Author Topic: Cb500 hard shifting when hot :SOLVED! (Read 9713 times)

78whiteorbs · « **on:** May 07, 2017, 08:15:56 pm »

Took a pretty long cruze today on the 73 cb500 and towards the end the shifter was incredibly stiff and was getting worse by the minute. Thankfully was near family so pulled in and let her cool for an hour or so and was back to shifting smooth as butter. Hightailed it home and same bit when I got there. As it seems the shifting gets stiffer the hotter the bike gets. 30-40 mins and done for. Clutch still works and feels totally normal. What the heck is going on?
I did some searching and maybe my google-fu is rusty but only found cluck pack issues on cb750's
Read some posts in regards to inherent design flaws of the 500's but no soultions or solved threads. Anyone ever ran across this and fixed it? Shifts and rides fine for first 30 minutes or so. Smooth as silk. This is a new one for me...

TwoTired · « **Reply #1 on:** May 07, 2017, 08:22:03 pm »

When is the last time you changed oil?

Did you overheat the oil?

78whiteorbs · « **Reply #2 on:** May 07, 2017, 08:33:40 pm »

Cant say for sure , several bikes and a wasted youth .
Guess thatd be a good place to start. Oil looks clean. Im not sure I know how to over heat oil in an engine. Having an incredibly low oil volume and riding the snot out of it count because I most surely didnt do that....ugh....did not!

Btw welcome back TT!
What oil would you recommend?

TwoTired · « **Reply #3 on:** May 07, 2017, 09:29:05 pm »

There are several ways to overheat oil in an air cooled engine. Most involve air deprivation, like stationary running. Moving slow in hot summer traffic. And parking your bike over a campfire.

I happen to favor Honda HP4 without moly 10-40W. I like the semi synthetic motorcycle oil in case I do get stuck in slow moving traffic when its hot outside, as synthetics have a higher breakdown temperature. I think it gives me some extra heat protection. I recall using golden spectro oil, too.

I always felt that even expensive oil is cheaper than an engine tear down.

Deltarider · « **Reply #4 on:** May 08, 2017, 12:40:21 am »

The phenomenon you describe is not unusual be it to some extent. Question: did you perhaps ride at too low rpm for too long? Although it may feel counterintuitive, higher rpm is effective to lower oil temp as the oil will be gushed around at a higher rate. In US people are used to drive cars al low rpms (oversized engines) and have a tendency to ride their bikes likewise. Our bikes don't like that. Experiment with it and please report back. But on a hot summer day when I've been out on country roads and return in the city (traffic lights) the last miles home I also feel somewhat what you describe. It's not abnormal for an aircooled engine.

Scott S · « **Reply #5 on:** May 08, 2017, 03:54:28 am »

If that bike's been sitting for a while, look between the cooling fins on the cylinders and head. I've removed GOBS of dirt-dobber nests from those areas before.

78whiteorbs · « **Reply #6 on:** May 08, 2017, 05:03:53 am »

Quote from: Scott S on May 08, 2017, 03:54:28 am

If that bike's been sitting for a while, look between the cooling fins on the cylinders and head. I've removed GOBS of dirt-dobber nests from those areas before.

Clean as a whistle.
Motor seems hotter than whats normal though. Gonna hit it with a temp gun today. I wonder if the timing may be advanced excessively. Got it with the electronic ignition already installed . One thing I dont do is lug the engine..Rjide em harder llike 2 strokes!.. Its definately a heat related issue.
Rides perfect for first 30 mins.Shifts perfect, find neutral easy shift excellent.

calj737 · « **Reply #7 on:** May 08, 2017, 05:09:16 am »

Quote from: 78whiteorbs on May 08, 2017, 05:03:53 am

Motor seems hotter than whats normal though. Gonna hit it with a temp gun today. I wonder if the timing may be advanced excessively. Got it with the electronic ignition already installed .

You would be well-served to also examine the plugs for a "too-lean" fuel condition.

Deltarider · « **Reply #8 on:** May 08, 2017, 05:37:55 am »

You didn't add 'stuff' to the oil, did you?

Quote

I wonder if the timing may be advanced excessively.

Usually it's a retarded timing that brings overheating.

Quote

You would be well-served to also examine the plugs for a "too-lean" fuel condition.

+1 If plugs are whitish, you're running too lean.
Then you have these easy steps:
Verify fuel supply is as it should be and no 'extra' fuel filters that can bring 'extra' problems, sometimes intermittent!
Although I've not heard of this being a problem with our bikes, verify tank ventilates. When in doubt do a ride with opened tank cap.
No airleaks around the intake manifold? O-rings between the intake manifold and the head harden over time, become brittle which causes leaking. Are the rubber boots still OK. This can be checked by spraying some brake or carb cleaner there at idle and listen if rpm changes. On the other hand leaks here are often accompanied by a too high idle that won't go down and you did not report that.
(Partially) blocked jets? You didn't mess with the floats, did you?
If all this brings nothing, I'd go for a spirited ride, Italian style. 7000 rpm is nothing for these bikes. I used to maintain it for hours on end and when I left the highway the engine felt reborn. These 500s are rather sensitive for carbon build up.

78whiteorbs · « **Reply #9 on:** May 08, 2017, 09:34:24 am »

Nope no additives. Yep said that backwards.
No air leaks or carb weirdness, freshly cleaned and synced.
Aside from the hard shifting to the point were I think If I rode it much more it wouldnt shift. I didnt notice anything strange or unusual besides the engine feeling hotter than normal. So I then observed as it warmed like after 30 mins up the shifting became harder. Throttle response is excellent and power is excellent. I always ride spiritedly ! More of a sportier rider than a cruiser. Rpm range generally always 4-5 k and climbing. Checking the timing today. Bike came with a file of service tickets and one was something to do with ignition timing advancer stuck or something like that IIRCC.

calj737 · « **Reply #10 on:** May 08, 2017, 10:43:23 am »

Freshly cleaned and synced carbs doesn't constitute an evaluation of the AF mixture or the lean/rich state of your combustion. Either pull a plug and verify their condition, or speculate as to their health.

78whiteorbs · « **Reply #11 on:** May 08, 2017, 11:13:53 am »

Quote from: calj737 on May 08, 2017, 10:43:23 am

Freshly cleaned and synced carbs doesn't constitute an evaluation of the AF mixture or the lean/rich state of your combustion. Either pull a plug and verify their condition, or speculate as to their health.

But of course- I will most certainly pull a plug! Thanks for the suggestion I can use all the ammo u fellas can spare!! Keep it coming! And thank you-

Deltarider · « **Reply #12 on:** May 09, 2017, 01:32:14 am »

Quote

one was something to do with ignition timing advancer stuck or something like that IIRCC.

Aha!

78whiteorbs · « **Reply #13 on:** May 09, 2017, 08:33:52 pm »

All plugs light mocha brown. Next is to check the timing. Gotta get my strobe back tomorrow...Gonna go ahead and change the oil although it looks like fresh clear oil should. Is overheated oil generally darker? That was my assumption...
I recall when I got the bike the PO said that there was something the matter with the "gear linkage" or something to that effect. I asked him if the transmission was in working order or if it needed repair and he said he said it wasnt anything internal but a linkage binding ir something...
He said hed see if he could fix it before I came by.
When I got the bike home you could see the clutch lifting mech was kinda bent were the end of the cable fits in it like someone had tightened it up with pliers or something after it being bent like what I assumed was it being forcefully stripped through there thus bending and distorting the end of the clutch mech were the end of the clutch cable was retained.... Shifted fine though and while I was on the look out for another I just rode it as was. Those are clues perhaps...

I rode it all around tiwn and too work for the next two weeks or so and it started up like clock work and never gave any hint of stubborness but those were all short trips...29-39 mins so it never got a chance to build up any heat I am guessing. First over an hour trip and I noticed very "sure" click shiftin at first then few minutes later barely could move the shifter with my foot ( and this was mostly my toes as the 500's dont have alotta room to get the meater portion of your foot in there.

Weird I have never heard of this everand been reading and lurking for like 10 years. Seem like if it were bad selectors in the gearbox then it would be consistant eh? Not good when cool bad when hot. Frustrating wanna get some miles on her...

Stev-o · « **Reply #14 on:** May 09, 2017, 08:56:47 pm »

Never believe a seller. Change the oil to eliminate that possibility.

Deltarider · « **Reply #15 on:** May 09, 2017, 11:59:50 pm »

Quote

When I got the bike home you could see the clutch lifting mech was kinda bent were the end of the cable fits in it like someone had tightened it up with pliers or something after it being bent like what I assumed was it being forcefully stripped through there thus bending and distorting the end of the clutch mech were the end of the clutch cable was retained....

Wouldn't think too much of that. Mine is also like that. Has to do with difficult opening the slot further to free the end of the cable when it needs replacement. Anybody here has a tip?
Why not collect the oil that's in your motor now (just save it in a yerrycan) and see what new oil brings? I'd go for 15W-40 (recommended to me by an expert in oil and tribology who owned a CB550K3 himself).
Oil clear or black doesn't mean much. As a matter of fact, I know of mecs that prefer used oil (which already contains some soot) over new oil to quiet the valvetrains in their Audi's. My impression is that the people that change oil the least, are... professional mecs. But you must change, simply because in your case you never know... I'd also check the oil circulation. Is the oilfilter fitted correctly? Maybe even drop the sump pan to see if the screen is still open. I don't expect there will be a problem. I've inspected mine twice in all those years and the last time after some 60.000 kms it looked like this (see pic). If new oil doesn't bring anything, you still have the oil. It's a bit of work, but the good thing is you can rule causes out and have grown familiar with some aspects of maintenance. But before all this, check ignition timing and the correct functioning of the advancer assembly in particular. Succes!

DaveBarbier · « **Reply #16 on:** May 10, 2017, 05:01:40 am »

What oil are you using? It says specifically that it's for motorcycles with wet clutches?

Not turning this into a "which oil is best" thread, but I was using a Castrol oil and although it worked ok, when it got hot it was very hard to find neutral and shifting was clunky, but not hard. Switched to Spectro Golden 4 semi synthetic which has zinc in it, and it drastically improved. I could ride for hours and at a stop light neutral came with a slight flip of the foot every time.

I'm just saying that oil plays a big part in clutch operation and changing brands to something else could help. Possibly to a known (anecdotally) smooth shifting brand.

Deltarider · « **Reply #17 on:** May 10, 2017, 06:22:47 am »

Best shifting I ever had is with a conventional 15W-40 Castrol oil, like their High Mileage. It's not even motorcycle specific and in my experience better for the seals than other oils that I've tried. Whatever you choose, do not add additives! Not in your oil. You may spoil something good.

DaveBarbier · « **Reply #18 on:** May 10, 2017, 06:51:20 am »

I've never used Castrol's high mileage. If Spectro is hard to find in the future I'll check it out. The Castrol that I didn't like was the Power RS Racing 4T fully synthetic.

Sent from my iPhone using Tapatalk

Blue jacket · « **Reply #19 on:** May 10, 2017, 04:59:39 pm »

I am having a similar problem. Though I think it's clutch related not tranny, When my 73 CB gets hot the clutch won't hold. Pull up to a light and it will pull even with the clutch all the way pulled in. Almost impossible to get into neutral. Let it cool and there is not an issue. I tried adjusting the clutch cable thinking it was getting lose, but that wasn't the issue. Broke or pulled clutch cable out so I need to check the linkages now and see what I did. Though that is because I think I tightened the cable too much.

Just did it tonight Oil is fresh and since it leaks a little has been topped off, also clutch was recently replaced.

It can't ride it after about 20 minutes, Any help would be greatly appreciated

78whiteorbs · « **Reply #20 on:** May 13, 2017, 06:40:05 pm »

Well everything is in order- switched to Shell Rotella T 15w-40 filter was skanky! Hit all headers with a temp gun and number 2 is about 60 degrees hotter. 200-1. 250-2. 200-3. 200-4.

Resynced carbs and engine idles and runs buttery smooth.
Seems to shift way smoother but still has hard shifting after really heated up. So strange...

Ran across this thread :
http://www.sohc.co.uk/index.php?topic=4253.0

I had the gearbox rebuilt and new clutch on my CB500 but once it was warm I still found it difficult to change up from 1st-2nd or to find neutral. I was using 10/40 mineral oil but am now using 15/40 Shell Helix. It has made a noticeable improvement, the change is very smooth when the engine is cold to warm but is still a bit reluctant to shift in to second when really hot.

What the hell is causing this?

?

78whiteorbs · « **Reply #21 on:** May 13, 2017, 07:07:58 pm »

And this:

http://www.dotheton.com/forum/index.php?topic=38090.0

Same prob no solution-

HondaMan · « **Reply #22 on:** May 13, 2017, 07:25:50 pm »

Here's some 'inside skinny' on the CB500 clutch system, which led to the CB550 changes:
The clutch rod is steel: the engine cases are aluminum. The cases expand at nearly 3x as much distance-per-heat than the shaft, partly because the shaft is also suspended by its ends and never gets as hot as the tranny. In the earlier bikes (like the CB160, et al, where this design came from), they all suffered this same scenario. So, we all learned this particular way to adjust the clutch, which is:

when cold (like in the AM, first thing), the clutch is adjusted at the cases, with the handlebar adjuster all the way in, to just take up all the cable slack. The lever should just feel like it is coming up against the lifter about 1/8" from the full release. Then, when the engine heats up fully, the lever will have the 1/2" of "play" as shown in the manuals. True, the shift point will move as the engine heats up, but we oldsters used this point to know when the engine had reached full operating temperature, because it had 1/2" of free-play at the clutch lever. Further: when this play INCREASED with a hot engine, it indicated the oil was running too thin: depending on the oil mileage or the temp of the day, this could indicate need to change oil.

On my own CB500-4 (K1 model), I used this indicator to tell me when to change oil, in particular. It hit almost exactly at 1100 miles, every time. In the 1971-72 Shop Manuals for this bike, that was the recommended oil interval. This changed in 1973 along with all the other manuals, but that's how these started.

Keith · « **Reply #23 on:** May 13, 2017, 08:24:43 pm »

I can tell you, with all due respect, as a retired vw/audi factory trained technician, I cannot imagine anyone suggesting putting used oil in an Audi engine. Lack of oil changes is what caused the noisey lifters in the first place.

78whiteorbs · « **Reply #24 on:** May 13, 2017, 08:38:39 pm »

Quote from: HondaMan on May 13, 2017, 07:25:50 pm

Here's some 'inside skinny' on the CB500 clutch system, which led to the CB550 changes:
The clutch rod is steel: the engine cases are aluminum. The cases expand at nearly 3x as much distance-per-heat than the shaft, partly because the shaft is also suspended by its ends and never gets as hot as the tranny. In the earlier bikes (like the CB160, et al, where this design came from), they all suffered this same scenario. So, we all learned this particular way to adjust the clutch, which is:

when cold (like in the AM, first thing), the clutch is adjusted at the cases, with the handlebar adjuster all the way in, to just take up all the cable slack. The lever should just feel like it is coming up against the lifter about 1/8" from the full release. Then, when the engine heats up fully, the lever will have the 1/2" of "play" as shown in the manuals. True, the shift point will move as the engine heats up, but we oldsters used this point to know when the engine had reached full operating temperature, because it had 1/2" of free-play at the clutch lever. Further: when this play INCREASED with a hot engine, it indicated the oil was running too thin: depending on the oil mileage or the temp of the day, this could indicate need to change oil.

On my own CB500-4 (K1 model), I used this indicator to tell me when to change oil, in particular. It hit almost exactly at 1100 miles, every time. In the 1971-72 Shop Manuals for this bike, that was the recommended oil interval. This changed in 1973 along with all the other manuals, but that's how these started.

HM - thanks for the skinny. So if I am understanding this correctly: the clutch cable should be adjusted all the way out at the case to allow for the most absolute minimum clutch lever "Pull" that will eventually "end up" further in about a half inch (friction point) as the engine reaches peak operating temperature. I think I understand the concept but not %100 on the procedure.
Is that correct?

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Author Topic: Cb500 hard shifting when hot :SOLVED! (Read 9713 times)