About the Honda Trail 70

[Dave H]

Now that I have it home and it is apparently the real deal, I am going to have to do some work on it. I am a tractor guy. International tractors to be specific. I am a fair hand at getting them running and keeping them that way. I know gravity feed carbs and other old school technology. This is my first cycle of any kind...so the adventure begins.

Wondering what forum is best to ask questions if not this one? Best manuals and where to get them? Since this is a popular bike (or so I have been told by many) is there a good source(s) for parts?

When I "restore" a tractor, I make it look pretty nice...but not new. I restore it to where you can use it with comfort. This is the plan here too.

To start with, the auctioneer seems to have lost the keys. How hard are keys to replace?

 

[bigrob]

welcome to the fun

Try DrATV they are a great source of parts and more :thumbsup:

 

[ponytail]

Congrats on the CT. Just picked 1 up recently. Be GLAD its not a knock off. check my thread on pg 5 of general minibike talk, called Honda ct70. The advice from our members is golden:thumbsup:

 

[b52bombardier1]

Not to steal you away from here but only to further support and enable your new found addiction. Try:

Www.LiLHonda.com

Old school Honda bikes is all that we talk about there.

Look at the number on the key face of the ignition and go to:

Www.hondakeys.com

Look up the letter and number and ask to see if he has any. There is also an Ebay vendor, same mode of operation.

Rick

Two CT90 and two ST90 bikes

 

[minibikedude]

Great little bikes I have a few of them, If the engine is in good shape I would fix it up, I also will install the bigger Lifans engines into them for a much faster Trail 70. There is a lot of aftermarket stuff out there for them and the Z50,s.

 

[Dave H]

Thanks all!

Checked out all the links...been all thru DrATV site, Looked at LilHonda, page 5 post etc., sent in a key request. Lots of good info, thanks! Gave the bike a good look over this morning. Gas tank is reasonably clean for sitting 10 years in a shed. Some very fine powdery surface rust in places in there. On the tractors I run an inline filter for a couple tanks of gas to remove this before it gets into the carb, but tractors have bigger carbs and there is some fuel flow restriction from these. Don't know yet if there is a fuel filter on these bikes. Is this a gravity fuel flow with a float shutoff? Kind of looks like it and I have read references in forum posts. Other stuff I noticed:

- Itty bitty battery does not register a tick of juice on my VOM. Not sure if this is - or + ground system at this time.

- Red battery "cable" (wire actually) is broke before the white harness plug.

- Harness disappears into body so haven't followed that yet but there is something that could be a coil next to the battery.

-Moving on the boots over the front shocks are both cracked in two and there is some indication the fork took a hard hit at some point...some distortion in the metal on one side.

- the headlight switch does not move. Either stuck or there is a secret to moving this.

- Has blinker control but no blinkers, there are 4 pigtails loose in the rear that might be for the blinkers.

Everything else seems to be complete and in normal condition for a 30+ year old bike. VIN tag has what appears to be large numbers 1979 across it. Is this the year or do I need to verify that with the VIN? So much mat-black paint on this thing I have taken to calling it the "Stealth Bomber". It is cold and snowy here in Michigan so my very generous wife is allowing me to keep it in the kitchen for a bit while I sort out some stuff. Any info on the above appreciated!

 

[b52bombardier1]

Hello Dave,

The CT70 does not need a good battery to start or run but the harness wires do at least need to be connected and/or the battery needs to be good enough to NOT be an "open" circuit break. It is a negative ground system - green wire is the ground.

However, however, however!!! With no battery, you will fry every operating lamp and bulb in the bike the instant that you rev up the engine because that flooded lead acid battery is the voltage regulator on these bikes. And that sealed beam headlight is expensive.

It is a gravity feed fuel system with no original inline fuel filter but there is a brass mesh screen in the carb if it has the original Keihin still installed. Most of us install clear plastic inline filters into the fuel lines and I would definitely replace your fuel lines before your bike becomes a rolling Molotov cocktail with that old dry rotted rubber. There are options if you want a modern carb on Ebay - search for a PZ19 or a PZ22 with the choke lever and fuel valve on the riders left. Cost? About $28 bucks from the WebLLC vendor.

As this might be a 1979 bike, be careful with any switch or plastic trim - probably no longer available. I would try to spray some contact cleaner into the switch before getting any deeper to see if that frees it up.

Rick

 

[Dave H]

I think we have a way to go before this is a rolling anything! :laugh:

It always amazes me when, after 20 years of rebuilding and restoring antique farm machinery of all kinds, I come across something I never heard of before. The battery is the voltage regulator?!?! Appreciate the tip on that before I stepped in a nasty pile of something and sent my headlight to that great landfill down the road. Being an optimist, I am assuming that the light works! If there are any odds and ends like that you want to pass along, I am all ears! Guess a key and new battery would be the starting point and then take it from there. If I can get a lamp to light it might inspire me to continue. Then I think I will find some manuals. After that, maybe see if it has spark. Then spot of gas to see if it wants to run at all? Am I at all close on the order of things?

Thanks for all your help!

Dave
( ut: )

 

[b52bombardier1]

Yes. That is a good way forward. But a few additional caveats for you.

1 - Run only JASO MA rated motor oil for wet clutch engines. I like Honda GN4 but there are others. Full synthetic Energy Conserving motor oils or any with friction modifiers will ruin the friction disks in your clutch pack. They may already be glazed and useless but let's not hasten our way there so fast.

2 - Very soon, we will need to remove the right side engine case to gain access to the oil screen low in the center case and the centrifugal oil "slinger" area under the outer clutch cover. These get plugged up and were almost never cleaned but will starve the engine of oil if neglected. You will need a JIS #3 screwdriver (not Phillips) for the side case and a #2 JIS screwdriver for the outer clutch cover. They look like Phillips but they are not and will cam out of these screws and strip. Then you will say a few bad words and reach for your Black and Decker drill. McMaster Carr sells these screwdrivers and please trust me here.

Your valves will also likely be too tight. They wear at the seat and the back side of the valve which then means you lose clearance at the adjuster. But then the valve elongates ever so slightly when hot and you lose compression. It's also a blow torch then at the seat and the valve also burns.

I will think of a few more tips as we go along. These are all easy tasks to perform and we are here to assist you.

Rick

Two CT90 and two ST90 bikes

 

[Dave H]

No kidding! I just looked up Japanese Industrial Standard. I guess the PO never heard of these either because I spot a stripped screw on the left handlebar. I'll have to get a hold of those and the oil, battery, etc. Key guy has not e-mailed me yet today. I took some cleaner and got the light switch to move normally. That was an ice breaker! One thing has me curious...the bike is loaded with broken glass. Looks like automotive glass and it is stuck everywhere except under the seat. Even under the chain guard there is some. I think I need to get a hold of an operators manual and a service manual also. I see DrATV has parts schematics on the website. I rely on those heavily on farm equipment. Plugging along here. If there is anything else I should add to the list, let me know and I will get to ordering. Thanks!

 

[b52bombardier1]

Hello Dave,

Let's talk about your selenium rectifier in the CT70 electrical system. It is quite likely to be shot given its age but we can test it once you get your bike running. It converts AC from the stator to DC and if it is letting much AC through, the life span of your battery will suffer. And if your rectifier is shorted to ground, it will drain your battery.

You could install a silicon rectifier as a replacement and either a Radio Shack pn 276-1185 will work or a Digikey GBPC2504DI-ND. Both are about $4.50 or so but the Digikey part is the stronger of the two at 25 amps and 400 volts peak inverse - only 50 volts PIV for the Radio Shack part. However, these two are both really overkill for a CT70, physically too large and leave one diode unused.

Try this from Jon Pardue:

http://www.parduebrothers.com/cub/makeyourownrectifierforthecuborpassport.pdf

His design is more compact and is well suited for a CT70. And just as inexpensive - no need to buy an original OEM Honda rectifier. These more modern rectifiers are also more efficient by nearly one volt DC and run cooler as well.

Jon passes through here often and maybe he can chime in. His artwork at the web site above is top notch - easy to read. His wiring diagrams for old Honda bikes should be hanging in the Louvre . . . they are eye candy to look at and study.

Rick

 

[Dave H]

Cool link! I can handle that easily. I rebuilt a 1950's Seeburg Jukebox a few years back so a little soldering doesn't worry me. I see on LilHonda that a pdf service manual is available too. So I need to find time to do a little homework and get an understanding of how cycles work...I am used to distributors and 4-6 cylinders. I think it is different, but hopefully not too different! Meanwhile get the battery and other things on the list. Maybe there will be time this weekend to tinker around with it. Is it likely I will have to take the carb apart? Fuel lines were disconnected so I dont think any gas dried up in there.

 

[b52bombardier1]

Hello Dave,

Yes, the carb will need to be thoroughly dismantled including the often missed emulsion tube above the main jet - gently tapped out from above with a wooden golf tee or a #2 lead pencil. Then rod out every little hole in the idle jet, main jet and emulsion tube with soft copper lamp cord strands - not steel tools - to keep from widening the holes too big for a 70 cc engine. Brake Kleen spray through the little red tube and compressed air will usually be good enough after that. But for my worst carbs, I have boiled them (minus the anodized throttle slide) in CLR bathroom cleanser on an old Coleman stove outside (that stuff stinks) to get all of the white oxide out of all passages. Hopefully yours will not be that bad.

I do not know why they package things this way but you will likely need to buy the carb rebuild kit and the packing kit to get everything you need for the repair at roughly fifty bucks total.

And then there is always this:

PZ22C Pz 22 CT90 CT110 Ct 90 110 Carb SL 125 Lifan China Pit Bike Honda ATC XR | eBay

The PZ22 might be jetted a little rich for 70 CC's but the jets are swappable, if necessary. And the price is pretty good. The trouble here is this carb's mouth is a little wider than the original Keihin which makes the carb boot have to stretch just a little - not much though. And this new carb is a little shorter from front to back which will make for a "reach" problem for the air cleaner bellows. However, I have created a thicker manifold to carb spacer out of a no kidding, regulation NHL hockey puck to solve this problem - I can send it to you.

There are MANY new carbs listed on EBay for a CT70 but also very many of these carbs have the fuel valve and the choke lever on the wrong wide of the carb - very close to the exhaust pipe. Do not buy one of these. Just use caution when buying an Ebay carb without a careful examination.

It's all up to you but you whatever you do, have fun. These bikes are so much fun and I love bringin' 'em back from the dead.

Rick

1973 Mighty Green ST90 K0
1974 Mars Orange CT90 K5
1975 Topaz Orange ST90 K2
1976 Shiny Orange CT90
2006 Honda Foreman 500 (resto in progress)

 

[Dave H]

Well, I've done my share of carbs so not scared of them. Hopefully the rebuild kit has some general instructions. If not the service manual will likely walk me thru it. Just to catch those subtle differences. On at least one tractor I did (Cub) there was a copper tube that required you to separate the carb halves by lifting straight up or you would break the tube. PO had not known this and the it was with some difficulty that I extricated what he left behind and installed a new one. If this carb has any peculiarities maybe someone could give me a yell.

Current frustration: the key guy never emailed me about a key! Guess I need to follow up with this and see if there is a problem. Not thinking I am going to get too far without a key. :no: