Topic: The Runcible Racer - maduncle's CB450 project

[lordmoonpie]

UPDATE - a very learned fellow from the Honda Twins forum told me to use a magnet on the chamber, if it did not stick then the chamber is aluminium and therefore a 500T head (as 450 heads have a steel 'skullcap' inserted in the head for the chamber).

Yay - it is a 500T head.

It's a common swap for the 450 head - the CB500T head's lower compression can be tuned out easy enough if you're building a race bike as oppose to a street bike. Where it scores over the CB450 head is it's easier to machine to do the valve spring conversion to allow high lift and extreme profile race cams. Machining around the iron skull is a nightmare and often leads to junked heads as the machined area is so thin. If you're going for an extreme race 450 I'd go with the 500T head for this reason alone. I put about $15,000 of engine development into my CB450 race engine so have done the journey on this one. It's a fantastic fun engine to work on and develop, you'll have loads of fun doing it. Here's a couple of pics of mine - hope they add some inspiration and good luck!

[Terry in Australia]

It looks absolutely lovely Lord Moony, but spending $15K on developing a 450's engine is kinda silly to me. I presume that you're a rock star, or a crack dealer? Cheers, Terry.

[lordmoonpie]

It looks absolutely lovely Lord Moony, but spending $15K on developing a 450's engine is kinda silly to me. I presume that you're a rock star, or a crack dealer? Cheers, Terry.

It was an exercise it what was possible Terry - I was lucky enough at the time to be able to do it and learned a lot which to me is priceless.

BTw, rockstar, drug dealer and people trafficker if you don't mind

[Terry in Australia]

 

[maduncle]

Thanks for the information on using the 500T head Lord Moony, I have put it on the 'spares' shelf for now and I am going to use the 450 head that is being repaired as I write. I am building a regular use road bike, so the engine will need to remain in the 'slightly tweaked but sensible' modification range.

Today I stripped down the front TLS hub, got it parted out and started to remove the spokes. The front rim is an old DID chrome steel shouldered rim. I do like the shouldered rims, but I am thinking of getting new alloy (lighter) ones from Queensland.

UPDATE: Having got a price on new alloy shouldered rims, I am now in the market for an old 18" 40 spoke shouldered rim that I can use on the bike!

[cbfnut]

maduncle, I think the later k 450s must have been sandcast.  I got 2 heads and jugs that are sandcast.

[maduncle]

Thanks cbfnut - I am learning more and more about Honda engine casting each day.

My mystery head looks like the mould was carved out of a loaf of bread with a pair of blunt scissors by a pre-schooler. So I am very pleased my original M1 head has been well repaired.

[cbfnut]

lol!  I know, it has that grainy look to it.  I am going to take one of the jugs and one of the head and polish them up to see how they come out.  I want to make it look like mirror chrome.

[maduncle]

lol!  I know, it has that grainy look to it.  I am going to take one of the jugs and one of the head and polish them up to see how they come out.  I want to make it look like mirror chrome.

When I get mine back from the blasters (who are using a special vibra polishing unit to polish them up) I will post some photos for you so you can see how shiny they are!

[cbfnut]

awesome, can't wait to see it.

[maduncle]

Righto - how do I start a poll on the big question that is vexing me...

CB450 with a K1 tank and headlamp bowl in silver.

Silver and black seat.

Frame...

 - blue or red???

I have just seen a bike with silver tank and headlamp, and the red frame looks amazing. If I do this to the CB450 it will sit well with the pedigree race colours that were used in the 70's.

But - I could break out of the mould a bit and do a blue frame, which would look sweet.

Any ideas gang?

[Terry in Australia]

Whatever color scheme you come up with will look nice Cliff, don't follow the herd, use your imagination, and we'll all like it. Cheers, Terry.

[maduncle]

Cheers Terry - I count that as one vote for pink then!

I am tending back to blue as there are a lot of red frames about.

Meanwhile - today's efforts on Runcible parts polishing.



That is all the polishable head parts done now, including the head bolts. Next step - the wheel hubs and lower forks.

By the way - ever wonder where all that gunk ends up as it flies off the polishing wheel?



Glad I had goggles on, I think I will add a respirator next time (still spitting out black stuff).

[Terry in Australia]

Ha ha, paint your bike pink by all means Cliff, I'll still talk to you, but you might have to leave your wife and move to St Kilda? Have fun with that polishing, I hope you're going to laquer it afterwards, or it'll look like crap again within a few months. Cheers, Terry.

[maduncle]

Is there a good lacquer that won't slowly turn yellow?

I could do it I suppose - I was going to look at clear powder coating for the hubs and then just do a weekly hand polish on the engine parts to keep them shiny.

[Terry in Australia]

2K clear is good, it'll keep your polished pieces nice and won't go yellow. Unless you get a garage to park your bikes in, the humidity/moist winter air will corrode your polished parts, and a bike cover won't do much to stop it. Cheers, Terry.

[maduncle]

2K clear is good, it'll keep your polished pieces nice and won't go yellow. Unless you get a garage to park your bikes in, the humidity/moist winter air will corrode your polished parts, and a bike cover won't do much to stop it. Cheers, Terry.

Is 2K clear coat in a rattle can?

[scunny]

mothers aluminium mag wheel polish. it leaves a "waxy" coating that doesn't #$%* off with the first sign of rain. outer engine cases still look good after 2+ years. give them a wipe over every so often and thats it.

[maduncle]

mothers aluminium mag wheel polish. it leaves a "waxy" coating that doesn't #$%* off with the first sign of rain. outer engine cases still look good after 2+ years. give them a wipe over every so often and thats it.

I like the sound of that, thanks!

[maduncle]

This weekends efforts...

I got a cam chain tensioner, an oil filter cover and as set of new engine O ring seals in the mail this week. So I polished the oil filter cover and the cam chain tensioner and put them away with the other shiny bits.

This evening I stripped my two stock carbs down. Everything went fairly well, although I have had to drill out two rusted screws in one of the throttle valves to get the valve disc and pivot out. The thread in the pivot looks okay to me.

I am now soaking the main carb bodies and float bowls in Yamalube carb cleaner. I have polished the carb tops and soon discovered the plastic disc in the centre. So I scraped the old gunk off and gave each plastic disc a wet rub with 1000 grit sandpaper.

My only concern is that one of the throttle valve pivots looks like the end has broken off it, and the carb body where it protrudes from is chipped too. The carb body will be okay, but I am now looking at parts diagrams to see if I am missing an end off a throttle pivot.

A couple of questions:

- What is the best way to clean the surface of a vacuum piston? It has some old dried surface gunk on it and I didn't want to use anything abrasive on the soft metal surface.

- I haven't dropped the vacuum pistons in the carb cleaner - is it safe to do so?

- How hard is is to undo the screw in the vacuum piston to release the needle? Mine are well stuck.

Finally - anyone got any spare CB450 carb parts in case I need one or two?

[cbfnut]

unc, how's the build down-under?  I just got my engine out of the frame on Friday and I am about to tear in to it soon right after the carbs.  I had a quick question for you, when you look into the carb body intake side, is your valve more oval than circular?  I looked on the parts fiche and I couldn't find the proper name for it. thanks.

[cbfnut]

I just found the name of it.  I guess it's called a choke valve.  Mine doesn't seem to be the proper shape and won't seal or close.  Or at least it doesn't look it like.

[maduncle]

Having just stripped down the carbs, I can tell you all my valves are nice and round, and close well.

So - here are the main carb body parts after a soak and scrub (and a polish for the tops).



The pistons cleaned up well with a light rub with a soapy scotchbrite pad.

Nice and clean inside...



Okay, remember the old Sesame Street song "One of these things is not like the other"...

Well - one of these four valve holders has a broken end (bottom left one) and i won't know which part I need until I assemble both carbs and then see if I need to track down an old 'left' or 'right' carb body for the part.



I might do some assembling tomorrow night.

Meanwhile - one week to go and the factory is back at work where my frame and engine parts are sitting, waiting to be blasted and (the engine parts) polished.

Once I get them back, I can put the engine parts aside and start work on the frame.

[maduncle]

Well, this evening I 'mostly built' a pair of carbs.

(That reminds me of Billy Crystal in 'The Princess Bride'...).

I got my left and right a bit mixed up, but that is not an issue until you get to which intake and outlet valve pivot rods you use on which carb, which affects the way they link to each other.

Fortunately - I remember seeing an 'L' cast inside the top of one carb body so I checked, and sure enough, one has L and the other has R - so I was back on track.

The other issue is that I have now determined (from my Clymer manual) that these are Keihin 14H carbs off a later model 5 speed CB450 (not off a black bomber). They will still work fine, I just didn't have the right assembly diagram on hand. The side entry for the pilot screw into a 14H carb body as opposed to bottom entry for an earlier one gave it away.

Question - does anyone have a left and right assembly diagram for Keihin 14H carbs?

And (stupid me) I have lost a brass fuel intake spigot out of one of the carb bodies (I am pretty sure it was there before I cleaned them) so I will be chasing an old carb body to salvage one from soon. I just need to wait and see if I need any other parts, then I will track down either a left or a right 14H carb for parts.

But overall, I think they will go back together nicely and work well on the bike. The linkages may challenge me yet - but I will get there.

Photos once all done.

[cbfnut]

nice and clean. can you post a photo of the choke valve once you get it back together? thanks.