Carburetors xj750 question

Cleaned the carbs multiple times still won't fire up my question is what's the worst that can happen if I take them off spray starting fluid in each of the 4ports on the motor itself and try to crank it for a couple seconds that way? If itd work and I know 100% carbs are bad I'd be going to buy a new one but I'm wondering if something is torn up in the motor or I've got something wrong elsewhere on the bike

 

Make sure you prime the carbs using the PRI on the fuel petcock. Those cab bowls will be dry as heck after cleaning them. If you have the air box pulled back a little you can put your hand over the intake of the carbs to get a little more fuel going at well, this will pull more fuel up and you should get it to fire.

Bottom line yes you can us starting fluid, I do. Depending how wet the cylinder is or how fowled the spark plug might be. I don't know how your battery is, but the battery has to be FULLY charged to make sure you get good spark. I normally have a car battery jumped to my bike when I am bringing them back to life. This way I know I have enough battery power to make the TCI fire.

If you could get us some pics of those carbs that would be great. Being bad to one person could be just a little more cleaning to another person. Good luck.

 

Alright I'm about to take some pics of the carbs in a little while when I go tinkering but when I take them off completely and spray a shot of starting fluid in each port of the motor do you think it'll fire up or do I need to cover each port after spraying starting fluid in them, would this mess up the motor at all? All I'm trying to see in doing this is will the motor fire up it was ran for about 60secs without oil about 5times I'm trying to see of anything's torn up in it or of it'll fire up

 

I do this all the time to see if a motor will fire, no harm at all. It'll pop/sputter or rev up for a second. Good enough to validate spark etc. but won't tell you the condition of the motor. Need to do a compression check and check valve clearances.

So 5 minutes of runtime without oil in the crankcase?

 

Yeah now I've been told to bench sync the carbs that's my issue I can't seem to get them synced what's the exact method? 82 xj750

 

Very big issue now just happened, oil out of crankcase breather when the motor spins what causes this?????

 

If your float heights are set correctly or the needle valves aren’t sealing, it’s very possible the crankcase filled with gasoline. Open your oil filler and look/smell for gas.

 

check oil level first with bike on centerstand you want to see an air bubble at top of sight glass bike wants to be level left to right.

to high of an oil level can cause oil to blow out the vent pipe.
oil level can be high gue to over fill or gasoline in crank case.

if above is not the issue and oil level is proper you are getting blow by at the pistons

 

bench sync.
if you look into the carb throat from the motor side you will see little holes in the top of carb throat.

start with idle knob and adjust carb 3 untill the plate lines up with rear of hole. cycle the throttle linkage a few times make sure the plate is still lined up with back of hole.
then do carb 4 the screw with springs on it is the adjuster turn it untill plate is in same location , cycle linkage check alinement. then do carb 2 followed by carb 1. when all done adjust idle knob on 3 untill you only see half of the hole.
your done.

when you start bike you will have to adjust the idle knob when it warms up

 

this is a seca 750 correct?

 

Maxim 750 yics

 

Drained the oil replaced with 10w40 valvoline 2quarts when I try to start it here in a bit should oil again puke from the crankcase breather? If so how do I fix this

 

Is your oil Jaso ma ma2 motorcycle oil?
The oil spec for your bike periodic oil change 3.81 us quarts with filter replacement 2.64 us quarts.
Does your bike have a center stand if it does put bike on center stand and check oil level through the glass sight window on the clutch cover right hand side of bike you should see an air bubble in the top of the glass site.
If your bike continues to blow oil out the vent tube then you have internal pressure build-up. This could be caused by bad rings or you have a hole in one of the Piston tops

 

4 temperature is 60 degrees Fahrenheit 15 degrees c and below you should use 10 w 30 the temperature is 40 degrees Fahrenheit in above you should use 20w 40 this just makes it easier for the bike to start and then we'll to flow where it needs to go.
You have about 6 oz of extra oil in there right now it should not be a problem but you will not see an air bubble in the glass site

 

So I've got 2quarts of 10w40 valvoline and turned it over no more oil squirting out but when I sprayed starting fluid it would spin and spin a little rumble then one time fired for like .5 second then I ran outta starter fluid and used intake cleaner and couldn't get it to fire up kept sounded like it wanted to after I covered 2 ports and soaked them in intake cleaner..

I'm wondering if the timing is off it used to run every time I hit the button what could cause timing to jump and how do I test and fix it if so

 

. to check ignition timing remove left crank cover there is a timing mark and pointer if timing is off you will need a new tci.

you could check valve timing as well requires checking cam location dots and tdc mark on plate under crank cover.

you should start by ohming out your ignition system . pick up coils from the plug at tci , ignition coils from other connector at tci and through spark plug caps 1 and 4 then 2 and 3.

excess starter fluid will foul spark plugs remove and clean or replace and make sure battery is fully charged do a voltage drop test after charging resting battery should have 12,8 volts and cranking voltage should not drop below 10 volts.

carbs Have yu bench synced them and set mixture screws to 2-1/2 turns up from soft bottom?
how did you clean carbs?

is your fuel tank installed? full of fuel? if not is vacuum hose plugged?

 

Update bike runs took a piece of fabric tied a couple knots soaked them in gas stuck em directly in motor ports where carbs would plug in and bike fired up so carbs are either shot or need syncing I tried bench syncing but one of the screws where it screws in at is stripped so I'm going to use afro enginuity and take 2 square nuts one on top one on bottom and thread a bolt through the bolt will sync that carb. Also going to have to figure something out with the idle adjuster bolt it's not threading enough to open the valves with the throttle the bolt itself is about a quarter inch away from it I'm thinking put a nut on thread it halfway and put another bolt in the rest of the threads to make up the difference. Eventually if I'm keeping the bike I'm thinking look for a brand new set of carbs this whole time I think they were the issue of it not running all the f***ing headache this bikes gave me and it was the carbs the whole time smh guess that's what u work with when you buy a basket case from the scrap pile for $200

 

Xj550h I appreciate ya you've replied the most to the few questions I've posted here about the bike thanks yall

 

i would get the next size screw then drll and tap metric ot inch. what ever fits through springs

 

I had a similar issue with my 700. Cleaned the carbs (minus the enrichment tube and mixture screw port) but couldn’t get it to go. Took them off, cleaned the tiny enrichment tubes and mixture screws and it fired up. Not sure what you did to yours, but that was my experience.
Maybe your cylinders were flooded too if you had oil and gas mixing....?