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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I haven't tried them on the 650, but I suspect HD takeoffs might be a good replacement.
 

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CX650 motor project into a CX500 Turbo Frame - ongoing
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I haven't tried them on the 650, but I suspect HD takeoffs might be a good replacement.
Most harley's being over 1200cc, are you saying one muffler for both cylinders?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Usually a pair. Older Dynas are a good choice, but getting harder to find.
Used with the stock h-box, too free-breathing isn't a concern. Might need re-jetting with the mid-pipes.
 

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Discussion Starter · #64 ·
Usually a pair. Older Dynas are a good choice, but getting harder to find.
Used with the stock h-box, too free-breathing isn't a concern. Might need re-jetting with the mid-pipes.
what pipes does murray recommend with his carbs?

also, thoughts on this? I mainly need the headers, though the bigger mufflers would be nice. My concern is that it appears that the baffles are rotted out of these..

1983 83 Honda GL650I GL650 650 Silverwing Interstate Exhaust | eBay

also, how restrictive are the 650 mufflers? reason i ask is, I had an '86 vf500f, and when I swapped the stock mufflers out for aftermarket ones designed for the bike, it gained a quite noticeable bump in power.
 

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'82 GL500 '83 GL650 '21 RoyalEnfield INT650
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Surprised not to see SidecarBob in this thread. He put a 500 in a GL650 He might have some insights.
 

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'82 GL500 '83 GL650 '21 RoyalEnfield INT650
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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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im trying to do the opposite lol. im putting a 650 in a 500 frame.
Bob was working with GL and Eurosport frames. They're close enough to identical that the engine was almost a direct bolt-on.
I believe it was Gerard who recently put a GL650 engine into his GL500. Here again, there was no CX500 frame involved, so it was almost a direct replacement.
It's the single- vs triple-spine frame that necessitates all the adaptation.
 

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CX650 motor project into a CX500 Turbo Frame - ongoing
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Those mufflers look very unrestricted lol
Bob was working with GL and Eurosport frames. They're close enough to identical that the engine was almost a direct bolt-on.
I believe it was Gerard who recently put a GL650 engine into his GL500. Here again, there was no CX500 frame involved, so it was almost a direct replacement.
It's the single- vs triple-spine frame that necessitates all the adaptation.

And I'm doing a CX650c into a Turbo 500 frame; both triple backbone frames, I feel it's the easier situation to be in.

@Randall-in-Mpls The only thing off the top of my head for @SirFoxx to worry about is the carb body issue; where the 650 carbs need the space the 500 frame takes up, the 500 carbs being spaced to the outside of that. And the radiator return area is different on the 500 from 650. Was there more?


@nolimitz I'm probably a catalyst in your confusion since I started in on the turbo stuff with my 650 into a turbo 500 frame. Probably should have stayed out of it. But like he said, general discussion lol
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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@Randall-in-Mpls The only thing off the top of my head for @SirFoxx to worry about is the carb body issue; where the 650 carbs need the space the 500 frame takes up, the 500 carbs being spaced to the outside of that.
According to the respective FSMs, both the GL650 and '78 CX500 use 35mm carbs. My first attempt will be to mount a pair from a '78 CX. I think it was Charles who said the CX500 stock isolators can work on the 650 engine. Maybe I'll need to adjust the brackets and transfer pipes a little. I think that would be easier than straightening and spacing the 650 carbs. It might be easier still to 3D print custom intakes, assuming the ASA I'd use could take the heat.

And the radiator return area is different on the 500 from 650. Was there more?
I'm tempted to use the CX500 radiator with a GL1200 cooling fan (the one with the flat motor) that I have on hand. That would mean less modification to the engine hanger. I'll need to mock that up before deciding.
 

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2021 Benelli Leoncino - 2017 CSC RX3 - 2017 SSR Buccaneer 250i - 1979 CX650 Street Scrambler
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So, the CX500 carbs can be used with fresh, new, pliable insulators. It's a tight fit every time and every time you risk cross-threading the M6 bolts that secure the plenums to the heads. Worse, if you use the new reproduction intakes, the stress from the connection will eventually pop the rubber bit off of the aluminum bit, leaving you in the lurch. (Duct tape will get you home).

Ideally, you'd want to separate the CX500 carbs and extend the brackets, crossover pipes, and linkages. The brackets are easy, just cut and weld (they're steel). The crossover tubes are also easy; Any machinist can make those for you. Hell I could make those on my hobby lathe. Make them out of brass so you can drill and tap the hole for the "T" for the fuel line, and then solder it up. The linkages between the two carbs is where you'll have to get creative.

Also, if you're doing all that, it might be a better idea to make custom brackets and crossovers to mount the 650 carb bodies in such a manner. I don't know if the linkages will be easier or harder, I haven't held a set of 650 carbs in my hands in at least a decade. But going from eBay pictures, the CX500 will need the throttle shaft elongated (easy to do, as it's steel, cut and weld), as well as the choke finger. (Piece of flat steel welded to the end should do it). For the 650 carbs, it looks like the linkages are more or less separate, and you could unbolt the stock linkage and make an adapter. Not sure about the choke, but it looks like swapping in a CX500 choke for the right side carb should work, and then you can extend the linkage as needed.

Charles.
 

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'84 CX650E that is evolving into a GL500
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Bob was working with GL and Eurosport frames. They're close enough to identical that the engine was almost a direct bolt-on.
Which is exactly why I didn't post in this thread sooner.
BTW: I was among the first on the forums to put a 650 engine (actually from a CX650E) into a GL500. At the time there was very little knowledge about what was required and there was even some speculation that it might not fit or the frame and drivetrain might not be strong enough. I had to us the 650 carbs & intake runners because the 500 ones wouldn't line up with the 650 and the 650 airbox because the boots between airbox and carbs are completely different but it turned out that the biggest issues were that I would have to modify the GL500's rad's mounting lugs beyond what I considered reasonable to make it fit the 650 hangers (I went back and bought the 650 rad) and that I had to put the 500 engine's final shaft into the 650 so that it would mate with the GL500's u-joint (the GL650 uses the same final shaft as the GL500 so this is only necessary if you have a CX650E or CX650C engine).
And about a year later the camchain broke and I ended up putting the 500 engine &c back into it.

15 years later I found myself putting a GL500 engine into what had started life as a CX650E. I had replaced the original rear end with a GL500 swingarm & driveshaft, CX500 final drive & wheel and a brake with CX and GL500 parts when I first got the 650 (& installed a 500 final shaft in the original 650 engine) and the rad and electric fan are neither stock or in the original location so that wasn't an issue. I think spent more time on cleaning & painting things than I did actually taking one engine out and putting the other one in. You can read about it here
 

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2021 Benelli Leoncino - 2017 CSC RX3 - 2017 SSR Buccaneer 250i - 1979 CX650 Street Scrambler
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Which is exactly why I didn't post in this thread sooner.
BTW: I was among the first on the forums to put a 650 engine (actually from a CX650E) into a GL500. At the time there was very little knowledge about what was required and there was even some speculation that it might not fit or the frame and drivetrain might not be strong enough. I had to us the 650 carbs & intake runners because the 500 ones wouldn't line up with the 650 and the 650 airbox because the boots between airbox and carbs are completely different but it turned out that the biggest issues were that I would have to modify the GL500's rad's mounting lugs beyond what I considered reasonable to make it fit the 650 hangers (I went back and bought the 650 rad) and that I had to put the 500 engine's final shaft into the 650 so that it would mate with the GL500's u-joint (the GL650 uses the same final shaft as the GL500 so this is only necessary if you have a CX650E or CX650C engine).
And about a year later the camchain broke and I ended up putting the 500 engine &c back into it.

15 years later I found myself putting a GL500 engine into what had started life as a CX650E. I had replaced the original rear end with a GL500 swingarm & driveshaft, CX500 final drive & wheel and a brake with CX and GL500 parts when I first got the 650 (& installed a 500 final shaft in the original 650 engine) and the rad and electric fan are neither stock or in the original location so that wasn't an issue. I think spent more time on cleaning & painting things than I did actually taking one engine out and putting the other one in. You can read about it here
I did the 650 swap into an 82 cx500 way back in 2004. I used the stock cx radiator and a cbr electric fan on a modified hanger bracket. Cx carbs and stock air box.

Pretty sure I had to swap the output shaft too.

Charles.
 

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the bottle breather on the 650 as i was told in a honda class (there is a service bulletin about it have seen it ) was to relieve extra crankcase pressue
caused by our higher speeds and more prolonged distance riding
the higher crank case pressure would force oil by the weaker oil control rings (due to increased piston rock) and cause oil consumption and oil
building up to quickly in the breather catch can so we fitted the kit to twin the vents to all the gl650s and cx650e we sold in canada

that was my understanding of it
 

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According to the respective FSMs, both the GL650 and '78 CX500 use 35mm carbs. My first attempt will be to mount a pair from a '78 CX. I think it was Charles who said the CX500 stock isolators can work on the 650 engine. Maybe I'll need to adjust the brackets and transfer pipes a little. I think that would be easier than straightening and spacing the 650 carbs. It might be easier still to 3D print custom intakes, assuming the ASA I'd use could take the heat.


I'm tempted to use the CX500 radiator with a GL1200 cooling fan (the one with the flat motor) that I have on hand. That would mean less modification to the engine hanger. I'll need to mock that up before deciding.
the bad part of that is you don't get the honda OEM rad fan switch IMO the best way of controlling the fan all else is fiddly and does not work as well or as long as the direct control switch in the 650 rad or the gl 4 cylinder direct contact controller that is designed to handle the full amperage draw of the fan for years and years
 

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'84 CX650E that is evolving into a GL500
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According to the respective FSMs, both the GL650 and '78 CX500 use 35mm carbs. My first attempt will be to mount a pair from a '78 CX. I think it was Charles who said the CX500 stock isolators can work on the 650 engine. Maybe I'll need to adjust the brackets and transfer pipes a little. I think that would be easier than straightening and spacing the 650 carbs. It might be easier still to 3D print custom intakes, assuming the ASA I'd use could take the heat.
I don't think that will work very well. I know the GL500 runners & carbs won't line up with the 650 engine (& vise versa) so I doubt the CX500 ones will work either.
You might be better to use the 650 carbs and print something to mate them with the bike's airbox.
 
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