u/YeeOfHouseHaw

Hello everyone, I have an 80 CB750C Custom with a little over 5,000 on it, it’s my first bike project, with that being said I’ve run into a snag with what I think is the carbs but I’m not 100% sure at this point. As for preliminary tests, I have checked for good solid spark from each coil to plug, did a dirty test for compression as I don’t have a proper compression gauge to fit the engine yet, fresh carb rebuild with a K&L kit for each carb (the jets were the only replacement brass since there was prior damage to the old ones unfortunately) and I just polished the float valve seats and bores, and also before and after tried to replace float needles and floats, all of which made very minimal if any difference in it’s behavior, between test fires I make sure the plugs are clean. Beyond all that I’m getting an intermittent exhaust backfire and it doesn’t even sputter or try to start up otherwise. Any help would be greatly appreciated.

Hello all, purchased my first motorcycle with a little over 5,000 miles on it, and while I have several years of automotive experience, bikes are a new playground for me, I’m struggling with what seems to be the carbs, preliminary tests, I have tested for good spark, and good battery voltage (new battery as well) I have done a rough test for compression, no real numbers as I don’t have a compression gauge adapter that will fit that yet. I went through and rebuilt and cleaned the carbs, against my better judgement bought a cheap rebuilt kit from eBay and due to needing the bike moved in a short time period hastily and poorly rebuilt the original carbs and ended up bending the choke linkage rods while trying to put them back together (oops) so I bought what I thought were the same rack of OEM used carbs that were in good condition, however they were off of an 81 cb750, I’m not sure of the difference or if it effects my problem but I learned my lesson and bought a K&L kit for all 4 carbs and went through and cleaned passages and made sure they were free and clear as well as the jets and emulsion tubes and replaced the float needles, and now after installing the carbs I’m running into what seems to be a float issue, the carbs do not leak anywhere and are fine until I try to start the bike, and they seem to be flooding out of the emulsion tubes and flooding the engine and causing it to backfire from the exhaust, since these carbs don’t have adjustable floats I wasn’t sure as to what the issue was or how I could go about fixing it, any help would be greatly appreciated, thank you in advance

Hello, so I have a 1980 Honda CB750C Custom, Its got about 5,000 miles on it, I’ve been trying to get it back into riding condition again, however I’ve ran into a snag with seemingly the carbs, I got a whole new K&L carb kit and replaced all the gaskets and the accelerator pump and other diaphragms, made sure all the passages were cleared out and that all the jets were cleaned and able to see though the holes, and checked that the floats didn’t have any holes or leaks, and also ensured that they don’t leak out from the bowl vents, however putting it back together I still cannot for the life of me get it to start, it still seems like it’s flooding out and backfiring out of the exhaust intermittently and I’m not sure why, I did also ensure the firing order is correct as well as the fact that it does have good strong spark on each cylinder and that the plugs are new, and that each cylinder has compression, I will say I’m very experienced when it comes to cars, this is my first time delving into a motorcycle so any help would be appreciated, thank you in advance