YZF 750 wont start

craigy · Post by **craigy** » Thu Aug 11, 2005 12:09 pm

<img src=http://img.photobucket.com/albums/v209/ ... ng_sad.gif ALT=":sad"> It all started after a winter rest for the bike i went to start ot for the first summer ride and i could not get the bike to start,i always had to put the choke full on when cold to get it going but now it's as though the choke just aint doing its job, symptoms are: 1. Will turn over bike in attempt to start until battery is flat 2. Onto donor car battery will eventually fire up i'm guessing because the friction has taken the chill off the pots. 3. Will just to say grasp onto life with a slow idle with no throttle response. 4. Idle picks up but will not rev still when throttle twisted back 5. Eventually kicks into life wind throttle open, it revs clean and black stuff comes out and you can ride as if nothing was the matter. 6. Next day when the bike is cold you go through it all again. <img src=http://www.ezboard.com/images/emoticons/mad.gif ALT=">:"> Any help appreciated, iv'e stripped the carbs in situ and clean the float bowls out and an checked and cleaned the carb diaphragms, i dont know what else to check. <img src=http://img.photobucket.com/albums/v209/ ... ng_sad.gif ALT=":sad">

dragracer1951 · Post by **dragracer1951** » Thu Aug 11, 2005 12:13 pm

carbs are dirty. remove them and disassemble them and clean them very well...clean out ALL the jets. The mains, pilots, main airs...everything. spray carb cleaner down EVERY orifice in the carb body. Set the float level and resync... Jim <img src="http://img.photobucket.com/albums/v209/ ... Cheers.gif" style="border:0;"/> <img src="http://img.photobucket.com/albums/v209/ ... states.gif" style="border:0;"/> Hey Kid...Is my taillight working?

craigy · Post by **craigy** » Thu Aug 11, 2005 12:41 pm

Thanks for the quick reply, i used some carb cleaner to do the best i could and sprayed it down all the jets i could see or get to from looking at the carb set in situ. But yes your quite right i really do need to get them out and on the bench for a clean, now comes the next question, how on earth do you get them out! i tried but access is impossible unless i drop the full engine out, or so i figured. same goes for a carb balance, i cant get access to the connecting ports. Is there a magic way to achieve all this ? Or just struggle

dragracer1951 · Post by **dragracer1951** » Thu Aug 11, 2005 12:48 pm

hte manifold clamps are a PITA!! I removed mine (FZR1000) and replaced them with stainless hose clamps. Those have a hex head screw not some little wimpy philips head. Anyway. Remove the airbox, then loosen the manifold clamps and off come the carbs...remove the choke cable and throttle cables. Drain and clean ... the manifolds (aluminum) can now be removed to install the adaptors for the manomometers, and reinstall with the hoses on them...otherwise you can't get to #3 under the thermostat. Reinstall the carbs and sync. then remove the carbs and remove the manifolds....ad nausium Jim <img src="http://img.photobucket.com/albums/v209/ ... Cheers.gif" style="border:0;"/> <img src="http://img.photobucket.com/albums/v209/ ... states.gif" style="border:0;"/> Hey Kid...Is my taillight working?

craigy · Post by **craigy** » Thu Aug 11, 2005 1:19 pm

Thanks for the help Jim i'm just gonna have to get brutal with them and get the things off one way or another i have no choice, if a remember they had 2 clamps a piece with an allen screw head. looks like a job for the weekend all being well.

creed12r · Post by **creed12r** » Thu Aug 11, 2005 2:06 pm

You will find that the allen bolts that you need to undo are on the engine side of the carb rubbers and the rubbers come off with the carbs. Access is easier if you first remove the coils with the baffle assy (3 bolts), and the four allen bolts that you need to undo all point toward the front centre of the bike. chris

craigy · Post by **craigy** » Fri Aug 12, 2005 5:25 am

Thanks for all the help guys

craigy · Post by **craigy** » Mon Aug 29, 2005 3:26 pm

Damn it cleaned carbs twice , and thoroughly still no joy, what next ? compression test

dragracer1951 · Post by **dragracer1951** » Mon Aug 29, 2005 6:57 pm

It's funny how when you come back to a thread, the solution smackes you up side the head. Have you adjusted the valves????? Jim <img src="http://img.photobucket.com/albums/v209/ ... Cheers.gif" style="border:0;"/> <img src="http://img.photobucket.com/albums/v209/ ... states.gif" style="border:0;"/> Hey Kid...Is my taillight working?

craigy · Post by **craigy** » Tue Aug 30, 2005 1:50 am

No i havent, to be honest iv'e never done a re-shim / valve adjustment on a 4 stroke before the bike has done 31.000 Km do you think it sounds about due ?, Surely it can't need a rebore yet. Could it be true, could it be the very reason my YZF has been off the road for 2 years now! I'm getting to my wits end with this thing and was close to swapping it for my mates old GSXR slabside, maybe he secretly knows and is not letting on what may be the cause.

craigy · Post by **craigy** » Tue Aug 30, 2005 2:03 am

my bike when it used to work <img src=http://img.photobucket.com/albums/v209/ ... oapbox.gif ALT=":soap"> <a href="http://homepage.ntlworld.com/craig-shaw ...

Post by **FZRDude** » Tue Aug 30, 2005 2:13 am

Can't hurt to check them. (For those of you that don't like to do the math, 31K km is about 19,262 miles.) <img src="http://img.photobucket.com/albums/v209/ ...  There are some who call me........Tim? Top Speed = Mach 0.197 or so...  1994 FZR 1000 <img src="http://img.photobucket.com/albums/v209/ ...

craigy · Post by **craigy** » Tue Aug 30, 2005 4:04 am

i have found the following for clearance specs: inlet valve exhaust valve 0.11-0.20mm 0.21-0.30mm does anyone know if that is correct

dragracer1951 · Post by **dragracer1951** » Tue Aug 30, 2005 6:01 am

I think those numbers are close to what you need... Open up the cambox cover and see what ha got... And at 19k miles I would certainly think it's time for an adjust. Have you done a compression test? What were the numbers??? Jim <img src="http://img.photobucket.com/albums/v209/ ... Cheers.gif" style="border:0;"/> <img src="http://img.photobucket.com/albums/v209/ ... states.gif" style="border:0;"/> Hey Kid...Is my taillight working?Edited by: <A HREF=http://p072.ezboard.com/bexupbrotherhoo ... cer1951</A> at: 8/30/05 11:55 am

craigy · Post by **craigy** » Tue Aug 30, 2005 1:32 pm

No i aint done a compression test, i aint got a compression tester at hand though sure i could get one, one of my friends should have one.

craigy · Post by **craigy** » Wed Aug 31, 2005 10:53 am

Ok progress, checked valve clearance today, happy to say exhaust clearances are ok apart from one. As for inlet clearances all are closed, i think i found my fault, now how i shim up for inlets i'm not sure seeing as they are closed right up, unless i take away 0.20mm which is the way i may go and if they rise anymore after the cam is fitted hopefully the gap reaches at least the min of 0.11mm Also is there a special tool available or a way to get to the shims without removing the cam ? it looks like there isn't so i may have to cable tie the chain to the top pulley and keep tension on the chain on removal. craigy.

dragracer1951 · Post by **dragracer1951** » Wed Aug 31, 2005 11:08 am

Pull the motor to TDC on #1 and remove the cams. then change the shims that you need...install the cams and recheck clearance...adjust as needed Jim <img src="http://img.photobucket.com/albums/v209/ ... Cheers.gif" style="border:0;"/> <img src="http://img.photobucket.com/albums/v209/ ... states.gif" style="border:0;"/> Hey Kid...Is my taillight working?

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YZF 750 wont start

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