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third thread, looking for a jet chart and more info 750 carbs cleaning

3K views 12 replies 4 participants last post by  93gc40 
#1 ·
so i got the carbs apart and the jets are
factory pilot (of course)
slow speed is 40s in both
and the main is 106 in both.

bike has stock air filter container but K&N fliter
and cobra pipes, not sure of size but not real big maybe 2" diam but i would get 1.5"




so i took the carbs off (2002 750) because i though there was a clog issue, but there clean well way cleaner than i though they would be.

the bike will not start unless the choke is on and even then it only sputers for a few sec, give it any gas even if you try playing with choke or throttle it just dies.

if you keep the starter going it will evetualy start going but only for a very short time.


the bike acts like its geting no fuel at all, on carb/starting fluid the bike will keep running and if you keep it going on that stuff it will at some point start to run on gas, but will not hold a idle or any thing near an idle you have to hold the throttle a good bit to keep it going.




tested the fuel filter fuel flows with great volume form the line both res and on.

how ever... not sure what the out put of the pump should be but the flow is far less than the grav feed is this normal. i didnt think to see if it builds pressue. could this this be the issue? i feel the pump kicking or pulseing. when starting or when it running.

is it poss able i have a bad pump and this is all it is?

well thanks for the info for now the carb (all torn down ie no rubber parts) is in a one gal can of crab cleaner, and the jets are soaking in b-12 gonna flip the carbs in the mornning and let it soak another 12 hours or more then put it back together.

there was some varnnish on the bowls and on the pilot jet (it was set at 2.5 turn out) would this have caused this run issue?



bike sat for well over a year with no one doing any thing to it.



again thanks for the help.
 
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#2 ·
#3 · (Edited)
the pump pumps but the flow is slow.
if you just test the flow out of the filter the flow is much faster. so the filter is good.

i rechecked the jets only the mains were changed 104 and 106 slow speed jets were not touched. there is varnish (was) on the pilot jets.
best i can tell from the main neddles and the main jets it has a stage one kit and c clip in the 3rd spot.

the carb has been soaking all night as well as the jets. i plan to try to put it back together tonight.

bowls, floats, and the bowl jet(or meter) also is in good shape.

got plenty of spark. when the bike was able to get fuel it would run just fine.

the gas was/is fresh.

i havent pulled the plugs yet... but plan to tonight just to check them

i read some were how you could use a pump form the parts store to replace the one on the bike for far cheaper. does any one know what one i should look for.

i plan to do the bypass for the pump so i can keep it running when it is all back together.

i haven't been able to find a good thread with good large size pictures that show what the relay looks like. because there are two on the bike that look like it.


thanks again
 
#5 ·
i haven't been able to find a good thread with good large size pictures that show what the relay looks like. because there are two on the bike that look like it.
If there is only 2, test both. If they are the same part# on the relay SWAP them. See if the issue follows the relay. Be sure to check fuses. Is battery strong?
Sounds like too low on the idle screw. You said it will run if you hold the throttle open a little. Opening the throttle does NOT add gas it increases the air flow, same as the idle scew. The throttle JUST opens the butterflies and the idle screw adjusts the butterflies. Fuel flow is controled by vacuum and the vacuum slides and the float needle.
 
#6 · (Edited)
i maxed out the idle screw you got about another 1/4 throttle to go before it gets to the idle stop screw and it will stop running at that point.

after that 1/4 throttle it will run just fine to max throttle with no lag or hesitation (spell)

in any case i figure the idle circit is what is clogged and i got ti all apart (ecexp for the carbs separated) and soaking in carb cleaner. i got a air compressor we will hit it with that when we pull it out tonight.





edit for got to add, the battery to be honest i cant believe this new battery has held up to all this cranking. i will need to put the trickle charger on it be sure this will not be a issue latter.
 
#7 · (Edited)
ok.... i'm working now, well sorta


fuel pump tested all good.
carbs put together and set

bike will now idle like a kitten


new issue how ever
start to open the throttle the ruffer it gets till it starts shooting flames out of the exhaust and the more you open the more it starts to die out.

i think i have a vac line that is not hooked up right. its the (AIR VENT TUBE) i think the neddles are not raising as the rpm comes up. were should this line go?

i tried to pull a vac on the AIR VENT TUBE and got fuel all over me, not sure if its a vac or if it a pos side line. all the rubber diaphragms are good no rips or tears.

any help is greatfull
 
#9 ·
more research has shown to me that the tube i sucked on is the vent for the bowls.....
no wonder i got a mouth full of gas.


still got to figure out why the needles are not raising when the gas is given. i may have to pull them off (the carbs) and recheck the install. all the marks were inline (per the service manual)


o well at least im making some sort of progress. the more i work on it the less dirt and oil is on it and on me.
 
#10 · (Edited)
well, found the main issue.

forward cyl is flooding out while runing so the float and or needle needs replacing or ajustment.

but.... was able to ride it for the first time, i just had to play with the fuel on/off to keep it from flooding out


abut after ridding it more and more it seemed to get better and better but that front cly is still getting flooded out.

also it kinda falls on its face in the upper rpm and pops in the exhuast so jets need to go way up im thinking from
104 in the front to a 108 and the rear from a 106 to a 110 (unless someone thinks i need to go bigger) and
the slows from 40s to a 45 or 44

bike has drop in K&N and cobra 2" pipes no baffles and were on the coast (sea level)


but due to lack of what i know i think taking to dealer to have this all done would be best (floats and all)
i can clean them and if it only needed jets that would be easy.

or would a rebuild kit have what i need. you guys tell me, i already had them apart it isn't that hard to do. how hard is it to set the floats if that is the issue. the float jet has a rubber tip it looked good but it may be worn. i didn't know it was rubber when i put it in the B-12 cleaner. could that be what is causing this issue? thoughts.
 
#11 ·
but due to lack of what i know i think taking to dealer to have this all done would be best (floats and all)
i can clean them and if it only needed jets that would be easy.

or would a rebuild kit have what i need. you guys tell me, i already had them apart it isn't that hard to do. how hard is it to set the floats if that is the issue. the float jet has a rubber tip it looked good but it may be worn. i didn't know it was rubber when i put it in the B-12 cleaner. could that be what is causing this issue? thoughts.
I used B-12 and it caused no problems whatsoever.

As far as taking it to the dealer, if you can take the carb apart to clean and replace jets, then you can adjust the floats and replace any worn or damaged parts. The Honda Service manual will have all the info you need.
 
#13 ·
You had the carbs apart.... Have you synchronized them yet. You will never solve this issue to you get the carbs into sync, FIRST. Here is a home made sync tool, $1.55 Carb Sync Tool by Marty Ignazito, you will need to make adapters or buy them from Motion Pro for $5.00. This tool is required to get your carbs working correctly. This may be you whole fuel issue.
 
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