New project 72 CL450. Blown engine

Countryscooter

Countryscooter

Member
Joined
Mar 10, 2025
Total Posts
16
Total likes
9
Location
Manitoba Canada
Going to need lots of parts for this baby. Suggestion for sources especially in Canada? I have good cylinders? Pistons and head are good.
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Cool. Gots to do your new member introduction before we get rolling here. You'll get a PM (upper right) from the admins with info.
 
I have got a few parts for my 72 CB450 build from vintagecb750.com which is located in Canada. Looks like they carry a number of common cross over parts such as coils, condensers and such. Prices were Fair and the one problem I had they resolved with no hassle.
 
Hello. We're just beginning to put together a 1971 CL450. I've ordered most of the gaskets needed fir an engine rebuild but decided to tackle the carbs first. Looked fairly straightforward and was going smoothly til I lost a float pin. I gather it's 2.5mm diameter but hope to verify that measurement. Can someone verify that or tell me the correct dimensions?
 
I can't check with calipers immediately, but a Google search turns up 2.5mm diameter and 23.5mm length. They are available in a replacement float kit.

Have you checked your floats for leaks? (Submerge in hot water and look for air bubbles escaping.)
 
Thanks for the info. I've got some 2.5mm round bar stock on order that we'll cut to length. We tested the floats and both passed. Right carb had the throttle shaft seized but after a good dunk in the sonic cleaner and some penetrating fluid it freed up. Also we wired and blew out all the holes. Hope fully all that will be enough but we're a long way from finishing. I'll try to post pics when the main parts are out of storage. Btw does anyone have a recommendation on how to flush the crankcase? Pretty sure some bugs made a home in there.
 
Countryscooter said:
Btw does anyone have a recommendation on how to flush the crankcase? Pretty sure some bugs made a home in there.
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The title of your thread suggests the motor was “blown”. I read this to mean in a bad way, not good, as in “hopped up” with performance mods. Correct me if I’m wrong?
With that said and to answer your question, the only reliable way to clean the crankcase of a vintage Honda twin is to do it the old fashioned way: Take it all apart!
It would be nice if there was a magic, simple fix such as an engine flush but if you dump a solvent into that crankcase I feel you would literally be stirring up trouble. Just my opinion man.
 
That's what thought the best advice would be. Guess I was hoping for a "majic" fix. No such thing but thought I'd ask. And yes it was blown in a bad way. Right piston was seized and wouldn't move after lots of lubricant and persuasion. We did get it apart and had the cylinder bored out over stock. New pistons, rings, wrist pins, etc ready to install but crankcase for sure has lots of organic material in it and possibly some metallic. Gasket kit is here as well as new camchain. Just waiting on a master link. Time to dig in. Fortunately I have 2 journeyman mechanics helping out when they're available.
 
Read the FSM and then read it again for each step. Take videos with a big grain of salt but they are good to see how parts are arranged.
 
Absolutely. One of the first questions these guys asked when looking at the head was "where are your manuals?: One guy who is retired is going over tons of 450 OHC videos. In his youth he worked in his dad's Suzuki motorcycle dealership. Lot's more experience than I have. I'm very fortunate to have them on board. I'll be looking at the videos on this site as well.
 
I downloaded the FSN from this site. Very helpful. The Clymer manual is pretty vague in some parts. After getting the left crankcase cover off I discovered there was no rotor magnet there. The stator/ coils are there. Also in the process of removing the clutch plates. We'll see if they need replacement or just cleaning. I expect they'll be stuck together. Any suggestions on cleaning the friction disc's? Also sorry for using term that may not fit here. I've done several Harley builds and am more familiar with their terms. Eg rotor/stator
 
There are several ways to go regarding the rotor. Used ones appear on eBay (cheapest option), there are new OEM ones available at a relatively steep cost from CMSNL (maybe David Silver Spares, too), or you could look at an aftermarket rotor from Rick's Electrics. I have one from Rick's in my dohc 450 with an OEM stator. You are also likely missing the starter clutch and its components which mount on the rotor. Have you taken stock of those parts?

Have you checked the stator? You can measure resistances between pairs of leads (pink, yellow, and white) to see if it's in spec. Something like the following values:
  • 1.5Ω = White + Yellow.
  • 0.6Ω = White + Pink.
  • 1.1Ω = Yellow + Pink.
The steel clutch plates can be cleaned with brake cleaner and elbow grease, if necessary, and should be checked for warpage. The wearable friction discs I would only clean with brake cleaner, but would probably opt to replace them rather than clean and reuse.
 
With help from this website, YouTube, factory manual and helpful buddies the motor is stripped down to the oil filter rotor. And that's where it stays till we find the tools. While there is an American supplier Ive found I haven't found a supplier here in Canada. Shipping being so expensive, is there any alternative ways of removing the oil filter rotor ?
 
Countryscooter said:
With help from this website, YouTube, factory manual and helpful buddies the motor is stripped down to the oil filter rotor. And that's where it stays till we find the tools. While there is an American supplier Ive found I haven't found a supplier here in Canada. Shipping being so expensive, is there any alternative ways of removing the oil filter rotor ?
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21mm deep socket and a dremel or angle grinder
 
I made one from a 24mm deep socket. Easy to make with a dremel tool. These sockets are hardened and so they are brittle. Once you cut almost all the way through, a pair of pliers will break out the unwanted pieces. File any rough edges and you are good to go. There is also a lock washer that will have a tab in one of the slots of the lock nut, make sure to bend it out of the way before using the tool.


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Sorry for being tardy in posting results. The engine is tore down as far as we're going. Using a borescope we inspected the crankcase and found very little debris other than some hardened oil deposits. We're going to do a flush after a bit of a soak in diesel fuel. Hopefully that will loosen the deposits.
 
This is what has been keeping me from the CL450
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All ready for riding. New front-end, bars and some wiring.
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Should be ready by summer. Massive oil leak. Was in storage for 20 years. New gasket, carb clean, etc.

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A long way fron being done but should start reassembly soon.
 
The BSA made reminisce about right hand shift left hand brake on the old BSA I had. Another bike I regret basically throwing away after it had some issues.
 
Yup 1993 Evo Softail homebuilt. I hope it doesn't leak but we'll see.
The BSA is a 1970 650 Lightning . Interesting back story but a bit lengthy. Hoping to be finished this coming week so the CL450 frame can go on the lift.
 
Countryscooter said:
Going to need lots of parts for this baby. Suggestion for sources especially in Canada?
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Just to make sure that you know of this re-cycler in the U.S. state south of your province :

www.sportwheel.com and also www.siriusconinc.com in Toronto for new and good aftermarket parts options...
..and, lots of Canadian sellers (along with MANY in Minnesota & Wisconsin) on eeeBay.
Best to find them using the Honda part number(s) of the parts your hunting...
 
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