Help with recently restored engine.

[cornishrooster]

First start up after the engine tear down. This carb is a repop from chpmotorsports. Seems like the engine only runs on choke, so maybe I need a bigger pilot. Does it seem noisy to anyone else? Shifts through the gears fine though I can't seem to find the neutral. Down shift makes the gear move faster but full shift up the gear still moves.

 

[allenp42]

Are you sure the throttle is moving the slide and needle in the carb? The fact that you turn the throttle and nothing changes makes me believe the cable is too long, slipped out on one end, or something.

Regardless, you should be able to get it to idle even if the cable is too long by adjusting the idle speed screw.

Yes, it does sound a bit loud, as if the exhaust gasket (donut), or baffle is missing? Hear a little ticking as well. Maybe the valves are a little too loose?

 

[cornishrooster]

Are you sure the throttle is moving the slide and needle in the carb? The fact that you turn the throttle and nothing changes makes me believe the cable is too long, slipped out on one end, or something.

Regardless, you should be able to get it to idle even if the cable is too long by adjusting the idle speed screw.

Yes, it does sound a bit loud, as if the exhaust gasket (donut), or baffle is missing? Hear a little ticking as well. Maybe the valves are a little too loose?

Definitely have both of those the donut and the baffle. I adjusted valves when I rebuilt the head but maybe I missed something. If I turn off the choke all the way the engine dies but if I stop just short of choke off it'll idle. I pulled the plug and its black as night, running super rich. No matter what adjustments I make to the idle or air screw I can't get this thing to idle choke off. I'll have to order some jets and mess around with it. I am concerned with the noise, clicking is pretty loud, sounds like it's coming from the stator/flywheel area. The headlight and tail lights are working though so that's a plus.


When I pulled the slide and tested the throttle it definitely moves up and down. I can hear it moving in the carb but can't actually see it to make sure.

 

[allenp42]

Did you adjust the valves at TDC on the compression stroke? If not, the valves will tick rather loudly I might add. Some time ago, I ran across one where the points were set way too tight (~0.010", foggy memory) and the valves were way too loose, and it gave the symptoms of being too rich, but not to the extreme that you're experiencing.

Never had to change the jets on a standard build and new carb, and unless you got a "bad carb" from CHP, seems rather strange you would have to dink around with the carb?

 

[cornishrooster]

Did you adjust the valves at TDC on the compression stroke? If not, the valves will tick rather loudly I might add. Some time ago, I ran across one where the points were set way too tight (~0.010", foggy memory) and the valves were way too loose, and it gave the symptoms of being too rich, but not to the extreme that you're experiencing.

Never had to change the jets on a standard build and new carb, and unless you got a "bad carb" from CHP, seems rather strange you would have to dink around with the carb?

I did put I'm going to pull the engine and recheck them again. Also I wrongly assumed that engine would only run on full choke but it's the opposite. When I take the choke off it jumps to full throttle. It was idling when I was putting the choke on (closing it). So maybe I have an air leak somewhere?
Also I did check to make sure the slide was functioning properly when I pulled the carb, it opens and closes all the way.

 

[cornishrooster]

Well not sure what changed but pulling the carb and putting it back on seemed to make it run normal for a bit. Thinking maybe the slide was stuck open. It fired up and I was able to rev the engine but it died after a bit and won't start again. Pulled the plug and there's a faint smell of gas but it's not wet. I'm going to leave the plug out, kick it over a few times and give it time to air out. See if that helps. As a side note I'm not really sure which line i'm supposed to use. They both have gas in them so does it really matter?

 

[allenp42]

One of the lines is your reserve line. It could be that the throttle did not return all the way. Many times, you have to return the throttle back to idle because the spring in the slide is just not strong enough. Sounds like you're on the path to getting your carb problem sorted out.

 

[cornishrooster]

One of the lines is your reserve line. It could be that the throttle did not return all the way. Many times, you have to return the throttle back to idle because the spring in the slide is just not strong enough. Sounds like you're on the path to getting your carb problem sorted out.

Thanks for all the input btw. If hoping I can get this straightened out without having to remove the engine and check the timing and valves.

 

[allenp42]

You do not have to remove the engine to check the valves or points. Can do both while it's still bolted to the frame.

 

[cornishrooster]

You do not have to remove the engine to check the valves or points. Can do both while it's still bolted to the frame.

Thanks. Yeah I just got down on the ground and did them they were waaaaay off. Sounds really good now. Thought I had the engine dialed in as it was starting every time and reving smoothly. Once I put it under a load though it was popping and sputtering. First gear is dicey and it dies a lot. After a couple runs I got it to 2nd and it sounded smooth for a bit but then died.Pulled the plug and it's pretty white. Looks like I need to go up a main jet, I have the air/fuel screw turned all the way in. Is the popping a timing thing still?

 

[69ST]

It's been my experience that repop carbs tend to be a bit on the rich side, as-delivered. That earns a solid thumbs-up from yours truly, it's easier working from rich back toward lean.

That said, breaker point gap, valve lash and vacuum leaks are the most common items that erode hairlines. Fortunately, two of them are dead easy to correct. Vacuum leaks can be frustratingly difficult to isolate. Easy starting & a strong, stable, idle usually mean no vacuum leaks.

Based on your postings, thus far, I'd say that you should be able to dial-in the carb with jet needle height & idle screw (pilot airbleed & throttle stop) adjustments, alone. If you've fouled the plug, it'd be easier to just stab-in a fresh one. Sparkplugs can be cleaned but it's not always easy or effective.

 

[motodevo]

Check your points gap, too wide and it will idle fine but pop and fart when you rev it up

 

[cornishrooster]

Check your points gap, too wide and it will idle fine but pop and fart when you rev it up

I watched a video on setting the points gap when I was rebuilding the engine. I understand how the points work but still a bit confused as to how to set them properly. They open on the F mark and I set the gap when they're open? 0.3 - 0.4mm?

 

[cjpayne]

The throttle on these is notorious for sticking and its just the twist assembly.

Since your bike is a fresh build, set the intake @.002 and the exhaust @.003. The exhaust set @.003 will help the engine run alot cooler. Set them at TDC on the compression stroke.
When diagnosing a problem and the points have been changed, I set them @.014 (TDC on the flywheel). Later when the bike is running fine, I will reset them @.016. That way I can rule out that the points may have accidentally been set to far open.

 

[kirrbby]

That's .014 inches and .016 inches...not mm

 

[cornishrooster]

The throttle on these is notorious for sticking and its just the twist assembly.

Since your bike is a fresh build, set the intake @.002 and the exhaust @.003. The exhaust set @.003 will help the engine run alot cooler. Set them at TDC on the compression stroke.
When diagnosing a problem and the points have been changed, I set them @.014 (TDC on the flywheel). Later when the bike is running fine, I will reset them @.016. That way I can rule out that the points may have accidentally been set to far open.

Thanks for the info. Well I got the points set to 0.014" and now I don't have any spark. Not sure if the two are related. The spark plug had been fouled a few times so I have a new one on the way. When I replaced the stator the included capacitor didn't fit right so I used the old one. Maybe the old capacitor died. The ignition coil is brand new so I doubt it's that. I'm about ready to buy a lifan and put this guy on the shelf.

 

[69ST]

These engines are relatively simple, as are their electrical systems...and the fixes. The difficult part is making an accurate diagnosis. Get through that and there will be an "aha!" moment.

Throwing a different engine at this may bring more issues than it solves...and you'd still have these taunting you. If you removed the original condenser, then reinstalled it, the odds of a failure are high. They don't like heat and solder requires it. Point gap can only be set so big, before the points will no longer close. IMHO, it's close to being failsafe. You could have fouled points, either from oil, cam lube, or storage protectant. A little cleaning solvent & 600-grit sandpaper can make quick work of the cleanup.

Do take a close look at the stator wiring. It's easy to unintentionally short-out a lead from the condenser. Changing point gap to 0.014" should not kill spark output. Thus, I'm guessing that something else was changed, along with point gap.

 

[cornishrooster]

These engines are relatively simple, as are their electrical systems...and the fixes. The difficult part is making an accurate diagnosis. Get through that and there will be an "aha!" moment.

Throwing a different engine at this may bring more issues than it solves...and you'd still have these taunting you. If you removed the original condenser, then reinstalled it, the odds of a failure are high. They don't like heat and solder requires it. Point gap can only be set so big, before the points will no longer close. IMHO, it's close to being failsafe. You could have fouled points, either from oil, cam lube, or storage protectant. A little cleaning solvent & 600-grit sandpaper can make quick work of the cleanup.

Do take a close look at the stator wiring. It's easy to unintentionally short-out a lead from the condenser. Changing point gap to 0.014" should not kill spark output. Thus, I'm guessing that something else was changed, along with point gap.

Thanks for the tips. I'm not giving up on this thing yet. Question regarding the stator - I used the original felt when I put the engine back together even though it had shriveled up and hardened. Before I reused the felt I saturated it with air compressor oil and squeezed out the excess. Would old felt have a negative affect on the motor?

 

[allenp42]

If you have spark, you're probably ok. If you want to be sure, you could spray some contact cleaner on the points to remove any trace of oil splatter that may have landed on the contacts.

Personally, I would install a new felt pad. Cheap insurance to make your points last longer. NEVH is very good at not overcharging for shipping....and to go one step further, very good in general. Great source for parts. They don't get any better.

http://cart.hondanuts.com/Ignition-Points-Felt-Honda-Z50-CT70-SL70-OEM-P5155742.aspx

 

[69ST]

Old felt can be reused. I'd only do so in a pinch. Brakleen can be used to over-saturate it and flush-out all traces of old grease...doesn't take much solvent to do, either. Then you squeeze/blot is dry with paper towel, give it time to dry, then apply fresh tune-up grease. The felt used is stiff, even when new. IDK that there's really anything really wrong with cleaning, re-lubing & reusing unless it's worn out. For the few pennies a new replacement costs...why bother? And no, felt has nothing to do with your no-spark condition.

FYI, I'd not use compressor oil. Use tune-up grease only, it doesn't drip and get flung from the point cam.