Purple People Eater Project 81 CM400T

esmith250624

esmith250624

Veteran Member
Joined
Nov 2, 2023
Total Posts
467
Total likes
527
Location
Prescott AZ
I made a joke about this and put it in the joke of the day. But I had to go take a look at it to see how bad it was. I guess I'm not scared of a little overspray because its mine now. I offered the guy $200 for it and he said yeah. it has an in state title also. it is missing a few things but first thing will be to find out the viability of the engine. I will start this project thread with the good and the bad that I can tell right away. The reason I am taking on a project is that I have several spare parts left over from my CB400T that came with it from the PO. So I thought I would put those to good use. Odometer reads around 12500 miles.

THE BAD:
All the cables are shot
Tires shot
Manifold boot have cracks
No foam on the seat pan
Tank pretty rusty
Overspray on everything
header pipes heavily pitted.
Missing side covers.
Mis matched wheels.
Headlight housing Broken (I have a spare one!)

THE GOOD:
Title (In State)
airbox and airbox boots good
keys for ignition steering lock and gas cap.
lights all work minus the flasher working but they do light up.
Neutral light works
Looks to be mostly unmolested.
all foot pegs and brake linkages intact.
Mufflers look solid power chamber intact.

I will start a more comprehensive list and report what is working and not working. Feel free to add anything you see in the photos.

Barney1.jpg


barney2.jpg
 
Looks like it has potential, hopefully will be a fun project. Since you already own one, I'd say you can't lose. I find it nice to have 2 similar old bikes, when one don't work, I got the other, or can swap parts.
 
used the c-clamp method to break the bead on the rear tire. rear tire was missing valve stem, I bought some of the cheapy Walmart stems to see if it holds air, it seams to have a small leak but holds air long enough for me to move it to my shop in the basement, So I got it moved to my shop now the disassembly can begin.

Motor is stuck so i have the cylinders soaking for now. hope it will free up just so I don't have to cut the timing chain. The PO said it has been sitting 12 years at least.
 
Here is your carb porn for the day.


Carbs are free
CmCarbs1.jpg


Looks like throttle was getting sticky so someone kept spraying something on it and the dirt and grime kept building up. Its pretty locked up now!
CmCarbs3.jpg

Lots of varnish and pistons were pretty stuck
CmCarbs2.jpg


Yuck! I bet you can smell it from there.
CmCarbs4.jpg
 
kbongos said:
Oh man, those carbs are really dirty!
Click to expand...

yeah they are, I separated the carbs. The throttle shafts on both sides were very stuck. after lots of soaking i finally got both sides to fully open, but they still are very sticky, so I will be soaking some more. This is definitely not your average one day carb clean.

I did extract the jets, this is a set of VB22A's from 1981 and the jets are 72 and 118. still have to work on the pilot jets i have been digging black tar substance from them. I will need a few more days to get those out,
 
I was waiting for some impact JIS bits to arrive, which they did today. So I started removing the stator. it was pretty rusty, but it came out after some tapping and pulling. after pulling the stator I was going to reinstall the rotor without the stator and try to get some leverage to free up the motor. I put the rotor back on and it spins freely by hand. I checked the parts more closely and found what I think was the problem. One of the magnets in the rotor is peeling or delaminating causing it to bind up on the stator. I will need to get another rotor , but now I can focus on carbs and connectors. most of the connectors have turned to dust.

1745616442201.png
Rotor_Stator area CM400.jpg
 

Attachments

  • 1745615607548.png
    1745615607548.png
    1.5 MB · Views: 5
  • Rotor CM400T.jpg
    Rotor CM400T.jpg
    1.6 MB · Views: 5
worked on the carbs some more today this is after soaking in gasoline and freeing up the stuck throttle shafts. still some detail cleaning left to do but going good so far.

1745716932823.png

1745717005433.png
 
LongDistanceRider said:
The PO snapped off the idle mixture screws, those need replacement
Click to expand...
Saw a slot in those for a flat head? I've seen that one where they just carve into the sleeve a little. I'd probably use my dremel with the skinny abrasive wheel, but I suppose a hacksaw could work as well.

You got those carbs looking respectable given all that black sludge shown earlier. Great if rotor was locking up engine and not the pistons. I bet you wonder what you've got yourself into with this bike. Thanks for sharing the trials and tribulations.

And then there is that idle emulsion tube that is pressed in on earlier carbs that need to be pulled out with the 4-40 threaded bolt trick, but maybe yours will be the later that they switched to threaded with the flat head slot.
 
I was thinking if this project works out I will be putting some of my CB parts on it to make it work, and If I just put a hondamatic engine in it we can call it a CBM400ETA. What do you all think?
 
1) mixture screw area, you can see where they hacksawed a slot to help remove.
2) idle emulsion tube, older style pressed in, no screw driver slot.
idle_emul_and_mixture.jpg
 
yeah you guys are right about the mixture screws. when it had all the sludge on it it was not obvious and I thought it was a plug but when I put my cheater glasses on now I see it, those must have been some real el-cheapo mixture screws. that is such a small cross section where it snapped off.
 
kbongos said:
You got those carbs looking respectable given all that black sludge shown earlier. Great if rotor was locking up engine and not the pistons. I bet you wonder what you've got yourself into with this bike. Thanks for sharing the trials and tribulations.
Click to expand...
This one is definitely a bigger project. but I went into this knowing this was a likely scenario. Yes it is good news about the rotor being the stuck motor cause. If you remember my CB400 was also a rotor issue. what are the odds? At least i did not have to drill out the nozzles this time.

I have a long way to go but eventually I will need to figure out what to do about the unobtanium side covers for the CM. I know it has been well documented that the right side covers are hard to find. good thing I don't have a 3d printer like you, I would be too tempted to try and make one.
 
esmith250624 said:
yeah you guys are right about the mixture screws. when it had all the sludge on it it was not obvious and I thought it was a plug but when I put my cheater glasses on now I see it, those must have been some real el-cheapo mixture screws. that is such a small cross section where it snapped off.
Click to expand...
They are probably originals, the skinny post was to press on that silly knob that would limit travel, probably government regulation. Good job getting those idle emulsion tubes out, were they pressed in or threaded?
 
kbongos said:
They are probably originals, the skinny post was to press on that silly knob that would limit travel, probably government regulation. Good job getting those idle emulsion tubes out, were they pressed in or threaded?
Click to expand...
oh gotcha, now I know what you are talking about, I have only seen those in photos not in person.

The idle jets were the pressed in kind.
 
Yup, coming from Prince Land in MN here. And I ride the Prince bike in blue(close enough to purple). Well mine is not an automatic, but I like to tell people I got the same bike ;)
 
I took off the front wheel and was working on the brakes today, old hardened grease had almost seized up the brake. took everything apart cleaned off the old grease and put it all back together and before putting the wheel back on I noticed when I spun the hub the speedometer drive did not spin. messed with it for way too long until I decided to check the parts diagram. I am totally missing both #2 Washers. So those are now on order and i get to play the waiting game again.

1746402441210.png

Everything inside greased and working again, just waiting on those washers.
1746402522068.png
 
Some of the other work that I have done (sorry no photos).

Rear brake pedal would not return to normal position after being pressed, so I removed the pedal and cleaned everything and put it back, but in the process I saw some suspicious rust on the swing arm, I removed the swing arm and sanded down the rust spot to inspect the metal underneath. although there is some pitting It seemed solid and did not appear to be a structural issue. I sanded down the swing arm and primed and painted it. while that was happening I cleaned all the bushings and tested the grease fittings, they are allowing grease to enter the swing arm, so once the swing arm was painted I reinstalled it and greased the swing arm pivot shaft and bushings.

The paint on the tank was stripped down the the bare metal, was set aside for work later. there is one small pin hole on the underneath side about 3-4inches from the fuel outlet. since it is hidden it will probably be soldered soon. the inside of the tank was soaked with vinegar and rinsed and oiled, it looks pretty good now but I may do another soak when it gets closer to time to get it running.

I have spent way to much time just scrubbing grease and grime off of the frame and engine. I had a little SNAFU with the carburetor kit I first ordered so I had to cancel that order and order a different one. that one should arrive this week along with some cables and the washers for the brake.
 
Cables and Carb kit came in the mail today. these are some nice cables if they are in fact 44 years years old. they move very freely and only a few nick and dings on the sheathing. That got me thinking that some of the motorcycles being parted out are probably nicer that the ones we are trying to restore. Not that I can do anything about it, but it just seems backwards.

In my case I'm using the word restore very loosely.....
 
Partially assembled carburetors. I will probably pull the black floats from my spare VB21 carbs and use those instead of these white ones. The black ones have the adjustable tabs. all original jets were re-used. I am going to try to reuse the mixture screws also.

Model and jetting is: VB22A Pilot=38, Primary/Secondary Main 72/118

carb_assembly.jpg

1746544703792.png
 
The pivot stands on the VB22 carbs are @1mm higher than the VB21's. Result is the floats sit slightly wrong and the level adjuster tab needs way more adjustment.
Solution is to rebend the pivot on the black floats so the float needle sits in the middle of it.
 
I'm a little confused on this one. manual looks to holding carb vertical. i measured at 45 deg but vertical gets me the same result. top of float in this position is level with the mating surface but not 15.5mm. horizontal like in my last photo measurement is 15.5 on the lower end, but not level with the bowl mating surface. Would you go with this setting or keep adjusting. I made and adjustable "TANG" for these while floats.


1746656290904.png

floats3.jpg


floats2.jpg

floats1.jpg
 
ok too many measurements to discuss but comparing the new white ones with the old white(ORANGE) ones. I think the image below demonstrates the most critical one which is a discrepancy in the centerline on the mounting pin. the new one sits higher is the running orientation which more "float" and would cut off fuel flow earlier?????

I am leaning toward assembling these and filling on the bench and use clear overflow lines and open the drain screws and check the actual levels.

1746659453336.png
 
LongDistanceRider said:
Where did the right hand floats come from, left are obviously Honda
Click to expand...
They came in a kit from ebay, I know, I know not recommended. You saw the picture in post#1 of this thread, obviously this whole thing is an experiment. So I am going to try and make them work. I will save the old (orange) ones so I can buy some OEM honda float needles and put them back in if this experiment goes wrong. The backup plan was always to part it out and keep the engine as a spare.
 
Still working on thee Carbs, I assembled the carbs but had trouble with the sync screw. I got them together but found that the sync screw did not quite line up well with the slot in the throttle mechanism, it was not centered in the slot, it was wedged more forward. Also when I tightened the plates holding the carbs together the throttle was binding and still sticky. the throttle shaft and butterfly on the side where the cables connect was also still a bit sticky even after soaking the throttle body's several times. I felt I had not choice but to remove the throttle shaft and clean whatever gunk was still in there. it would free up if I gave it a shot of carb cleaner but if I let it dry for a day it would harden back up and get sticky again.

after separating the carbs again, I took a closer look at the sync screw connector on the right side carb, it seemed slightly bent, meaning the factory bend angles on it did not appear to be at right angles. I carefully bent it back to what I felt was square again. After recleaning the throttle mechanism I reassembled everything, and it when together perfect this time. got the throttles bench synced very well to where they both close evenly on both sides.

I don't have a picture of it right now, but the throttle cable that came with it were snapped in half, and from all the grime and gunk caked around the throttle mechanism in post #5 my guess is somebody just cranked on the throttle hand until the cable broke and bent that connector. Anyway, all fixed now and next in to bench test the float level that I talked about earlier.


1746811881813.png

1746811991019.png

Sync Screw better lined up after bending the connector just a bit.
1746811923786.png

Bottom side of sync screw with washer.
1746811953060.png




 
Last edited:
Only one leak from the drain screw on the right side carb, I kinda expected it, those o-rings did not fit right, I will get some better o-rings. Float level looks ok to me, it is just slightly lower that when I did this test on my CB400. if you did this test and got different results let me know. should be good enough for a test run. (other items not quite ready for that yet, maybe another week or two.) I tried to make the camera angle show exactly what I am seeing in real life.


floattest1.jpg

floattest2.jpg

floattest3.jpg
 
Welcome to the ratty carb club. I like your bench test with the clear tubes. I have done that only on the bike, but it's a bit of work taking the carbs in and out. I've gotten better at taking bowls off with a homemade stubby screwdriver, but there is only so much you can do in that position.
 
Now I am having an interference fit issue with the rotor/flywheel. some of the magnets seem to sit a little proud of the inner rotor housing, and take a look at the edge. not sure if this is an epoxy that glues these in but there are screws holding the individual magnets, so not sure if those are epoxied as well. Can these be repaired or should I look for a different one.

1747068909244.png


1747068951255.png


1747069004336.png
 
Shouldn't be any interference with that rotor. I would polish/sand the magnets as well as the stator poles to remove any/all corrosion and debris. Being a strong magnet they collect all sorts of FOD.
Do Not mess with the magnet screws.
 
LongDistanceRider said:
Shouldn't be any interference with that rotor. I would polish/sand the magnets as well as the stator poles to remove any/all corrosion and debris. Being a strong magnet they collect all sorts of FOD.
Do Not mess with the magnet screws.
Click to expand...
ok, i will do some more cleaning, I wanted to ask before I tried anything.
 
Ok I cleaned it up some more and it fits just fine now. whether it will throw a spark or not, we will see. but fits ok and no rubbing.

I threw the battery on it and hit the starter button, sounds fine but compression is about 110 on both sides, but I have not even looked at the valves yet , so I will look at those next, and the connect the ignition parts and see if there is spark. original coil and CDI so it might not spark.

rotor2 CM400T.jpg
 
pluged in all the ignition parts and it has good spark, I am resisting the urge to fill the bowls flip the switch and see if it will run. I really need to tidy up some things first. I started cleaning up some of the electrical connectors in the headlight bucket. while I am there I am swapping out a cracked headlight bucket. I really should wait until I get the new front tire tube on thursday. I have the front end propped up on blocks so if it did fire and had a vibration it might fall over.
 
Got a couple more questions before I try to start this engine. the cam and valves in the head are very dry. I have not known oil to evaporate over time, but maybe? Before i try to start it , guess I should pour a little oil into the wells for the cam lobes? This got me a little worried about oil flow. So I pulled the inspection cap for the balancer chain and made sure the oil pump chain was turning when I rotate the crank, that seems fine. is there enough pressure to send oil up to the head by just running the starter motor? if so should I verify this first?

Is there anything else I should check?

for the front wheel picture should I pack that entire gear cavity with grease, or just coat the gear teeth?

1747332667841.png


1747332701594.png

1747332804044.png
 
Pour your first quart of oil over the cam/rockers to fill the oil baths, the rest will end up in the sump. Then add another 1.5+ to top off the oil.
Just grease the gears, no need to pack the area.
 
You must log in or register to reply here.
Back
Top Bottom