[Irving]

Update: When I add a bit of oil into the cylinders the psi jumps up to over 170psi. From what I understand this typically means worn rings or cylinder walls. But as described below the rings are brand new and the cylinders were honed. What else could this mean?

Compression is 85 psi on both sides. That's exactly half of the 170psi that it should have brand new. Compression tested with the throttle wide open, choke off and both spark plugs removed.

I replaced all of the piston rings and honed the cylinder walls. The pistons are standard pistons and the engine has not been overbored as far as I know. The rings are NOS honda standard rings. (I used this hone: https://www.amazon.com/gp/product/B00A4AI972) Replaced the cam chain. Replaced all gaskets including head gasket of course. Lapped the valves and replaced the valve stem seals. I level sanded the head with 220 grit so that it was dead flat for a good head gasket seal. I torqued all of the head bolts in the correct sequence down to 16 foot pounds torque.

When installing the rings I spaced the ring gaps at equal distances apart as called for. I also made sure that the rings were all installed with the right surface facing up.

It seems conspicuous that both cylinders are basically exactly half the proper psi spec. Maybe doesn't mean anything but is there something particular I may have done wrong that would give this result? What do you think?

 

[Simo]

Have the ring been seated (has it been run in), is the timing correct? Are the carbs wide open? Did you buy your
Compression gauge from harbour freight?

 

[Irving]

Have the ring been seated (has it been run in), is the timing correct? Are the carbs wide open? Did you buy your
Compression gauge from harbour freight?

Yes as written above I'm compression testing it with the throttle wide open. Compression gauge is good. I believe the timing is correct but even if it was off that shouldn't effect compression results should it?

I have not started the bike yet. Only done the compression test. Are you saying that only once the bike has run and broken in will the rings "seat" and show optimal compression? Yeah I figured compression would rise a bit after things wear in but 85psi just seemed extremely low.

 

[HondaCB200Lady]

Do you know the history of the engine Irving? Could it have already been over bored by a previous owner?

We got Olive's engine bored and skimmed and used .50 pistons if I remember rightly and she is running great.

 

[Simo]

Yeah 85 is very low, the smaller twins generally wont even run below 90 and arent at all rideable at that. Unseated rings will lower the compression, but not that low. However unseated rings and a bad gauge, or choked carbs etc could give you a lower reading

 

[Irving]

Do you know the history of the engine Irving? Could it have already been over bored by a previous owner?

We got Olive's engine bored and skimmed and used .50 pistons if I remember rightly and she is running great.

That is a very interesting thought. It crossed my mind too. I don't know it's past history well but I don't believe it had ever been worked on before. It had about 9000 miles on it when I bought it. It appeared all original. The old cam chain was incredibly loose and slapping against the wall. I would be very surprised if it had been overbored and given new pistson/rings previously. I guess I would have to open it back up again to find out for sure. I'll have to do some more brainstorming before I open it back up.

 

[Irving]

Ok so one of the pistons measures exactly 2.168" in diameter. I'm measuring right above the oil scraping ring below the middle ring. Measuring down near the bottom at the "skirt" it measures 2.181". The only writing on it is the word "ART" and the number "1" Does anyone know if this may be a stock size piston? Or is it an oversize? Also, the only markings I can see on the old rings is a letter "R" on one side.

 

[HondaCB200Lady]

Not sure but mine had just over 6000 miles on it and needed reboring, it had already had one piston replaced badly and the second one had broken rings. There had been no oil feed to the top end and it had to have the camshaft and end journals replaced. There are some original standard sized pistons on ebay with pictures which may help. HONDA CB200 STD PISTON KITS 13101-354-000 .PATTERN/GENUINE PARTS. | eBay

I may possibly have the old pistons in the garage so let me know if the link doesn't give you the answer.

 

[HondaCB200Lady]

Have a look at picture number 5 for this 0.50 oversized ART CB500 piston Irving

 

[Yendor]

Did you do the Hone yourself or did a shop do it?
It's not hard to hone cylinders into an OVAL Shape or a Taper (different diameters from top to bottom) if you don't do it correctly.

Use too course of a grit hone for the job?
Smaller displacement motors need a finer gain grit for the hone job or the cross hatch will be too deep and leak pressure.

Did you mix up the rings?
Top Ring in the 2nd slot or upside down.

Rings wrong side up?
Rings have a required Up side vs Down side.
Typically there are DOTS Stamped or other Identifying marks that indicate this side up.

Did you measure the RING END GAPS.
Too much space between the ends of the rings would indicate they were not the correct rings.
IE: Standard Rings in a .50 over bore.

With the compression that far out of spec - I would assume something is wrong, and a tear down is in order.

 

[Irving]

Have a look at picture number 5 for this 0.50 oversized ART CB500 piston Irving

Picture number 5? Where are you referring to?

 

[Irving]

Did you do the Hone yourself or did a shop do it?
It's not hard to hone cylinders into an OVAL Shape or a Taper (different diameters from top to bottom) if you don't do it correctly.

Use too course of a grit hone for the job?
Smaller displacement motors need a finer gain grit for the hone job or the cross hatch will be too deep and leak pressure.

Did you mix up the rings?
Top Ring in the 2nd slot or upside down.

Rings wrong side up?
Rings have a required Up side vs Down side.
Typically there are DOTS Stamped or other Identifying marks that indicate this side up.

Did you measure the RING END GAPS.
Too much space between the ends of the rings would indicate they were not the correct rings.
IE: Standard Rings in a .50 over bore.

With the compression that far out of spec - I would assume something is wrong, and a tear down is in order.

I honed it myself. I only did maybe 15 or 20 seconds of honing per side. I used just one hone. It was this one: https://www.amazon.com/gp/product/B00A4AI972

I felt certain at the time that I got all of the rings correct side up and in the correct positions.

I did not measure the ring end gaps.

 

[Irving]

With the compression that far out of spec - I would assume something is wrong, and a tear down is in order.

Do you think it's worth starting up and riding and seeing if the compression increases with use? Or do you think I ought to tear it back down now without doing so? My 85psi readings are without having been started at all since being rebuilt.

 

[Richard_Pitman]

I'd certainly run it, see how it goes, before stripping it down.

I have a standard CB200 piston in front of me here, and all it says is 'ART' on one side. Inside the skirt is an up arrow '^' symbol, with '10' underneath.

55.5mm diameter, so far as I can measure it without digging the Vernier out from the garage tonight.

 

[HondaCB200Lady]

Picture number 5? Where are you referring to?

Sorry Irving I meant to put this link on ART PISTON OS 0.50 FOR 1971 72 73 HONDA CB500, REPLACES 13103-323-000 (*3089*) | eBay

 

[Irving]

I'd certainly run it, see how it goes, before stripping it down.

I have a standard CB200 piston in front of me here, and all it says is 'ART' on one side. Inside the skirt is an up arrow '^' symbol, with '10' underneath.

55.5mm diameter, so far as I can measure it without digging the Vernier out from the garage tonight.

Yeah it certainly seems to turn over healthy. And the wet compression test is showing that my valves are in great shape. So I think I'll put the exhaust on and take it for a ride.

Yeah I've been looking at a bunch of cb200 pistons and they all seem to say different things without much rhyme or reason that I can tell. My old pistons say ART with a ^ symbol and the number 1 underneath. I have seen some on ebay that are original size that have a number 2 and you say yours have a 10. I don't know what these numbers mean.

My old rings simply have an R on one side. That's it. If they were oversize wouldn't they say .25 or .50 etc?

 

[Irving]

Just had it out for a ride for 10 minutes. It went reasonably well. Had it up to about 70mph or so. I'm fairly new to bikes and the cb200 though so I don't have a real good sense of how a great running bike should feel. It does have a pretty bad hesitation and will die on full throttle which I believe is a carburetor issue. PSI now reads at 100 for both cylinders. This is the compression tester I'm using: https://www.amazon.com/INNOVA-3612-Compression-Tester-Piece/dp/B000EVU89

 

[HondaCB200Lady]

Just had it out for a ride for 10 minutes. It went reasonably well. Had it up to about 70mph or so. I'm fairly new to bikes and the cb200 though so I don't have a real good sense of how a great running bike should feel. It does have a pretty bad hesitation and will die on full throttle which I believe is a carburetor issue. PSI now reads at 100 for both cylinders. This is the compression tester I'm using: https://www.amazon.com/INNOVA-3612-Compression-Tester-Piece/dp/B000EVU89

If it is managing 70 mph there can't be that much wrong with the compression Irving. If you know there isn't a problem with rust/debris in your fuel then set the carbs up and that should sort out the other problems. For my carbs I had to change the needle valves which stuck occasionally and flooded. The clips on the needles are both on the top notch on mine and I have read similar for other CB200 owners on the forum.

Here's Steve's technique for carb setting*copied from a thread on the forum

I start with the slides synchronized (cable adjustment), throttle stops backed out, and the mixture screws turned to the center of their specified range......

Hold the throttle slightly open and start the engine..... Back the throttle down until you get an idle ~1200 RPM, HOLD it there, and gently turn in the throttle stops until it starts to rev.....adjust back to 1200.... Once it is again idling at 1200 with both throttle stops set, you are ready to do the actual adjustments......

Pick a carb....adjust its MIXTURE screw throughout its spec'd range to find the point of highest idle RPM, and leave it there at highest revs...adjust that carb's throttle stop back down to 1200 RPM...

Same procedure, other carb......
Repeat on both carbs to verify/fine tune.......Repeat again IF necessary....

Re-verify slide sync...Adjust IF necessary (usually no more than 1/4 turn on the carb top adjuster, often they are still fine)...
If you did this correctly, vacuum , exhaust pressure, and exhaust heat will be the same on both sides (hard to verify last two on the CL)

Engine response to throttle should be "crisp" and smooth throughout entire range....

 

[Irving]

If it is managing 70 mph there can't be that much wrong with the compression Irving. If you know there isn't a problem with rust/debris in your fuel then set the carbs up and that should sort out the other problems. For my carbs I had to change the needle valves which stuck occasionally and flooded. The clips on the needles are both on the top notch on mine and I have read similar for other CB200 owners on the forum.

Here's Steve's technique for carb setting*copied from a thread on the forum

I start with the slides synchronized (cable adjustment), throttle stops backed out, and the mixture screws turned to the center of their specified range......

Hold the throttle slightly open and start the engine..... Back the throttle down until you get an idle ~1200 RPM, HOLD it there, and gently turn in the throttle stops until it starts to rev.....adjust back to 1200.... Once it is again idling at 1200 with both throttle stops set, you are ready to do the actual adjustments......

Pick a carb....adjust its MIXTURE screw throughout its spec'd range to find the point of highest idle RPM, and leave it there at highest revs...adjust that carb's throttle stop back down to 1200 RPM...

Same procedure, other carb......
Repeat on both carbs to verify/fine tune.......Repeat again IF necessary....

Re-verify slide sync...Adjust IF necessary (usually no more than 1/4 turn on the carb top adjuster, often they are still fine)...
If you did this correctly, vacuum , exhaust pressure, and exhaust heat will be the same on both sides (hard to verify last two on the CL)

Engine response to throttle should be "crisp" and smooth throughout entire range....

Great info. Thank you so much. I will get hold of another compression tester and see if mine is off. That would be great. As far as I know this compression tester works well though. We'll see. I also need to get my carbs running properly before I can really tell how well this bike is running.

Full story in a nut shell: I rode this bike for about 3000 miles over the course of a year and then one day out of the blue I melted a hole in the top of a piston and lost full power in that cylinder. I then put the bike in storage for a year and just now finally got down to taking it apart, replacing the piston and doing a top end rebuild.

I never was quite able to get the carbs running right. I also have the needles on the top setting as you do. That's the only way I could get it to run fairly well. I rebuilt both carbs last year and still could not get rid of the hesitation and severe bogging down on full throttle. I'm considering maybe just replacing them.

 

[HondaCB200Lady]

Do you have original style air filters on or pods? I have read that having pods and not enough air flow can cause the piston to hole as you have described.

The other thing that we replaced on both our CB200's to help get the bikes running correctly was NOS petcocks. No amount of cleaning seemed to make the originals flow correctly.