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Problems dialing in my cb160...

10724 Views 16 Replies 6 Participants Last post by  Minnesota Driver
Got my bike together. Cleaned & set the points. Set the timing. Carbs are sparkly clean with new kit in each, they seem to be synched right on. Throttle cables are nice and free. Got spark to both plugs (although it seems kinda white, sparkly. Does that make sense??). Plugs are Ngk D8HA (new set of what was in it when I got the bike).

Bike is running rich--symptoms... Starts up great cold with no choke, smells very rich (no smoke, though) plugs are sooty black. Right side plug was also wet. I understand these bikes are very sensitive to float height, so i've been playing around with that. I got the right side to fire better, not as wet.

I'm having a hard time getting bike to idle, can't really get idle speed to respond to mix screws (they're 2+ turns out) and the idle speed screws are turned way in. It will hold an idle for 20 sec. or so and dies out.

At about half throttle it really starts sputtering. I can take it up the road, but no power beyond half throttle (guessing about 3-4000 rpm).

I'm no mechanic, but i've done my time working on old snowmobiles. Not alot of experience with 4-stroke twins. Any help would be appreciated!
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Chokes work well and are definitely up on both carbs.
gs1327 said:
Up - as in opened right? The carbs I have are choked when the lever is up, open when the lever is down.
Yes, lever down, open wide.
66Sprint said:
Standard plug is D8HS....
Standard idle/mix screw setting is 7/8 +1/8
Standard float level is 21mm

What size jets were in the kits?
The kits had 92s, but I left the 90s in.
jayel said:
Minnesota Driver said:
Got spark to both plugs (although it seems kinda white, sparkly.

Bike is running rich--symptoms... Starts up great cold with no choke, smells very rich (no smoke, though) plugs are sooty black.

I'm having a hard time getting bike to idle, can't really get idle speed to respond to mix screws (they're 2+ turns out) and the idle speed screws are turned way in.
are the points throwing a arc or just a sharp clean pop? arcing is caused by bad condensers,
check those slow speed jets again for your idling problem the orifices are so small it's easy to miss cleaning them,
it should flow straight thru, just had a guys Honda scooter in and he swore up and down the carb was clean,
someone had told him about the cross holes in those jets so he had cleaned them but didn't see the thru hole (top to bottom)
I went out and kicked her over after dark. Nice spark from the plugs, plenty of sparking from the points as well. I would assume in the dark they should put out some light, but they did seem to be arcing quite a bit.

I'll be going through the carbs one more time tomorrow, just to be sure.
This morning I pulled the carbs, everything checked out good, blew 'em out, lowered the needles 2 slots (now maxed out) and I was able to get a decent idle going. Ran it up the road about a mile and back and it went ok, as long as I didn't give her more than half throttle or so. Max speed is about 35-40. It really sputters if I don't ease into the throttle, and if I twist it wide open fast it will just die out until i release it.

Got home, grabbed my glasses and thought i'd go the other direction and cruise through town. This went well (at 30 mph city speed) until about mile 2 when I turned around, I was losing power fast. I shifted up through the gears and limped it a ways at little more than idle, but I couldn't give it any gas. I was able to push it a block and coast down a long hill (about 10 minutes cooling down time) where I was able to start it up and it got me home.

Is this sounding like a weak coil? Condenser? I'm really hoping it's electrical cuz i hate to tear it apart again. My friend is bringing his compression tester over tonight and I'll check that.
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My friend is bringing his compression tester over tonight and I'll check that.
MilestoGo said:
Minnesota Driver said:
66Sprint said:
Standard plug is D8HS....
Standard idle/mix screw setting is 7/8 +1/8
Standard float level is 21mm

What size jets were in the kits?
The kits had 92s, but I left the 90s in.

Based on experience with my '65 160, if you put new needles from the kit in, swap them out with the originals and see if you have any performance gain from that.

Tom
Thanks for the advice. I put them back in and it seems to make a difference. I even got to raise them back up to the middle position.

I discovered what my main problem was. The spark advancer was stuck. I got it freed up and had to tighten one of the springs, and now she runs like a top!
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