Saturday, December 18, 2004

Installed a CX650 engine

Not many pictures this time, but I've made some rather major modifications. I installed a CX650 engine in the chopper. After an initial test period of a couple months to make sure the engine was solid, I took it back out and painted it with VHT Brake Caliper paint. Looks spectacular. I'm currently in the process of polishing every piece of aluminum on the bike. You can see the valve covers, clutch cover, intake manifold, exhaust flange, cx650 emblems, and several other parts already polished. The new CX650 engine (actually 673cc) is more powerful than the 500... but vibration isn't reduced much and the overall gearing (ie: vibration felt at speed) did not change much. However, I believe this is because I do not yet have the cylinder head motor mount bolts installed yet. I need to take the front engine hanger to a welder and have him modify it to fit the wider spacing of the 650 engine mounts.

In addition to the engine and polishing work, I've re-mounted the rear fender at a more suitable angle, re-mounted the seat with a bracket in the front (rear bracket isn't finished yet), mounted saddle bags, mounted the sissy bar at a closer approximation to the front fork angle, and painted "Suicide Machine" logos on the tank. The green thing on the top of the tank is a pickle, in case you're wondering. Hope you're old enough to get the reference :)

I'll do a detailed parts assessment later... but basically, the 650 engine was free, I already had the polishing compound to polish the covers, I made the seat bracket out of scrap steel I had in my garage, the saddlebags are off my V65 Magna, and everything else was already on the bike. So, this month's mods were basically free!

Parts Breakdown:

  • VHT Brake Caliper paint (2 cans): $15 
  • Gunk Engine degreaser (3 cans): $10 
  • Paint stripper (1 can): $7
  • Total: $32

Running total for Chopper: $1237


  1. How hard was it to install the 650 engine? was it mostly a bolt on affair?

    1. It depends on the bike you begin with. For a GL500, it's a bolt-on affair. For all CX500s except the 1982, you will need to also replace the entire wiring harness, handlebar controls, and ignition coils. The CX500s run CDI ignition, and the 650s and GLs run transistor ignition. So you'll have to swap that over if you want to run a 650 motor. The front engine hanger needs to be extensively modified. For the GL bikes, you can swap the GL650 engine hanger over. For the CX, you have to cut, modify, and weld the front engine hanger. The heads are taller, so the studs that the hanger bolts to are further out. If you're using a 500 radiator and a custom fan like I did, that's all you need to do. If you're using the 650 radiator you'll also need to cut out the cross brace from the engine hanger, and weld in a piece of metal tubing to brace it. This is so the hose has clearance. (CX500 radiator has intake on the side, 650 has intake in the center). See the other posts in this series for more pictures. Also, depending on the source of the 650 motor, you may need to swap the output shaft, otherwise it will not mate to a CX500 driveshaft. 500 carbs will need to be rejetted for a CX, whereas for a GL you can swap over the GL650 carbs without problems.

  2. This comment has been removed by the author.