Top End Build Help!

[Neilw]

I've been rebuilding the Top end on my CB550, and it's not been without its challenges, but I have the rocker cover on now and am now attempting to set the valve clearances.

Quick back story - I had the top end bored out and new pistons and rings - which all went back together again quite nicely. The cam chain was another story, but I got there in the end. I had previous revoved all the valves, lapped them and reinstalled, including new seals.

When i installed the rocker cover, I loosened all of the valves to make it easier to get on; now I'm at the point of trying to find TDC. The video i'm following is pretty straightforward, but assumes you already have clearances that work, so you can identify whether 1 or 4 is on its compression stroke, so that you know you have the cam in the right position - hope i explained that correctly. Anyway, an alternative method was to put your thumb over the park plug hole of no 4, so you could feel the compression. This is where I'm having trouble - in fact I have two areas of concern

When I turn the engine over using a spanner, I get a loud snap back from one of the valve springs - could this be because of the slackened clearances? I can get it to happen on other valves by screwing in/out the adjuster. OR is there something more sinsiter going on?

How do I approach doing the valve clearences  - is there something i can do to "reset" the clearences so i can work out if 1 or 4 is on the compression stroke?

Also, and i don't have a good feeling on this one - when i put my thumb over the spark plug hole for No.4, i got no compression or feeling of pressure, but i did when i repeated the process on No 1. 

I guess i need to sort out the value clearences so i can see if that sorts out the snap back noise and also allow me to put a kick starter on, so i can test the compression properly.

It's quite possible i haven't installed somthing correctly, I'm new to this, but have been very careful as i've put the head together.

Any help or advice is greatly received - I'm just at a loss of how to proceed and need to clear thinkers to help me :-)

Many thanks in anticpation.

[Bryanj]

A loud snap is worrying as it usually means a bent valve that is sticking in the valve.

Loosening all the clearances is simply NOT ENOUGH when refitting the cam cover, you have to hold all the adjuster ends up(rubber band trick) to make sure the followers are on the lobes so that the adjuster end can not get jammed on thetop of the valve stem and push against it bending the stem.

To set clearances you have to have the T 1-4 mark lined up with the static mark, at this point the lobes of the cam on either 1 or 4 will be pointing down, this is the one on compression, after setting turn crank CLOCKWISE 360 degrees and set the other cylinder, same for 2 and 3.

I hope you have not bent a valve but it does sound like it

[Johnwebley]

Refitting the 500/550 rocker cover needs some care


Ideally 4 rubber bands holding each cylinder rockers up from the valves

This is to stop the tappets bending the valve stems

When setting the clearance, 1-4 should be at tdc,just set the cylinder with the closed valves, then rotate one 360 degrees

2-3 are 180 from 1-4



Sent from my SM-A546E using Tapatalk

[Neilw]

A loud snap is worrying as it usually means a bent valve that is sticking in the valve.

Loosening all the clearances is simply NOT ENOUGH when refitting the cam cover, you have to hold all the adjuster ends up(rubber band trick) to make sure the followers are on the lobes so that the adjuster end can not get jammed on thetop of the valve stem and push against it bending the stem.

To set clearances you have to have the T 1-4 mark lined up with the static mark, at this point the lobes of the cam on either 1 or 4 will be pointing down, this is the one on compression, after setting turn crank CLOCKWISE 360 degrees and set the other cylinder, same for 2 and 3.

I hope you have not bent a valve but it does sound like it

Oh S**t, that doesn't sound good.

So next step is to remove the head and check the valves, then go from there. If the valves are bent, could there be any other damage I shoud look out for?

[Otis]

Do you have this or similar?

[Otis]

Have a look in Ash's Dropbox at top of page as well.

[Neilw]

Do you have this or similar?

I do.

[Johnwebley]

A loud snap is worrying as it usually means a bent valve that is sticking in the valve.

Loosening all the clearances is simply NOT ENOUGH when refitting the cam cover, you have to hold all the adjuster ends up(rubber band trick) to make sure the followers are on the lobes so that the adjuster end can not get jammed on thetop of the valve stem and push against it bending the stem.

To set clearances you have to have the T 1-4 mark lined up with the static mark, at this point the lobes of the cam on either 1 or 4 will be pointing down, this is the one on compression, after setting turn crank CLOCKWISE 360 degrees and set the other cylinder, same for 2 and 3.

I hope you have not bent a valve but it does sound like it

Oh S**t, that doesn't sound good.

So next step is to remove the head and check the valves, then go from there. If the valves are bent, could there be any other damage I shoud look out for?

If you have bent a valve ,and turned the engine over  you might have broken a guide

Best wishes

Sent from my SM-A546E using Tapatalk

[Bryanj]

Yes i hate to say it but to be certain remove the head(again), remove all the springs and check the valves slide easily through the guides, you should be able to see if a stem is bent, if not you are lucky , if one is check the valve guide carefully.
Should you end up in trouble all 500 and 550 heads are the same

[Neilw]

Yes i hate to say it but to be certain remove the head(again), remove all the springs and check the valves slide easily through the guides, you should be able to see if a stem is bent, if not you are lucky , if one is check the valve guide carefully.
Should you end up in trouble all 500 and 550 heads are the same

Thank you, I'll report back, may take a day or three :-)

[Bryanj]

Thats ok, i am at work for 4nights from tuesday!, my email is in my profile if you want to contact  direct, i also have a garagefull of "bits"

[Oddjob]

Not being critical here Neil but sometimes I wonder how people do these things. You need cylinder 4 on TDC to fit the cam, you know it's there, you've been looking at it for ages. Why turn the engine? It's setup for installing the camcover, which incidentally I've never ever wound the tappet adjusters out, never used the elastic band trick either. I just hold them up with my fingers whilst looking at where the adjusters are settling as the cover goes down, a small turn on each bolt to ensure it goes down evenly. Never had a problem.

You had the valves out? I'm wondering if one of pot 4s valve springs have shed the collets.

Where in the UK are you? sure to be someone experienced near you who is willing to help out.

[Neilw]

Not being critical here Neil but sometimes I wonder how people do these things. You need cylinder 4 on TDC to fit the cam, you know it's there, you've been looking at it for ages. Why turn the engine? It's setup for installing the camcover, which incidentally I've never ever wound the tappet adjusters out, never used the elastic band trick either. I just hold them up with my fingers whilst looking at where the adjusters are settling as the cover goes down, a small turn on each bolt to ensure it goes down evenly. Never had a problem.

You had the valves out? I'm wondering if one of pot 4s valve springs have shed the collets.

Where in the UK are you? sure to be someone experienced near you who is willing to help out.

I'm learning as I go, so happy for my mistakes to be pointed out. As they say, every day is a learning day.

I can see the collets, so they are good. The Haynes manual didn't have much of a process for installing the rocker cover, so it looks like that may be the culprit. I was careful though and seated it the best i could before tightening the bolts down, a bit at a time. I didn't have any resistance, so no reason to doubt there could be an issue waiting round the corner.

You can bet your life that I won't be taking 6hrs again to fit the camshaft and chain when i get to that point.!

I'm based in Tonbridge, Kent.

I'll know more when i inspect the valves and head,

[Neilw]

Thats ok, i am at work for 4nights from tuesday!, my email is in my profile if you want to contact  direct, i also have a garagefull of "bits"

Thank you, Bryan, i may well be scavenging for parts, hopefully not too many.

[Bryanj]

Having worked on Hondas for more years than i care to admit I, like Ken, use only fingers but mention the rubber bands as its a known trick and helps the novice, we all had to learn

Go to Ashs dropbox at the top line and download the original Honda Manual, you will find a small pic in there of what we are talking about.
Glad to help however i can