1978 KZ400 B1 - Scramber to be

Unfortunately not a lot of updates recently. First reason is that the next several things on my To-do list all start with "Buy..." and unfortunately I cannot buy everything I want to all at once and once I do buy them I need to wait for them to arrive before I can do anything with them. The second reason is that Spring has sprung and most of my free time lately has been spent on getting the lawn mowers, lawn/yard equipment, and ATVs ready for spring as well as cutting down some dead trees, cleaning up flower beds, getting the garden prepared, etc.

A few days ago I got the forks leveled in the yokes and some fork oil in them. The speedo and tach cables have arrived. I'll be hooking those up this evening. Next up will be ordering carbs and throttle cable. I'm still trying not to pull the VM30s off the 76 and get this thing started but it is becoming tougher and tougher not to every day.

The good news is while my To-Do list still has a lot of "Buy..." things left to do, I am now down to only about 12-15 tasks remaining to complete this project assuming no surprises. That's a pretty big relief because I'm sure there are nearly 100 items that are scratched through as being done. But the remaining ones are pretty big: intake and exhaust.

Tach and speedo cable were lubed and attached.

VM28s arrived in the mail yesterday. Man, they look tiny compared to the VM30s I have on the 76 KZ400. I popped them into the intake boots just to take a look and figure out what size filters I'll need, whether they will need to be angled, etc. I'll be taking some measurements tonight with something mocked up to be the size of the filters. Throttle cable is on the way, should be here by Saturday. I'm hoping to get that along with the carbs in place this weekend and fire it up for the first time since I've owned it. I'll post some updated pics once that is done.

Next up after that will be torquing and double checking nearly every nut and bolt. Then comes figuring out what I'm going to do for the exhaust. I'm leaning toward buying some tubing and a small flux-core welder and cut and tack everything together myself and then take it somewhere to have everything finished up. I figure doing that would cost me about the same as just paying someone to do the whole thing and I'll end up with a welder out of the deal along with being able to build the exhaust exactly as I want. I have a buddy who builds custom exhaust for a living. I will check with him first to see what he will charge me. I may just have him do it if the price is right.

It runs! And it started right up as soon as I pushed the start button ( well the second time, after I gave it a few seconds to let some fuel get to the carbs ) and it idled great. It was pretty warm yesterday, I had to take the chokes off in just a few seconds so that is a good sign. Between that and based on the jetting I'm using with the VM30s on my 76 I think the stock jetting on the VM28s will be pretty close. Though this one has had a little porting work done to the heads so it may flow a little better.





VM28 carbs, throttle cable and Uni filters were installed. Carbs synced and throttle cable adjusted. Had one small hiccup with the petcock, it leaked a little, but that was simply because the bolts holding it on had not been tightened - rookie mistake. Tightened them up and everything appears to be working fine - didn't spot any leaks at all. Then I put in fresh plugs and put a few squirts of oil into the cylinders. I kicked it over a few times before trying to start it to get some oil moving and make sure everything rotated okay.

Before I take her on her maiden voyage and start tuning the carbs I need to do a few things. I have the clutch adjusted for lever feel but I need to pull out the manual and make sure I have it adjusted properly. All the motor mount bolts need tightened to spec, everything is just finger tight now. The swingarm needs greased and torqued. The front and rear axles need torqued to spec and cotter pins added. And I need to check all the fork and triple tree and shock fasteners to make sure they're correct too. And for some reason my turn signals stopped working so at some point I'll have to track down a loose connection somewhere I'm sure.

It is pretty loud with just the open headers. I believe I have a pair of cheap emgo slip on mufflers sitting around somewhere, I will probably put them on for the time being until I start working on the new exhaust.

Based on the 2 minutes I had this running yesterday I'm feeling like VM28s are a better option for a KZ400 than VM30s. It started easier, throttle response was more crisp. And that's based on using a pair of 28 carbs that are bone stock and not dialed in yet vs a pair of 30s that are dialed in pretty good, though I am no expert and I'm sure someone could get them better. And I may also have a little bit of confirmation bias and am seeing/hearing what I want to see and hear. We'll see how it goes from here.

Updates have been few and far between because time spent working on it has been few and far between.

I found the issue with the turn signals - the connector from the left control became disconnected when I was tidying up the wiring. Easy fix.

I tightened the axles, swingarm, motor mount bolts and everything else I checked - which reminds me that I still need to put in cotter pins on the two axle bolts. I'm glad I went over everything - the top and bottom shock bolts on each side were just finger-tight.

I tried to get it started up yesterday to take it for a quick spin so I could start adjusting the carb jetting and while it started up pretty easily it did not want to stay running and I only had a few minutes to spare so I had to put it on the back burner again. Next I'll pull the the air filters back off and check the carbs are still synched and idle is set the same between them as I was messing with it while trying to get it started.

I don't think I'm going to be able to use the old mufflers I had sitting on a shelf because they will not fit due to where I currently have the headers positioned under the bike. I cannot run them under each side where they are supposed to be routed because of interference with the rock guard and the case savers. So they bike will have to be open pipes until I start building the new exhaust. I'm not going to be riding it anywhere than around the house until it has the new exhaust anyway.

I have spent a few minutes here and there trying to get it running without much luck. I have changed plugs a few times here and there but while that helps some it has not cured all my ills. It will turn over a few times when I use starting fluid but it will not stay running. Yesterday I pulled the carbs off to take a look to validate the stock main and pilot jets and make sure floats, float needle, etc. were all working and everything seemed fine. When putting the carbs back on before putting the air filters on I acted on a hunch - I attempted to partially cover the carb intakes with my hand and it tried to fire up! Though it also tried to suck my hand into the carbs as well so I was not able to keep them there. The stock pilot jet on the VM28s is a 35, I cannot remember what they were on the VM30s (maybe 40?) but I had to go down to a 25 and I know another guy who went down to 22.5. I think the 35s that are in the VM28s are just too big. Unfortunately I do not have any jets that size on hand - the smallest I have are the 25s and those are in my other bike. I had 30s but those are in my Dad's 72 Triumph Bonnevile. I'm ordering some smaller pilot jets now. I'd love to get them here by this weekend but I don't think that will be possible unless I find some on Amazon with Prime. In the mean time I may try to partially block off the air filters with something to see if I can get it going that way.

In other news I have been seeing small drips of oil under the right side of the engine. I tracked it down to the points cover. I removed the cover and cleaned out a small amount of oil hoping that it was a one time thing. But it is back so I need to order a new crank seal for the right cover too. Hopefully I can figure out what dimensions it is so I can order a regular seal rather than having to order a KZ part number.

Also I noticed a few drops of fluid under both the left side and right side of the front fork. I tightened both of the drain bolts on the left and right side forks - they were both only finger-tight. The next day there was no longer a leak from the right side but there were still a few drops from the left. I tightened it bit more - it was still turning fairly easily, I didn't try to put too much torque on a small bolt in aluminum. But I should have stopped and just tried adding another brass washer or a fiber washer because the additional little turn I gave it cased the bolt head to shear off. So I'll have to pull the forks off, try to extract the rest of that bolt and replace it. .

The pilot jets in the VM28s were 35s. I figured that was a little too high since I run 30s in my VM30s on my 76 KZ400 and my Dad runs 30s on his VM30s on his 650 Triumph Bonnevile. I ordered some additional jets from Niche Cycle. Once they arrived I installed the 25 pilot jets but it just did not want to run at all. It would fire but would idle very low and felt like it was running out of gas. On a hunch (well, okay, it was my Dad reminding me that neither of our bikes would run at all with the 25s) I changed to the 30 pilots and it fired right up. It is running really well. So now it's time to get the air mixture screws, mains and mid-range dialed in.

Except there is one problem (okay 3 but one major one):
1. There are some drips of oil from the timing cover - it appears the crankshaft oil seal in the right side cover needs replaced. Not a huge job, but I'm going to have to drain the oil, remove the right side cover and replace the seal. I planned on waiting until I get a few miles on the bike and get the carbs tuned at which point I planned on doing an oil change anyway. But other things have come up where I may have to do it sooner rather than later.
2. I mentioned before about the right front fork leaking. It appears to be from the allen head bolt in the bottom of the fork. I'm going to have to pull the forks and figure out what is going on there: if it just needs tightened, needs a copper/fiber washer replaced, etc.
3. The big issue is that it dies when I try to put it in gear. If I pull the clutch back in it will go back to idle. If I feather the clutch I can get the bike moving but I have to keep pulling it in to keep it from dying and then letting it out a little to give it some power.

I did some searching on my phone while in the garage and found a few things to check but have had no luck with diagnosing the issue so far:
a. Kick stand safety switch (I'm fairly certain this bike does not have one - I had the wiring harness completely off the bike and put it back on and I've been over and over the wiring diagram a hundred times and I'm pretty sure there is no kick stand safety).
b. Timing advance frozen - I pulled the timing cover off to make sure that the advance moves freely and it does. Seems to be no problem there.
c. Clutch cable needs adjusted. I had just set the clutch per the FSM and have since adjusted it looser and tighter but have not noticed any difference.
d. Clutch frozen - I have had this happen before on my 76 after sitting all winter and while it was scary when it happened I was able to break it loose pretty easily by rocking the bike back a forth a little while in a high gear. I put this bike into 3rd and when I pull the clutch it rolls, there is some noticeable drag but it does roll. One thing that I do remember is that when getting the bike put together I do remember that I though the clutch might be frozen because I when I adjusted the clutch feel after installing the lever/perch and cable I tried putting it in first gear, pulling the clutch and trying to roll it and it did not want to roll. I figured I just needed the clutch adjusted which I did later.

So I am at a loss at what to do next. I think that my next steps are to go ahead and drain the oil and pull the right side cover and replace the oil seal and while I am in there pull the clutch basket and disassemble, inspect and lube the clutch plates. Hopefully I will not find anything amiss. This engine has set for a couple of years so perhaps the clutch just needs a little love.

Any other advice?

I believe I got my clutch situation worked out. I think it was just sticky from sitting for a while. It came loose (I could feel when it did) by a combination of
- rocking the bike back and forth with clutch pulled in 1st gear, then 2nd, then 3rd, etc.
- with bike started and warmed up I put it in gear, kept holding the clutch in and give it a few throttle blips
- it was better at this point but it still would not take off from a stop without dying when I released the clutch, though it was not dying so quickly now. So I set about giving it plenty of throttle and feathering the clutch to keep it running until I could get up a little speed ( I was riding in the yard so maybe 5-10 mph ) and then I was able to release the clutch. After a couple laps around the yard I felt something give and the bike then picked up speed and revved freely. After that it was no problem taking off from a stop.

So hopefully that fixes that issue. My next step is to get the idle circuit dialed in. It feels like it is running lean to me. When in gear it gets an idle surge and takes a while to come back down. I do not think I have any air leaks but I will check. And it feels like it is running hot, though it is a fairly hot day out ( 80 degrees ) and I had to rev it quite a bit to keep it running and break the clutch loose.

I got quite a bit done this weekend.

1. I pulled off the right engine cover and replaced the leaky RH crank seal. After removing the cover I could see why it was leanking, it was in pretty rough shape. The Kawasaki part number is 92050-065. I found a few on ebay and other motorcycle specific parts stores for $10 and up including shipping. It is a simple 25x40x7 oil seal. I did not check at local auto parts stores, but I'm sure it could be found. I bought a National oil seal from Advance Auto Parts for $4.99 with free shipping. Started the bike up and rode it around the yard a few times and no more leaks.

2. I pulled the forks and found in one of the forks that the copper washer underneath the allen bold was just not sealing well enough. On the other fork apparently I had completely forgotten the copper washer altogether. I happened to have a couple of old o-rings sitting on my bench that looked like they might fit and they worked well. I reassembled everything, refilled the forks and no more leaky forks.

That should do it for any remaining mechanical issues with the bike. Everything seems to be in order. I will need to pull the valve covers and re-torque the heads soon but I really hate the thought of doing so since this thing has no signs of any leaks at all. I also should recheck the valves. I set them to spec when I assembled the engine but it has gone through a couple heat cycles now and I ought to make sure valves are set correctly before I really get into carb tuning. Also I'm kicking myself for not replacing the valve seals while I was assembling this thing from scratch. At the time I thought they looked okay but I should have spent the $20, cheap insurance, on new seals. Hopefully this will not come back to bite me.

The bike was running lean with the 30 pilots and air mixture screws turned 1-1/2 out. I did some testing and it ran quite a bit better at 1 turn out and even better at only 1/2 turn out. I've read that once you are more than 3 turns out you need to go to a smaller jet. And if you are at 1 turn out or less you need to go to a larger jet. I swapped in 32.5 pilots but did not get any more testing done and that is where I left off. Rather than go much further with the carb tuning my Dad reminded me that I'll basically need to start from scratch once I have the exhaust in place. The bike will run much different once it does not have open pipes and has some back pressure. So my next step is the either having the exhaust fabricated or take a stab at it myself. In the meantime I will be turning my attention back to the 76 KZ400 which currently has the top end torn down to fix its numerous oil leaks. I have received almost everything I need to reassemble other than the base and head gaskets which are on the way.

I am glad I have this thread here to remind me of where I left off and what all was done before now. This will help a lot!

After much indecision about what to do for the exhaust a few days ago I stared cutting up the old pipes into small pieces and tacking together something that should work. I am still working on it but I hope to have some pics in the near future.

Looking forward to some pics of the new system.

I finished putting the exhaust together, got it started and ran it around the yard a few times. No glamour shots yet, but this is just after I pulled it out of my shop, complete but dusty. I still need to tidy up a few loose ends, primarily what to do for mirrors and get the carbs dialed it. It was tough to start but ran great at idle. But it was rough going under load. I have adjusted air screws for the pilots that I currently have in it, 27.5, and it seems to run fine at idle and giving it slight throttle it will rev to 4K easily. Any more throttle than that and it bogs, coughs, drops RPM. So next up I'll be doing some carb tuning to see what this thing likes.