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Discussion Starter #1
Ok so hello, im new around here and i have some quick questions
im about to purchase a 1970 cb350 and everythings good on except the motor, i was wondering what my motor options were, and how hard would it be to put a 400 in there?Would it mount straight up ,or would be severally complicated? Ugh so many questions anyways thank you
nice to meet you all, you guys have a great website here.
 

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and specify which 350 (four or twin in the subject). and 400-4 engines are harder to find than 350-4s and its better to have a 400 engine in a 400 frame anyway (much cooler bike). and if you like the size of a 350, just find a twin and start over....more parts, better bike. and what's the matter with your engine and what's so good about your chassis?

others will have more to say.

but welcome and good luck-
tt
 

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if you are talking about a 350F four cylinder, the 400F four (SOHC) is a direct bolt into the frame and is a much better engine than the 350 lump in there (plus you get an extra gear). Everything should bolt up and work fine except you may need to use the 350F's exhaust. 400 motors are more common than 350 four motors these days.

personally if it is a 350four and you haven't bought it yet, don't buy it. they are dogs and overpriced cult bikes for which there is no aftermarket for whatsoever.

if it is a 350 twin, the only thing that will fit in a cb350 twin chassis without a welder is a 350cc motor. No 360, 400t, or any other honda twin will go in. Besides a 400 twin motor is garbage compared to the cb350 powerplant.
 

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Discussion Starter #5
well the only reason im getting the cb350(twin) i want something to work on and its the only one in my price range in these parts (memphis) (250$) everything on its good except the motor which is locked up. so idk i guess i should bail on the idea?
 

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350 twins have a really good aftermarket and you should be able to find a 350 motor pretty cheap. a 400 twin hawk motor is not an upgrade, that motor is a fucking boat anchor and disearves to be at the bottom of a lake. the 350 is a little hot rod by comparison.

funny thing about hondas, let the cylinders sit in penetrant oil (pb blaster, acetone and ATF, etc)for a couple of days and then try to break the rings loose by putting it in gear and popping the clutch while moving (with the plugs out). If she breaks free there is a good chance she will run (but smoke slightly), or you could break a ring. depends on how rusty the rings are. make sure you change the oil after you have broken her loose since all that penetrant will just dump straight down. Honda motors are hella tough, Ive gotten years out of motors that were locked up and I freed with this method.

stop being cheap, buy the best bike you can afford and if that means saving up to get a good running example then do so.
 

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If it has a title then you can't really go wrong for $250. If you can not get it unlocked then you could part it out and make a few bucks. If nothing else you can learn about wrenching on old bikes and be ahead of the game when it comes time to buy another bike. Many engines that are "locked up" are really just a little stuck. They may seem locked up but they just need a bit of help to get moving again. Like the other guy said pour some PB Blaster (not WD40), Marvel Mystery Oil or even diesel fuel into the cylinders and just let it sit for a few days. Then rock it back with the clutch in and then forward and drop the clutch. Do this until it breaks free or you get tired. If it does not budge then oil the cylinders again and let it sit some more. This is all assuming it was not left outside with the plugs out or it was not starved of oil while riding. If so then the motor is garbage. If it is stuck from sitting then it will break free with enough work and patience.
 
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