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1980 CX500C (turbo)
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Discussion Starter · #1 ·
Hey folks.
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Finally got the new turbo setup installed.
I had a catastrophic oil line failure while riding on the highway a few months back. The oil drain let loose and subsequently The motor lost oil pressure and the crank bearings disintegrated. The light came on, but it was already too late. A sad day with many emotions and swear words. After somehow sourcing and rebuilding a new motor. I decided I would continue to pursue the turbo project. Much bigger turbo (ihi rhb5) and more compact intake manifold design. Way better exhaust flow in and out of turbo. Only thing left is to have the intake Manifold 3d printed, once I complete more road testing. This seems like it will be the final iteration though.
Essentially everything I wish I could’ve fixed last time, I’ve got corrected for this setup. Can’t wait to bring it to the show and shine next weekend and watch the minds blow. this has not been an easy project but man was it worth it. Again, this is a blow through carb setup that uses and efi pump in conjunction with a malpassi bypss fuel regulator.
SBeatty
 

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'84 CX650E that is evolving into a GL500
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Interesting project, but it always amazes me when people put so much time & effort into extensive modifications like that and leave the 40 year old rubber brake lines on. The manufacturers of rubber brake lines recommend replacing them every 2-3 fluid changes (= 5-6 years) so replacing them should have been among the first things you did.

BTW: Please add your location and your bike's model and model year to your profile (see Forum Settings link in my signature).
 

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1980 CX500C (turbo)
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Discussion Starter · #3 ·
Interesting project, but it always amazes me when people put so much time & effort into extensive modifications like that and leave the 40 year old rubber brake lines on. The manufacturers of rubber brake lines recommend replacing them every 2-3 fluid changes (= 5-6 years) so replacing them should have been among the first things you did.

BTW: Please add your location and your bike's model and model year to your profile (see Forum Settings link in my signature).
Thanks. I will get those brake lines swapped out right away. You’re the first person to mention that to me. They passed the visual inspection and leak testing, and have worked well since I got the bike.
 

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'84 CX650E that is evolving into a GL500
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Try wrapping one hand around the rubber line while you squeeze the lever with the other hand. I'd bet you will feel the line expanding under pressure and any force lost that way is braking effort wasted.
 

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Nice job!

The usual placement for the nuts on the clutch cable is both above the perch. The nut on the perch is for adjusting the free play, the one above it acts to lock the nuts in place. With both nuts above the perch the end of the clutch cable has a little freedom of movement as the clutch is operated.

What is the purpose of the fitting on the timing port? Perhaps for crankcase ventilation? If so, what is on the other end of that line?

Stock CX front forks are quite noodlely. The front end would benefit from a fork brace.
 

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Wow, that's cool @Sbeatty! As @krugerjq said, how is the before & after ride impressions? How does it ride before and after the turbo kicks in? I've never seen a homebrew twisted twin turbo in the wild before, unique bike for sure.
 

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Discussion Starter · #8 ·
Nice.....does it make a big difference in performance?
Its give the bike a ton of low end torque, which is what I like and mostly use it for. With the previous setup, using an vz21 turbo, it made 10psi and would turn into warp speed in the top end. I have yet to push the limits of this setup, as it is still going through initial break in and road testing. But yes, it makes a great difference in performance. It was lots of work to make it all play nice though.
 

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Discussion Starter · #9 · (Edited)
Wow, that's cool @Sbeatty! As @krugerjq said, how is the before & after ride impressions? How does it ride before and after the turbo kicks in? I've never seen a homebrew twisted twin turbo in the wild before, unique bike for sure.
I have to give the concept credit to Kingston Customs. I was on google during the infancy of my cx500 marriage and happened to see a bike they had produced that is basically the same as what I have created. Albeit, much nicer. As for the ride, it was a bit of work dialing in the jetting and getting the transition into boost to be as smooth as possible. Now that I have it all playing nice, the bike is a true Jekyll and Hyde. Boost on tap for when you want to go wild.
215776


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I have to give the concept credit to Kingston Customs. I was on google during the infancy of my cx500 marriage and happened to see a bike they had produced that is basically the same as what I have created. Albeit, much nicer. As for the ride, it was a bit of work dialing in the jetting and getting the transition into boost to be as smooth as possible. Now that I have it all playing nice, the bike is a true Jekyll and Hyde. Boost on tap for when you want to go wild.
View attachment 215776

View attachment 215776
that was a great build...
 

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Discussion Starter · #15 ·
I don’t have a build thread, but I would be happy to answer any questions you have. Basic requirements are a efi fuel pump feeding into a bypass fuel pressure regulator, which is boost referenced from the intake manifold. You will need a fuel return in the tank. Other than that, you need to block off all the atmospheric vents in the carbs. There is two for each carb. The jetting needs to be increased. I run 92 and 132 (I think) have to check the values. I would recommend the smallest turbo you can find, as 500cc does not produce much exhaust gas velocity in the lower rpm’s. I started with a rhb31/ vz21 off Amazon, they are really poor quality and tend to leak oil no matter what. I was easily hitting 10psi, but it was like warp speed when boost kicked in. I upgraded to a larger unit, an ihi rhb52w, which doesn’t come on boost until 5000 rpm, and tends to max out at 7 psi, which is plenty. Oil feed and return are done using the oil pressure sensor and teeing off. Then I used the oil filler as my return port.
 

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I don’t have a build thread, but I would be happy to answer any questions you have. Basic requirements are a efi fuel pump feeding into a bypass fuel pressure regulator, which is boost referenced from the intake manifold. You will need a fuel return in the tank. Other than that, you need to block off all the atmospheric vents in the carbs. There is two for each carb. The jetting needs to be increased. I run 92 and 132 (I think) have to check the values. I would recommend the smallest turbo you can find, as 500cc does not produce much exhaust gas velocity in the lower rpm’s. I started with a rhb31/ vz21 off Amazon, they are really poor quality and tend to leak oil no matter what. I was easily hitting 10psi, but it was like warp speed when boost kicked in. I upgraded to a larger unit, an ihi rhb52w, which doesn’t come on boost until 5000 rpm, and tends to max out at 7 psi, which is plenty. Oil feed and return are done using the oil pressure sensor and teeing off. Then I used the oil filler as my return port.
Thanks for the info! What's the PSI requirement for the pump? I was thinking of eventually doing an EFI conversion at some point as well, so already having a pump would be great haha. I also have a set of Mikunis (@murrayf's kit) so I'll likely reach out at some point to get some insight on tuning those for a draw-through setup. What RPM were you getting boost with the smaller kits? Were you using a boost controller of any kind? I was probably going to grab one from work just to make sure that I don't go too crazy

Did I also spy a BOV on there too?

-Nick
 

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Discussion Starter · #17 ·
Thanks for the info! What's the PSI requirement for the pump? I was thinking of eventually doing an EFI conversion at some point as well, so already having a pump would be great haha. I also have a set of Mikunis (@murrayf's kit) so I'll likely reach out at some point to get some insight on tuning those for a draw-through setup. What RPM were you getting boost with the smaller kits? Were you using a boost controller of any kind? I was probably going to grab one from work just to make sure that I don't go too crazy

Did I also spy a BOV on there too?

-Nick
The pump I use is low pressure, from 4-9psi. The vz21 had an internal wastegate, set at 10psi, and boost would come on at 4K rpm.
No boost controller was used.
you will not need a fuel pump, or return line on draw through set up. You’ll need to get a single, larger carb, but won’t need to mod it on a draw through, other than fine tuning jetting. Overall It’s a much easier set up vs my blow through.
Yes I have bov installed, but that is mainly for when I shift. It allows the bike to run better by letting off the pressure. Before that, the bike would buck when shifting. You can’t hear much of a bov sound bc the exhaust is so loud. I’m switching to a turbo smart kompact bov this summer, as the one I have now is a pos. It was more for proof of concept and testing. Didn’t want to unload 200$ unless I knew it would be beneficial to the project. Now I know, ill spend the dough.
 

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The pump I use is low pressure, from 4-9psi. The vz21 had an internal wastegate, set at 10psi, and boost would come on at 4K rpm.
No boost controller was used.
you will not need a fuel pump, or return line on draw through set up. You’ll need to get a single, larger carb, but won’t need to mod it on a draw through, other than fine tuning jetting. Overall It’s a much easier set up vs my blow through.
Yes I have bov installed, but that is mainly for when I shift. It allows the bike to run better by letting off the pressure. Before that, the bike would buck when shifting. You can’t hear much of a bov sound bc the exhaust is so loud. I’m switching to a turbo smart kompact bov this summer, as the one I have now is a pos. It was more for proof of concept and testing. Didn’t want to unload 200$ unless I knew it would be beneficial to the project. Now I know, ill spend the dough.

Gotcha! Thanks for the info! And sorry blow-through. I'm definitely more of a fan of at least the look of the blow-through setup. Good to know about the BOV, I'll add that to the list. Ideally I'd like to do this upgrade this season, but I'm planning to have my heap of parts back together by April/May and I'm about to have an $800 powder coating bill haha.

If you get a minute, would you be able to grab any photos of your manifold? Just for some inspo

Thanks again!
-Nick
 

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Discussion Starter · #19 ·
I can help with whatever you need. I’m planning remake the manifold this spring using aluminum, because right now it’s (shame) pvc. But tbh it works really well and is cheap. But not something I’m looking to stick with.
 
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