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right guys, swapped the engines in the zxr750 last weekend and lack of daylight and lying in the snow is doin my head in, can't get the bike to fire up.Now everything worked fine b4 i swapped and i've swapped a good engine for a better one but why do i now have no fuel? have filled the tank up today to rule that out.bike spins and with a squirt of easy start will try and fire, today i checked for fuel, open the float bowl drains and dry as a bone so no fuel in the carbs, fuel is coming out of the tank and goes to the filter, but thats as far as it goes, now i dont know if the fuel is getting to the pump but its certainly not coming out of it.Have i created a vacuum somewhere or have i done something i've forgotten? any ideas? have checked connectors on the fuel pump and all connected.

tommorrow i'm gonna check the relay and if i get chance will run a direct feed to the pump. am i missing something?

Have you connected the fuel pipes the right way round on the pump ?
Inlet and outlet

connect the fuel pipe directly to the carbs and bypass the pump with a full tank of petrol there will be enough of a head of petrol to fill the carbs. That will at least get it started and allow you to check it's running ok

definatly check the fuel pipes are the right was round as cargo said!! i bought mine as a non runner as the bloke couldnt get it to run, turned out after 10 mins of fiddling the pipes were the wrong way round!!

i've not disturbed the fuel pipes, only disconnected the one from the carbs which is now reconnected.They put the fuel pump in the most stupid place!!

charged the battery up overnight and checked for voltage at the fuel pump connector 6-7v? anyways tried to fire it and fire it and fire it, battery is shagged i think so on with the jump leads off the bus and away it went, but boy it sounds like a bag of sh*te.So come the weekend the plugs are coming out maybe new leads then go from there.

had the day off today so thought i'd crack on with the zxr as its doin my head in not havin a bike on the road, fires up ok now but sounds rough as sh*t so thought i'd check the plugs and leads today, cut all the ends off the leads and put the caps back on, hadn't got a socket to get the plugs out so stuff it, anywayz i did notice the great hole in the top of the carb tops.

so methinks i'll swap the carb tops with my originals, i then checked the slides were moving freely and one of them was stuck solid, so whipped all the carb tops off and cleaned what i could, all moving ok now.Then methinks the bowls need checking so took the carbs off but why do kwaks come with screws made of cheese? couldn't get em off so took the drain screws out and they were all clean so i thought there's a good chance the insides will be.

Back together and fired it up, still sounds like sh*t, its p*ssing me off now. so i swapped the carbs that came with the engine for my original carbs, fired it up to find it sticks around 3-4k revs so i sprayed wd40 and casrb cleaner around the intakes to check for leaks, nothing there??? took it out for a spin it splutters and revs like mad! with revs hanging when changing gears.

think i'm gonna stick the old engine back in cos this is doin my head in.
anyone got any ideas what it could be?

another thing i noticed when messing with the carbs my originals have long springs and the carbs that come with the engine have short springs, why? and what difference does it make?

Its reving and spluttering sound slike the choke is stuck on to me. Thats what my 400 was doing last week, for one reaon or another the whole lot became stuck and choke was fully on. Would rev the toad out of itself at the lights and ran really crap.

sounds feasible rob but the choke seems to be working fine.i'm using my original carbs at the mo as i know they are working perfectly.

are you sure you not dislodged a wire when replacing engine? gotta check them plugs. put the old set in maybe? another thing, i stripped my engine down cos 1, the head gasket had gone and the block cracked, 2 , my bike was running just like yours. as i wanted to line up the timing marks i whipped off the cam chain cover and f*** a rubber duck if the ig nition coils were loose. and by loose i meant both bolts had fell out and oil suction was holding the plate on.


worth checking?

i bought the engine as a quick changeover to save servicing mine as i dont really have the time but its been nearly 2 weeks now and still not running, think i should have just serviced the old one. need to a get a new plug socket cos you can't get a socket in to change the plugs.i have a new set of plugs to go in.

think i will service the old engine and put it back in.

get a new plug socket first. its quicker and easier. will take u 10mins. if u sort it, job done. if not, then u can swap engines. be as fucker if the same prob still persisted indicating a wiring prob tho

tbh i think there's only 3 wires that were messed with, alternator, starter & pickup wires, i aint got any loose ones anyway lol.

can you not swap the cover with the hole in for one of your other ones, and balance em up and try that?
are the new carbs working with the engine, just rough like?
i put shorter springs in my zxr4 carbs, and it leaned evrything off slightly, and made it rev fkin quick, which makes me think that your original carbs are making you new motor run a bit rich, hence the raised revs?
i may be talkin total poo tho

it ticks over and sounds fine just the revs hang at 4k, with the original carbs it sounds like a bag of sh*te, think i'll whip the airbox off again and double check for intake leakage, will swap the springs over see if that makes any difference too.go from there i think.