Can we get wings for these things?

Well I went for my first short ride today and holy crap it moves!

I have a bit of trouble that I need to iron out yet, think it’s the coils.

The bike always started fine, one touch of the button and she’s running and it idled great. I took it down to the corner gas station and put some mid grade gas in it, paid, went back out and first hint of something amiss with the idle. I figured it was still a cold issue and it would straighten up with some speed! I went up hill to a friends place for a bit of show off, the bike goes like stink, gave me a great big grin on my face and a lot of WOW. 8O

I have about 1 block to go and the bike starts acting up, bit of a miss developing. Just as I make the turn into my friends driveway the bike died. I couldn’t get it to restart, so I pulled the plugs and they were black with soot, obviously too rich. I cleaned them, plugged them into the high tension wires and lay them on the valve cover and cranked. Very little spark, leads me to think toward a coil issue?

I left it sit for about ½ to ¾ hour, went back out, touched the starter and she fired up. I went back home and the bike had again come to life, lots of power, big reserved grin this time. By the time I got to my place I could hear the sputter starting again and will die at idle.

I have an Ebay TCI that I swapped in, no difference to the idle. I’m leaning toward the coil upgrade and see if this solves the problem.

This is a complete reassembly for those who aren't aware. New fuel line and in line filter. Float levels set while on bench. Carbs were cleaned, new shaft seals. New plugs. I did a vacuum guage syn just after assembly of engine last spring. I haven't done the color tune yet.

Any suggestions?

 

I think I would do the colortune. Starting right up cold could be a sign that the carbs are rich. I would also pull the pug end caps and measure the coil secondary resistance. (11K ohms). Then measure the end caps for continuity and resistance. (5 to 8 ohms.) New plugs would be a good ideal too!

 

It sounds like your barking up the right tree. Coils tend to get worse with higher temps and your exibiting classic symptoms. What color were the sparks your plugs were making? If it wasn't that beautiful bunsen blue to white, your probably looking at new coils. Do an ohm test when they are cold and again when they are hot. If your primary (12V) or secondary (25KV or better) side increases in resistance, bingo. Get ready to spend a couple of bills.

 

Before you buy new coils, check the old ones with a meter to make sure they're bad/borderline. It might be a problem somewhere else.

 

You guys BOTH beat me by one minute! :lol:

 

Why don't you take a peek at your Alternator Brushes before you start buying coils, battery's, wire's, plug cap's and who knows what.

The Alternator cover is just left of the starter.
Undo the three screws and measure the lengths of the two brushes on their mounting plate, on the inside of the cover.

If either one, or both, is less than than 10mm ...

As soon as you replace the worn-out brushes you can start filling-out the forms for Yamaha Test Pilot.

 

Before you start tearing things apart, try making sure you dont have a kink in your fuel line.
Carbs might be filling up and running rich then suddenly you get down the road and she runs out of gas.....1/2 hour later enough gas seeps by to run the bike for another little bit!?


Just a wild hunch.

 

Thanks guys...

BlueMax, colortune is in the works, just had to take it for a ride. I've been itching for some time to see how it ran. It has new NGK plugs, and a new battery.

BlueMax, Robert, and Flooglebinder - 40 degrees F. in my garage, bike had sat for many hours and I tested secondary coils only ( need to pull tank to get to primary, didn't want to do that at this time )

coil 1 & 4 with caps off 11.17 k ohms
coil 2 & 3 with caps off 11.27 k ohms
plug cap #1 5.30 k ohms
plug cap #2 5.84 k ohms
plug cap #3 5.89 k ohms
plug cap #4 6.14 k ohms

Robert, it was very difficult to see the spark during the check when the "problem" occured. Had to look really really hard to see a very thin spark. If I had to put a color to it, would say blue, just not enough of it (spark) however. I will need to take it out for another flight and test the coils at time of failure ( if it happens again )

RickCoMatic, I can't remember how much of the brushes were protruding from their housing and I've been reading your posts thinking I need to pull the cover and check. It will be on my list of things to check out over the next few days. Thanks for the reminder! The way the bike was running seems to suggest temp related problem. It got warm with load and failed, cooled down and ran great once again. Temp increase, started to miss, wouldn't idle, needed around 1500 rpm to stay running.

Thinking on pulling carbs once more to make sure things are clean and at same time install new needle and seats that I purchased.

 

Classic Alternator Brushes symptoms; too.

Battery recovers a little bit to be able to run the bike.
Alternator is trying to keep-up with the load when rpm's are in the charging range. Bad brushes keep the charging system from supplying enough juice to keep the bike running.
Yadda, yadda, yadda.

 

Could it just be that your new NGKS just got fouled out quick and not making good spark? It did it on my bike a few weeks ago because it was to rich. I got it running much better now but I think I am gonna try and lower the needle circlip one notch to lean it out a bit more.

 

Well it snowed here today, didn't stick but still not quite riding weather.

Fuel line is not pinched, I made sure of that when I was running in the new clear line with inline fuel filter.

I don't think it's a power issue RickCoMatic, the turn over speed the starter was cranking is right up there. The battery is new, was on my trickle charger the whole week prior to this maiden voyage.

I have a few things that need to be checked and will post back when I get them done.

Coils when it craps out.
Alternator brush length.

One thing I didn't mention in my original post, the total round trip distance on the maiden spin was only 2.8 kilometers.

Thanks for all the suggestions. I will narrow this down eventually.

 

Alternator brushes are a 10 minute job. Even at 40 degrees. Easy elimination there.

 

Update:

Well, looked the bike over pretty closely.

Looked at the alt brushes, measured close to 11 mm sticking out from brush holder. Went to Yamaha found out how much they wanted and said ouch. Their service dept says they are good until they reach the scored line in the side of the brush, as marked in my photo.

I found some oil drops on my rubber boot for the drive shaft, tracked back to the air box drain. Drained oil, found close to 5 litres! Crap, fuel in oil. Checked air cleaner, half covered with oil.

Filled with cheap oil, ran, drained, changed oil and filter. Fixed up air cleaner and box.

Ran bike in garage, seemed okay. Stuck in my colour tune. All cylinders seem to be bunsen blue. Checked coils after warm, both up by about .32 kohms.

Took it out for a spin yesterday after work, put on 7km. Seemed to be fine, shut off and fired up without any problems. A bit of a stumble at low rpm, but once reved goes like stink.

Took it out for another spin today, put on 15km Didn't want to get off, even with the drizzle. Still have that low rpm sputter, need to pull the carbs off once again, just too interested in riding at the moment. I would put in some seafoam, but parts guys around here haven't heard of it yet.

 

Last fall I was having a bit of a problem with a sputter at lower RPMs. Got a nice (very nice) day in Nov. and had to ride. Dumped in a good dose of whatever carb cleaner was in the garage (CD2 maybe?). Ran for a few minutes to get into the carbs. Let it sit while I had breakfast and got the gear on. Topped off the tank at the corner fuel station at the start of the trip.

About 15 miles into the trip I started to have kick ass power. Stutter was gone. I had the carbs apart this winter - clean as a whistle.

Long way of saying - Doesn't necessarily have to be Seafoam.

 

I had that idle/low rpm sputter/burble/farting sort of issue, and it turned out to be the petcock not flowing enough gas. Try running it on prime.

 

Magnificent photograph!
Let's put that shot in our "Hall of Fame"

If we don't have one ... START One!

Right there is a better look at Alternator Brushes than you can get if you were holding the whole assembly right in the palm of your hand!