Has this engine had internal work done to it?

Posted: Thu May 24, 2012 10:56 pm

When I got the bike the owner said the PO had put a race cut transmission in there. When I asked about this a few days ago it seamed as though someone would only do that if there were internal engine mods to create a lot more power and thus justify the upgraded transmission.

So Im about to put the BSTs on and when I get the insulator off I see what looks like some grinding to the intake port, what do you guys see?

Think the head has had some work done?

Posted: Fri May 25, 2012 12:37 am

I have several 1100 heads that look just like that. I believe it is stock.

CB1100F Joined: Feb 17, 2009 Posts: 2105 Location: Oz

kenc42 wrote:

what do you guys see?

A black hole. Got a better picture?

Posted: Fri May 25, 2012 1:05 am

The bottom part that isnt black, it feels likes its been ground down.

Posted: Fri May 25, 2012 1:42 am

The picture is hard to see. There are two curved lines in the pics, on the sidewalls of the port running from the port back in toward the valves. They look like they might be casting flash from when the head was cast, can you feel those lines and tell if it's actaully a 'ridge'? If it is the casting flash, then your head is probably stock as the first thing you would do in porting a head would be to smooth the casting flash over.

Beyond that, if the PO told you about the trans work, wouldn't he also tell you if the motor was built? The 'race cut' transmission might just be back-cut gear dogs that were cut to stop the bike from popping out of second gear. If the bike was shifted hard from 1st to 2nd by the PO, or even the PPO, it could easily wear down the dogs and let the bike pop out of second gear. Back-cuttuing the dogs would be the fix.

Also, some of these bikes had a problem with hard shifting due to the design of the shift mechanism. There is a fox where you trim part of the mechanism and it allows for better shifting. Maybe the trans work was done to fix hard shifting, or maybe the shifter mod is the trans work the guy was talking about.

Posted: Fri May 25, 2012 5:00 am

If you are looking at the shiney line at the outside edge,that is just Honda crappy machining.

The heads are dipped in black epoxy type paint. The entire head casting inside and outside is black except for where machining has taken place. This like the surface where the cover gasket goes,the holes where the lifter buckets move,etc. If anyone did any porting they did an absolute piss poor job since the black paint is still there and the septum dividing the ports still has a casting line.

As to transmission this is standard job to repair or improve a transmission. The dogs and the corresponding hole get the edge rounded off and jump in and out of gear. They machine a reverse taper on the dog and hole to sharpen the rounded off edge and the negative angle pulls it into gear instead of jumping out.

What bike is it 900 or 1100? The head would look the same so no joy. The shifter on 1100 usually has been fixed from new with Honda. The 900 as well as the 750 needs the shifter mod done,look up in common documents for more info. Basically the shifter window was not large enough on the upshift side,down shift usually fine. This prevents shifting fully into the next higher gear and the result is the rounding off the shift dogs causing the problem the back cut as part of the fix.