help bogging.

HI i just joined and i need your guy's help.. i have a 84 gpz 750 34,000 on it compresion is #1-170 #2-175 #3 175 #4-170 no air box bike runs good at idle when you go to give it gas warmed up of course sometimes it rev.'s all the way up but other times when you go to give it gas right after it bogs and wants to die if you dont let off. its not drivable like this i thought it might be coils so i put a msd. ignition on with acell coils and wires. that came off my other gpz 750 which runs good so i know the wires and msd. where good. tryd the ingtior box. tryd the ignition off my other bike. tryd the carb's off the other bike but nothing if some one chould tell me how to check the timing i will check it but i don't know the steps to do it, I have a timing light.. i had the mufflers on at first. but took them off when i put my 02 gsxr swing arm on. the plugs are brand new. sinch i took the mufflers of there pretty black maybe to much fuel? at first i didn't know if it was getting enough fuel so i took the tank off and put a small fuel cell on the top runing stright down with a inline fliter just to make sure its getting fuel. maybe its getting to much? i'm all out of ideas i would take the carbs off and clean them but its doing it on both the carbs so i was trying to check everything eles first before i got into them. does anyone have any ideas.?


thanks,
Andrew

I would say it's probably running too lean meaning it's getting too much air. I would get either the stock airbox with filter or get some pods and upjet.

definetly upjet.

so you guys don't think it's timing? I thought where the spark plugs where blak it was running rich. what jets do you guys rec.? I got some pods coming

Make sure you have enough gas in there or try switching to reserve.

you are going to have to have some type of filters on the carbs to make any kind of changes, if not what ever you do will have to be redone.

WELCOME 1984gpz750! Glad to have you aboard.

As interpreting -- 1984gpz750, with no air box or muffler, idles okay but either revs or bogs when warm, good compression figures, not drivable. Good coils, plug wires, ignitor and ignition. Same problem using good carbs from another bike. Timing not yet checked. New plugs are black. Fuel supply to carbs is okay.

You're correct in seeking to assure compression and ignition components being to specs before addressing carbs, as carb performance depends on all the other components.

So before any carb adjusting, would reinstall muffler and pods and also check/set ignition timing (with strobe-type timing light) and valve clearances. And with plug removed and grounded against engine, transmission in neutral, ignition turned on -- crank engine over and check for fat blue spark which provides evidence of good wiring connections in the ignition system. A weak yellow spark would indicate an ignition problem (in this case perhaps voltage to the coils is being reduced by poor wiring connections - just guessing at a possibility).

Would also test voltage reading between battery terminals for about 13 volts at idle and 14-15 volts at 4000 rpm (might have a weak or failing battery or poor ground connection from negative terminal to engine, or poor connection somewhere between positive battery terminal and feeds to coils).

Looking forward to progress report about the spark quality at business end of plugs, battery condition, voltage to coils, timing and valve clearances. As substituted known good carbs made no difference, am guessing the problem is resulting from a weak ignition (or possibly too tight valve clearances).

Post edited by: Patton, at: 2007/12/13 12:36

Did you say it had "NO AIR BOX"? Does it have pods?
Sounds like you have an air problem, suckin in way too much air, have an air leak somewhere, maybe around the carb boots?