hope this is the right place to post this

i purchased a 1989 VFR 400 on sunday the bike was sold running and great few bits of work to be done ie new tyre, minor cosmetics, etc,

but on the way home the bike stalled, and would not restart, we waited for it cool (10mins) and it restarted, we rode say a further 5miles and stalled but this time wouldnt start. so we popped in the back of the van and drove the remained home,

when i got back i removed the plastics and set to work on the carbs, only to find a previous owners attempts of destroying them, emulsion tubes in the worng way as were the needles, cracked fuel pipes, damaged seals so i bought a set of rreconditioned carbs off ebay, £54.99,

to day i have rejeted 118 front, 120 rear, lifted the needle up 0.5mm, drilled the slide out to 2.5mm dia, clean and sealed them up set the adjusters, etc

i also changed fuel tap to a gravity and got rid of the vacuum supply, by putting a small ubend from the 2 smalled pipes.

put the choke on and bingo 3 turns later it fired up, however i needed to adjust the throttle cable and set to work stripping it all back down, put it all back and now it wont start at all battery is back on the optimate, the 4 plugs seem ok all sparking, and doesnt smell as if its flooded,

im just curious about the heat when it gets hot why wont it restart i must be doing somehting wrong.

you help would be hugely appriciated, i passed my full bike test monday and im eager to get out and stretch the cable!

Thanks RB

rickyb_dj wrote:
i also changed fuel tap to a gravity and got rid of the vacuum supply, by putting a small ubend from the 2 smalled pipes.

If you have removed the diaphragm out of the tap you need to block the vacuum spigot on the no3 cylinder. Also, the 2 smaller pipes ont eh tap - one ios for vacuum, the other is a drain, so don't block it..

Ideally, sticking with vacuum is the way to go, especially if you ar enot 100% your carbs are spot on.

The plugs on these bikes can be easily killed, as I suspect you have just found out. get them out, dry them in a gas flame..cross your fingers and when you stick them back in, choke, no throttle and see if you can get it running. If you do, get out on it and give it a blast. the plugs don't like to be started and stopped all the time.

good luck with it..this is the right place to be

thanks fella, i cleaned the plugs before i posted managed to rig up a frankenstein extension bar and 1/2" socket to get the front plugs out without dismantleing the rad,

im not feeling 100% today screwed my back up so no bike play time today, just need R&R but will get back out there tommora evening,

how do i test the fan, i put to female spade crimps across 2 of the terminals in the plug and shorted on the battery but nothing span/spun up, so i guess maybe the fan maybe up the duff,

which pipe on the tank tap is the vacuum and drain, i just did a small loop 2 the two holes to block them without damaging it, but will block them off individually and pop a little bold in the hose, i removed the vacuum hose and nipple from right rear cyclinder and popped a 5mm allen bolt in it.

thanks again in advance for your advice, i think ill like it here

BINGO its started

the problem was i hate to say this id left the kill switch off! what a KNOB

but now i have her running i stripped the throttle handle and cables out to lube and clean as i seem to have problems getting the carb to idle correctly. ill tell you what i have done and see if i have missed anything out

carbs jetted 118 front 120 rear
slide drilled to 2.5mm dia
needles all raised 0.5mm (now 1.0mm)

all butterflies manualy synched with drill bits until vacuum clocks/guages go on to be fine tuned.

all screws on 4 carbs at 2.25 (2&1/4) turns thats 2 full turns not easily done half turns

throttle off on bottom of carb with 1x 10mm lock nut
throttle on on top of carb with 2x 10mm lock nuts

bike is currently fueled with normal unleaded as the optimax was sat dormant i believe so scrapped it, will be fueling up with vpower tomorrow when i get her out

when the bike idles its sits at 3.5k quite high tbh, when i put extra pressure on the throttle to close the revs drop nicely to 1.5k but when i steadily let go the revs slowly pic up back to 3.5k again

what could be the cause bare in mind i havent riden her yet as ive not managed to get the plastics back on yet.

i hope this gets seen so i can hopefully get this last niggle sorted

thanks Rick

so whats the crack with this vacum pipe, been doing searches and keep finding diff things to do to it depending on set up.

iv got my tank off at the moment and using an auxilary tank so gravity fed, although i was hearing a hissing noise earlier trying to start my bike and blocked a fat pipe off with a screw, and it fired up.... so are there 2 vacum pipes? one on top of the tank and one coming off the tap under the tank!?

ill have to route the pipe i blocked off earlier to see where it goes and if its even connected lol

iv also got a small pipe coming from my rear right manifold leading to the cylinder....its not connected to anything and with my finger on it i can feel it pulseing!?

the bike seems to be running ok now like this, just wondering if it will all goes tits up once tank goes on and the vacum is reconected!?

the pipe on the top of the tank is a breather thats all, follow it down it will go to a T piece where it connects to 2 more pipes they hang down the left hand side of the engine and and are not attached to anything as there breathers ,
the pipe you have connected to the right rear cyclinder is the vac pipe and is connected to the fuel tap the pulsing you feel is the suction caused by the cylinder that opens the diaphram in the fuel tap to let the fuel flow

ah right! i never knew about this little pipe lol cherrs mate

Holy thread revival, my first post i believe! Yeah if you have the vacuum unconnected it will make the bike idle at 4k ish, put your finger over it and it willl drop to normal.

even with the auxilry tank! and not the normal one mate! as this makes sense coz i had to lower my idel once started . i later found the pipe and felt it pulsing.