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Discussion Starter · #1 ·
Hey--

Just wanted to start a general discussion about the thoughts, or personal experience of a cx/gl650 engine swapped onto a 500 frame. I've got a cx500 standard that I rip around every now and then, and I think the extra power from the 650 would be nice!

I've talked to murray about it several times, and I know he loves the extra power the 650 has to offer, even with the slightly longer gears.

What got me going on wanting to do this is, I picked up two GL650 engines from an estate sale for $100. One has the end of the camshaft snapped off, where the water impeller goes, and the other is complete. I need to stick my endoscope into the complete engine and see how the cylinders are, make sure the complete one is in decent shape and not blown up from lack of oil. Makes me curious why the PO was trying to take apart the other motor, and how hard he was prying at the impeller to break the cam.

I've been trying to get a 2nd starter as neither engine has one so I can also crank them over and listen for anything funny, but it seems they are becoming hard to come by and rather expensive. I'd use the one off my cx500, but I'd rather not drop the engine just to borrow a starter...

(if anyone has one they'd sell to me cheap I'd really appreciate it~)\

I think I have everything mentally written down that I am going to need / do for the swap:

Rae-San ignition, timing jumper to aggressive
12v coils
murray mid-pipes
rejet murray carbs
modify cx500 engine hangar
gl650 radiator + efan wiring
swap output shafts
inspect cam chain, replace mechanical seal while swapping output shaft
Swap over HD clutch springs?

I don't think I'm missing anything..but I probably am. If the cam chain tensioner isnt stretched to the max, I am going to leave it. No reason to change good parts. Same with the stator.

Only thing I have ordered right now is the 650 radiator, mainly because it was in great shape, came with the efan and the shroud for $70 shipped!

I may make a build thread once I get this project going. The hardest part will be modifying the engine hangar, but theres a video on youtube doing it, and its pretty easy if you have a welder (which i do lol).
 

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... I'd rather not drop the engine just to borrow a starter...
The starter can be removed with the engine in place. See FSM.
 
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Discussion Starter · #4 · (Edited)
Some pics of the motors and my cx500 standard~

edit--looking at the auto adjuster on the motor with the busted cam, the chain is toast since the hole on the plunger is exposed. Might be why the PO tore it apart. Prolly means the internals are good on it.
 

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Discussion Starter · #6 ·
i have a starter if you need one
how much do you want?

Also, question--

If I wanted to convert it back to a manual tensioner, will my 500 case work on the 650, and if so, will the same rae-san v4 module fit the 500 case? If I remember correctly, the v4 module will work on all motors...
 

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CX650 motor project into a CX500 Turbo Frame - ongoing
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If I wanted to convert it back to a manual tensioner, will my 500 case work on the 650, and if so, will the same rae-san v4 module fit the 500 case? If I remember correctly, the v4 module will work on all motors...

Just curious, what do you mean convert it back to a manual tensioner? afaik, none of the 650s had manual tensioners?
 

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The rear covers are different-no hole for the tensioner bolt on the back of the 650 and the water pump and cover for the ignition are different too...
Cheers.
Ross
 

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Discussion Starter · #10 ·
The rear covers are different-no hole for the tensioner bolt on the back of the 650 and the water pump and cover for the ignition are different too...
Cheers.
Ross
right, but if i use my cx500 back and the rae san ignition, that wont be an issue.

how is the water pump different?
 

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The 650 water pump impeller is taller. I think that you would be OK using the 500 rear cover, water pump impeller and water pump cover.
 

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The 650 uses a taller impeller and pump cover.

I've not done this mod on a 650 and can't tell you which pieces you should be using but it will become obvious which bits you can use when you delve into it but I think you'll be using the 500 pump components.
 

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CX650 motor project into a CX500 Turbo Frame - ongoing
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Just in general, why shy away from the auto tensioner? I've come across a couple other threads on doing this to the CX500s and the general consensus seemed that it wasn't worth doing. I thought the auto works fine as long as it's monitored, and the manual will require your attention just as often.
 

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Discussion Starter · #14 ·
Just in general, why shy away from the auto tensioner? I've come across a couple other threads on doing this to the CX500s and the general consensus seemed that it wasn't worth doing. I thought the auto works fine as long as it's monitored, and the manual will require your attention just as often.
according to murray, the manual tensioner, when serviced correctly, will get you almost double the life out of your chain vs the auto tensioner.
 

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My understanding is the manual tensioner gives you longer/greater adjustment on the chain...more chain life
 

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The auto tensioners also break when left too long with a worn out chain and are virtually unobtainable.
 

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according to murray, the manual tensioner, when serviced correctly, will get you almost double the life out of your chain vs the auto tensioner.

Yeah I remember that point, and the point of them breaking when left unchecked.

I have a turbo 500 case (with a severed water pump end as well) and a 650 motor, hence my interest in that part of it.

Someone here was making parts for the auto tensioner that made the plunger part against the guide thicker, giving you a bit more range out of it. I think the same guy making new water pump impellers. Never did see anyone say they tried it though.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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You MIGHT make the CX rear cover work, if the Rae-san kit will work with the CDI ignition cover, and you can modify the crankcase venting. Easier just to get a GL500 rear cover.
Use the 650 water pump impeller and cover.
You'll need a specific thread adapter to host the tension adjuster lock bolt. I know of one seller on Amazon with the correct adapter. I posted the link in a similar thread within the last month or two.
I've been running a manual adjuster on Nimbus since I reassembled it last summer.
 

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Discussion Starter · #19 ·
You MIGHT make the CX rear cover work, if the Rae-san kit will work with the CDI ignition cover, and you can modify the crankcase venting. Easier just to get a GL500 rear cover.
Use the 650 water pump impeller and cover.
You'll need a specific thread adapter to host the tension adjuster lock bolt. I know of one seller on Amazon with the correct adapter. I posted the link in a similar thread within the last month or two.
I've been running a manual adjuster on Nimbus since I reassembled it last summer.
CX CDI to 12V coil Conversion Kit | Rae-San Electronics

that solves the ignition issue

this isnt something ive thought about in awhile--doenst the crankcase vent come out from the middle section of the motor, not from the back cover? what issue do you see with the venting?

do you still have the link for the thread adapter?
 

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CX650 motor project into a CX500 Turbo Frame - ongoing
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You MIGHT make the CX rear cover work, if the Rae-san kit will work with the CDI ignition cover, and you can modify the crankcase venting. Easier just to get a GL500 rear cover.
Use the 650 water pump impeller and cover.
You'll need a specific thread adapter to host the tension adjuster lock bolt. I know of one seller on Amazon with the correct adapter. I posted the link in a similar thread within the last month or two.
I've been running a manual adjuster on Nimbus since I reassembled it last summer.

That Nimbus is a 650 motor, right? If it's not terribly difficult to do I might be tempted. My problem would be sourcing a manual tensioner, I don't see any on ebay and I think the Turbo 500 I have is automatic.


@SirFoxx I'm putting my 650 into a 500 Turbo frame. I think the 650s drop into a GL frame with modifed GL650 hangers but on mine I may be fabricating completely new hangers because I hate the stamped sheet metal ones. What are your engine hanger plans looking like? If you've caught Murray's attention I'm sure he's discussed it with you I'm just curious.
 
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