1977 CT70 tune

I'm working on a 1977 CT70. I overhauled it with brand new OEM Honda pistons and rings, New cylinder. New valves. All oem Honda gaskets and seals. New shift forks, pins, clips.
Brand new Honda points. Felt.

First I started off with a brand new carb from trail bikes. Came with a 60 jet. Was too rich I jetted down to a 58 which is factory , still too rich.

Then I cleaned up an original 533 carb and made sure it had the 58 jet. Still rich. I've had the air screw 2.5 turns out or better. The clip on the needle all the way up. I'm rich, I can't pull much power and barley get to 30 mph. My plug is black.

I just don't feel I should jet under the factory specs with the original carb? Not sure which direction to go now and looking for some help. Thanks

How's the inlet side airbox boot & airfilter foam?

Check your points gap. If its set too wide it will pop and fart and act like its too rich when you rev it up. I spent days messing with a carb/s because i was sure i had a carb issue, ended up i had hamfistedly set the points gap too wide

racerx said:

How's the inlet side airbox boot & airfilter foam?

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Boots are very nice and brand new filter

motodevo said:

Check your points gap. If its set too wide it will pop and fart and act like its too rich when you rev it up. I spent days messing with a carb/s because i was sure i had a carb issue, ended up i had hamfistedly set the points gap too wide

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I set them to .016

Have you checked it again? I have found most feeler gauges are too fat to set correctly through the flywheel opening and set it accurately whilst trying tighten it up with a phillips (the feeler is at a slight angle so it ends up a wider gap). I tend to now set it by eye and check where its at after.
Like i said, i only mention it because it caught me out and had me cleaning/swapping carbs/adjusting valves/confirming cam timing/etc. for days

Also have you tried it without the airbox connected? If it improves slightly it would confirm its running too rich. I had similar issues with my mates z50 where it would idle but bog down like it was pig rich when you opened the throttle. The carb was cleaned many times, it was spotless. Ended up being the main jet which just pressed in had a dodgy o ring that seals around it, because it was cracked and had gaps it was probably letting atleast 2x the fuel through every time the needle lifted off the main jet. Pulled off the remnants of the o ring and wrapped the jet with electrical tape until it was a snug seal into the jet holder, cut off the excess with a razor blade and it ran like new. Hours and hours of tinkering to diagnose a 2c o-ring at fault, atleast i was drinking his beer whilst doing it!
Pretty sure he hasn't even bothered to put an o-ring in it, he'd still be running the bodge fix, and that bike gets backyard bashed atleast once a month when all the boys bash bars and tear up the yard of his rental property between beers.

And finally have you confirmed you cam chain is timed correctly? If your one tooth out it can act similarly to what you've described. That’s it, i'll finish my rant, that's all i can think of for now.

motodevo said:

Pretty sure he hasn't even bothered to put an o-ring in it, he'd still be running the bodge fix, and that bike gets backyard bashed atleast once a month when all the boys bash bars and tear up the yard of his rental property between beers.

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HaHa, sounds like fun, count me in, LOL... I'm gonna show up lookin' like James Caan in that "ROLLERBALL" flick, 10-4???

P.S. The fact that it's a rental property makes the bashing all the more fun, LOL.

Sidewinder said:

HaHa, sounds like fun, count me in, LOL... I'm gonna show up lookin' like James Caan in that "ROLLERBALL" flick, 10-4???

P.S. The fact that it's a rental property makes the bashing all the more fun, LOL.

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You'd be welcome anytime SW. Its just a bunch of country boys ripping up a suburban block like there's no neighbours, there are but they are too scared to say anything, we normally calmdown by sundown and crank up the tunes, light a fire, maybe cook a spit and get on it till we pass out.

In reality we are doing him a favour, you dont have to mow mud! With the yard torn up with mini bikes (a few of us run snow hogs so it gets trashed), the scorched areas from the fire pit (half a 44 gal drum) and the fact alot of guys drinking all day not using the toilet to take a leak, theres hardly anywhere to mow left. 10 mins with the whipper snipper and its all done

Sorry for the thread hi-jack Smitfire