'82 KZ550 LTD starting issue

I recently did a base, head, and valve cover gasket on my 1982 KZ550 LTD. I also replaced the intake hoses and such, but nothing else mechanical other than those gaskets. Anyway, I got it back together and attempted to start it. It'll crank just fine and even sputters a bit like it's trying to start (as if it's been sitting a while, that's all. It has been sitting about two months.), but after about 5-10 seconds of cranking with a little throttle here and there (like I've had to start it in the past, did everything the same way) it will backfire VERY loudly. I'm pretty sure my timing is correct, since I've done it several times before and did double check it this time. I checked the plug wires and ignition coils to make sure I had them in correctly, and they're good.

The only thing I can think of other than timing is that maybe it's just flooded. Last night my dad attempted to start it for a bit while I was out and said it never did backfire but also didn't attempt to fire like it did today. Any ideas?

Also, quick question about the carburetors. We pulled them well over a month ago and then ran out of time (I'm in college and don't live here, so the time to drive out here and work clashes poorly with studying), so we're forgetting one thing. There are two hoses that come from the rail that runs across all four carbs on the intake side. Where on earth do those hoses go? They are relatively small, not much larger than the bowl overflow hoses on the bottom.

Hi, I would first say it sounds like you timing isn't right or you got your coils on the wrong plugs. But, that last comment might be the issue too. If you are talking about the 4 vacuum ports on the boots, they should all be capped off, otherwise you have a major vacuum leak. If you are talking about the fittings on the carbs, there is a vacuum port for the fuel tank. If you have the evap emission system on your bike yet, I believe two of the small hoses go to the boot nipples. (I don't exactly remember, I removed mine quite some time ago)

Anyway, long story short, you cannot have any vacuum fittings on the boots open or it'll run like garage or not at all.

I believe the hoses you're talking about are just vent hoses that route upwards and don't attach to anything

nickleo373 wrote: I believe the hoses you're talking about are just vent hoses that route upwards and don't attach to anything

+1

And it does sound like your timing is 180 out like Apbling said.

D'oh, I'm an idiot. We finally broke down late last night and just checked the timing, and as we were taking things apart realized we completely ignored the spark advance portion of the timing when we set it a month ago, so we did indeed have it exactly 180 degrees out of phase. Our cams were right, but we set 1 and 4 at TDC without checking the spark advance. We had been marathoning my car at the same time while I was free for break and completely glazed over that part somehow! At least we were 180 out and not 90! We got it to idle for a bit last night, so it should just need some idle and throttle readjustment and be ready to hit the road again.

Ah yes, the vent hoses. Forgot about those too.

As for the timing... I once wired my coils opposite of what they should be (swapped 1&3 and 2&4) and it had the same symptoms.

Glad you got it running.

Since I already have a topic running, another quick follow up question. I'm working on getting it to idle right now, but its having a rough time. I can get it to start with a little effort, but it keeps puffing air out of the airbox. Each time it puffs, it goes towards killing the engine, and eventually it dies out after a few seconds regardless of throttle. Tips? I'm better at cars than bikes so far, but I'm catching on slowly haha.

If not already done, would check the valve clearances to determine whether they are within specs.

For instance a too tight intake valve will cause backfire through the carb.

Good Fortune!

I believe the valves were all good when we had it pulled apart over Christmas. Unfortunately today is my last day to work for a while, or I'd double check.
After trying for a bit more, it really sounds like there's just a ton of air in the carbs. Lots of gurgling and burping out the air box. Sounds like maybe a vacuum leak, but I'm not exactly sure from where. It WILL idle for a couple seconds somewhat roughly, but regardless of choke any throttle will help kill it after half a second. The only thing I can think of off hand are those two unknown hoses out the top, intake side of the carbs. They are on that rail running above the openings from the airbox, with one between the first and second and the other between the third and fourth openings. Are they ones that should just run to were ever? The odd part is that one is flanged and pliable on the end as though it's been connected to something, and the other looks quite similar apart from more age.

Dresgeve wrote: I believe the valves were all good when we had it pulled apart over Christmas. Unfortunately today is my last day to work for a while, or I'd double check.
After trying for a bit more, it really sounds like there's just a ton of air in the carbs. Lots of gurgling and burping out the air box. Sounds like maybe a vacuum leak, but I'm not exactly sure from where. It WILL idle for a couple seconds somewhat roughly, but regardless of choke any throttle will help kill it after half a second. The only thing I can think of off hand are those two unknown hoses out the top, intake side of the carbs. They are on that rail running above the openings from the airbox, with one between the first and second and the other between the third and fourth openings. Are they ones that should just run to were ever? The odd part is that one is flanged and pliable on the end as though it's been connected to something, and the other looks quite similar apart from more age.

Are the mentioned hoses shown in this photo or any of the following illustrations?









Good Fortune!

Ah, yup, they are indeed the bowl vent hoses. Dang, I was hoping those could lead to a solution. Sorry about the mix up with those, I wasn't sure exactly what they were for!

Well, if you have time off from the bike, maybe you can catch up on some reading. You can download several manuals and check out the carb website. It's all in my signature.

Also, make you read the valve train warning before checking the valves. Since you did the top-end, I hope you saw the warning before putting the valve cover on.