Voltage drops problem

Hi all, ive start to work on a project bike xj550, and ive got problem with voltage, aterer turning ignition it have 11,5 max v, when cranks 8-9v. Because of this bike wondt start, battery new yousasa 180A, Fuse box replaced, terminals on battery clean, on starter motor clean. Carbs are clean to, starter brusches are barely new, Where i should looking?, ive read alot on forum but maby im miss somethig, Please help guys because im loosing hope to get this bike started

 

Inspect and clean the frame grounds, along with every electrical connector on the bike. Corrosion causes increased resistance. Increased reisitance causes voltage drop. Voltage drop causes bikes to not start.

 

does the headlight go off while the starter runs?

 

this was my thought too.

CN

 

thanks for advice guys, where i can find frame grunds? i found only one under air filter housing.
Polock hard to say because i dont have lightbulb instaled...

 

the new battery, has it ever been on a charger? a new battery needs to be charged.
a bad ground will make the voltage drop less at the battery but check the plugs anyway.

 

I agree. I think you need to charge the battery.

The voltages you're seeing are too low both before and when cranking.

The battery should be showing you at least a good solid 12V if not more, before cranking; and if it drops below about 10V while cranking it's not going to fire.

 

fresh news from battle field, battery fully charged 12,6v on battery, bike voltometer shows little bit under 12... ground point on frame clear and shiny, bike still not starting, ive check and spark is good. I only synchronnize carbs with paper clip method, maby this is the reason? but to proper synch i need to start this damn thing :evil:

 

Is there fuel in the float bowls? Have the carbs been cleaned?

 

This is a good question...hwo many frame grounds should you expect to find and where should they be located?

 

Hook that thing up to your car battery and report back. Then we can eliminate your battery as a possible problem. Have you got full choke when starting? Does it fire at all? Are the plugs wet after starting attempts?

 

2 good points k-moe, they can be hard to start after carb strip down, try a shot of quick start, see if you get any sign of life.

 

Are you using fresh fuel? That is, not the fuel that's been in the tank for months.

My XJ750 isn't starting at the moment, and I'm sure that it's because I haven't started it since the middle of December. The fuel from the tank is going into the car this afternoon, and the day before I start riding it again I shall buy some fresh stuff.

 

FLOAT LEVELS?

I see mention of a bench sync; did you accurately wet-set the float levels?

When did this motor run last? Do you know it makes good compression, valves in spec?

 

If it's not starting on the button, then you could jump from a car as Adrian says, you could try and pushstart the bike or you could use the Polish equivalent of east start to fire her up. Easy start might not be good to use on a regular basis, but you need to know that she will start.

It's either start the bike and troubleshoot what might be wrong, or else assume everything needs doing and do everything properly.

If the problem is with the starter (how quickly does it spin ?) then push starting will show that everything else is working.

 

Gas is fresh,valves set (one was too tight), float levels are good( litle bit below floatbowl and carb line) its a second battery tested in shop and its good (youasa) i use carb cleaner to inject into carb and still nothing, i cant push start because i dont have seat yet... I also think about puting carbs into sonic cleaner, maby they are still not clean some how... Im loosing my mind because of this bike. I forgot to say that when i bought this bije it was a problem with cold start, po always inject fuel into filter housing and bike starts...

 

Have you looked for vacuum leaks?

 

Ok guys, i dissembled carbs again and clean them in ultrasonic cleaner this time ive break the rack, ive notice that throttle shaft seals are slightly loosen. Ive check when bike was runing and spray some easy start near carbs and rpms doesent grow, but i would like to replace them, could this be a cure for this bike? Unfortunately they hare not abaliable in poland so i have to order a custom made seals, which are quiet expensive :/

 

the parts man "chacal" or Len might be able to help you out. click the engine on the top right of the page.
they can be replaced with two o-rings per seal also but you have to know the two sizes that fit

 

Polock so uou say that i can simply replace the seals with the orings? that would be great! is that safe and long term solution? and what do you mean two sizes? are they 2 different sizes per one seal?