Accidentally Purchasing a Rare Honda | CT70 PART 1
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- เผยแพร่เมื่อ 23 ก.พ. 2023
- New Project! Join as we dig into this 1969 Silver tag CT70.
Let me know in the comments what you think the diagnosis for this non running bike is ? Have I missed anything?
Silvertag numbers are approximatley 16,000 units..... Not as rare as the initial 2000 assumption but still super cool!
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My Instagram is below where you can keep up to date with the builds and all projects! PART 2 COMING SOON!
INSTAGRAM: mason_bennett54
As Always, enjoy the video and thanks for watching! - ยานยนต์และพาหนะ
Following the completion of the engine build, I can confirm that this bike did not run due to a faulty flywheel! It had de magnetised over time meaning it could not produce a strong enough spark to successfully run! A full build video is due to come out covering it all!
Well you prove a person is never too old to learn something new, I just never had anything like that happen. Sometimes when I work on things and use a screw driver and I can't hold the screw or don't want to lose it, I take a magnet and slide it down the screwdriver shaft several times and it magnetizes them so they hold the screw.
I have had some for around 30 years that are still magnetized. The old CRT Television tubes would build up magnetism around the picture tube, they had a thing called a degaussing coil around the tube to de magnetize it. So I never knew a magnet could lose it's electrons north to south. over 50 years, I have never ran across a magnet going bad but I believe you. You were real lucky to find the bike, but very un lucky to have a bad flywheel lol. Glad you figured it our, So that means you can put the pointless ignition back in now if you have a good flywheel. Thanks for your video and for being so kind.
It is certainly a strange one but its good to get it sorted.
Luckily my Z50A has the same flywheel but much better condition and I'm planning to run that one on the original points so a simple swap and we are all sorted. If not, It would of been a very difficult and expensive part to find. I suppose you could say the issue lies in the changing from points to electronic..... It will perform much better but this would have never been an issue if kept standard ignition, oh the joys.
As for the bike, its going to be great and I am excited to finally get it finished!
Thanks for the chat, I hope you watch the rest of the series! @@melfrank8379
Those are awesome I had a Honda 90 trail bike growing up I had all kinds of old logging roads in Camp Road so I can go on Hunting fishing goofing off seeing all the animals that 70s fun little bike you treat them right they last forever just like a good woman🤣
haha great comment!
Mason, the best way to test if your spark is hot is take the plug wire lose , take the plug out so you can turn the engine over faster and put something like a Philips screwdriver into the spark plug lead holding the shaft of the screwdriver near a clean ground of the motor. Then vary the space between the screwdriver shaft and engine ground as you crank the engine, the hotter the spark, the further it will jump. I use to think too that there was any difference in the spark inside and outside the cylinder, usually if I had a blue spark, it would arc further than a point gap and that is hot enough to do the job.
I was working on a sears 2 cyl garden tractor, I had lost spark only on one cylinder, It had only one coil with 2 plug wires coming from it so I ordered a new one.
I got it and installed it and could not get the tractor to even start but I had spark. I determined what you had that the spark must not be as hot inside the cylinder because it would not fire the motor. I adjusted the gap and tried everything so I tried switching the plug wires and it ran but again only on one cylinder. I was dumbfounded. The tractor had no points, just a condenser, I had no clue how it knew when to fire, or what caused the discharge to the plugs. Then I noticed something different about one end of the coil so I thought maybe it is upside down. I flipped it over and it fired right up ran perfect.
Turns out they have some kind of inductive trigger wrapped inside the coil insulation that takes the place of the points, triggering the coil to fire, if it is not installed right it does not trigger the timing of the spark right.
My point is, it is easy to assume when you know better if you find no other explanation, that it must be a weak spark, despite you knowing it had a good spark as you said in your video numerous times.
I have had DUH moments, I think you might have had a DUH moment not noticing you had only put enough fuel in for a reserve level in the tank, and never setting your carb to reserve when you tried starting it. I can tell you even a weak spark like with a fouled plug will still sometimes fire or mis fire if their is fuel, without fuel, you will get nothing.
I wish I had been there to help.
By the way I know I wrote a lot and it may not help you if your problem is fixed, but I hope it will be on the web when I am gone to possibly help others. I have always been the one people called when nobody else could figure things out.
I completely agree that it is easy to come to a conclusion. I think if the bike was not being completely rebuilt, then more time would of been spent trying to get it to run in its then current condition and maybe it would of been obvious. As it was being taken apart, I wanted to come to some sort of conclusion hence the outcome.
Your comments are valued and appreciated! As you know, its not always simple.
If you are in the UK you are more than welcome to make a visit and take a look at the engine, I can show you it running on one flywheel, then as soon as its changed it not running! Would be great to get your expert opinion on it!
Thanks
What a superb project and place to start . I've just finished my 89 ST it had a few issues that fought me , love these Bikes they are ace , the structure is standard but the motor is modded ,running a Takagawa 88 r kit manual clutch, z50 4 speed bottom end .
Hey that sounds awesome! I am really excited to get this thing finished up! I will be sharing my thoughts in a video on how it performs when done, thanks for the comment.
@MasonsWorkshop looking forward to see the progress Mason , 👏 enjoy the vids keep them coming
Last week my ct70 went through streams filled with huge boulders that made a large BMW turn back.
Awesome, glad to hear you are riding it !
I can't wait to see the results
Thanks!! New video coming soon of full engine build. It’s going to be a good one
Mason, I think you said you got it running, still does not sound right that the solid state ignition needed anything different than the standard flywheel as far as magnetism.
In my experience pointless ignitions put out a hotter spark, I just wonder if your problem in the video all along was the fuel petcock setting, perhaps you added more fuel or had the petcock setting in the right position on R , when/if you did get it running.
Then assuming the problem was the pointless ignition, when really you accidentally changed the circumstances where you got gas when it finally started, and just thought it was the new ignition system not working because your flywheel had bad magnets, when you said it would only work with a standard points ignition.
If it is running a good way to find out is to put the pointless system back in with the tank full, while making sure the gap between the coil and flywheel magnets is proper.
I still do not believe the pointless ignition would be any different than going stock except for one thing, it was made in China, that means they rarely get things accurate be it a bolt hole position, or a clearance. A magnet passing by coil has to have a certain gap to create the proper hot spark, some coils are adjustable like on Briggs and Stratton engines, they have a gap setting. I am not sure about Honda if they are adjustable, but before I would believe in weak magnets, I would suspect the Chinese mounting of the coils on the ignition plate was probably not very precise . The gap to the flywheel could be several thousandths off and weaken the spark. But magnets on the flywheel being weak, no way, that is unheard of.
I bought a Chinese knock off regulator for my old tractors generator. They had the tension on the springs way too stiff and the point gaps wrong, it quit working within a month.
I took the cover off and found the points burnt because of their failure to get tolerances right. I cleaned and set the points to specs and adjusted the springs that had been set way too stiff and never have had another problem with it.
I just hope when we go to war with China, their Military equipment is made as bad as what they sell us, if that is how they make things, the war won't last a month lol.
Well its just a plain ct70 3 speed
Dime a dozen in most us states
But their values are going upwards each day.
It’s a silver tag model, number 731, so very early model. Common place for some in the US, not so much in the UK, especially an early model bike in good condition 👍🏻 thanks for watching
Fyi
A ct70H which is four speed
Hand clutch
Is the most desired ct70
The one u have is a 3 speed
Three speed automatic like what you have
Are way more out there than the
Four speed hand clutch
Thanks for the info 👍🏻
I have the 4 speed.
Had it since I was a kid.
My cousin had thev3 speed.
We raced them several times.
Pretty much tied every time (I'm sure rider error played a part)
Never heard of a flywheel de magnetizing. I think you should try this, remove the carb at the intake port, get some starting fluid or gas in a squirt bottle. Use a drill set to counter clockwise with a socket to fit your flywheel nut, that will spin the engine fast enough to build compression, you might want to spray a little WD40 in the intake too, that helps the rings seal and sometimes if their stuck, it frees them Having the carb off allows you to be 100% sure you are getting fuel. Keep an eye on your spark plug, check it to see if it is wet, if it is remove it, stick it in a spark plug socket with the spark end up so you can fill the stem of the plug with gas, light it with a lighter and let it burn, this dries out the plug, de fouls it for the next starting attempt and warms the plug which seems to help them starting.
Another thing if you believe it is bad compression, squirt some 30 weight oil in the spark plug hole put your compression tester on and see if the compression increases from the pressure before you put the oil in.
If your compression increases, you have bad rings, if it does not change you have a leaking valve, an easier fix. Oil will seal a weak piston seal, but will not seal a bad valve seal.
Sometimes a motor can flood with fuel, it wets the plug and fouls it which just means the spark shorts and does not spark across the plug gap. My burning the spark plug trick dying it out de fouls it. Taking the carb off, that way you can be sure you are getting fuel, in case it is a no fuel condition.
Your pet cock on the carb also has to be set to R for reserve because the amount of fuel you put in was not enough to feed the on position of the petcock, that setting requires more fuel in the tank than what you added.
If you were getting a blue spark, your spark is not the problem, nor was your flywheel.
You have to do the above steps as a process of elimination.
I have had 4 strokes that ran with so little compression the engine ran but had no power.
I never saw you spray any starting fluid in to make sure you were getting fuel.
A de magnetized magneto seems kind of like a desperate attempt to find the problem that will have you just replacing parts, grasping straws, and will make no difference.
An ultrasonic cleaner won't always clean jets that might have a particle of sand jammed in them, the mixture of fuel to air is not that critical just to get it to fire, just pour a small amount of gas into the heads intake and with a wide open throttle kick it or use the drill to spin the flywheel, if it does not fire, remove the plug and see if it is wet, if it is do the spark plug socket thing and with gas in the plug burn it till it goes out, tip it over and light it again till it goes out, that will un foul the plug
Sometimes you create a different problem trying to fix the original problem, then when you fix the original problem, the other problem you caused confuses you.
So 2 things you did that might have caused a second problem, when you removed the carb and re installed it, Did you make sure the hoses were on the right ports on the Petcock? If you reversed them, you would have to have the petcock set in the on position, not the reserve position. That is an easy mistake if you are not paying attention, so if you want before removing the carb at the intake, try starting it on both the on setting and the reserve setting, or fill the gas tank with enough gas to be above the smaller section of the tank.
Not sure if it was possible, but make sure the 3 wires from your magneto are connected properly, through the harness, sometimes on different models the color of the wires are different, don't always trust the colors, trace the wires with an ohm meter.
Hi there, Thanks for the comment. A lot of useful information there!
Since this video the full bike and engine were stripped showing the condition of the internals. (video available along with a full rebuild)
The biggest takeaway point for me.... with a fully rebuilt engine, including brand new piston, barrel, carb we could still not get the engine to run on the standard flywheel using the electronic ignition kit. On a standard points and condenser system the engine would run with this flywheel. At the time of this I did not have the standard ignition, only electronic.
When using the electronic ignition it is essential the magneto is providing correct voltage to get a strong spark.
As soon as we swapped the flywheel it ran perfectly. so literally every component was eliminated leaving us only with the flywheel.
Not a common one, but one directly linked with the use of an electronic ignition kit. This is the reason I state the flywheel was the root cause of this issue.
Thanks for the comment. I would love to hear your feedback following your watch of the other videos.
Just started restoring a 93' and it has the exact same issue. Time for a top end rebuild
Check out my latest video on the engine rebuild! It actually turned out to be a faulty magneto not creating enough voltage to allow a strong spark! Regardless, if you have low compression it’s always worth a fresh top end!
You don't screw dipstick in to check oil you just rest it on hole and I hope oil you used was 10/40 mineral oil
Thanks for the info
It looks like the VIN number on the frame is punched through the original number
It does look a bit weird! the dash between the serial looks like it had a 0 stamped first, maybe a mistake on this frame… all has been sandblasted back now and aside from that the numbers all look good !
I gave you a lot of things to try, then went back and looked at your video again very carefully.
I could not tell about getting the hoses on the carb on the correct ports, you probably did that right, but I did notice your petcock setting and nowhere in the video did I ever see it in the Reserve position. It was either S for stop or on, never on R for reserve which is the only way it could get gas with the tiny mount of gas you put in the tank.
Right after you changed the spark plug and said it made no difference, the camera view changes to the left side of the bike where it appears you are un screwing the spark plug, at that point I saw what is probably your problem, your petcock was set at ON, not R. The amount of fuel you put in the tank was barely enough to feed the reserve hose, in the on position it got no gas.
The small amount of carb cleaner you sprayed in, you did it without the throttle open. There is no way you were getting any fuel into the cylinder especially if the engine was in the position where the intake valve was closed. Carb cleaner has a much higher flash point than gasoline, it will evaporate quickly so the little bit you sprayed probably evaporated before it ever made it in the cylinder. I have extensive experience in troubleshooting, I have seen how easy it is to lose focus when your grasping for straws with no clue what is wrong, sometimes you miss the obvious.
Magnets losing their magnetism, that means you have lost your way and are way off in left field at a loss trying to solve the issue. Throwing more money and parts at a problem is not the answer, it is just experimenting.
A am autistic, I have no social skills, but my strength is focus. Sorry hope I helped you anyway.
.
PUSH START IT ON
QUICK START.......ETHER...
Thanks for the comment! They would of both been a good option to try, in the future I will look to put a drill on the stator to spin the engine over much faster !
It should fire with that compression. Just an FYI, the silver tags were the first 15,500 bikes, a bit more than the first 2000.
@@MiniBikeMike Hey Mike, thanks for the comment Any thoughts on what you think could be the non running issue? Thanks for the clarification on silver tag numbers…….should really validate my source of information, bit of a difference between 2000 & 15,000. All the best, cheers
Funny you are second guessing yourself in the video, several times in the video you say you are getting good spark, now you are convinced the magneto magnets are weak. I guess you read my other comments trying to help, the obvious to me is your fuel tank had enough gas only for reserve, and I never once saw your Petcock on the Carb set to R. Especially immediately after you eliminated everything else. I could not figure it out either if I had the distraction of making a TH-cam video.
My thoughts are that the spark was good outside in normal atmosphere, yet when inside the cylinder under compression, was not enough to allow for it to fire and run correctly! As mentioned, when the engine is on the test rig and we have gone through all components, it left us only with the flywheel that proved to be faulty. As you say, diagnosing a problematic bike with a camera
Rolling is slightly more tricky than usual!