1981 KZ1000 J-to-K build

Busy day, but I got a bit done. First off the gas tank... whew what a LOT of crap the vinegar soaked loose! I got most of it dumped out, then flushed the tank once more with the last bottle of distilled water. Let it sit in the sun for a bit and used the compressor the blow out the rest of the water every few minutes. The last flush certainly drained out a lot cleaner, was almost clear. One unfortunate thing I noticed... the tall filter on the petcock is missing the rubber stopper from the end of it, and it looks like that means the gas can flow right into the petcock unfiltered. No wonder I was getting so much crap in the carbs before.

I pulled apart the petcock again to try and seal it up better. The wavy washer under the lever was a bit flattened so I applied some new bends around it. I also brushed a little synthetic grease on the rubber seal. Got it back together and wiped it down, and it seems to be sealing up properly now.

The new bank of carbs slid right in place. I got the inline filter fitted onto the line so I should be getting a lot cleaner supply of gas to the carbs now. The bike definitely looks better with the carb paint matching the engine...


It took a bit to get the bike to fire up. I finally resorted to a shot of ether, and got it running. Further restarts worked just fine without the ether. I had it running for a good hour just sitting there at an idle. That's the longest the bike has run for me so I got to play with the primary jets a bit, but they didn't really seem to have any effect closing them down a turn or two (I started at 2.5 turns open). The engine is still stumbling a bit though so there's probably still a bit of crud to flush out and I still have vacuum leaks. I sprayed a bit of ether around the head boots and got an RPM increase from all four of them. Not sure if there's anything I can do to make these things seal up? After awhile the RPMs went up and it started having trouble idling again, so I've probably flushed some more crap into the idle jets. Since it had a good run I want to re-check the float levels before pulling the carbs apart and cleaning the jets again. I also checked the battery as I went, and while it did slightly charge from the bike running, it was never enough to keep it running reliably. With the battery pack hooked up I was getting a solid 13.9V from the alternator, however when I turned that off the motorcycle battery couldn't hold more than about 9V. I'll have to think about getting a new battery, just not sure I want to get one right before the cold season arrives.

And finally, I broke out the soldering iron and got the new connectors fitting on the front turn signals. Hmm still not quite the right size but they'll do for now. I got some 2mm banana plugs but I think I might need 2.5mm. The plugs just barely hold themselves in place with a friction fit, so just slightly larger should be right. They've good enough now that I have turn signals though.

Looks good.
Steve

Thanks. They'll definitely look better once the bowls are painted too. Good news is this paint is a lot more gas-resistant that the original black paint was. While messing with the tank and inline filter today I managed to dump a bunch of gas over everything. I just hosed down the bike and it didn't do more than dull the finish a bit. I've also been finding that the paint seems to stick a lot better to the parts I didn't put any primer on. Seems odd, the primer was from the same manufacturer and also meant for engines, but I keep seeing chips in the paint that leave the primer behind, The carbs were done with straight paint, nothing else, so we'll see how that lasts. Of course this points out one of the reasons why I wanted to go with a DIY spray-paint job in the first place... if something gets chipped, I just clean it up and spray a new coat.

I'll have to try this again using an air brush, but I guess it turned out somewhat ok for a quick try with a can of spray paint...



It's pretty much the style I was going for, and doing a final coat in the orange really cleaned up the bottom edge so it fades off nicely, I'm just not too happy with the detail of the scales. Ah well, I'll keep practicing.

Well it's been a cold Winter but we're finally starting to get some warm weather again... or at least we HAD some this weekend until a storm started moving in this afternoon. Been a busy weekend but I wrapped up with getting a new battery for the bike. I also got a rebuild kit for the carbs for christmas, so once we get another break in the weather I'll pull those and get all the crappy parts replaced. After swapping the battery I tried starting it up, but I think the carbs were too fouled when I left it last Fall. Backfiring horribly and doesn't want to stay running except at high RPM so I'll leave it for now. Sounds like we might have more warm days coming again next weekend so I'll keep my fingers crossed.

This is going to be it -- the year I finally get her running. I only expected to take half this much time but then again I never expected to have to fix so many things. Honestly though I think I'm still under two grand for everything plus I have a number of extra parts to re-sell later which should recoup a few hundred dollars.

Will also have to finish the paint. I still have the old tank on the bike, and the new tank has been sitting in the garage all Winter, so the orange should be nicely cured by now. Will experiment with the scales some more on the side covers and fenders before trying to finish the tank but there's no need to rush it. I have everything I need to keep the bike running while working on these other parts. Oh yeah, one other thing -- the plastic fillets I glued in behind the the tabs on the sides covers held up through the Winter (lots of temperature shifts that I thought might break the joints) so when I pulled off the cover to swap the battery it had no trouble coming off or snapping back into place. Glad I won't have to worry about those breaking now.

So.. thus begins a new year. Can't wait to actually be able to take her for a ride around the block!

One of the issues I ended last Summer with was a leak around the intake boots between the carbs and manifold. Now I'm not sure if that is having any affect on the carbs, but I do know it will have a significant effect on how well the engine runs through the range of RPMs when I get to that point (not to mention it makes it rather difficult to sync the carbs! ). As a temporary solution I got some copper Permatex (rated to 700 degrees) and put a thin layer on the ring where the boots seat. While in the process of getting the first boot ready, I suddenly noticed that the boots have an orientation... The bottom screw hole has a square shoulder while the top one is rounded. Wow, that could have been the whole reason I was getting vacuum leaks before. Ah well, there is also some light cracking in the rubber so I might as well make sure they're sealed this time. I got all four back in place paying attention to the orientation, so one way or the other there should be a good seal now.

I'll be getting to the carbs tomorrow afternoon. After all the times I did it last Fall, it shouldn't take much to pull them apart and get in the new pieces. Unfortunately this means I'll have to level the floats again, and that does take some time. I dunno, if things go well there's a chance I could actually ride it up and down the street tomorrow. I won't hold my breath though...

Keep trying you'll get there.
Steve

Thanks. I never had any doubts I *could* do it, but with all the other things that come up each Summer it has really drawn out the time needed to get this project done. And even getting the engine running still leaves a lot of work to be completed, but at least at that point I can get some plates on it and start working on tuning and the paint details. There's a few minor details to look into as well, like why the odometer box doesn't want to sit down flush on the bracket so I can put in the little pins.

One thing at a time.
Steve

All right, I think I ran into my first 'gotcha' with mixing parts between the J and K, but it also probably explains some things. I got the carbs rebuilt, cleaned the plugs of all the carbon from trying to run it last year, and finally got it to fire up. The usual smoke for the first couple minutes and then that cleared up and as the engine warmed it started running pretty smoothly -- as long as I kept the RPMs above 3000. Yeah it won't idle at all. And it won't start unless I give it a small squirt of starting fluid (even after it was hot).

Once I decided I wasn't going to have any luck with it, I cleaned up and came inside, and it occurred to me to check the manual. Bloody hell the jets are different sizes between the J (127.5) and K (122.5)! The new jets I just put in are the larger ones, and I about 99% positive I kept the slides together with the original carbs. I am now running the K carbs which means the needle on the slides is smaller, so the carbs are probably passing through a lot of excess fuel?

So I need an opinion... Either way I have to pull the carbs out again. The easiest thing would be to pop the top covers and swap the slides to that the needles match the current jets. Would that work or are there other significant differences between the carbs that would cause a problem with this swap? The alternative is draining the carbs again so I can flip them and open up the bottom, but the problem here is that all of the old sets of jets have been mixed together and I can only really read the numbers on a couple of them, so I don't really know that I can match the 122.5's to make a full set again. Ugh I wonder if there is also a difference in the idle jets? Will have to check the manual again for that. Anyway, I have the K carbs on the bike and have to stick with those because I found broken bits on the J carbs. So what are the chances that swapping the slides will solve the problem with the incorrect main jet size?

Otherwise it seems promising. Unlike last year, once it warmed up and got all the crap blown out it was running nice and smooth. It felt like all four cylinders were running equally and I had the same amount of heat on each side. Now if I can just get it to run smoothly at idle. Oh speaking of which, the rebuild kit came with new idle screws as well, which I lightly seated and backed out 2.5 turns. I believe that's the right starting point?

I almost forgot, I scored on ebay today! The tail project requires building a new seat, for which I need a new pan to start with that I can cut to fit around the tail. I've had a watch running on ebay for about a year and a half now, and the only other pan I've seen was rusted so horribly that I wasn't going to touch it. Well a new pan popped up this week for $15 plus shipping. OK cool I'll keep an eye on it. Someone threw up a bid on Thursday and considering how few of these I've seen I thought I was going to have to fight for it. I put in my bid this afternoon about half an hour before the auction ended and was surprised to see that I was the top bidder for only $15.50. I came back in right before it ended to find that I was STILL the top bidder, and scored the pan for about $26 total. Holy cow I might actually be able to work on the new seat after I get the bike rolling! Yeah it's been a day of ups and downs, but progress is being made.

Took a closer look at the jets I pulled out of the K carbs yesterday, and as a matter of fact I *can* read the size stamps on that set, and they are all clearly marked as 122.5. Sweet! Dropped them in some pine-sol for a few hours and they look decently clean. Since it was only one more step to drain the carbs after pulling them off the bike again, I decided to go ahead and put the right jets in place. The original idle jets are clogged badly, but I found one of the originals clean enough to read and re-checked the numbers in the manual again. It turns out those jets ARE the same size for both carbs so I was able to keep the new ones in there. Finally the air screws... yeah that one is harder since nothing seems to be stamped on them, but the numbers in the manual do seem to call for different part numbers so I cleaned up the originals with some fine steel wool and dropped them back in place.

So now ALL of the jets should be properly sized for the K carbs and everything should be matched up. Got the bike fired up again but it still doesn't want to idle. Best guess is that the idle passages inside the carb may be clogged although I did take care to clean everything as best I could last year when I set up this set. That doesn't mean I got everything though. I had some sea foam sitting on the shelf so I threw a bit of that in the tank. Also noticed more rust from the tank seems to have soaked into the gas so I'm really glad I have the paper filter inline now. I decided to just let it run until the tank was as empty as possible and noticed I was having more troubles as it got towards the bottom but I think it is almost completely dry now. At least I can't keep it running more than a few seconds and there's no sound of sloshing in the tank. I'm headed out to check on a computer and on my way home filling up my two gas cans so I can put some fresh stuff in the tank and fill it up at least 1/4 of the way... get some pressure in the line and then see how it runs. Since all of the gas I had in the tank and the garage had sat over the Winter it might possibly just need some fresh octane.

ho
ly
crap

I GOT TO RIDE IT DOWN THE STREET!!!

All right so it wasn't quite that earth-shattering, but damnit I'm happy. I got about 1.5 gallons of fresh gas in the tank, fired it up and had even worse problems with holding an RPM and there was a lot of backfiring on one side. Once I got it warmed up again I noticed the right side was cooler so I checked the pipe temp and figured #4 wasn't firing. Popped the plug and it was wet so I hit it with the brass brush and put it back in. That did the trick, fired it back up and the RPM's shot up to around 4500 so I killed it and pulled the idle screw back out several turns. I played with it for about 20 minutes before it finally started calming down and settling into a smoother run and I managed to set the idle to about 1k which was just high enough to keep it running steady. Plus it was actually starting without the ether so if it died on the street I wouldn't have to push it back. Well hell, time to pull it out from beside the garage and see if I can actually make her run.

So the clutch feels much different than the Yamaha. Might actually be a little too mushy, maybe I have it tightened down too far (I have to let it out almost completely before it grabs). Got her rolling, and yeah this is definitely a heavy bike, and just has a completely different feel than the Yamaha had. It will take a little time to get used to it but I made a few trips up and down my street without any problems. One thing did come up that worried me -- when I got to the end of the street and started turning around I heard a grinding. I was feathering the clutch at the time and was afraid the noise had come from the transmission, but no I got moving again and there were no other odd sounds. Ok..? Made a couple more trips up and down, then once again heard that sound while turning in the same direction. WTH? Oh crap, the center stand is dropping because I never got the spring back on it! Kicked up tight again st the pipes and didn't have any other issues while I was moving. Brought it back to the house and briefly considered leaving it parked on the street, then thought better of it. No plates, not even a headlight, yeah this is just screaming for a cop to give me a ticket. So she's tucked back up beside the garage again.

Getting a load on the engine seems to have been really good for clearing the cobwebs. I never got above second gear but by the time I parked it I was able to start it without throttle, and she popped right up at 1000rpm. It will be interesting to see how it starts again tomorrow once it is cold. I also need to check the oil level since it still throws a lot of smoke when I first start it. But the most important thing is that it DOES idle now, which means I can start working on adjusting the air screws and getting the carbs balanced. Oh I just thought to look, it appears the actual idle speed SHOULD be set at 1000 rpm. Well hot damn. And that explains why she was really loping when I tried to let it drop below that. So I'm actually in better shape than I thought.

The other issue that I'll have to watch is that it hesitates really badly when I crank the throttle. Considering how much change there has been to the way it's been running today, I'm fairly confident there was some gunk still plugging the carb passages, but it is definitely getting pushed out now. So perhaps a little more riding will clear out the rest and solve this problem too. I should probably also check again for vacuum leaks, but then if it's running well enough that I can balance the carbs that will at least give me a good starting point for troubleshooting. So much more work to do and I'll have very little free time until April, but I'll squeeze in what I can and try to get her ready to get new plates. By next month we might even have some decent riding weather, or at least good enough to make some trips around town and try to shake loose any problems.

Last night I went to bed bummed out about the mix-up with the jets. Tonight I'm too excited to sleep. What a turn around!