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Discussion Starter · #1 ·
I've gotten a 75 CB200 running, and am trying to smooth it out. First thing i did was clean the tank, did POR-15 on it, and after putting new gas in it, it started up. I messed with the carb screws and had it running OK, but a little rough. Eg. was a little jerky doing slow speed U-turns in the driveway, idled rough at a stop, but acclerated through the gears OK. So, I took carb float bowls off and the bit of brass and sprayed them all down. Some of the jet holes had stuff in them, but I cleaned up so I could see light through them all.

I put it back together with new plugs, and synced the carbs. Only the air screws made a difference to the sync meters, si that right? When I back them our 1 1/4 they both sat at 1 tick on the vacuum side of the meter. I backed out the idle screws between 3 and 4 turns. Can't get it to idle below 2000rpm, or maybe the tack is off. Now, once it's warmed up, the idle and those low speed U-Turns are real smooth. However, it is rough and jerky in low gears (neighbor say 'dead spots'). Once I get to 4th, it seems to smooth out.

Any ideas what I've done???
 

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Are you certain the points are timed correctly, and the timing advance unit is working smoothly?........These will idle down to about 900 if you choose to set them that low, (provided you have good compression, clean & timed spark, and adaquate fuel supply)...What float settings did you set in the carbs? ...What were your compression readings?.....
 

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Discussion Starter · #3 ·
I didn't mess with anything but the carbs. I didn't take any compression readings. This is the first time I've ever tinkered, so off to do some more reading. Why, though, would replacing plugs and cleaning carbs mess up how it was running? I'd think it would only make things better, not worse.
 

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Some of those "bits of brass" are the floats.... If they aren't set at the correct level, the bike will run/idle poorly.... It is easy to accidently misadjust them while removing and re-installing..... The other brass parts are jets, also easily messed up while cleaning by an inexperienced mechanic.....
You could have dislodged a plug cap from its wire while changing plugs..... Lots of possibilities....
You'll just have to eliminate the possible causes one at a time, otherwise you won't know for sure what you fixed or where the problem originally was....
 

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Discussion Starter · #5 ·
Yes, there were floats, two jets, and needle and seat. I was gentle, and don't think I messed the float setting. I don't have a card to measure them, so was hoping they'd go back where they were.

The jets had some clogged holes, but sprayed and swished them in some cleaner, then gently ran a pipe cleaner through them. What could go wrong with these?

Might try to mess with the timing if I can borrow a tool somewhere. Starting to get out of my comfort zone now, might just have to take it in for a tune up and see how that goes.

Thanks for the info.
 

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You don't need a card to measure your float heights. You can use any piece of plastic as long as the measurements are correct when you cut it to fit. You could also use some beer box cardboard in a pinch.

You could also do your own timing if you read around on here about the process and take your time.. Ask plenty of questions if you're in doubt on any part of it.


GB :mrgreen:
 

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Discussion Starter · #7 ·
As long as you guys will tolerate my newbie questions, I'll ask...

I read about timing, and it says to check it at idle 1200 rpm and then again at 4000 rpm. So, this implies to me I've got to get the idle under control before moving on to timing, right? If I cannot get the idle below 2000 rpm w/o the engine dying, where do I start. Seems to me if there's an idle set screw in the carb, that's the most likely thing to work on, but I suppose the tach could be off???

I'll get or make a card to measure the floats, but otherwise where do I start?
 

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First, you must "static" time the points (NOT running)....Then you check (dynamic)timing at idle speed and at full advance (1200 and 3800/4000RPM, but for that you'll need a strobe type timing light).... I suspect that adjusting the points gap and static timing them will be sufficient to achieve a decent idle at 1200 to 1300 RPM....
......A 12V bulb in a socket with alligator clips on the wires will act as your timing indicator, if you don't have one, a regular 12V "tester" probe tool can be used....
Start by removing spark plugs...Then opening the round alternator cover and rotating the crankshaft CCW until the "F" mark on the rotor aligns with the index pointer on the stator....With the key on, the light should now light-up with one connection to ground (engine case) and one to the point wire terminal bolt.....If it does, you are hooked up correctly...(Turn key off) ...Now, continue to rotate the crankshaft (CCW only) until the points themselves open to their widest opening.... Holding the crankshaft in place, adjust the GAP of the points to specs (.012 to .016") by loosening the two screws that hold the points onto the plate and by using a "feeler gauge".....
Tighten the two screws back to hold that adjustment...
Rotate the crank CCW to the "F" mark alignment again and hold it there.
Loosen the two screws holding the PLATE ( turn key on ) and rotate the whole plate until the light JUST comes on....Lock it down there.....You are now "static" timed....

If you feel the need, you may call me and I'll guide you through this over the phone....
Steve 540 427-4256.....
 

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Discussion Starter · #9 ·
Thanks for that. Gonna be out of town for a bit, so over the weekend or maybe sometime next week before I get to this. I'll check in with progress. Having never worked on anything other than to change oil, I'm feeling really good I've got this to run even if it is rough. I'd really make may day if I didn't have to break down and take it to a shop. Glad I found this place. I really do appreciate the help.
 

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Discussion Starter · #10 ·
OK, here's what I found out so far...

Compression was between 30 and 40 on both sides. This was done cold and plugs pulled off both sides.

The cover for the points was/is missing one screw and the other's head is stripped. I tried an ez-out on it, which promptly broke off too. It's been one of those days. Finally got the @$*& thing off with a dremel and punch. But couldn't figure out how to get the light to come on. I looked for a light with clips, but couldn't find one so picked up a probe light with a clip for ground and a pointed, lighted screwdriver like deal on the other side - your basic continuity checker thingy. If I touch the battery, I get a light. If I ground and touch the + side of battery, I get a light. If I touch what I think is the right screw (the one with the wire attached to it), I DO NOT get a light. Now, when I line up to the 'F' mark, the points are not touching. I turned the shaft around until the points did touch and still not light. In fact, I held the probe on the screw and went all the way around with the shaft and never got a light.

A friend pointed out a white spot in the center of the points. He's thinking that means they are burned out, but isn't sure and suggested I provide that info. here too. My feeler gauges have a 010 and 004 that I held together. I might be able to snug the gap up, but it is close as is.

Some other tidbits I'm not sure if are important or not.
- The electric start does not work, so did compression test with kick starter.
- Battery is not holding a charge, but bike runs without it. Was holding off buying a new one until I know I could get this thing running OK. So, I have put a charger on the battery to do my test to make sure I have a good signal.
- And, yes, I did turn the key on. :)

I'm not sure what I do next. What do you suggest?
 

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Have you read around on here for the correct way to do the compression test? Throttle wide open. Chokes wide open.

With the numbers you've gotten, you're either in for a rebuild (valves or rings or both at minimum) or you've performed the test wrong.


GB :mrgreen:
 

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Discussion Starter · #12 ·
Um, no. I guess I'll do that. What number am I looking for?

OK, did some reading this is what I think needs to be done.
- Warm bike
- Remove plugs
- Test compression on both sides by kicking about 10x
- Do this holding throttle open and have choke open

So, my first numbers were just a single kick. I had no instructions with the gauge and didn't even think to look here. I just assumed a single kick. I guess it goes w/o saying this is my first mechanical project. Anyway...

In about 15 kicks, cold, I am up to about 120. It will keep going up if I keep kicking, just going slow at this point. So, will a warm bike have a noticeable improvement on things? Is 10 kicks a magic number, or should I keep kicking until I don't see it go up anymore?

Still curious about my timing problem if anyone can help there.
I really appreciate the help so far.

Thanks,
 

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Well, compression is at least part of your problem..... MINIMUM compression (time to re-ring/rebuild the top end) should be 150ish, with 170 being the "normal" (rings sealing well) reading..... Readings GENERALLY rise about 10 to 15PSI when warm, and if the adapter is seated correctly in the spark plug hole (screwed in and sealed by the o-ring), 10 kicks should be enough....But go ahead and kick until it stops rising.....You still need to see 135+ to 140ish cold.......

Your continuity checker should have one end on a good ground,(engine case or the battery negative) and one on the point wire terminal..... The light should come on when the point opens (key on, both plugs out so it can't start and break your wrench hand (wrench on the rotor bolt).....

Feel free to call me and I'll guide you through the tests..... 540-427-4256... Steve
 

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Discussion Starter · #14 ·
I'll do another compression check and see how far I can get it to go.

So what does it mean if I cannot get the light to come on? Does that mean I need to move the plate to get that to happen? Before I do anything, I'll try again. I'll get some test leads with clips on both ends and clip the probe in and make sure I've got good contact. I'm pretty sure I've got it hooked up correctly, but from where I've clipped to the frame for ground I can hit the plus side of the batter and get a light. Using that same ground I DO NOT get it in the points. In there, a wire comes in on the lower right side, but terminates at a screw on the lower left. That's the screw I'm trying to make contact with.



I appreciate the offer to help via phone. Will try not to call, but if I have when's the best time. I'm guessing your EST zone.

Thanks,
TT
 

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Yes, EDT.... Roanoke, Virginia.... About 8pm to 10pm is best....I screen calls, start talking when answering machine beeps...... Steve
 

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Discussion Starter · #16 ·
OK, did the static timing, and that did smooth out the bike a lot. No more dead spots or sputters while shifting thru the gears. I think their is some engine breaking when shifting and letting the clutch out, but this is my 1st and only bike so I've nothing to compare really. Well, the nighthawk I used in the safety course a while ago, but it's a lot newer so does that even count? I wasn't getting a light yesterday I think because the kill switch though switched on has a slight catch and didn't connect. After monkeying around with the bike for an hour tonight, I wiggle that and like magic the light lit up. Doh!!!!

Ok, this seems odd to me. I did the compression test after I rode it around a bit, and could only get 90 on each side. And also, when it hit 90 it'd back down half a click and then hold there. Didn't expect so low or to see it back off like that. So, it is possible to get a lower reading after it is warm?

My buddy took it for a spin, he's ridden years ago, but he thought it was smooth and suggested I ride it as is. He still thinks the points might need to be replaced, but otherwise thinks I worry too much about it. Said if my compression was really as low as 90 it wouldn't run and ride like it does. He doesn't trust the gauge.

I borrowed a carb sync gauge from a mechanic I know. I hope I can talk him into taking it for a spin around the block and get his opinion on it.

What say you guys?
 

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Discussion Starter · #17 ·
I'm so excited I got it running again, I forgot to say a big thanks for all the tips and help here.

Also, wanted to mention the idle. It does now idle under 2000. It doesn't really level out at a spot though. I have it set where the needle goes up and down between 1400 and 1800. I turned it down to 1200 to 1600, but it will occasionally drop to about 800 and cough. It can't recover and dies. So, I've turned it up a bit.

Thanks again
 

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Sounds like one carb needs attention......(probably float level and/or shut off needle and seat) and they need synched...... A good compression reading would be helpful, as at 90 the bike WOULD idle/die as you discribe..........
 

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Discussion Starter · #19 ·
So, thanks to Steve's help and suggestions, I attempted to adjust carb floats and check the valves. Only one of the 4 valves seemed more open than the rest (the left intake), but only just a touch. I adjusted it more just to learn the process than to do anything, but I think I snugged it up a touch. However, I broke the cap off the threads of one of the valve covers, so am waiting on a new one to recheck compression again.

The floats in both carbs were set too ???... rich??? It's the float that determines if things are too rich or lean to the plugs, right? Anyway, they were both less than the 21mm spec. One also had a twist or something, as the floats were at different measurements. But, they should be to spec now.

In the end, it seems the only real thing I did was adjust carbs. Waiting for new valve cover to see if it runs better or worse.
 

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Tony...Just FYI, the floats simply keep "enough" fuel in the bowl that it's available to feed up the jets without flooding the intakes......Improper float settings can allow that 'flooding" and foul the plugs, or expose the jets to air instead of fuel..... The air/idle mixture screw determines the fuel to air mixture at idle and the jet sizes and main needle taper vs the slide opening determine it at anything over idle speeds.....
 
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