Thursday, December 24, 2015

Differences between the RG400 and the RG500

When I was cleaning my mailbox I found some great information about the differences between the RG400 and the RG500, so here it is.
1. Carb slide needle and main jetting: 400 = #135 , 500 = #120.

2. Clutch: the 400 has some friction disks less (1 or 2, I’m not sure). See if your clutch will work OK so you may leave it as it is.

3. External sprockets and chain, 400 = 15 front /41 rear, 525 chain, 500 = 16/40, 530.

4. 400 pipes have only thiner stingers, all the bodies are the same.

5. Cylinder, piston: 400= 50mm 500=56mm 400 has 5 intake ports, 500 has 7 intake ports but smaller (but 400′s port in total I think give better flow – i.e. less divided area). External lower sleeve diameter 400=60mm , 500=66mm you need to rebore the upper crankcase. But I’m not sure if you can rebore your 400 cylinder sleeves to reach 56mm so you won’t need any crankcase machining (and won’t need to buy a 500 cylinder set). Remember the 400′s cyls may give a better intake port flow.

6. Heads diameter accordingly are of: 400=50mm , 500=56mm.

7. Conrods are the same, only its lower bearing consists of some more (1 or 2, I’m not sure) needles so they are closer each other. You may not bother splitting your cases and keep your 400′s bearings though if you go arround the stock 500 horse power (no much more).

8. Some small difference in the front brake rotors. 400′s are no “floating” type.

9. The rotary valves have different base, the 400′s is thinner and lighter so keep your 400.

Sunday, December 20, 2015

Central Classics Houten 2015

Seen at the Central Classics in Houten the Netherlands, December 2015. Aalt Toersen his old record machine, on this bike he has set 3 worldrecords in Elvington in the UK in 1968.
For more pics see 
Central Classics Houten 2015

Sunday, December 13, 2015

The Can-Am Bombardier 500cc prototypes

This time some pics of a very rare bike the Can-Am 500cc two stroke twin.
"The 1977 500cc CanAm street bike never made it into production. Only 2 or 3 prototypes were ever built (circa 1975). One was a street version which produced about 60 horsepower, while the other was an 85 horsepower road racing version. The engine was borrowed from a Bombardier snowmobile and modified to accept a 5-speed gearbox. The powerplant was liquid cooled and utilized a single horizontal rotary valve. The exhaust system was unique. The lower pipe on each side was an expansion chamber, and was connected to the top pipe (mufflers) with a small tube. This allowed expansion chamber performance while remaining quiet enough for street use. This machine never went into production because proposed EPA emission standards threatened its marketability in the United States. Tony Murphy wrote a magazine article about this motorcycle in 1976. He recently informed me that the prototypes are still running strong somewhere in Canada."
This information came from 
Tony Murphy's article
Giant killer 
For more pics see
Can-Am Bombardier 500cc prototypes