Kelum Posted January 5, 2013 Share Posted January 5, 2013 I did a total engine overhaul and fitted new rods and piston rings in the engine. Bought a reconditioned manifold that comes between two engine heads but the manifold was shorter than the gap between heads. So the garaj guy gave me some thick mat-like/plastic-like material with which I cut matching shapes for both manifold-head ends like below. After fitting the bike started very well. But later it wouldnt start..the engine cranks without gas...vacuum pipes are well sealed. The fuel pump does not pump fuel, I checked inside of it and its ok, but I doubt the vacuum-operated end of the petcock...the fuel is not pumped because there probably is a vacuum leak...cant figure out where this leak is.. When I Prime the engine, the fuel enters carb through the pump, but in that Prime position at least bike doesnt start....I checked and removed dirt inside the carb. I am pretty sure the problem lies in the fact that pump doesnt pump fuel in...I removed the the pump - carb hose and while cranking there is no fuel jet coming out from pump...the vacuum is not powerful enough to operate them... the carb - pump hose is a see-through one so I can see if fuel is pumped or not. Doesnt the bike suppose to start at PRI position when there is no vacuum? I checked floater needle too, it works ok. My guess is either the petcock housing or pump housing having a vacuum leak. What do you think guys? PRI position has the capacity to start and run the bike when vacuum doesnt work? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 5, 2013 Moderator Share Posted January 5, 2013 cant see the picture kelum Link to comment Share on other sites More sharing options...
dt502001 Posted January 5, 2013 Share Posted January 5, 2013 Put shaving cream around the suspected areas of vac leak,start the bike and look to see where the shave cream disapears presto vac leak found. Also aply vac( using a syring or vac pump) to the petcock and see if fuel will then flow Link to comment Share on other sites More sharing options...
dt502001 Posted January 5, 2013 Share Posted January 5, 2013 Give it a secon the pict comes up Link to comment Share on other sites More sharing options...
Kelum Posted January 6, 2013 Author Share Posted January 6, 2013 cant see the picture kelum pic is visible buddy, please have a look and comment.. Link to comment Share on other sites More sharing options...
Kelum Posted January 6, 2013 Author Share Posted January 6, 2013 Put shaving cream around the suspected areas of vac leak,start the bike and look to see where the shave cream disapears presto vac leak found. Also aply vac( using a syring or vac pump) to the petcock and see if fuel will then flow The bike doesnt start buddy, did u mean cranking? Petrol wouldnt be pumped out by pump...thanks for the tips buddy... Link to comment Share on other sites More sharing options...
dt502001 Posted January 6, 2013 Share Posted January 6, 2013 1stpost..... PRI position has the capacity to start and run the bike when vacuum doesnt work? last post ... The bike doesnt start buddy, did u mean cranking Ok confused but I'll go with not running .If you fill the carb or from another fuel source ie gravity feed tank then the bike will run ...right? If so run it that way with everything else hooked up Ie fuel pump vac lines to tank and see if the pump,pumps fuel into a bottle and at what rate and check for vac leaks/vac supply to pump. If you have a good vac to pump and fuel supply to pump is not blocked then pump is shot. Link to comment Share on other sites More sharing options...
Kelum Posted January 7, 2013 Author Share Posted January 7, 2013 1stpost..... PRI position has the capacity to start and run the bike when vacuum doesnt work? last post ... The bike doesnt start buddy, did u mean cranking Ok confused but I'll go with not running .If you fill the carb or from another fuel source ie gravity feed tank then the bike will run ...right? If so run it that way with everything else hooked up Ie fuel pump vac lines to tank and see if the pump,pumps fuel into a bottle and at what rate and check for vac leaks/vac supply to pump. If you have a good vac to pump and fuel supply to pump is not blocked then pump is shot. When I turn on PRI, I see petrol flowing in the carb, and the floater compartment does have fuel as petrol seeping when I unscrew the bowl knob at the lower end. But the manual keeps saying that you should not run the bike at PRI position, you should only use PRI when the carb is emptied of fuel supply? Why? If PUMP doesnt work, u should be able to ride at PRI position right? I did remove the carb feed hose from the pump and cranked the engine...pump sometimes pumps fuel, but mostly dead...my petcock valve, the circular black rubber with holes/valves under rotating knob, had some wears...so am guessing probably the petcock having a vacuum leak which affects bad on pump too as they both are connected by same vacuum line... But my logic here is, at PRI position, since petrol keeps flowing into the carb, she should start..why does the manual say not to run at PRI, It asks only to prime system and start u can use it, but when running turn it back to the ON position...I know if there is a prob with floater needle, at PRI position it fuel will flood the engine..the reason is that? I checked the floater needle, cleaned it, attached a long hose to the carb breather and kept it near my ear and blew some air through carb feed line to see if floater needle turns on and off airflow to my ear when the floater is up and down..it works perfect.. You need to slant the carb so the floater moves up to open - so air flows in to ear, and down to close the air flow. Link to comment Share on other sites More sharing options...
Kelum Posted January 7, 2013 Author Share Posted January 7, 2013 Another thing, when I try to bump start, the engine seems to fire up few cycles and doesnt seem to hold on..like it has some fuel starvation...plugs working ok! Can someone explain me how the membrane (opposite side of fuel floater chamber) in carb works, what makes it operate, a vacuum? I feel there should be some problem with it? membrane is not torn..some block? Link to comment Share on other sites More sharing options...
dt502001 Posted January 7, 2013 Share Posted January 7, 2013 Ok if fuel flows during prime,but not when vaccum is aplied to the petcock, then the small diaphram in the petcokc is not moving to allow fuel flow. Run the bike and make sure the small hose from the intake to petcock has a good vac not torn or loose at either end.You can run the bike with it disconected when in the prime position As far as running on prim ,yes it only if the float is not seating/stoping fuel when full.Otherwise no reason why you can't run on prime just have to shut it off (ie turn to run )when stoped and you no longer have reserve. The diaphram on the top of the carb works by the difference in air pressure on either side of the carb, the oval slot at the top of the inlet side of the carb if you blow air across it (not in ) the slide will move up.If it's no good the bike will still start and idle just won't rev up or rev up weird. Get a bottle and hang it higher than the carb with fuel in it and run the bike that way,this will give you a gravity feed set up, eliminating the need for the pump just to prove you have a fuel delivery problem.Also pour a tea spoon of gas right into the spark plug holes put the plugs back in fast and try to start. Get a spray bottle and squirt fuel into the carb air inlet if it will run this way then the pump is shot or you have a vac Link to comment Share on other sites More sharing options...
Kelum Posted January 8, 2013 Author Share Posted January 8, 2013 Ok if fuel flows during prime,but not when vaccum is aplied to the petcock, then the small diaphram in the petcokc is not moving to allow fuel flow. Run the bike and make sure the small hose from the intake to petcock has a good vac not torn or loose at either end.You can run the bike with it disconected when in the prime position As far as running on prim ,yes it only if the float is not seating/stoping fuel when full.Otherwise no reason why you can't run on prime just have to shut it off (ie turn to run )when stoped and you no longer have reserve. The diaphram on the top of the carb works by the difference in air pressure on either side of the carb, the oval slot at the top of the inlet side of the carb if you blow air across it (not in ) the slide will move up.If it's no good the bike will still start and idle just won't rev up or rev up weird. Get a bottle and hang it higher than the carb with fuel in it and run the bike that way,this will give you a gravity feed set up, eliminating the need for the pump just to prove you have a fuel delivery problem.Also pour a tea spoon of gas right into the spark plug holes put the plugs back in fast and try to start. Get a spray bottle and squirt fuel into the carb air inlet if it will run this way then the pump is shot or you have a vac Ok...sounds a big checkup...sure I will check one by one... PRI position is not safe once the floater needle is worn out ( as it can flood the engine, kill the lubrication by oils ruining engine) thats why the manual always asking to turn petcock to ON. Bike does attempts to start when I bump start it but wont hold on.. I blew some air from the top oval channel of the carb and slider moves. There's no prob with the floater needle as it cuts off air as floater closes the opening when I slant it. Will update by and by..thanks mate! Link to comment Share on other sites More sharing options...
Kelum Posted January 9, 2013 Author Share Posted January 9, 2013 The fact that bike wont start even at PRI is a problem...There is a prob other than vacuum? I plugged in another TCI and tried..no luck... Can someone check if bike starts and runs ok at PRI for me? Link to comment Share on other sites More sharing options...
neversaydie Posted January 9, 2013 Share Posted January 9, 2013 The fact that bike wont start even at PRI is a problem...There is a prob other than vacuum? I plugged in another TCI and tried..no luck... Can someone check if bike starts and runs ok at PRI for me? Hi Kelum I recall running out of fuel on the XVS dragstar once, turned the fuel tap to PRI, cranked the engine over and as soon as it fired, switched onto reserve. I assume the xvs and the xv are the same system. I am currently still running my Radian with the fuel tap always on PRI, the fuel level in the carbs is controlled by the floats. I switch the fuel tap to ON when the motor is not running as the vacuum valve in the fuel tap doesn't work. Pull off the fuel line at the carb and turn the tap to PRI, does fuel flow out? Link to comment Share on other sites More sharing options...
Kelum Posted January 10, 2013 Author Share Posted January 10, 2013 Hi Kelum I recall running out of fuel on the XVS dragstar once, turned the fuel tap to PRI, cranked the engine over and as soon as it fired, switched onto reserve. I assume the xvs and the xv are the same system. I am currently still running my Radian with the fuel tap always on PRI, the fuel level in the carbs is controlled by the floats. I switch the fuel tap to ON when the motor is not running as the vacuum valve in the fuel tap doesn't work. Pull off the fuel line at the carb and turn the tap to PRI, does fuel flow out? Yes fuel flowing out...the carb is getting fuel...I dont think its the petcock...its like the carb doesnt feed the heads...must check wiring and all...what do you think buddy? Link to comment Share on other sites More sharing options...
dt502001 Posted January 10, 2013 Share Posted January 10, 2013 Did you try squirting fuel in with a spray bottel? Or puting gas in the cylinder? Link to comment Share on other sites More sharing options...
Kelum Posted January 10, 2013 Author Share Posted January 10, 2013 Did you try squirting fuel in with a spray bottel? Or puting gas in the cylinder? Not yet...doing it saturday...either of these will be ok right? Please explain, did you mean that I hae to remove gas tank, leave carb open..(funnel from air cleaner removed )...add some gas into the carb from top and crank the engine? that wouldnt cause any issue for carb, I mean direct feeding? Link to comment Share on other sites More sharing options...
dt502001 Posted January 10, 2013 Share Posted January 10, 2013 Wow your complecating things,just spray some gas in the carb inlet and crank the thing over if/ when it starts keep squirting gas at the carb if it dies when you stop spraying gas at it then the pump is not lifting the gas to the carb. If it dosen't start then you have other issues. Link to comment Share on other sites More sharing options...
Kelum Posted January 10, 2013 Author Share Posted January 10, 2013 Wow your complecating things,just spray some gas in the carb inlet and crank the thing over if/ when it starts keep squirting gas at the carb if it dies when you stop spraying gas at it then the pump is not lifting the gas to the carb. If it dosen't start then you have other issues. K sure will do it and update u... Link to comment Share on other sites More sharing options...
Kelum Posted January 21, 2013 Author Share Posted January 21, 2013 OK guys here comes the update! Checked the spark with old spark plugs and they were sparking ok, but I put new plugs on both heads and tried, no luck, just cranking. After that leaving her in new spark plugs I removed the tank plus pumps and petcock and put a teaspoonful of gas ino the top of the carb and cranked. Bike started right away. When I opened the carb before for the first time after this issue came up, there was some gel like thing inside, probably some liquid gasket inside the gas bowl, I cleaned all the idle and main jets plus the metal filter under the float needle. But I didnt open the membrane/diaphragm side and the black piston moving horizontally inside carb. Now I have the feeling that while the float chamber has been cleaned ok, there is some block inside the needle like thing inside black horizontal piston operated by the diaphragm...everything else is ok, carb does not deliver fuel to inlet manifolds. Should I clean the needle inside the piston? Is that the one to blame? Is it possible that glue like thing which was inside gas bowl or float chamber has been sucked up and blocking the jet/needle inside carb piston? Help me guys! Link to comment Share on other sites More sharing options...
Kelum Posted January 21, 2013 Author Share Posted January 21, 2013 Ha ha, I removed the carb and all seem to be ok... ( I did some stupid thing ha ha , after removing the carb I wanted to make sure if I pour some gas direct into carb joint would it fire up the engine...did so and bang it started right away but there was fire on carb joint...ha ha..it didnt harm anything. I killed it fast.. ) Now back to the issue...I'm assuming that the needle on the piston does not deliver petrol into inlet manifold(s). Probably the membrane with piston stays stuck? Its operation is governed by the air filter line ( frame ) right? And membrane has no tears or wears... What should I do? .......................................... I just blew some air with a compressor through jets and holes of the carb in order to clean it. Waiting for your responses! Link to comment Share on other sites More sharing options...
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