81 carb installation issues

[Weinbergn]

Hey guys,

I'm new to the forum but I've been lurking for a while. I've always been into building offroad trucks but my job moved me to the city so I sold my trucks and am now beginning to get into motorcycles. I'm no stranger to wrenching. I've been around engines my whole life. I just bought a 81 cb750 i plan to turn into some sort of cafe style bike. When i bought it i knew the carbs were messed up since it ran like shit and was leaking gas out of the overflow in the bowl. I pulled the carb and rebuilt them just fine. The biggest problem I'm having is getting everything to go back together! I feel stupid but is there some sort of secret how to get the carb back under the bike? I can either get the front hoses which go to the motor in place or the ones that go to the intake box, but never both. I became extremely frustrated so i figured i'd make an account and throw up this post. I plan on playing around with the intake an exhaust eventually I can imagine its as difficult as i'm making it.

Any advice would be apprieciated.

Thanks guys and i look forward to becoming more active in this community. I'll at some point put together a build thread once i get the time.

 

[Weinbergn]

Seriously, no one has any advice?

 

[Boulder82]

Sometimes those carbs make me wonder why I own one of these things. Anyway, what works for me is make sure the air cleaner box is pushed all the way to the rear. There should be a bolt on top of the air box in a slotted hole to allow for this. I put the carb bank in from the left and I tilt the fronts down while holding it with my left hand. The rear of the carbs will be above the air box boots. When the first carb (#4) is about at the middle of the engine attach both throttle cables and the choke cable. It will be much easier now rather than later. Now put the carbs all the way in so they line up with each inlet rubber. Let them sit on the inlets and straddle the bike like you would ride it. Grab the bank of carbs with a hand on both end carbs (#1 and #4) and pivot the carbs down getting the fronts in the inlet rubbers. I use a little oil on the rubbers. At the same time the backs will be hitting the air box boots. It's a tight fit, get the fronts in first and worry about the backs later. Most inlets have lost any flexibility and I have to push hard from the outside carbs to get them all the way in. Once the fronts are in use a screwdriver to unfold any air box boots pinched during the pivot. Sometimes the pivot goes great and sometimes it just doesn't cooperate. Almost always some air box boots are pinched and need to be unfolded. Take your time and use a light under the carbs to see what's going on. This works for me, although sometimes (most times) with much cussing. Someone might have a better way and I'm sure I left out a couple details. Good luck.

 

[pjmule]

I do pretty much the same as Boulder82, but I also heat the boots up with a hair dryer first.

 

[losttravlyr]

about those intake boots,,take them off the engine and boil them in 4 oz of wintergreen oil mixed with a pot of water for about 45 mins. they will be much more flexible and easier to slide the carbs into. do it outside being the fumes are intense and rinse the boots off after removal from the pot or your bike will smell minty fresh. after decades those boots get hard from the heat and gas fumes,wintergreen oil contains xyelene which renews the rubber and makes them pliable again. it works great unless they have holes or cracked badly. the cheapest place for oil is e bay rather than a drugstore. doesnt help with the airbox being in the way though but as for the boots on there,just warm them good with a hair drier and they will slide on easier.