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I ride everyday with another guy who has some 650 cc street legal dirtbike and he can smoke me from the line. it is embarrassing.
I thought about a 650 top end with 750 sleeves and pistons but parts and machine work will kill my wallet.
The guys over at the sohc forums dont seem too privy on me cuttin and choppin on this bike so no real input there.
I completely see their point of view but I never could leave well enough alone haha.
I saw a thread where a guy put a 600rr engine in one but he never finished it and I cant find the thread now.
So....I am a welder by trade so no fear at all there. And that labor is free for me. lol
What would be a good motor to wedge in there.
The main problem I have seen so far is the carbs/throttle bodies need to be angled towards the back of the bike as much as possible//from what I hear most of the newer carbs are aiming up????
I tried google but do not know specific engine nomenclatures to look up as I am fairly new to motorcycles.
the problem with newer engines is they're better designed, so the ports come off the cylinder at an angle as opposed to straight out like older bikes, meaning the block is usually tilted with downdraft carbs which keep the exhaust coming more or less straight out front. fitting an engine in an older frame is really hard, esp with the downdraft carbs running into the top tube of the frame. next on the list is that putting an engine producing somewhere around 2x the power in a spindly old frame is going to give you all sorts of problems. the 550 doesn't have too many bolt on hopup parts available for it though, so it's going to be harder to work with. I'd say sell it and get a cb750 if you're dead set on riding an older bike. there are plenty of options for the engine and you can get it putting out close to 90hp for about $1300 and some research, the frame is pretty okay strengthwise, it can handle a bigger front end and swingarm too
So I just looked around c-list and ebay and saw some motors. I see what you are saying about the slant. I need to question why I could not fabricate some intake runner elbows? will this fundamentally change the function of the throttle bodies?
Where I am located, the machine work alone on a 750 to get it at about 836 cc would be around 3500 bux...ouch
then the cost of buying the bike and/or motor.
I forgot to mention that this is my first bike ever so it will not be leaving anytime soon if ever. so why not pimp it out.
I have already worked out the frame rigidity and rear swingarm and I am now looking into the front fork swap. ie what parts will work.
I have been around and around thinking of what to do with this bike. I have owned and worked on plenty of classic cars and I became a professional at ls1 gm swaps. So logic would state that I would be highly inclined to go this route come what may.
I dont care if I have to cut the backbone into 13 pieces but sure dont want to lol. Its gonna happen but I thought I better check here first to see if there is any prior experience on such a swap or will I be blazing a trail here? I have seen plenty of bikes with a late model engine set inside the frame but nothing even close to being a runner.
A parts bike should theoretically provide everything I need but I must be fairly certain as to which type. guess im going dumpster diving with a camera and tape measure.
There are many reasons why a late model 600 motor won't fit in a CB frame. You've mentioned a few already.
But even if you could fit it in and work out how to make it run, you probably still wont be able to beat your buddy off the line with his 650 dirt bike. He will have you all the way until you get to around 60, then he'll run out of puff.
It would be far easier and cheaper to put a big bore kit in the 550 and tune it up. They are pretty good performers when they are tweaked, but it will never pull off the line like a 650 dirt bike.
The cb750 route is the way id go too. I know for a fact that a decent running one is capable of 135mph with a little trimming. If you are set on the 550, talk to kemp on here. He has a big bore kit in one that's capable of about 115, and comes off the line a lot faster than stock. Spark and fuel should be considered too. Get all you can out them.
kz900 rd350 h1 h2 or a mid 80s gpz/ninja will run circles around a hot cb anything. The first step is admitting you have a problem. Yamaha won the 750 race class with a 350 what does that tell ya. There is plenty of fast 70 and 80 motors that will fit with just a little work. It sounds like you have all ready put down the dotheton cb flavored koolaid. The money you will spend making that motor run good will buy you a running parts bike. Now make it happen.
old drag racer from down the street from my house quote to me "you got a HONDA!! If they ever made a bike that ran they kept it, you wasting your time boy" (long pull off a smoke shakin his head)
This here is a link to making your 550 a 718 with fairly easy to find parts. There's a bit of machining but overall the work will be a lot less than trying to shoe horn some big modern engine in there and heaps cheaper. http://forums.sohc4.net/index.php?topic=40414.0 the guy is great, he can answer any questions you have along the way too.
A big bore will just give you a over heating bike most the guys on sohc4.com thinks on the 7th day god made the cb750 befor he took a break, it was better that the brit bikes but that not real hard all it had to do is start 75% of the time lol. I think your on to something with a swap but i would not go modern rocket that kind of power is pretty demanding on a frame, companys spend millions on reserch & development
Well I guess that is it. Im gonna have to build my own frame...mwuhahaha
how would I title an all new bike in mississippi? or should I just severely mod the 550 frame and use the neck for title purposes.
I have built race car frames and 3 story buildings but nothing this small.
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kinda shape it like this very technical drawing to go around the motor but still keep the cafe racer look and just leave the 550 alone and ride the darn thing.
got some google work to do thank goodness I have some brownies and koolaid with me, lol
First, you should make sure it's running as well as it possibly, valves adjusted correctly, carbs re-jetted for the exhaust you have, etc
If you just want it to accelerate off the line, change rear sprocket for one with more teeth
CB550 chassis isn't 'up to' a large increase in power.
1980's CBR600 should have plenty of room in there as they are much smaller than 550 motor. (or ANY modern 600)
Down draft carbs are not a problem although frame mods to fit airbox would be extensive
You won't get a 750 in there but modifying motor will get around 700cc.
I would just do the 591cc overbore (listed just about everywhere as a 605 : )
Wow bradj, I don't want to be associated with the whole sohc4 group that thinks God made the cb750 by any means. And yeah I wont contest a mid 80 kaw anything will stomp the plugs off a 550 or 750. (I've owned both, loved my old gpz750) but I was thinking he sort of wanted to keep the cb profile, so it would make sense to keep it cb. Besides it always makes me smile to see a lowly "average" bike stomp a "superior" bike.
Back to the original post tho, there's a few other factors we need to flesh out for stomping the other bike. Do you know exactly what 650cc bike this guy is running? If 2 stroke, forget it, lol. The sprocket idea is a good one so long as the race length doesn't exceed the point where your larger sprocket starts to kill top end power.
If a modern motor is what you do end up with, a ninja 500 would be a good choice too. Plenty of build potential, load of em around in junk yards, and considerably more power than what ya got. But seriously, think of the bragging right s to out running a bigger motor with a motor that is historically lagging in the raw power dept
I love you guys. I tried to be nice this time pj.
There are a few good points as of late you need to look at,
Is your bike running right, are you trying to run with a real deal 2 stroke it490 cr500 or something cause you wont, is there any state laws aginst motor swap where you live. I would not just ask the dmv but there is way to find out
I would just make the motor fit your frame and leave it titled and taged historic and stay away from injected bikes so you dont have a fuel pump to deal with
No rules against a swap as we go by the frame VIN here.
it is a kawasaki 4 stroke 650cc Im losing to.
My bike is running great. I just went through all the electrical, rebuilt carbs, and adjusted tappets and points correctly.
So here I am with a cb550 and maybe 46 horses.
I am getting 34 mpg right now and yes a sprocket change will get me some more giggles but it is already screaming at 60 mph.
My wife will KILL me if I bring another bike home. unless its a parts bike that wont hang around long.
I am trying to track down pics of a 550 with an 04 600rr engine in it. I know I saw it somewhere.
Although I think its an interesting experiment in "why not", I certainly have to agree with the folks who have stated that an 04 cbr600 engine in a cb550 frame is a real quick way to end up meeting your local EMTs up close and personal. That motor will twist that frame to bits. Im sure you might be able to reinforce it, but that would be a massive amount of work, and will ruin most of the "looks" of the original 550. Not to mention all of the shit that needs mounted to the bike. Computer (if EFI like an 04), radiator, oil cooler, fuel pump, CBR wiring harness, etc... All that, then theres the other details. Skinny 70s CB wheels and tires, half assed 70s brakes, spindly 35mm forks, and so on. Sure, it would be "neat", until you ride it... Just buy a killer 80s CBR. Fast, cheap, and not as likely to kill you.
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