start.

I really don’t think that’s it. Before I changed the coil, when it was really giving me fits, I checked the timing when it was hot and it was right on at idle.


If I get this right you have a different new coil. And Coils are affected by heat
I had massive starting problems when hot with stock coils and kick start.
Weak charging. many years ago.
Had to take a walk sometimes. letting it cool off.
So the starting problems hot can be that please google " hot coils difficult to start "

Yes, I suspected the coil was breaking down, that’s why I replaced it. Since replacing it, the bike is generally running much better. The bike runs great once you’re past idle. No problems at all.
My problems are too fast idle when hot and a little hard to start when hot.

I’ll try taking it back out again in a couple days and see what it’s doing.
 
Just awhile back my 79 was having a increased idle after warm in town at stoplights. Very annoying.. It was very weird because in the driveway at start up it idled perfectly. Ran great on open roads but, I suspected an airleak. Tightened carb holders etc. Still testing the carb jetting I ignored the idle and went for a full throttle highway test. 105mph wide open. (Ran out of road)
After that the idle issue was gone :umm:
I think there was a passage block in the mixture passages or pilots or somewhere because it did not happen again.
-R
Try That! Nothing to lose
 
Still ponderin'.....
When it's hard to start when hot, are you leaving the throttle at idle, or are you cracking it open a little while cranking?
 
Still ponderin'.....
When it's hard to start when hot, are you leaving the throttle at idle, or are you cracking it open a little while cranking?

I’ve been trying everything from closed throttle to cracked open a little to opened a lot. I really feel like I’m close to being right, but I’m missing something. :shrug: I’m going to take it out again in the next day or two.
 
throttle shaft seals???

I have brand new Throttle shaft seals after a rebuild .But varying idle with temperature BS34 Carburetors
Stock type intake filters
Larger Jets Pilot and Main. Needle adjusted also cant remember how much.
Probably a little to Rich .. mixture but not massive since the spark-plugs at least a little Brown
Cleaned the carbs in ultrasound cleaner a lot before assembly. So they should bee rather clean.

I suspect the replacement coil behaving a bit different in Mr M s case.
 
I have brand new Throttle shaft seals after a rebuild .But varying idle with temperature BS34 Carburetors
Stock type intake filters
Larger Jets Pilot and Main. Needle adjusted also cant remember how much.
Probably a little to Rich .. mixture but not massive since the spark-plugs at least a little Brown
Cleaned the carbs in ultrasound cleaner a lot before assembly. So they should bee rather clean.

I suspect the replacement coil behaving a bit different in Mr M s case.

Not saying it isn't the coil...........that's your line of thought...........mine, I'm Just throwing it out there and asking if he changed the seals........seems the symptom, is a lean type of symptom, and a lot of shit went through those carbs so...........Its up to Bob to answer and if he changed the seals then it eliminates one other possibility and makes your leaning a possibility just a bit more. But he has changed the coil. is the second one a dud as well .........does happen
 
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Not saying it isn't the coil...........that's your line of thought...........mine, I'm Just throwing it out there and asking if he changed the seals........seems the symptom, is a lean type of symptom, and a lot of shit went through those carbs so...........Its up to Bob to answer and if he changed the seals then it eliminates one other possibility and makes your leaning a possibility just a bit more. But he has changed the coil. is the second one a dud as well .........does happen

No Sir that is unlikely two coils An the proverbial one time can go wrong Sh*t happens but second time it is a rule to work on
Second coil no change its time to look elsewhere
I have missed that part .Not read properly. Not noticed why the first one was replaced
Believed it fried of other reasons.. My Bad Sorry.
 
In my experience erratic idle (at operating temp) in the absence of a vacuum leak is usually carbs out of sync. I recently had this same problem with the wife's CJ, it ran great until it warmed up and the it would idle erratically It would do it randomly though. It seemed to alternate between idling slightly to low and slightly to high. I did a bench synch with some craft paper. And found that they were WAY off. I remounted them and put my vac gauges on and fine tuned them. The bike idles consistently and pops off on lightest of first kicks now.
 
To check the throttle shaft seals it is easy to drip light oil with a small bottle and tube directly on the seal area crack.
If a shaft seal is leaking doing this should temporarily at least show a change in idle behavior.
I oil my throttle shaft :)
 
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All kinds of recommended things to look at. Here's one more that I experience. Although I carefully aligned the butterflies when rebuilding my carbs, when the carbs get hot, they tend to "stick" ever so slightly at idle. It will idle at around 1700 but if I reach down and slightly push down on the throttle lever, it drops to a smooth 1200 rpm idle.
 
Thank you gents for your suggestions. Let me try to address them.

The butterfly shaft seals,
I can’t tell you how many times I’ve had these carburetors apart in the last year trying to make them perfect. The last time they were apart was a couple weeks ago, at which time I removed the butterflies and shafts and the seals and closely examined them, they were replaced not very long ago, and they still look perfect. They are very flexible with no signs of wear whatsoever, when I reinstalled them I applied a light coating of dielectric grease to them and the throttle shaft where it passes through them , just to make sure that they are sealing properly.

Float height and clean / check all small passageways ,
I checked and double checked float height , they are right on. I sprayed carb cleaner and blew out all passage ways and verified that all the openings are clear.

The new / used coil,
I bought a pair of the Honda MP-08 coils, they came off of a fairly late model Honda, I tested both coils with an ohm meter before installing and both of them were to spec. They have a well deserved reputation for being bullet proof. I have a pretty high degree of confidence in them.
8A203166-0E46-468E-91E2-2AAD325F825E.jpeg

Carb synchronization,
Being that the carbs are not linked, i synchronize them on the bench before installation. This is how I set them up , the port at the top of the butterfly just beginning to be exposed , about half way. This setting was recommended by 2M and it always works well. Through careful observation, I have determined exactly how many turns of the throttle stop screw it takes to get this setting. I consider this my “ factory setting”.
The air mix screw, I usually set to factory setting, at least to begin with. I sometimes make small adjustments to that.

B1654DE1-6695-4CDE-8CD1-A9F94D564A77.jpeg


The throttle shaft sticking / hanging up,
I’ve never noticed that happening but it is sure worth checking out.

One suspect that is still on my radar is my battery, I’ve been buying cheap batteries and even though they check ok for voltage, I still can’t help but wonder if maybe their voltage is dropping when I crank the starter. Maybe I should try kick starting to see if there is any difference?

I’ll report back after my next ride. Thanks again for your support and suggestions.
-Bob
 
Yes, try kick starting. I kick start mine quite a bit when the weather is cooler. I'm always leery of the starter motor sucking too much juice and robbing the ignition of the power it needs to function. But, once warmed up, I usually electric start. I roll the throttle open a hair and hit the button. The bike usually roars to life almost immediately. Your cold starts don't seem to be of concern though, only hot starts. It does sound like a lean condition. Have you tried popping the gas cap open to see if the cap vent may be plugged and is causing vacuum build-up and subsequent slower fuel flow?
 
Bit late to the party but, we all know the effect sticking bob weights have on the idle speed.
So as your not using a mechanical advance it seems as Jim eluded to that the e advancer is holding the advance.
Now cause or effect, how to prove it’s what’s making the high idle or something else.
Is it possible to run the engine with the e advancer disconnected, and does that make the ignition retarded?
 
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