Topic: Cb550-650 Cam Mod

[88BuckMeister]

I know there are several posts/topics on this here, but none that specifically answer my question...

It's been made clear "if you want to do the mod, avoid the German export cams because they have a similar profile to the stock 550 cams".

Once I get a 650 cam in my hand, how can I tell to be sure? If I have the serial number on both the bike and engine it came out of, how can I find out if this bike was a German export? Can anyone give me the measurement of the entire INT/EXH lobes so I can use a micrometer to confirm? I measured a new 550 cam and the lobes were 1.368 and 1.340.

I want to be sure this 650 cam I purchased is actually an American 650 cam before I go torquing the head. If there's no clear answer to this question, I'll accept that. Thanks, Buck

[newday777]

I don't have a specific answer to your question.
But does it have a US vin plate on the steering neck and a title? Or was it imported to the states? I see you are in Illinois.

[newday777]

BTW this probably should be in the SOHC4 Bikes section or the High performance section so a mod might move your 2 posts. Did you hit the notify button so you get an email when someone replies to your posts?

[88BuckMeister]

I don't have a specific answer to your question.
But does it have a US vin plate on the steering neck and a title? Or was it imported to the states? I see you are in Illinois.

Here are pics for you

[Stev-o]

Once I get a 650 cam in my hand, how can I tell to be sure? If I have the serial number on both the bike and engine it came out of, how can I find out if this bike was a German export? Can anyone give me the measurement of the entire INT/EXH lobes so I can use a micrometer to confirm? I measured a new 550 cam and the lobes were 1.368 and 1.340.

I literally have a 650 cam sitting on my desk, unsure how you measured but mine is 1.4 & 1.37

Why do you think it might be a German bike?

[newday777]

That vin tag appears to be a US Model.
I don't have the codes for the plant it was built but the 11th character (M) is the plant.

[88BuckMeister]

Once I get a 650 cam in my hand, how can I tell to be sure? If I have the serial number on both the bike and engine it came out of, how can I find out if this bike was a German export? Can anyone give me the measurement of the entire INT/EXH lobes so I can use a micrometer to confirm? I measured a new 550 cam and the lobes were 1.368 and 1.340.

I literally have a 650 cam sitting on my desk, unsure how you measured but mine is 1.4 & 1.37

Why do you think it might be a German bike?

I just wanted to know if there was a way to confirm or deny whether it's a German bike. The only thing I've gathered from these threads about doing the 650-to-550 cam mod is that you want to avoid at all costs grabbing a cam from a German export 650 because the cam specs were extremely weak due to environmental regulations on horsepower. The question is once you know that, how in the hell do you determine whether the bike you're buying the cam from was a German export??? haha

[Flyin900]

If your in the US and bought the CB650 donor bike or cam in the US then the chance of it being a German export cam is extremely low. Forum members have access to the FSM from Honda on most bikes available N/C (under Manuals and Technical documents) In the section for CB650 bikes you will get the specs for the lobes, with a correct in service spec and a worn out of service spec for the CB650 cam. If you measure the cam you have against those specs it should resolve your concerns on the question.

http://manuals.sohc4.net/cb650/

[newday777]

If your in the US and bought the CB650 donor bike or cam in the US then the chance of it being a German export cam is extremely low. Forum members have access to the FSM from Honda on most bikes available N/C (under Manuals and Technical documents) In the section for CB650 bikes you will get the specs for the lobes, with a correct in service spec and a worn out of service spec for the CB650 cam. If you measure the cam you have against those specs it should resolve your concerns on the question.

http://manuals.sohc4.net/cb650/

Do you know what we need to open up the downloads? My phone isn't opening the files.

[scunny]

The service manual lists it as 1.40  1.39. That is the service limit. I can measure my spare, but will be in a few days.

[Kelly E]

I don't think that they sold the 82' CB 650SC Nighthawk in Europe.

[Flyin900]

If your in the US and bought the CB650 donor bike or cam in the US then the chance of it being a German export cam is extremely low. Forum members have access to the FSM from Honda on most bikes available N/C (under Manuals and Technical documents) In the section for CB650 bikes you will get the specs for the lobes, with a correct in service spec and a worn out of service spec for the CB650 cam. If you measure the cam you have against those specs it should resolve your concerns on the question.

http://manuals.sohc4.net/cb650/

Do you know what we need to open up the downloads? My phone isn't opening the files.

I don’t use a phone for this stuff only my desktop or IPad and the link opens fine on either device. I believe phones can have issues with different applications though.

[BomberMann650]

I may have gotten an earlier model year 650 cam from an ebay seller overseas.  Or someone snuck in a cam for their build.  Either way, i measured it.  Mentioned in my turbo race build thread

Intakes came up 0.300 on the dial - exhaust was not far behind.  There is visibly more duration than the oem 550 cam.  Didn't write down the open/close marks since there's not much i could do about that for my purpose.  Because of this added lift, the amount of degrees i could safely retard the cam timing was limited to 3° off the stock mark.  Advancing for NA street could be a different story.  Though i have deepend pockets in my race piston and ample deck clearance.  Shes a tight fit.

This cam also required trenching out the oil valley on the head by quite a margin.  Along with some of the ribs in the rocker box.  This must have been cast on a Wednesday or cut with a new grinder guide in the factory.  As my previous 650 cam install was a direct drop in with no clearance issues.

[denward17]

Well, I'm confused, I thought you were working on a CB550 engine, not a 650?

[calj737]

Well, I'm confused, I thought you were working on a CB550 engine, not a 650?

550 motor with a 650 cam swapped in.

[denward17]

Well, I'm confused, I thought you were working on a CB550 engine, not a 650?

550 motor with a 650 cam swapped in.

Right, but his picture on the frame VIN indicates a 1982 650.

[Mark1976]

   I believe its the vin tag of the donor bike, '82 cb650sc...

[denward17]

   I believe its the vin tag of the donor bike, '82 cb650sc...

Oh, missed that part.....I'll be quite now...