Another scary noise thread

[Devin]

Hey guys, I've been lurking and learning since I bought this bike and this place is awesome. Printed out both service manuals and got to work getting this $100 1979 xs400 2f on the road again. She's running and riding now, new points, condensers, plugs, battery, new carb boots, oil change with 10w-30, added Harley mufflers to replace the grungy aftemarket ones that came on it, cleaned carbs and I'm trying to get them dialed in(forum is full of info) but the thing that's concerning me is this tapping noise that comes on around 4-5k. Yes these bikes are noisy already but this noise is almost louder than the exhaust when riding. I set the valve clearances per the book at .005" intake and .008" exhaust, no change. I posted videos idling and revving but you can't hear it as well. Thanks for any help guys love the forum and I plan to become a contributing member!

Revving

Idling

 

[Devin]

This video you can hear it wayyyyy better at idle. Sounds like it's coming from the intake side.

 

[xschris]

First off you should have 20w-50 for wet clutch oil in it. That will make it much quieter. Also I would set valves .004 and .007 cold. Make sure when you do it NOT to turn the motor back to get TDC if you go past the mark always go forward. That would put slack in the cam chain causing a bad adjustment. How many miles on the motor?

 

[Devin]

I had 10w-30 in it cause its still cold here in MI. But regardless it's draining out and motorcycle grade 20w-50 is going in with a new filter. I'm gonna reset the valves again to those specs. I use a wrench and a jack to prevent the rollback issue.

 

[Devin]

First off you should have 20w-50 for wet clutch oil in it. That will make it much quieter. Also I would set valves .004 and .007 cold. Make sure when you do it NOT to turn the motor back to get TDC if you go past the mark always go forward. That would put slack in the cam chain causing a bad adjustment. How many miles on the motor?

Ok, we got somewhere. Made one hell of a racket till the fresh oil made its way to the head. That's some thick stuff, but it did quiet everything up nicely. Now the only valve making any noise is the left exhaust and it's fairly prominen. So I'm gonna tighten that one up a tad more. And the bike has 11,225 miles.

 

[xschris]

If the bike has sat a while it may need to be run for a bit to loosen things up.

 

[Devin]

If the bike has sat a while it may need to be run for a bit to loosen things up.

Not to sound dumb but how long should that take? I've probably put about 10 miles on it just ripping up and down the dirt roads tuning the carbs. And this was it's second oil change.

 

[16VGTIDave]

It may take a couple thousand miles. More if you are just going for short runs since the oil never gets hot. Trying to tune the carbs with the engine (oil) cold is futile.

With the cold and wet weather we've been having in my area, the only time I've seen oil temps above 50ºC (122ºF) was stopped at a traffic light after a highway run. And it fell off as soon as I started moving again. Oil temps below 80ºC (176ºF) I consider "cold". I prefer my oil to be 100ºC (212ºF) or hotter, but that takes very aggressive riding to accomplish, even on the hot days.

 

[xschris]

Keep an eye on the oil levels with the bike on it's center stand and cold to ensure proper level. I would say drain the sump, drain the oil and put a new filter in it after 1k miles of more than just short rides. As for temps I use an I.R. gun on the head at the exhaust side of the spark plug. 260-280f seem to be where these run with 60-85f air temps and a long ride. I have five of these bikes and they all run the same.

 

[Devin]

It may take a couple thousand miles. More if you are just going for short runs since the oil never gets hot. Trying to tune the carbs with the engine (oil) cold is futile.

With the cold and wet weather we've been having in my area, the only time I've seen oil temps above 50ºC (122ºF) was stopped at a traffic light after a highway run. And it fell off as soon as I started moving again. Oil temps below 80ºC (176ºF) I consider "cold". I prefer my oil to be 100ºC (212ºF) or hotter, but that takes very aggressive riding to accomplish, even on the hot days.

I didn't realize these things took so long to warm up, I'm used to my old 2 strokers where after a half mile they're up to temp. And I just took it for a 5 mile cruise around the block compared to the mile sprints I've been doing. Yeah I definitely see where you're coming from about getting them hot to tune. It ran a lot worse hot.

Keep an eye on the oil levels with the bike on it's center stand and cold to ensure proper level. I would say drain the sump, drain the oil and put a new filter in it after 1k miles of more than just short rides. As for temps I use an I.R. gun on the head at the exhaust side of the spark plug. 260-280f seem to be where these run with 60-85f air temps and a long ride. I have five of these bikes and they all run the same.

I'll definitely do that and I'll have to pick up one of those damn IR guns. are there oil temp and pressure gauges that are easily added?

 

[xschris]

I would not worry about getting a gun as you can check the plugs for proper burn also. People call it plug chops. There are threads on the forum and stuff on the internet about plug condition. An I.R. gun is nice to have because you can also see the temp difference between each cylinder.

 

[Devin]

I would not worry about getting a gun as you can check the plugs for proper burn also. People call it plug chops. There are threads on the forum and stuff on the internet about plug condition. An I.R. gun is nice to have because you can also see the temp difference between each cylinder.

I've been doing chops and they're looking ok? I guess? Again my 2 strokes i like a nice coco brown color insulator but I'm reading that a light gray is ok on these bikes? I just got back from a 12 mile ride where I rode her pretty hard. That knock quietes down significantly when its up to temp so issue fixed! And I did a chop right after a 0-70 pull and cruise for about a half mile. They look good to me (light brown) but I'd like a second opinion. Thanks guys!
Right cyl

Left cyl

 

[xschris]

Looks good maybe even a bit rich on the left. Carbs been synced with manometer? I would look at iridium plugs and non-resistor caps from the stock setup. Burns/fires much better.

 

[Devin]

Looks good maybe even a bit rich on the left. Carbs been synced with manometer? I would look at iridium plugs and non-resistor caps from the stock setup. Burns/fires much better.

No they haven't been synced yet. I dont have access to a manometer. I read about a trick with 10' of clear line and a tiny bit of ATF or oil? And what iridium plugs should I run?

 

[xschris]

BPR7-EIX ngk plugs. If you get them in bulk they are cheaper. I paid like $20 for four of them off ebay a while back. For a manometer, yes you can make one easy. Lots of vids on youtube.

 

[16VGTIDave]

Both plugs look rich to me. I'm NOT looking at the centre electrode - that should be almost porcelain white on the tip and just show colour at the base on extended reach plugs. I'm looking at the end of the body that is in the chamber. Both plugs are sooty black where I'd be looking for grey.

I don't like doing plug chops because pulling the plugs on hot aluminium heads is risky, and I don't have the patience to let the engine cool. That said, the chop HAS to be done during the exact throttle/RPM condition one is testing. Not 2 seconds later or a false reading will be had. So, engine fully warmed up, full throttle in 4th gear at 8000 RPM, flick the kill switch then pull clutch and off to the side of the road. Read the plugs, take notes, and reassemble. Warm bike up again and full throttle and 5000 RPM chop. Repeat as required. Then back to base to change jets / adjust as required.

 

[Devin]

Both plugs look rich to me. I'm NOT looking at the centre electrode - that should be almost porcelain white on the tip and just show colour at the base on extended reach plugs. I'm looking at the end of the body that is in the chamber. Both plugs are sooty black where I'd be looking for grey.

You wouldn't happen to have a good plug pic would ya? Cause I'm just grasping this concept of white to gray plugs lol. The only place the bike feels rich is in the midrange it has a few little hiccups. And topend feels weak. But it gets slightly better when hot. So according to
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html
I should go up on the mains and lower the needle as needed. Is this info good?

Edit: I only saw the top 1/2 of your post on the email lol. That's exactly how I do plug chops so those plugs represent the 5k rev range.

 

[16VGTIDave]

Sorry, no pics. Just look ignore the tip of the centre electrode and look at it's base. Use a magnifying glass and bright light to see way down there. That is where your answers are! Expect to be installing fresh plugs very often for the first while, so use the cheap ones at first. The iridiums are great once the bike is dialled in.

I've followed those instructions with good results - once I learned the difference between hot and cold engines, lean surging and rich stumbling... One hint - if the bike runs well 2 minutes after a cold start without the choke, it is too rich. If it is falling all over itself, but gets better after running for a while you are close. Most people try to get the bike to run well cold and jet way too rich as a result. A rich condition will also improve as the engine warms up since the plugs will be able to clean off. But the soot will tell the truth. So many factors, so little time to learn them all...

The stock jetting isn't that far off, unless major modifications have been made.

 

[Devin]

[QUOTE="16VGTIDave, post: 167147, member: 5932"The stock jetting isn't that far off, unless major modifications have been made.[/QUOTE]

Well the mufflers weren't stock and then I added the Harley mufflers. But I agree if whats in the carbs now IS stock, it's gotta be close. I guess I'll just have to do more riding tomorrow to get it dialed in, shame. I'll keep you posted.

 

[16VGTIDave]

Well the mufflers weren't stock and then I added the Harley mufflers. But I agree if whats in the carbs now IS stock, it's gotta be close. I guess I'll just have to do more riding tomorrow to get it dialed in, shame. I'll keep you posted.

That would explain running rich. The mufflers flow too well and are allowing reversion to occur. My Sportster mufflers will actually suck dirt into them when riding. It's a common issue with free flowing exhausts that is even worse with open pipes.