1972 Honda CL70 problem
 

Hello all,

I am having some of the same problems as the other thread, but dont know what to do. I picked up this bike and the guy said he thought it would run ok. I have a new carb, charged battery, good spark, and fresh gas but cant get it to start. I checked the valves and adjusted the exhaust and their both looking good. Some of the wiring is messed up or not hooked up, mainly from tail light, blinkers and a few others. I am waiting on a new wire harness but thought that since I was getting good spark, the main wiring to get it to fire was ok. The points look good, flat and appear to be timed ok.

Any thoughts or suggestions would really help because i'm all out of ideas.

Also,
I know the ignition works, I have checked it with volt meter, the points when open show about 6.4 volts ( i just touch the tip of the pos terminal between the points and get the reading). most of the lights are broken or mising but they do have power getting to them, and like i said, it has good spark.
I'm not sure if the condensor would keep it from starting, but that and the points are the only thing I have not replaced or confirmed. but like i said, they appear to open and close at the proper times.

Are you getting fuel? Did you squirt a little fuel in the cylinder to see if it would ignite and pop or give any sign of life?

If you got spark then you got spark. Whether it's out of time is another issue so you should check that incase someone has been messing around and never got it to work after they rebuilt it maybe? Check the screws and bolts to see if they were tampered with. You can see if a bike has been taken apart or not by checking the edges of the hardware as you look at the engine.

Last thing you might want to check the compression. Does it feel like it has any?

Well I am using a "funnel fuel tank" just to get it started. I want to get the tank cleaned before I run gas through it. But it pulls the fuel down and I have gotten a few "blue flames" and a few backfires, but thats it.

It does seem to have good compression. I dont have a tester, but just putting my hand over the spark plug whole, and the exhaust port and it seemed to have good compression.

The points look "good" almost to good, so I think your right, someone must have replaced them and may not have got the timming correct. I ordered a new primary coil, lighting coil, condesor and points to rebuild the generator.

I have cranked on it quite a bit, and it really hasn't even sputtered, only a few backfires and a blue flam or two.

I had a backfire (blue flame) out of the back side of the carburator, that cant be good!

I covered the spark plug hole and cranked it a few times, it has little compression

how would you know if you have a stuck valve?

Well I got a compression tester and found it had NO compression. I squirted some oil down the spakk plug hole and re-checked it and none! Not sure what to do from here.

here are a couple pictures. I am still finding so many things that need fixing, I guess I should expect that with a bike that has been sitting for 20 or more years. I broke the exaust valve tappet or cover and was wondering if that being missing would affect the compression test.

Uh oh that doesn't sound good. If you take off the caps so you can see where you can check the valve clearance - then you can see if the valves are moving I suppose. The bikes engine would have had to be severely beat on in order to hurt it. They are so tough you would have to purposely take the oil out of it and run it to damage it.

I think the thing you said you broke is just the round cover that screws on and off to get to the valve train right? That won't have any effect on compression. It just keeps the oil in the engine and the dirt out. I wonder if maybe someone ran it without the air filter on and got some dirt or something into the engine causing damage. If the engine sat fro years and years there might be some rust inside but if it's turning over freely it probably is ok and not so bad. I wish I could give it a look up close for ya!

Hmm if it's just out of compression it's time for a rebuild! I was rebuilding CT70 engines when I was 12 years old with scroungy tools so I know you can do it. Just turn the engine to top dead center with the timing marks and pull the whole thing apart and see what condition the rings and piston are in. Easy stuff.

Smithers, thanks for the information, I think you right, i'm just going to have to take it apart and see what it looks like. If you dont mind, I will probably need some help, sometimes the manuals just dont explain things enough.

Well I removed the head and it looks like it had been sitting in poor conditions for all those years. Here are a couple pics of the head and top of the piston. My question is, do I just buy a new head assembly ready to bolt on or rebuild this one? and what about the piston and rings, can I get away with getting a standard size piston? probably need to measure it first. Probably looking like a total re-build.

Not TOOO bad. Just need to have the machinist clean up the cylinder and head. They can hone it out to get the cylinder walls clean then measure it and give you their opinion. I can't tell the condition of the cylinder walls so I can't take a guess at if you need a 1 or 2 size over piston and ring set. This is easy stuff for any machinist that does engines. I would probably just "lap" the valves in with a hand spinner thing and some compound and put it all back together.

Just keep all the original parts as much as possible. I've fixed worse than what I see in your pictures. Shoot you could probably just hone out the cylinder yourself with a drill and ball hone - and then just re-use the piston with some new rings and be on your way. Just lap those valves in while you have it apart and make sure the guides and valve stems are operating smoothly. Put some synthetic grease on them while assembling and get that show on the road. :-)

I would buy the following:

• gasket kit for engine rebuild
• oil seal kit for the kickstarter and shifter seals but you might as well do them all at this point - cheap.
• pistons are cheap so probably a new piston and ring set
• don't forget the wrist pin and circlips - all new don't re-use!
• borrow a ball hone or buy one for like $30 maybe they might cost

A local machinist here in my town has done all this stuff a million times in his life so he charges me like $100 (at the most I know it wasn't more) to bore and hone the cylinder LIKE NEW and he gives me all sorts of advice on to of that which is priceless. This is for a Honda 150 twin but I don't think they will do a single cylinder for less than that these days. He also told me to go buy the larger size pistons I thought I would need and he bored the holes to match each one. He measured them so precisely that he labelled each piston a number and told me which one went in each hole. I guess even the Honda brand pistons weren't exactly the same size when you measured them. but anyhow you only have one so nevermind. :D

The valves you can just get a cheap suction cup grinder thing and just spin them like you are starting a fire. Of course you will need to use the grinding compound and have released the springs and keepers on the other end to allow them so spin. :p I'm just covering all the basics for the sake of recording this info here. I'm not assuming you haven't done anything mechanical in your life so bear with me.

Well I strated with the head and valves, I took it apart and started cleaning it up. I have a couple pics so you can take a look and let me know what you think. I am ordering the other things you mentioned. I was just going to re-use the valves, but may just order a couple. I measured the cylinder and it was 46.75mm so i guess I can either do as you said and have it honed maybe to fit a larger piston? or pull it out clean it up and put new rings on it. I am going to do the other things like the oil seals on the gear shift and kick start as well.
I really appreciate the input and help, This is my first time doing this and you have been a great help,

Some more pictures of the cylinder.

blue flame in the carb sounds like you need a valve job,

i would try a hone first, but if there is any pits from rust left, i would go 1st over with the jug, you will need to buy the 1st over piston & take it & the jug to have bored & honed at you local shop.. also i make sure I bought a dome piston, or you can buy this kit on ebay. good luck.

http://cgi.ebay.com/ebaymotors/_W0QQ...sQ26Q5ffviQ3d1

Thanks for the info. Why a dome piston? is it possible to hone the old one out and put in a new piston? I was trying to keep it as original as i can, but if its better to use a dome, i certainly will.

Well I measured everything and suprisingly everything was with limits. The cylinder is not that bad at all either. So i guess I could go the cheap route and just get some new rings, or get a ,25 mm over piston and have it honed. I want to go the easy route, but I'm sure I will regret it. Here is a couple pictures of the cylinder.

it looks like you have the dome piston, not all they sell are dome, just make sure of what you are buying, good luck.. make sure you put all of the o rings back in the right place if you haven't done this before..

Ya, when I pulled it of a couple fell off so I will have to get in the book and make sure I put the new one correct. Also, the top 2 rings on the piston are immobile], seized up, so re-using the piston was out of the question. I now understand why you reccomended the kit you did, would be a heck of allot easier to go that route. I just bought a standart piston, rings, clips and think I will try to get by without honing it. These things can get expensive, but I will have an almost new 72 cl70. I'm looking forward to getting it all done. I have all the OEM parts including wire harness. After I get it running nice, I plan on a paint job and new spokes as well.

i would do a quick hone job so the new ring seat, i would also get the valves & seats cut, or at least new valves & the seats cut.. this will help it a lot, the valves will have a good seal, i would take it too your local shop & see if they have the pilot tool & the seat cutter, & if they do get the head apart all the way & ask them to clean & glass bead it, it will be like new,

Are CT70 and CL70 valves the same?

Not sure on that one. Don't want to guess.

BUY NEW PISTON AND RING KIT AND VALVES!! That cylinder is thrashed. No way I would put it back together with just new rings. :P If I lived in a third world country I would do some old school tricks to make things work but here in the modern world there is no reason you can't make it like brand new.. actually better than new for very little money. I know you are thinking about saving the money but a new piston and ring kit and valves won't break the bank and then take those to a machinist and it shouldn't cost you much at all to have him surface the cylinder. The valves you can lap into the valve seats in about 5 minutes and not break a sweat.

The bike will run so nice! Makes me want to go rebuild mine now just for drill!! :D

Smithers, you make me laugh : ) Got new piston and valves today, heading to machine shop tomorrow. Found someone to do the job.

So I figured I would get some painting done while i'm waiting on parts. I am following Smithers' advice to the tee. I found a great dremmel atachment that takes the old paint and primer right off! PWill post pictures after primer and paint.

Ah nice that bike is going to run great after your all done. Nothing better than having a 50 year old bike start right up in a parking lot while 10 people are watching you leave. They will be expecting to see you do the kick start slam dance but instead you will just hit the little button and glide away.

Kick stand huh! i will keep and eye out. Well here is the first coat of clear coat, and got my head and cylinder back today.. looking pretty nice. Just got to finish painting and then I will be bothering you guys trying to put it all back together.. : )

looks good they cleaned up well..

NOw that's more like it!

Finished engine
 

Well i'm almost finished with the engine. I tried reading the manual to put it all back together, but got a little confused so I just put it all together as best I could. I made sure the rings were offset, and the little oil rings were in. I have the cam chain alligned as the book says but I dont know how tight or how much slack you want on the chain. I also dont know 100% that I put that chain roller in correct. I dont think it matters because it looked the same either way.

update
 

Well I finally got it mounted and it fired up on the first crank. I didnt run it long because the idle was really high and as soon as i tried to adjust it, it would die. I guess I will have to keep adjusting it until it run normal. There is one concern I have, there is burned oil leaking from the bottom of the exhaust right were it attaches to the bottom of the head. I put that metal gasket up in there but there is still a little play when it is snugged up. I also noticed on the image attached a part (#1) but it is not listed in the inventory. I dont know if the oil out of the bottom is something to worry about, or if it is normal because the seal is not tight.

running
 

So if anybody is looking through this, i finally got it running, and very nicely... thanks to Will and Ryan. I found i didnt have the head and cylinder tight enough. I dont have a torqu wrench and worried of stripping things out. After removing the cylinder and head, inspecting that all seals and parts were correct, i re-assembled and then had to re-adjust the throttle cable but it fired right up and runs great! its been a good learning expeirance and now got to go to work on the rest.

body work
 

Well I took the engine off and stripped the bike down. sanded the tank down to bare metal and appled some bondo to some small dents that i could'nt pop out. I had car quest read the paint and I have it on file for restoration purposes, but I think I am going to change it up on the colors, the paint alone for the gas tank was $120.00 but that included clear coat..: ( not going to do it, so i think I am going to teach myself how to paint..

I'm back in town now. Looks really good. I've been hanging around a certain body shop a LOT in the last year and have learned the business up and down. I say just paint it yourself. There are SO many instructional websites and videos on Youtube now! You shouldn't have any problems. All the info on how to do it is online and easily available. I just painted the underside of a hood of a truck I have today and it's going on the truck tomorrow. It's amazing how fast the body shop guys do it because they do it day and day out. The fuel tank is a little tricky because of all the curves. I recommend making brackets for the tank mount holes and hanging it up like a turkey on a rotisserie. I've seen pros do this.

Ok, I was trying to figure out how i was going to do the tank. I stripped the frame down to metal because all of the chips in the paint, i just figured if im going to go through all this work, i may as well do it right. I found a nice bright red that im painting it, and silver for the tank. I will post some pictures as it comes along. So I was wondering, the front forks are pretty haggered and one of the springs is about shot. I found a rebuilt kit with springs and seals for 30 plus s/h but the rods are pitted up pretty bad, i also found new forks for about 85 delivered. I would think if the fork rod is pitted up really bad, then they probably wouldnt work that well.
I also bought the spokes on ebay for $29, and they are very nice, my weels look brand new, i also ordered a new front tire from Dennis kirk for $16 and inner tube. They have the best prices for tires that I have found, and fast delivery.

https://www.denniskirk.com/michelin/...prd/541776.sku

Those tires look great and people are really liking them. I'm sure they are far better than any period tires from when these bikes were in their prime! I found a really great forum thread in which the gents are talking all about installing them on their 175s and 200s. I'm going to order some as well. http://www.hondatwins.net/forum/view...hp?f=40&t=8153

Those prices seem pretty decent for those parts buddy. It will be very good knowing that you did the job right and your bike will be like new. No sense on saving 30 or 40 when you are doing such a good job on the frame and tank you know? I can't wait to see your progress.

Well I finally got most all the parts i need so I tried my best at painting and now putting it back together. Hope to have a ride on it this weekend.

hi it looks very nice...........can you tell me how many teeth are on your rear wheel sprocket?? it should be stamped on it?? i have looked on line & there are lots saying there the right one.. i want the right one for the most top end.. thanks will