Honda-SOHC

Thanks, I'm going back to the USA in a few weeks for 5 months and wanted to replace my current BMW R1200RS there with a CB550 Honda (!) but I prefer the look of the F model, like my UK CB400 four.  But since the 550F is rather rare in the USA I was thinking about buying the K model and converting it.

Re the oil pump rotor marks - mine was the same, marks on opposite sides, but there was no evidence the pump had ever been removed.  Others have said the same re the marks 'mismatched' so I think it wasn't a big deal upon assembly at the factory.

Interesting relevant thread, thanks!  In doing some general curiosity-type searching it seems  that various pilot/main jet sizes and velocity stacks to fit these carbs are not easily available in the UK.  They are in the US which seems odd because the bike is not/was never popular there.  Go figure...

Sorry to ask that question but my storage garage, where the bike stays, is a mile away and I'm hoping to get an answer without having to walk over there.   So the outer diameter of the carb where the air filter rubber attaches is...

 I'm thinking of velocity stacks, despite all the evidence suggesting it's a bad idea.  If someone already knows of a specific stack that fits I'd appreciate the info.

All sorted today.  The 17mm filter bolt arrived so I went ahead and used it rather than the old (now 11mm) bolt.  Filled it up with oil (Castrol Power 1 full synthetic 10w40 JASO 2), ran out and got the engine good and warm.  Did several WOT accelerations through the first four gears to 10K RPM.  Checked for leaks upon return; found none! 

Bike is essentially now ready for extended use with no further required 'interventions' other than routine maintenance and whatever items I may decide to change/modify.  I have a couple in mind...neither would be considered "smart." 

Thanks, NJ re the collar.  I would have thought the service manual, since it's for the 350 and 400 fours, would have noted the difference in the 400 section that shows differences between the two but it doesn't.

New washer was delivered a few minutes ago; new 17mm hex head bolt wasn't so I guess I'll remount the old 12 mm (now 11mm) hex head bolt and keep the new one for a spare when it arrives.

Very annoying!   Went to change the oil yesterday for the first time on my watch.  Drain plug was very tight - couldn't budge it with a 17mm 3/8" drive socket/ratchet but I finally got it off with a 17mm 1/2" drive.  The filter bolt was partially seized to the filter "case" and had been buggered/rounded so no wrench would fit. It was also extremely tight and very difficult to remove.   After removing it, I 'adjusted' the hex head with some file work to take an 11mm socket/wrench.

Then, in proceeding with the change, found that the washer that goes between the spring and the filter was missing.  I thought maybe it had stuck to the filter or maybe fell on the floor when I disassembled everything but that was not the case, in fact, I could see the imprint of the spring itself in the rubber on the filter.  So that was the end of the oil change procedure until I get a washer.  I went to the local hardware store but nothing of that size available so I ordered that and a couple of other small parts from DS, including a new filter bolt, which I decided was better than my 'adjusted' filter bolt.  I wanted to order a genuine part with the original 12mm hex but they were out of stock so I ordered the (much cheaper) aftermarket with the 17mm hex.  Can't really think why a 17mm hex is needed on a fitting that only needs to be tight enough to compress an O ring...    

TBH, I wonder about the relief valve on the aftermarket bolt vs the original but since it's just a spring and a plunger, I assume it's perfectly OK.  Any conflicting views re that?  If so, I'll just put my (now) 11mm bolt back in! 

The good news is that the old oil looked new and the old filter did not have any scary-looking deposits.  I was pleased to see that since the engine had been rebuilt by a shop (previous owner) last year.   OTOH, the absence of that filter washer and the buggered hex head on the bolt is somewhat disquieting.  I would have thought that a shop doing the engine work would have ensured the washer was present and that a new filter bolt was installed...