Topic: 350 vs 400 rocker cover/assembly interchangability - horror pics

[finkbuilt]

Are the CB400F and CB350F rocker assemblies the same?  I need a new one for my 350, and I was wondering if I could install one from a 400.

(I moved the following from an earlier thread, which was mostly about how to remove the rocker cover)

So, it seems that this "just needs the carbs cleaned out after sitting" purchased from the original owners bike, has a little more serious issue that gummed up idle jets.  I removed the rocker cover to retorque the head bolts and found this horror:





Man, I just keep getting further and further from having a motorcycle.

I found all of the big pieces, and lots of little shavings with a magnet.   The cam lobe in question is a little scratched, but not bad.  the cam journals seem fine.

what should I do?

Can I just replace the rocker? or should I look for a whole assembly on ebay?  Advice please.

thanks

[camelman]

Ouch, bad luck.  If everything else is fine, then you should be able to just replace that rocker.  Check the shaft it pivots on, the valve it contacts, and everything else around it for damage first though.  I have some extra rockers laying around too.  Send me an e-mail if you decide you want to just replace the bad rocker.  I'm pretty pricey though... at least $5 shipped.  ;-)

Camelman

[finkbuilt]

Send me an e-mail if you decide you want to just replace the bad rocker.  I'm pretty pricey though... at least $5 shipped.  ;-)

Camelman

OK, thanks Camelman,  I will keep you posted.  I might see what ebay can do for me in the way of a cover complete with rockers, then I'll come knocking on your door.  I'd rather bolt something on than take that apart. But maybe it's easier than it seems.

So, are the 400 covers/rockers the same as 350's?

-steve

[MoMo]

Rockers are the same and replacing one is very easy.  Take Camelman up on his offer if all your other parts look good.  Can't beat the offer...Larry

[scunny]

I wonder what happened there ? the rest from the pic looks alright.

[Triffecpa]

yes, the 400F and 350F cam covers are the same.  The heads are slightly different though (the front two center studs are longer on the 350F and the casting in the area is different).  You can put a 400F head on a 350F, but you need some spacers to fit over those two center studs.

I would be surprised if you don't have a bent valve though with that broken rocker.

Tracy

[HondaMan]

I wonder what happened there ? the rest from the pic looks alright.

I think it's a variation on an old 1970s trick, where some V-8 owners would remove a couple of pushrods from their engines to temporarily improve their gas mileage during the gas crisis of the era, making them into V-6 engines.

[CycleRanger]

Better make sure that valve isn't stuck.

[camelman]

I don't think the 350f and 400f covers are interchangeable. The heads are different and I don't believe the covers will seal if you swap them. I'll compare a couple when I get home tonight.

[finkbuilt]

I don't think the 350f and 400f covers are interchangeable. The heads are different and I don't believe the covers will seal if you swap them. I'll compare a couple when I get home tonight.

OK.  I'd rather just replace the single rocker anyway, since the other rockers are all "wear-mated" to their respective cam lobes.

The only thing that scares me is:  Why did it break in the first place?  Sticky valve? will it happen again when it is at operating temperature?

[MoMo]

I don't think the 350f and 400f covers are interchangeable. The heads are different and I don't believe the covers will seal if you swap them. I'll compare a couple when I get home tonight.

OK.  I'd rather just replace the single rocker anyway, since the other rockers are all "wear-mated" to their respective cam lobes.

The only thing that scares me is:  Why did it break in the first place?  Sticky valve? will it happen again when it is at operating temperature?

Was the adjuster still in the rocker?  If not that could be an explanation.

[finkbuilt]

I don't think the 350f and 400f covers are interchangeable. The heads are different and I don't believe the covers will seal if you swap them. I'll compare a couple when I get home tonight.

OK.  I'd rather just replace the single rocker anyway, since the other rockers are all "wear-mated" to their respective cam lobes.

The only thing that scares me is:  Why did it break in the first place?  Sticky valve? will it happen again when it is at operating temperature?

Was the adjuster still in the rocker?  If not that could be an explanation.

yeah, the adjuster is still in it.  If you look closely at the picture, you can see damage to the adjuster end as well, which tells me that it must have smacked pretty hard into the end of the valve stem.

[MoMo]

 If the adjuster is still there, bent or seized valve is another explanation. I guess metal fatigue could also be a possibility.  Pour a bit of liquid  through the port and see if it leaks...Larry

[finkbuilt]

If the adjuster is still there, bent or seized valve is another explanation. I guess metal fatigue could also be a possibility.  Pour a bit of liquid  through the port and see if it leaks...Larry

You'll have to forgive me, but I dont understand what you mean about pouring liquid through the port.  See if it leaks from where to where?

At any rate, the valve below the broken rocker is stuck.  I cannot push it down with my finger like I can the rest of the valves. 

I guess this means that I have to take the head off

[dave500]

my guess now is that the valve has rusted stuck from sitting and the first attempt to turn the motor broke the rocker,,if that had have snapped when it was running id expect to see far more damage?

[finkbuilt]

my guess now is that the valve has rusted stuck from sitting and the first attempt to turn the motor broke the rocker,,if that had have snapped when it was running id expect to see far more damage?

Yeah, I was sort of hoping for a scenario like that myself.    Maybe I should put some penetrating oil around the guide, and then tap it a little and try to work it free, then replace the rocker and give it a whirl?

[camelman]

Could the clearances have been so excessive that the rocker arm was battered to pieces?

Also, the intake and exhaust are the same.  The one I'm sending you has a little flash rust on it, but it literally wipes right off.  Wipe it down with a rag before installing it.

Camelman

[phil71]

Make sure that thing is getting oil up to the top end!

[MoMo]

If the adjuster is still there, bent or seized valve is another explanation. I guess metal fatigue could also be a possibility.  Pour a bit of liquid  through the port and see if it leaks...Larry

You'll have to forgive me, but I dont understand what you mean about pouring liquid through the port.  See if it leaks from where to where?

At any rate, the valve below the broken rocker is stuck.  I cannot push it down with my finger like I can the rest of the valves. 

I guess this means that I have to take the head off

You will have to remove the head either to replace it or have it rebuilt so go ahead and do it. By pouring liquid I mean pouring an ounce or so into the exhaust and intake ports, nothing should leak through the valve if it is seated correctly. I had a 400f head that had been sitting in a damp basement for years.  3 of the 8 valves were  so badly stuck that I had to get another head. Dave500's assessment may be right on...Larry

[camelman]

Could the clearances have been so excessive that the rocker arm was battered to pieces?

Also, the intake and exhaust are the same.  The one I'm sending you has a little flash rust on it, but it literally wipes right off.  Wipe it down with a rag before installing it.

Camelman

Never mind. I just read the earlier posts.

[Triffecpa]

per parts schematics at BikeBandit.com, the 350F and 400F cam covers are the same part no.

the rockers are the same part no. also.  However, the valves are different between the two engines.

Tracy

[camelman]

per parts schematics at BikeBandit.com, the 350F and 400F cam covers are the same part no.

the rockers are the same part no. also.  However, the valves are different between the two engines.

Tracy

Wow, you're right.  I just always picture them as different.

Camelman