That @#$%^&!!! KZ650!

I like that idea on the seat and am hoping you do a little write up on how the foam and cover fits your seat pan..... will look into Mark's threads too and see what he has ..... it might be something I might try as even though I love the look of my stock seat it almost needs the little step in it to help me hold on when I feel the need to hammer it..... and I do have a 79 pan with a ripped seat I could use.

750 R1 wrote: There should be a breather in the tank cap, I'm not as familiar with these bikes but, in the old 750 Honda's this is a common problem, if the tank can't breathe properly then it starves the carbs of fuel... If its not fully blocked it will not rev out properly under load, and if its completely blocked, or close to, you'll get a few miles down the road and stop, what confuses most people is that, after waiting for a few minutes, it will run again, but do the same thing, eventually running out of fuel each time...

It looks like you hit it right on the head, Senor.

She started right up this morning. I bled the float bowls just to be sure, but there didn't appear to be any water in the fuel.

I rode for about 10 miles at 60mph. She ran perfectly, and what a beautiful day for a ride!

I opened her up. This time, she topped out at about 95, where yesterday, she wouldn't go over 80. Not great, but better.

Sure enough, after about 2 miles at WOT, she started to die. I pulled off the road and opened the gas cap for a few seconds. She smoothed out immediately.

I cruised about 10 miles at 70, and it happened again. This time, she didn't smooth out as soon as I opened the gas cap. There's a spot in the fuel line right where it goes into the filter where the bend is a little sharp. I straightened it out, and the bike started running well. I guess the suction collapsed the fuel line at that bend. I'm gonna trim it.

I rode about 75 miles. It happened several more times. Once, opening the cap and playing with the fuel line didn't help. I messed with the petcock a bit, and it straightened out. I think the petcock is janky. It is REALLY hard to turn, and working it a dozen times, or so didn't loosen it up at all.

Here's the underside of the gas cap:



What's the best way to get the vent working again?

Also, when you're 59 years old, and haven't ridden in 4 1/2 years, 75 miles on the most uncomfortable seat known to man can be tough!

Time to get the Advil.

No eBay APP ID and/or Cert ID defined in Kunena configurationHi Sean, glad you've had some progress. The parts of your cap look rather crusty mate, I'd pull it apart and clean it well, replacing the gaskets/seals while you are at it.... Seems new ones are still available....

You can buy them direct.
z1parts.net/gas-cap-with-lock-kz900-kz1000-kz-kh-s1/
I'm uploading a clip on taking it apart.
Steve

Here's the clip. Hope it helps.
Steve

UPDATE:

So, I had several suspects:

1. Too-long fuel line crimping and restricting fuel flow.

2. Vent in gas cap clogged up.

3. Petcock, which is VERY tight, restricting fuel flow.

4. Crud floating around in fuel tank restricting fuel flow.

I rode her to work Sunday. I never went over 45 mph, or 3,000 rpm, and everything was fine.

I got out of work, and decided to ride to a friend's house in a town about 25 miles away. I rode on the highway at a steady 70mph/4,500 rpm.

Within 10 miles, she started running like crap. I pulled over and opened the fuel cap for a few minutes, massaged the fuel line where I thought it was being sucked shut, and worked the petcock a few times. It cleared up.

10 miles later, same thing. This time, the fuel cap/fuel line/petcock thing didn't help. I left the fuel cap cracked, and rode the last 5 miles on the shoulder at 25 mph with the choke on full, running on 2 cylinders. It was all she'd do. I got off the highway and pulled over to call a friend to come and get me. While I waited, I tried the bike, and she ran fine! I rode the remaining 10 miles to his house at no more than 45 mph, or 3,000 rpm. No problems.

A few hours later, I rode home on back roads, again at no more than 45 mph, or 3,000 rpms. She ran perfectly all the way home.

Monday afternoon, I rode to work on the highway at 60 mph and 4,000 rpms. Within 3 miles, she was barely running. I pulled over, and did the Cap/Line/Petcock thing. She ran a bit better, but not right. She died and I had to repeat the process 4 times before I got the 10 remaining miles to work under my belt.

When the problem happens, It's like she goes from running on 4 cylinders to 3 cylinders, to 2, to 1, then none. It takes full choke for it to run at all, and eventually, it won't do that..

There's this awesome guy, Turbo Rick. He drag races Turbo KZ1000s, and works on bikes. He's amazing. I got out of work 2 hours later, and went to take her to Rick's shop, about 10 miles away.

She ran like crap from the first startup. I limped her about 5 miles at 30 mph before she quit for the first time. I did the Cap/Line/Petcock thing. It was ineffective. I tried rocking the bike back and forth and from side to side to dislodge any crap that may have been in the tank, blocking the petcock. She ran a little better, and I limped her some more. She quit 3 more times before I got there.

We shortened the fuel line, and checked the petcock. It is VERY difficult to cycle between Run, Off, and Reserve, but it flows plenty fuel on Run and Reserve.

So, the crimped fuel line and the petcock have been crossed off the list of potential causes. The petcock being so tight still has to be addressed, but I believe it is not causing me to be sitting beside the road cursing The Heavens.

I took the bike out to test it. I ran it about a mile up the road, and a mile back down the road in second gear, at 4,500 rpm. Before I completed the first lap, she was running like crap again. Rick had told me if it did it, he wanted me to take my helmet off and put my ear right next to the cap when I opened it, and listen for a "whoosh". He said if the vent was clogged enough for the bike not to run, there'd be a vacuum in the tank, and I'd be able to hear it when I opened the tank. There was no "whoosh". Since I'd ridden on Sunday and Monday with the cap open several times, and it had kept running poorly, and there had been no "whoosh" when I'd opened it, Rick said he didn't think a clogged cap vent was the problem. I'm still going to disassemble and clean it, but he doesn't think that's causing the bike to run so poorly.

He pulled the carbs and took the bowls off. He'd cleaned them less than 300 miles ago, but there was some brownish residue he thought was rust in the bowls (more on that later). He didn't think it was bad enough to cause my problems, though.

He buttoned her back up, and she ran fine. I repeated my 2nd gear/4,500 rpm run, and again, after less than 2 miles, she was running like crap.

Rick said he had another thought. He said he'd had trouble in the past with Dyna S ignitions getting hot, and causing similar problems. He pulled the points plate, and said the ignition was hot. He left the points plate off, and sent me on my way. He said if it turns out it's the points plate causing the problem(s), I can have a machine shop put some cooling vents in the plate.

I rode home, never going over 45 mph, or 3,000 rpm. She ran perfectly. I'm going to take her out this afternoon and see what happens.

I'm left with two questions:

1. Has anyone else heard of Dyna S ignitions causing problems like mine? I'm not crazy about the vents in the points cover idea. Moisture and dirt in there can't be a good thing, can it?

2. What is the best way to clean the tank and get both the rust AND the Red Kote out?

Years ago, I de-rusted the tank by putting BBs in it, putting it in the drier with packing foam jammed in all around it, and letting it spin till the BBs got all the rust out. I then rinsed it out with Acetone, and coated it with Red Kote.

The guy who cleaned the carbs for me last month said the tank had been rusty, and he'd treated it with this Metal Rescue stuff:



He said after he'd treated it, he'd washed it out with water, and blew it out with air. I'm thinking he didn't get all the water out, as in my initial post, I described the problems I'd had with water in the fuel bowls. I've run HEET through two tankfulls, and when we bled the bowls last night, there was no water, so I think that particular problem is behind me.

Here's the tank now:



Clearly there's rust, but I'm also wondering if the Metal Rescue has reacted with the Red Kote, and it's coming off. I'm wondering if the reddish residue we saw in the fuel bowls is liquefied, or semi-liquefied Red Kote.

I'm thinking I need to not only de-rust the tank, but also de-Red Kote it, too.

Does anyone have any thoughts?

What's the best way to straighten out the tank?

Rather than the Dyna I'd suspect the coils. Pics of the plugs? I don't care for tank coatings. :whistle:
Steve

Es No Bueno.

I rode her for about 10 miles to get her good and warmed up; 45 mph, never over 3,000 rpm. A little burbling, but nothing else.

I then put her in 2nd gear and held her at 5,000 rpm. Less than 3 miles later, she was back to running like crap.

Swest, how do I test to see if it's the coils? Also, if it's ignition-related, when she's acting up, why would she run (barely)with the choke on, but not at all with it off?

As far as tank coatings are concerned, once I de-rust the tank, how do you keep it from rusting again if I don't use a coating?

Coils might be weak. Using the choke kinda makes sure there is fuel present when a spark comes back then goes away. Coils can fail in many ways. When it happens to me I will pull one spark plug wire at a time while riding to see which cylinder isn't firing. Sometimes one plug will be fouled just enough to misfire but still have a path for the other one to fire. It's been suggested to use a heat gun or hair drier to heat up the coil and see what happens. Same can be done to the Dyna pickups. Bad coils cam mimic fuel problems.
Steve

swest wrote: Coils might be weak. Using the choke kinda makes sure there is fuel present when a spark comes back then goes away. Coils can fail in many ways. When it happens to me I will pull one spark plug wire at a time while riding to see which cylinder isn't firing. Sometimes one plug will be fouled just enough to misfire but still have a path for the other one to fire. It's been suggested to use a heat gun or hair drier to heat up the coil and see what happens. Same can be done to the Dyna pickups. Bad coils cam mimic fuel problems.
Steve

Thanks for the help, Steve.

What should I be looking for when I heat up the coils with the heat gun?

With it running on the centerstand you heat the coil and listen for a change. Same with the pickups. Never had my Dyna do this but I guess it's possible. I've had coils do all kinds of funky things.
Steve

swest wrote: With it running on the centerstand you heat the coil and listen for a change. Same with the pickups. Never had my Dyna do this but I guess it's possible. I've had coils do all kinds of funky things.
Steve

So, it's kind of the ignition way of spraying carb cleaner into an idling carb to see if it's lean, or fat .....