My '82 CB900F has never run properly since I've had it. I knew it didn't run right when we bought it and believed it was ignition (90% of carb problems...), but after putting new plugs in it didn't improve it I came to the conclusion it needed the carbs rebuilt. The bike was one of many owned by a guy in Sebring FL and was the last to be sold off, so it sat longer than all the others. It ran very typical of a bike that needed the carbs cleaned, needed more choke when cold than it should, didn't run well at all until very warmed up and ran poorly above midrange. It had supposedly been jetted for a set of red, cheesy pod filters that were on it (Dynojet sticker under the seat on the inner fender) but with the PO deceased I was unable to get any accurate information.
A local riding buddy with lots of salvage connections both here and in his home state of Wisconsin managed to find a couple of stock airboxes for the CB900C, which uses the same box but with a different top bracket. Unfortunately all the ducts (hoses) to the carbs were long gone. CMSNL did not have originals, but they did sell aftermarket replacements. Not finding anything else anywhere, I ordered them. Not overly expensive and of course, likely much cheaper than NOS had they been available.
Well, I've never had to use replacement ducts in a used airbox before but they looked the part and were pretty soft and flexible, after all they're new. I never dreamed there would be anything else to consider. And because of the airbox shape, you want it in the frame first before you put the carbs in and with others here having some success moving the ducts into the airbox to make more room for the carb re-installation, that's what I did. Needless to say the carbs were a PITA to get the cables connected and back into the intake stubs, but the real fight was still ahead.
While these ducts look good, they miss the mark on the manufacturing specs. The groove molded into them for the body of the airbox is not the correct width so they are ridiculously difficult to properly seat. It took my buddy and I - yes, all 4 hands, 3 on the outside and one of mine inside the airbox to assist, in order to get them properly seated. After days of trying to get the outer 2 done by myself, it was finally done.
Except it wasn't. The minute I tried to put the battery box back in the bike and it bumped into the back of the airbox, even with the ducts on the carbs and all clamps in place, it shifted the airbox a little and 2 of them popped out.
I didn't go to work on the bike right away after I received the ducts because I was busy with other things, and after looking at them out of the box it appeared they were correct. So now I have no recourse, and trying to slice a millimeter off the width of that groove to make them fit more correctly is NOT an easy task, I've already tried. But short of taking the carbs back out and starting over and somehow gluing them in place, that's about my only option.
A local riding buddy with lots of salvage connections both here and in his home state of Wisconsin managed to find a couple of stock airboxes for the CB900C, which uses the same box but with a different top bracket. Unfortunately all the ducts (hoses) to the carbs were long gone. CMSNL did not have originals, but they did sell aftermarket replacements. Not finding anything else anywhere, I ordered them. Not overly expensive and of course, likely much cheaper than NOS had they been available.
Well, I've never had to use replacement ducts in a used airbox before but they looked the part and were pretty soft and flexible, after all they're new. I never dreamed there would be anything else to consider. And because of the airbox shape, you want it in the frame first before you put the carbs in and with others here having some success moving the ducts into the airbox to make more room for the carb re-installation, that's what I did. Needless to say the carbs were a PITA to get the cables connected and back into the intake stubs, but the real fight was still ahead.
While these ducts look good, they miss the mark on the manufacturing specs. The groove molded into them for the body of the airbox is not the correct width so they are ridiculously difficult to properly seat. It took my buddy and I - yes, all 4 hands, 3 on the outside and one of mine inside the airbox to assist, in order to get them properly seated. After days of trying to get the outer 2 done by myself, it was finally done.
Except it wasn't. The minute I tried to put the battery box back in the bike and it bumped into the back of the airbox, even with the ducts on the carbs and all clamps in place, it shifted the airbox a little and 2 of them popped out.
I didn't go to work on the bike right away after I received the ducts because I was busy with other things, and after looking at them out of the box it appeared they were correct. So now I have no recourse, and trying to slice a millimeter off the width of that groove to make them fit more correctly is NOT an easy task, I've already tried. But short of taking the carbs back out and starting over and somehow gluing them in place, that's about my only option.
