Can't Decide - CB450 Dohc Vs 1979 Cb400t - Honda Twins

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#1 · Jul 27, 2020 Good morning everyone, I am looking for some thoughts on my dilemma. I have decided to get a vintage Honda CB. My goal is not a full on resto project right now but just something to tinker with and ride up and down the back roads in my spare time and commuting to work occasionally. After much searching, I've found two possible candidates that I like. Both have been restored to some degree and look and run excellent. The first is a 1970 CB450 DOHC which is very clean and has all original parts. The engine has been rebuilt with new pistons (oversize) piston, head redone, tires ect. Engine rebuild was done by a professional outfit that is experienced in vintage Hondas. My concern on this one is that I understand that their cam shaft and followers are prone it wear and parts are hard to find for the bike in general but particularly the camshafts and followers. It's had about 5000 miles since the overhaul. The second is a late 70's CB400T Hawk 1. It looks like new - the chrome even shines still and runs perfect. Seems like parts are easy to get on these and they have respectable performance too but doesn't seem like it has the collectable appeal of the 450. I would appreciate any thoughts as I'm having a really tough time here. See less See more Sort by Oldest first Oldest first Newest first Most reactions #2 · Jul 27, 2020 You think parts are easy to find for the CB400T, try finding an ignition, or stator which these bikes always seem to need. Then there is the problem with the head bolts seizing and stripping out the holes in the cases. The CB 450 does not have cam/follower problems. They have owner/neglect problems. However, parts are easy to find/get for the CB450. I would buy the CB450 and not look back. TOOLS #4 · Jul 27, 2020 +1, the farther one can stay away from that CDI business, the better. 0 Reply #3 · Jul 27, 2020 Hi gentleman. Thanks for your thoughts! so the CDI system is more of a liability on the CB400T rather than a plus which I was assuming! So if the CB450 is warmed up without driving or racing the engine to give time for oil to circulate to the top end and oil is changed frequently enough, it should be a non issue hopefully? Of course assuming that everything is in good shape at the moment. The CB450 definitely seems to have better collectable value as well which is always nice. #5 · Jul 28, 2020 Just out of morbid curiosity, what is so bad about the CDI? is it just very failure prone or is it just the fact that parts are not longer available to repair it when it does fail? #6 · Jul 28, 2020 Both. TOOLS #7 · Jul 29, 2020 I like my DOHC, I would never trade it for a SHOC. The cam follower problem can easily be mitigated. Do this: 1. allow the bike to run for at least one minute before riding off. Even do this when it is warm. The oil pump takes a bit of time to pump lil up to the top end. 2. perform the recommended oil changes. Clean oil is important to longevity, 3. use an oil with zinc/phosphate. Modern engines have roller tappets. The EPA has banned the use of zinc/phosphate in motor oils. I use REV X ZDDP Oil Additive. It gives the added protection any flat tappet engine needs. #8 · Jul 29, 2020 The DOHC is head and shoulders above the later 400/450 models. Keep the oil clean and perform regular changes. Never, ever let it idle on the side stand. Bill Silver said parts are getting hard to find for the DOHC but parts are hard to find for the later 400/450 bikes too. #9 · Jul 29, 2020 Not to mention the DOHC 450/500T engines have IMO THE best looking twin engine Honda ever made. #10 · Jul 29, 2020

connecting_rodd said: Good morning everyone, I am looking for some thoughts on my dilemma. I have decided to get a vintage Honda CB. My goal is not a full on resto project right now but just something to tinker with and ride up and down the back roads in my spare time and commuting to work occasionally. After much searching, I've found two possible candidates that I like. Both have been restored to some degree and look and run excellent. The first is a 1970 CB450 DOHC which is very clean and has all original parts. The engine has been rebuilt with new pistons (oversize) piston, head redone, tires ect. Engine rebuild was done by a professional outfit that is experienced in vintage Hondas. My concern on this one is that I understand that their cam shaft and followers are prone it wear and parts are hard to find for the bike in general but particularly the camshafts and followers. It's had about 5000 miles since the overhaul. The second is a late 70's CB400T Hawk 1. It looks like new - the chrome even shines still and runs perfect. Seems like parts are easy to get on these and they have respectable performance too but doesn't seem like it has the collectable appeal of the 450. I would appreciate any thoughts as I'm having a really tough time here. Click to expand...

#11 · Jul 30, 2020 Hello, On the issue comparing the CB450 DOHC vs CB400/450T SOHC. The design of the DOHC dates to 1966 "Black Bombers" the early K0 model was a 4 speed. The CB400/450T SOHC had 5 or 6 speed trans depending on year. The major difference between engine design is the oil pump and crankshaft bearings. The roller and ball bearings on the DOHC has a very basic oil pump that does not generate measurable oil pressure, but supplies a flow of oil to all those rollers and balls, but the uppermost area of the engine, the camshafts don't get a lot of flow, so the followers and cam lobes tend to suffer from the lack of oil delivery. Also the cylinder head has several cam chain rollers, sprockets, tensioner, 2 cams, all are subject to wear and replacements are not easy to find. The SOHC uses a hy-vo link plate style cam chain with a long "slipper" type guide in front, and slipper blade type tensioner in rear. No rubber rollers or steel sprockets. So if you want to put miles on your bike more needs to be done to a DOHC than the SOHC. The DOHC has 2 sets of points, NO points on the SOHC. The oil system on DOHC uses a piston pump to flow oil thru a "spin filter" that does not do a good job of cleaning the oil and the spin canister is difficult to clean. The DOHC valve adjust clearance is twelve- tenthousands, of an inch. that's 0.0012" , or just over one thousandth of an inch, which is more difficult to get correct than the .005" or .007" for SOHC with a easy to get at (2 bolts) removable cylinder head cover, with reusable rubber gasket. its easy to do 6 valves in 30 mins. max, start to finish. The DOHC valve adj. takes 2 hours or more to set 4 valves. many parts need remove and re-install, along with about 40 fasteners The SOHC has a more modern design with a plain bearings on the crankshaft, that is fed hi pressure oil from a automotive style pump, thru an easy to replace paper element filter that replaces on a few mins. and does a better job of cleaning the oil, and supplies all the oil ever needed. A much better design, easier to service. Also the carburetors of SOHC are mounted together on a sturdy bracket that has linkage for a push/pull throttle, The DOHC has the single pull throttle cable that does not stay synchronized as well as the SOHC If you love the look of either model that's a matter of personal preference. But from a mechanical standpoint the later SOHC model is a better choice, with more modern design and ease of service. Hondajohn Land vehicle Vehicle Motorcycle Car Motor vehicle

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#12 · Jul 30, 2020 A bit of correction on the above. The later models of DOHC have 5 speed transmission not 4. Only the K0 bombers are 4 speed #14 · Jul 30, 2020 I posted the "early model K0 was 4 speed", read it again, all the following, K1 thru K7 were 5 speed, also posted some SOHC models (1980 and later) are 6 speed, there are many variants of the SOHC. The DOHC had fewer variants and was little changed K1 thru K7, 8 years production.. The SOHC had only 4 years or so production, but there were about a dozen variants, with several available each year of production. The photo of the CL450 K1 is one of mine taken outside my shop, this bike is all original, runs well too. I like the DOHC 450 but they require more difficult service. The SOHC is a simpler package with some key improvements to design. hondajohn Show more replies 0 Reply #13 · Jul 30, 2020 I have owned and ridden both DOHC (CB/CL450 as well as CB500T) and SOHC (CM450) models and I personally prefers the DOHC both in styling as well as performance. This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread. Insert Quotes Post Reply

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