Ct70 died while riding and won’t start

#1
This one is long sorry guys. so my dad passed down this Honda trail 70 to me that I learned to ride on way back when I was a kid. Engine stoped running way back when and I tore it apart to rebuild but became a teenager and found “better things to do”. Long story short dad couldn’t get it back together so bought a whole brand new engine, cdi, rectifier, coil for it a few years back from CHP Motorsports and put it back together. Ran great! Only had maybe 10 hours on the engine. Anyways get it back to my house and riding around with my girlfriends kid on it and he’s learning how to drive it and he pops the clutch and it dies. I go to start it back up and won’t start. Try push starting nothing. Get it back to the house and get new spark plug and coil, nothing! New cdi and rectifier, and I can get it to push start and run for few seconds and die unless at full throttle and even then wants to die and only runs at super low idle speed. Took apart carb cleaned it up best I could and same result, only runs at full throttle. Think maybe blew a ring or gasket. Take it apart to replace all gaskets and check rings, everything looks good. At this point I am tied of chancing this problem and have other pressing issues things so sits torn apart for few months (AGAIN) finally get it back together and no change. So put it on the back burner for another few months which brings me to today. Pulled it out figured give it another look. Kick the kick starter and give it full throttle, starts up but still same problem of sound like it’s at a “struggling” idle with it at full throttle. Let off throttle just a little and dies. Start it back up and messing just letting it run listening and smelling see if I can figure it out. After about 30 sec starts to finally pick up engine speed and little more until it’s running like it should at full throttle. Go to let go of throttle and it immediately wants to die. So back to full throttle and revs back up so now I’m reving it so not running at full throttle but not dying. Trying to adjust carb so it will idle but eventually dies. Start it back up and takes a struggling couple secs to get to idle (with it at full throttle still). But ends up dying again so let it sit and racking my brain. Checking over making sure everything is tight, spark plugs got good connection, fuel is still flowing out of carb. All good. Go to check oil and it looks like chocolate milk. WTF! Smell it and smells like fuel. Shit. Drain it and refil. Start up to see if it does it again but now it just sits at that crappy wanting to die idle again when at full throttle and then dies, it won’t even eventually catch and run up to full rpm’s like it was before. Any ideas. Thinking about getting new carb and replacing piston rings but seeing if anyone has any other ideas or has run into this before?
 
#2
oh and the fuel in the oil don’t know when that happened. Checked it back right before I tore it apart and everything was fine. Don’t know if it got in there from when it was sitting torn apart and it leaked into the case (I know I’m a terrible mechanic for this) or if it blew past the rings today when it was running.
 

DaddyJohn

Well-Known Member
#3
Fuel in the oil is usually a bad float needle in the carb. This is usually something that happens as it’s sitting. If the petcock is on and the float needle is bad, fuel can leak past the carb into the intake.

You didn’t mention if you’d checked your valve clearances. Improperly adjusted valves can lead to poor compression. It’s easy to check and worth a look.
 
#4
Awesome thanks. Yeah it has been sitting after I put it back together in nov. definitely looking more and more like carb is bad. Does make sense if fuel is leaking into the compression chamber and past the rings from sitting to long.
I haven’t checked my valve clearance. They have not been touched since the engine was bought new and only has a few engine run hours on it so didn’t think would be an issue, you would think they should be good but will def give them a check. Also going to double verify I got my timing lined up right too when I put it back together. Never hurts to verify!
 
#5
No offense but you are spit balling instead of throwing darts. You are all over the board with solutions without knowing what the problem is first. So he popped the clutch and then it wouldn't start. Something got jarred in the wrong way. Ignition/timing, compression and fuel are the three components of internal combustion. Start with one of those and move thru the three to find out what is missing. Make sure you have through put as in intake and unrestricted exhaust. Best of luck and I look forward to seeing what the problem was.
 

Doc1976

Active Member
#6
Ct70 is a chain driven cam right? Maybe with the pop of the clutch, the chain jumped a tooth on the cam and now your valve timing is off. Would explain the low compression and idling issues
 
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