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Old 07-26-2011, 01:03 AM   #1 (permalink)
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i used to have a 550 a few years ago and just picked up 2 88 js440s one for me and one for my gf, it was a great deal they are stock and run perfect, looking for some info on a 550 swap, what parts do i need, just head jugs and pistons? or do i need the head and other parts like exhaust? will my 440 carb work for the 550, its runing perfect so i wanna know what i need to buy before i tear it apart, also what are some good starter mods and where can i buy parts , rideplate,impeller, and such, i am a bigger guy 215lbs and i need a tad more low end, it handles good when im up but takes a few seconds to pull me up

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Old 05-17-2012, 07:05 PM   #2 (permalink)
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did you ever figure this out? I'm attempting the same thing and everyone seems to swap these over but never tells people how they did it...
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Old 06-02-2012, 05:00 PM   #3 (permalink)
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Quote:
looking for some info on a 550 swap, what parts do i need, just head jugs and pistons? or do i need the head and other parts like exhaust?
So are you wanting to swap the whole engine or are you wanting to just put a 550 rotataing assembly in what you've got now? I'd recommend just finding an intact 550 rather than tearing what you've got down.

I used the same carburetor from the 440 when I did my 550 swap. All I had to do was tweak the mixture settings a little bit.

My 550 came with the exhaust manifold so I'm not sure about using the 440 exhaust, but I dont see any reason why it wouldn't work. The 440 exhast would not mate up properly since the 440 and 550 are machined from the same block and crankcase.

Quote:
i am a bigger guy 215lbs and i need a tad more low end, it handles good when im up but takes a few seconds to pull me up
The biggest difference I notice between the 440 and 550 is the low end power more than the top speed. I think a 550 driving a 440 pump with a good stainless impeller ought to be stout enough to move you pretty well.

As far as engine mods go, I dont really get into those. I know there's a folks here who have a different philosophy, but I like to keep my engines pretty close to stock. In my experience, they're more reliable that way, and I'd rather sacrifice a little bit of performance for knowing that when I hit that little green button it's going to crank easily and run well.
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Old 06-13-2012, 05:34 PM   #4 (permalink)
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are you ready for a real head scratcher...? I swapped in the 550 cylinder, pistons, rings the whole sha-bang. Now i can't get it to fire up...

Here's the crazy part... I noticed quite a bit of white smoke belching out of the carb, wondered why my pressure was moving that direction instead of through the exhaust. So... I stuck my shop vac hose on in the exhaust hole and BANG! Ignition and a great idle... pull the hose, dies immediately.

I am beyond confused... Hopefully you aren't.
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Old 06-14-2012, 03:25 PM   #5 (permalink)
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that is puzzling.

I'm just speculating now so take all this with a grain of salt. Did the cylinders and pistons come from a 550 of about the same year as the rest of the engine? I say that because, in 1990 or so, the 550 got reed valves. I was wondering if you might have gotten a head that was made to have reed valves and are running without them, you might get some strange results.
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Old 06-14-2012, 05:04 PM   #6 (permalink)
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Yeah... I already looked into that. A little more digging on here makes me think that my vac pulse might not be working properly. That suction in the exhaust would assist with drawing fuel into the carb... a carb rebuild would be a great problem to have a this stage!
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Old 09-16-2012, 06:20 PM   #7 (permalink)
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Did you figure this out? Are you running the smaller 440 carb or did you upgrade to the 38 or 44? Pics?
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