Topic: Bomber Oil Pump Problems and Input Needed

[RRRToolSolutions]

Guys, I've attached 4 pics. The problem is this - I've assembled the clutch and case on the right side of my CB450 Bomber. I used the Honda parts fiche and attached the arm as shown on their fiche diagram. Today I was reading up on the pump and it's operation theory and discovered a specific drawing showing the pump arm installed completely different than the fiche - I'm really pi$$ed. Now it's a new gasket, and cleaning of perfectly powder coated cover where I used Hondabond (I awlays do in wet areas). But I'm still confused as to the right direction to go with this eccentric arm. This manual's drawing and angle look all wrong and would place a lot of side loading. I think I'm really, really confused.

I had found several discrepancies in the manual and factory published fiche. Engine mounting bolts were the first thing noticed. the fiche shows them coming from the left to right. The Honda factory manual says clearly in "C" they should come from the right to left.

This pump arm is a serious issue/question for me. The way the manual has it puts a lot of side-load on the pump because it's a steep angle at all times. The fiche places the arm at a more straight in/out angle.

No, I didn't take photos. I've always used the fiche and factory manuals to do over 25 restorations. If it's not shown, it's normally a logical approach that works. Here is one case where logic is not applicable.

Help is appreciated.

Thanks,
Gordon


http://star.walagata.com/w/ilbikes/CB450_Manual_Errors0002.PDF
http://star.walagata.com/w/ilbikes/CB450_Manual_Errors0003.PDF
http://star.walagata.com/w/ilbikes/CB450_Manual_Errors0004.PDF
http://star.walagata.com/w/ilbikes/CB450_Manual_Errors0001.PDF

[Raul CB750K1]

For me it seems more logical the parts diagram than the shop manual. As you say, the angle of the plate seems more "straight" with regard to the plunger.


I read the "Zen and the art of motorcycle maintenance" a few months ago. Can't forget a paragraph about shop manuals. It went on the line of "normally, in the factory, skilled people is busy in the design room or the prototyping. When the time comes for the manuals, they will find anybody who is not busy to do the job". That is, you can't never really trust official manuals at 100% because the ones who write them are not the same than the ones who designed or built the product.


What about the engine mounting bolts? In general, it doesnt make any difference. It all depends in where do you like the nuts to be seen. You can either put all of them in the same place, or alternate so the number of heads and nuts is even. For example, in the CB350 twin, the lower engine bolts have the nuts facing inwards. From a mechanical point of view, it wouldn't make any difference. From an aesthetic point of view, it's a nicer view the bolt head than the nut.

[Bob Wessner]

When the time comes for the manuals, they will find anybody who is not busy to do the job.

Works that way in the software industry also.

[bryanj]

Now its a long time ago but from memory the 250/350 has the same arrangement and if you fit the eccentric "backwards" i seem to remember it locks up, so if it turns over easy i suspect its ok.

[mark]

FWIW, I've attached the relevant image from an old Clymer book. The drawing looks like a copy of the parts fiche, except that the pump rod position agrees with the shop manual. hmmmm.

The pic of engine mountings shows bolt heads right and nuts on left side.

In an argument between the manual and the parts diagram, I would tend to side with the manual.

Probably not what you wanted to hear. sorry.

[Raul CB750K1]

I guess it all depends on the relative position of the center axis of the oil pump to the center of the clutch basket. These pictures are from my CB350 twin. As you can see, it would match with the shop manual.

Come to think of it, I removed the arm and don't remember what did I use as a guide for reassembly. The bike is running fine now, so I guess that it either doesn't matter or I was lucky -had 50% chances....-

I just looked at the parts manual and, for the CB350, the plunger arm is completely symmetrical; it doesn't matter how do you install it. The eccentric washer makes it go up and down with the turn of the clutch basket. Could it be the same on the Bomber? Think about a steam locomotive; a longitudinal motion is converted into a circular motion. The plunger center axis should cross the center of the wheel, so the relative angle of the arm would be the same in the forward and backwards movement, if you know what I mean. Check the cutaways in the oil pump cylinder; if they are the same lenght is because the plunger arm makes the same angle in both directions of travel.

[mark]

The 450 got a new oil pump with a symmetrical push rod a few years later - along with 5th gear. Not very many interchangeable bits between 4 and 5 speed models.


Happy trails.

[RRRToolSolutions]

Raul, Mark,

I wish it were as easy as having an arm with equal sides. This arm is definitely meant to go only one way. I've posted a new photo showing the relationship of the pump and the clutch hub. With the ecentric centered on the shaft and the arm "down" as in the manual, the movement looks too low for me and would certainly creat a side-load. Take another look at this link too. This is exactly how the pump looks when the arm is down - pushing sideways. I've got it all apart and will wait until we figure it out.

I agree it should be equal in the up/down motion and I think the factory Honda Manual is just wrong. this is why I posted, so confused.

Thanks,
Gordon

http://star.walagata.com/w/ilbikes/CB450_Manual_Errors0003.PDF

[RRRToolSolutions]

My factory manual is a copy of a copy and poor at best. On page 42 is the drawing I've already posted (shows arm at bottom). On the top of the next page is an actual photo of the clutch hub and pump all assembled. My crappy photo won't show the detail. Do one of you have an original copy and would you look on page 43 to see if the arm is coming from the bottom or the top in that photo?

Thanks!

Gordon

[mark]

Sorry, I never got the Honda book for that one. I have a '72 vintage Clymer book that stayed around after the bike left.

At the front of the book, there are cutaway drawings of the engine that look like they were lifted from Honda literature. They show the area in question. Unfortunately, it shows the 5 speed model. Is there a pic like that of an early engine in your copy? At the front of the book, or the front of the engine section?

After looking at some parts fiches at hondaparts-direct, I would say that the manual would probably be more reliable. '67 CL450 fiche shows the late pump complete(wrong). '68 CB450 fiche shows early pump with late rod - inside out(wrong). Your fiche shows the rod opposite the pix in both service manuals(?). Two things constant here - both shop manuals agree, all part fiches screwed up.

damn.

[Raul CB750K1]

You say you dismantled the engine cover? Then it's just a matter of you checking out which way seems to be a smoother working. I can bet you have enough common sense to know by yourself. C'mon, in our daily life we fix many things without needing a manual! Forget your manuals and do what it seems to be better, and if you find a way to improve it, then go for it!

At least that's what I would do if I were you. I don't recall having noticed many Black Bombers owners here that could help you. How about finding another internet forum for Bombers? They could probably tell.


Sorry I can only give this cheap advice. I would love to take a ride on your bike once is finished though....    Actually, I have always thought that my Sanglas 400E is a copy of the Black Bomber. When was the CB450 launched?

[RRRToolSolutions]

Raul, in 1965 and ran through 1967 basically unchanged.

I've never seen one of those like you have, so yes- we can swap rides if you can figure out how to get it to South Carolina

It looks more modern - I mean the seat looks 80 - ish? What cc's and how does that big single feel at 6,000?

Here's mine - still a way to go yet.

Gordon

[Raul CB750K1]

Mine is a 1974 model, with electric start. Seat is not original. The original Sanglas 400T was launched in 1966. The Sanglas book clearly states that the engine was "inspired" by BSA and the tank by japanese bikes -didn't say which one-. But check the sidecovers, at the right is the oil tank. They look pretty similar to the Bomber's

It is 423 cc, and vibrates a lot. And a lot means A LOT.

[Bodi]

Tough call. I can't see a reason for it to not be symmetrical, except to clear some obstruction.
It seems like the force would like to travel along the offset arm pushing with the eccentric on that side (ie in one direction of rotation), but analyzing the action I conclude that it doesn't matter; the force has to act from the centre of the arm's large hole directly toward the small hole at the plunger attaching pin. There is no side load, the load is just carried in a straight line between hole centres in an arm with a complicated stress distribution compared to a straight centre-to-centre arm. So a straight/symmetrical arm would be "best", meaning the offset must have a clearance problem to solve.
I've been thinking about this for a while and trying to recall my long-ago engineering classes about such things, so if I'm wrong please enlighten me. But working from the theory that the offset doesn't serve any mechanical purpose I would fit it up both ways and use the way that looks better and avoids any close calls or actual contact with other parts in there. Clearance in the oil pump body slot may be an issue with the arm one way?

[Jerry Rxman Griffin aka MuthaF'er]

Gordon,

Another great looking job!

What year and model is the bike? My thoughts (and they are just thoughts mind you) are dependent on the rotation of the pump arm/clutch and the angle of the oil pump shaft . Without actually sitting there with you it's difficult for me to drawn a mental picture. Picture this if you can. I would guess that if the arm was rotating clockwise then the ecentric "top" would be down whereas it's not being jammed/hammered into the oil pump shaft and it is more gently exited/pulled from the shaft. Now picture just the opposite for counter clockwise rotation (referring to the setup on page 26) whereas the arm has been installed just the opposite. So I'm inclined to believe the diagram on page 26 would be correct if the clutch is rotating counterclockwise. 

It'd almost bet that the later models without the ecentric offset have a different angle on the oil pump shaft pointing directly towards the clutch shaft. 

[RRRToolSolutions]

Update - question answered. Much to my surprise, the straight side of the arm does indeed go down. I had a friend that had photos of his original engine during tear-down.. I will next time..This is one of those things I thought was a no-brainer. I've always used the manual.

The pump does have a low-side bias. The arm never goes up above center of the pump - in fact, it specnds 100% of it's time below center. I blasted the pump, wahsed it religiously, and re-installed the arm "down" and put it all back together.

Thanks for all of the input.

Gordon

[bryanj]

Glad you got it sorted Gordon. looking forward to seeing the totaly finished bike after the test ride!

[Raul CB750K1]

Glad you found an authoritative answer. If only I found a Black Bomber for me so I could follow your steps....