Topic: '76 CB550F: Randomly Revs up while riding, but no increase in speed?

[magner]

I took my longest ride yet today (probably 40 miles) and took the highway back for my second time. Overall the bike did fine, however I noticed when I was cruising around 60 on the highway, the revs would suddenly shoot up while the bike just stayed the same constant speed with no reaction to the sudden change. By looking at it, the bike would just be riding steady and cruising, but if you listened the revs would be up and down sporadically. Also when I up shift, the revs stay high for a few seconds before going back down. I have also noticed recently the tach will behave normally when idling and up to maybe 4k, and then it will just start bouncing all over the place (doubt its related though).

Overall I have noticed it is pretty slow coming out of stops and just in general feel sluggish when trying to accelerate, yet the revs will go really high and sound like its working really hard just to get up to speed. This is the only bike I've ridden so I don't have a frame of reference, but it just seems pretty slow in terms of acceleration. My only reference point is when I ride with my friend (he's on a 2011 Triumph Thruxton): whenever we pull out of lights together, without him even trying he will be like 10 car lengths ahead before I am even up to speed, yet it sounds like I'm flooring it.

My only idea is that it has something to do with the clutch, otherwise how else would the speed of the bike not respond when the revs suddenly shoot up to 6000? Maybe the clutch is slipping or worn down? Thanks as always for any help!

[scottly]

Yes, it sounds like your clutch is slipping, but it might be as simple as adjusting it.

[magner]

Cool, I’d love it if I could get my bike feeling more powerful from a simple fix. I don’t know anything about working on the clutch, any chance you could point me towards what videos to search for?

[seanbarney41]

Stop watching videos and read the service manual.

[Bankerdanny]

The process is very straight forward. Use the step-by-step instructions in the repair manual

[TwoTired]

Stop watching videos and read the service manual.

Yeah...that^^

[magner]

Thanks guys; I have read the service manual and will follow it’s instructions, however I only ask about videos because I barely know what a clutch looks like and as someone who’s never worked in motorcycles, I need a little extra aid. I will have to get a caliper but I’d like to check those serviceable limits and report back.

Is it possible that it has to do with the clutch cable adjustment? The only reason I think that it is not that the clutch cable is because it will slip sporadically while cruising, having not touched the clutch lever for awhile.

[Scott S]

 If it's slipping that bad, you need to start with the lower adjustment first. If not new clutch plates.

[magner]

Thanks! By lower adjustment are you referring to adjusting the clutch cable where it meets the crank case, as opposed to the barrel adjuster on the lever?

[Smudgemo]

Thanks! By lower adjustment are you referring to adjusting the clutch cable where it meets the crank case, as opposed to the barrel adjuster on the lever?

Yeah, loosen the nut on the bottom of the clutch cover, adjust the slotted bolt until the marks line up, tighten the nut, adjust the cable pull.  Adjusting the cable is the hardest part, but start both ends screwed in for max slack and start by the clutch.  Fine-tune at the lever.  At least that's how I recall doing mine and it works perfectly (for a 42 YO clutch with an unknown number of miles and parts origin..)

[tlbranth]

I've never had a motorcycle where the clutch needed actual plate replacement. Wet clutches seem to last forever. You probably just need to do the adjustments as described above. When you're done, make sure there's a little play in the lever before disengagement begins .....and Bob's your uncle.

[BomberMann650]

Out of curiosity, have you added any motor oil to the crankcase lately?

If the answer is yes, what type?

[magner]

No I have not actually, and I have been meaning to get around to an oil change since I haven’t since the PO did. I do know the oil in there is motorcycle specific, but I can check on what the actual specifics are later.

[magner]

So this weekend I have been replacing the clutch plates and after a lot of difficulties I finally have them in, but I also have a gap in the plates that seems odd to me. Can anyone say whether or not this is normal? I checked and the 7 new plates I put in are identical to the 7 old plates I took out.

[jaytee-nz]

No, that is not normal. Have you replaced all the steel plates that go between the new fibre plates you installed ?

[magner]

Yes I took them out and put them back in just as they were before. Is it just because I don’t have the springs on yet so it’s still loose?

[jaytee-nz]

Yep, putting the springs and plate back on will compress all the clutch plates up tight.
Did you pre-oil all your new plates before putting them in ? If not, I suggest you take them out and soak them in engine oil overnight before final assembly.

[magner]

Yes I did soak them but thanks for looking out! Now the last thing I have to do is replace the oil filter but I have been wrestling with the oil filter bolt for hours now and I can’t get it off. It seems super over tightened and in top of that it’s made out of super soft metal that strips super easily... I even cut a deep slot in it to use a big flat head on and even that has stripped out somehow... out of ideas at this point.

[HondaMan]

Yep, putting the springs and plate back on will compress all the clutch plates up tight.
Did you pre-oil all your new plates before putting them in ? If not, I suggest you take them out and soak them in engine oil overnight before final assembly.

Yeah, what he said. ^^^
Otherwise you will be back in there, replacing the clutch plates in 10 miles or so.

[HondaMan]

Yes I did soak them but thanks for looking out! Now the last thing I have to do is replace the oil filter but I have been wrestling with the oil filter bolt for hours now and I can’t get it off. It seems super over tightened and in top of that it’s made out of super soft metal that strips super easily... I even cut a deep slot in it to use a big flat head on and even that has stripped out somehow... out of ideas at this point.

It sounds like someone overtightened it a long time ago. It probably happened because he put in the too-small O-ring that often comes in oil filters these days, then it leaked. Then he kept tightening until it stopped. Nasty...

Go to PartsNmore and look up your bike: they have a nice oil filter bolt for $10 that has a larger 17mm head. And it's a little better metal, to boot! The O-ring is special: if yours is even slightly loose in the groove, get a new one from Honda. It will last for decades.

[magner]

Thanks I will! Now I just need to figure out how to get the stupid thing off...

[Deltarider]

You didn't specify what model CB550F you have. Any CB550F owner who is working on the clutch should have the engine serial number at hand to check what clutch assembly he is supposed to have. This because the clutch underwent modification from engine number 1139189 on. Cf. p. 17 in http://www.honda4fun.com/pdf_parts_list/pdf_spac550/CB550F2/CB550F2_1.pdf  BTW, all models CB550 Parts Lists both 'K and 'F' are here: http://www.honda4fun.com/materiale-documentazione-tecnica/parts-list/parts-list-cb550

[BRG-BIRD]

I had a #$%* of a time getting mine off. Finally used a breaker bar with a very tight fitting 6 point socket and tapped on the end of the bar with a blacksmith hammer (carefully) to mimic an impact and it finally broke free. It sucked and like you didn’t think it would come free.