New to me 1973 cb450. need help. -_-'

[Buddy]

Hi all. My name is buddy.

So I've got this cb450, and I was really looking forward to working on it and riding it this summer. Problem is when I got it home, it was only firing and running off of one cylinder, right hand side.

So naturally dad and I started eliminating things that might be wrong. New plugs and we tested for continuity in the wires, coils, and points. There is continuity all the way from the points to the plugs.

So next we kind of went backwards and checked thd carbs after I found a couple of threads that hinted towards them as being the culprit for single cylinder running due to clogs or bad jets. Cleaned them and adjusted them 1.5 turns fromfull close for the screw on the outside. Still only right side fired.

So from there I checked ignition timing and adjusted it so when LF mark lined up with the line on the stator, a lightbulb I was using lit up. Did the same for the right cylinder. Tried to start it up, and she actually started up a lot easier, but again, RH only. :/ so we shut it down.

At this point, we decided to take carbs off again and look to see if valves were moving on the intake side. It was a go on RH and LH sides. So we moved to the exhaust side and saw that the exhaust side was NOT moving! So bingo, we now know its a stuck valve. Well not so fast, lol. I went ahead and removed the head cover on the exhaust side and both of our stomachs sank. The culprit, a broken rocker, shattered. so now the summation of my inaugral (sp? Lol) noon post on DTT, what is the most efficient way of replacing a rocker arm? And where might I even be able to find any? Insight willbe greatly appreciated. Im aware that this is probably not a noon issue, but I would really like to try and fix here at home. Anyways, thanks!!!

 

[Buddy]

Noticed that the valves don't seem to have opened since rocker broke... which would make sense because you need the rocker to move the valve. That means no little metal pieces should have left the cam housing area... hopefully.

 

[620dark]

bobjohnson posted a google docs link to the service manual over here:

http://www.dotheton.com/forum/index.php?topic=14403.0

It should have a good procedure for removing the rocker arm (bits) and replacing it. Plus, it's good reading - "It is no exaggeration to state that the quality of the engine reflects the superiority of the motorcycle."

 

[Buddy]

WOW!!! And that's because I searched thoroughly (so I thought -_-) for that! Lol well I suppose when you search for something its always in the last place you look. Lol

Thanks very much. You don't even know. I will be spending every free moment reading. Ha

 

[Flugtechnik]

First, I would try to figure out why the rocker arm (often called "cam follower") broke. Was something keeping the valve from going down? Is the valve bent? Did the cam follower seize onto the adjustment shaft? I guess it is possible that the cam follower just gave up the ghost.

These are probably the hardest parts to find for these engines. Your best bet is to watch ebay and/or post on here in the "Buying" section. I think you can get resurfaced ones from some of the performance parts places, but they are very expensive and usually they require a "core" which you don't have.

When I rebuilt my engine I bought an entire spare head just to get the cam followers out of it. The same cam followers were used for all CB450s, CL450 and CB500T (1968-1976).

Oh, also try the buying section over at hondatwins.net

 

[Flugtechnik]

Also, changing out the cam follower is no easy task. The proper way to do it is to break the cam chain. Then take the exhaust side cam covers off. These also serve as the bushings that the cams spin in. Then remove the exhaust cam. Then remove the adjustment shaft and cam follower. Then put it all back together. This would be very difficult if not impossible to do with the engine in the frame. Getting the cam chain back on and both cams aligned/timed properly is the hardest part of the job.

I personally think it is possible to do without breaking the cam chain and removing the cam, but I have not done it and you would have to be super careful about screwing up the cam timing.

Unfortunately, my suggestion is that you take the motor out and do a proper top end job while you are in there.

 

[620dark]

Thanks very much. You don't even know. I will be spending every free moment reading. Ha

My favorite part of forums like this is how helpful complete strangers are to each other. I try to help out because so many people have helped me over the years.

I ended up loading the service manual for my cb650 on my Android phone - it's handy to have that reference at hand.

Good luck with your build! Take lots of pictures for us - I love the "big" Honda twins and am eager to see what you do with it.

 

[Buddy]

@ flugtechnik: I figured it wouldn't be easy... and I noticed the fact that wherever I've seen the rockers for sale it says to send in a core.

As far as why itbroke... dad and I both considered this question, without really answering it... although since it doesn't 'look' like the valves are bent, we figured its probably just the face that its 40 years old, but since nothings actually been taken apart, I have no idea if it really is a bent valve or not. Ivan see that the exhaust valve is fairly coated in black sootiness though, but I dunno that it'd be enough to stick it shut and force breakage on a rocker. I was really hoping for a way to do this without dismounting... im not in a rush to get it done as I want to do it right, but im definitely on a tight budget. Everyone always says it just takes time and money... I got the time... someone else wanna give me money?

 

[Buddy]

Oh and remember im still getting my feet wet in all of this so... im not exactly sure what a 'proper top end job' consists of... :-[

As far as the cam timing... does that mean just to make sure no teeth are skipped when moving the chain? And when removing the cam are you talking about pulling it oh of the side from the covers where the ends sit in, or lifting it up? If you're meaning lifting it up, what bolts am I looking at for removal, and is there a sequence to removing those particular bolts?

Im prolly anit in over myhead, huh? -_-

@ worst cb650 ever: I know im learning a lot simply by being on the site and browsing around, im thankful I found this site. . And don't worry there will definitely be pictures to come. And I'll do my best. I've mentioned before that I can't wait to be the only guy for 20 miles around with an awesome cafe racer, but I DON'T wanna be the guy with a cafe racer that sux... lol

 

[Buddy]

As it sits now in my patio...

 

[620dark]

It would seem your best bet would be to pull the motor first of all and get it on your workbench as Flugtechnik suggested. I think that you might be able to remove the cam without breaking the chain by unbolting the cam gear from the cam, removing anything holding down the cam, and sliding it out the side of the head. Then you should be able to unbolt the head from the rest of the motor and overhaul it.

Proper top end job normally means going through the head, doing a valve job (basically making the valve seats and the valves match each other to reduce leakage, replacing valve guides if needed, and in your case, replacing a rocker arm. You could take the head to a knowledgeable machine shop to do the valves, but you should make sure they know motorcycles. You'll need new gaskets, so it's a good time to replace any other leaky gaskets on the motor.

Or, you could cheat it and just take apart as much of the head as needed to get the rocker arm replaced and then see if you can get it running and go from there.

 

[Buddy]

As tempting as 'cheating' sounds... id like to do it right... even though tearing down and going from there is what I will end up doing. If I were to take to a shop, what kind of price might I be looking at? $200? $300? More?

Ya a set of engine gaskets is a given. Good thing is those are relatively inexpensive. Although it seems that if I end up taking it apart like that, worrying about cam timing is a mute point. Am I correct in deducing this?

I have pics btw! Hopefully these will help any incoming advice! . First is a pic of left side exhaust.

2nd is a close up of right side exhaust. 3rd is a close up of the broken left side exhaust rocker. Last is the inside of the exhaust port looking at the left side exhaust valve.

 

[620dark]

As tempting as 'cheating' sounds... id like to do it right... even though tearing down and going from there is what I will end up doing. If I were to take to a shop, what kind of price might I be looking at? $200? $300? More?

Ya a set of engine gaskets is a given. Good thing is those are relatively inexpensive. Although it seems that if I end up taking it apart like that, worrying about cam timing is a mute point. Am I correct in deducing this?

For the shop to cut the valve seats would cost around $50 by me, but it really depends on the shop. They may want you to remove the valve springs, they may not. Some place like a NAPA might be able to do it for you, but again, you want someone who has done motorcycles before. You can also grind the valves yourself with some grinding compound and one of those suction cup sticks, but I will leave how to do that to people who know more about it than me. The whole point is to get the valves to seal very well against the valve seats so that there is no leakage.

Yea, if you pull the head, you're going to have to re-time the motor when you put it back together. I'm not sure how that's done on your bike, but the manual and this forum should be able to answer that question.

That is one messed up rocker. It doesn't look like anything else was wrecked, however, so that's good.

 

[Buddy]

When I rebuilt my engine I bought an entire spare head just to get the cam followers out of it. The same cam followers were used for all CB450s, CL450 and CB500T (1968-1976).

Oh, also try the buying section over at hondatwins.net

I found a set on ebay that came off of a '73 CB500, did it have the same rockers as the 500T?

 

[Buddy]

For the shop to cut the valve seats would cost around $50 by me, but it really depends on the shop. They may want you to remove the valve springs, they may not. Some place like a NAPA might be able to do it for you, but again, you want someone who has done motorcycles before. You can also grind the valves yourself with some grinding compound and one of those suction cup sticks, but I will leave how to do that to people who know more about it than me. The whole point is to get the valves to seal very well against the valve seats so that there is no leakage.

Yea, if you pull the head, you're going to have to re-time the motor when you put it back together. I'm not sure how that's done on your bike, but the manual and this forum should be able to answer that question.

That is one messed up rocker. It doesn't look like anything else was wrecked, however, so that's good.

Lol. Ya its messed up. Lol but ya it looks like everything else is okay

 

[Buddy]

Hi all!

Ok so I am so terribly sorry for not having posted in forever. Hope I don't get in trouble or something. D:

Ok so as in one of the previous posts, I was asked what might have caused the cam follower to break, well the left side exhaust valve was bent beyond spec, and has since been replaced... The head is reassembled with honed cylinders, new piston rings, new gaskets, new valves, new cam followers, and new torsion bars. The jugs are good to go and done with...

However, now there is another problem. Upon reassembly of the cam shafts and reinsertion; with new gaskets on the camshaft covers, there's a fitment issue. When torqued to spec, there is no rotation and something is binding oddly. Tried with the paper gasket in place and not in place and the fitment is loose, it seems that the cover gaskets are too thin. Using Athena brand set. ANybody have the measurement that the cam shaft cover thickness should be?

Has anybody encountered this problem and if so, solutions? :/ It's been a year and a half and still have yet to ride this little 450. Hopefully, this is the last thing.

I know I said I'd keep everyone upddated on this story, but time gets away, school and work go crazy, and things happen. Fortunately, I'm 4 classes shy from graduation. So yeah, that's what's going on! Any help would be GREATLY APPRECIATED!!!

 

[Honest Don]

Are the lash eccentrics backed off? You're talking about the side covers that have the cam bushings in them, correct?

 

[Buddy]

The cam shaft journals, yes.

I'm sorry I don't know what 'lash eccentrics backed off' means. :-[

 

[Honest Don]

The adjustment screws for setting valve lash. If they're not positioned correctly, the cams can bind when the covers are screwed in place. Wiggle the rocker arm and adjust the screw until it's at its loosest point.

 

[Buddy]

by cam shaft journals, I mean the points base, meter gear box, and other 2 similar coverings... not the A and B covers for valve and tappet adjustment