carb help,standard size of the holes in throttle slides,

[1992divvy]

hi guys, hope someone can help! i need to know the size of the two holes in the slides as mine have been drilled and i want to know if putting them back to standard will help with my running issues? idles fine,responds to throttle well its just when i try to ride it it just dies under load. got a k+n drop in filter and 107.5 mains(did have 110s but ran just as bad) it seems like its really rich as when it does decide to start again it smokes black and takes a while to start. if i dont try to ride it,it will idle smoothly till it runs out of fuel or i switch it off! only happens under load,oh non standard jet needle set on top(1st) slot. bit vague i know but gotta try something !

[Clanky]

Hi,

I've just stripped and cleaned a set of carbs off a FZR 400 (3EN1) and this has exactly the same carbs as the 600 3HE. The only differences were the size of the jets and that the 400 slide had much wider holes. These were not a DIY mod but made that way, so maybe your slides have been drilled or have come from a 400. If you look at the top of the slide where the diaphragm sits you can see where the two outer holes come through and around them at that point is a recessed hole. The recessed holes on the 400 were clearly moulded to accomodate the wider slide holes.

There seems to be a lot of discussion on the pros and cons of drilling slides but I don't think it would cause the issues that you have.

I have measured the 600 slides for you and the holes are 1.75mm. I can't measure the 400's because I just put the carbs back on the bike this afternoon. Here's a comparison pic that may help



I also found that three of my diaphragms had identical marks on them which had weakened and caused tiny tears. This had not noticably effected my bikes performance but they were very small tears, I was stripping the carbs due to an idle issue and rich running (confirmed by checking the spark plugs).



I did look around on the internet though and a torn diaphragm can be a cause of lost top end. I'd at least take the air filter off and operate the slides with a finger to check their operation. Best to strip the carbs check the diaphragms by eye, check float heights and all the rubber seals (the seals that hold the float arms into the body can shrink and leak too much fuel into the chamber, two of mine were way too loose). Do a bench synch and set the idle mixture screws.

Good luck with it.

[1992divvy]

hi clanky,thanks for all your help! already stripped and cleaned them twice now and i changed the fuel filter today,it was dirty but ive seen worse! didnt make a lot of difference but i did note today that increasing the throttle slowly from idle as the revs climbed to 4k it was fine,hold it there and it faulters and fades,trying to go further only makes it worse to the point of almost stopping,slowly let it return to idle and itll settle back ok then if i blip it...instant response again! im off in there again tomorrow to see if it is rich at that point or me being stoopid and its leaning out! thanks for the info on slides,just got to work out the safest way to resize mine, old rc car ariel tube may get pressed into service as a sleeve! ill let you know how it goes B-) .del.

[taggy]

as a quick fix check, you can use the rubber glue from puncture kits to seal holes in diaphragms. might help you rule that out as a problem. i have a set of 400 carbs in bits, think they are 3en so if i get a chance later i'll measure the holes for you.
i'd lose the k+n and go back to standard sizes, just out of interest, what exhaust are you running and do 600's have the exup?

[Nik]

as a quick fix check, you can use the rubber glue from puncture kits to seal holes in diaphragms. might help you rule that out as a problem. i have a set of 400 carbs in bits, think they are 3en so if i get a chance later i'll measure the holes for you.
i'd lose the k+n and go back to standard sizes, just out of interest, what exhaust are you running and do 600's have the exup?

Taggy,
the K& N is not pods but a big filter that replaces the OEM one in the airbox both Y-Geo and I run them and we never had to re-jet and i am only about 600ft above sea level here (I think Y-Geo. would have mentioned it if he had done his when we were doing mine last summer.)

[1992divvy]

hi clanky,thanks for the info on slides,measured mine and they are 3mm and as i found the inside was moulded they hadnt been drilled and im assuming they are 400s! done a sleeve job(yes my rc ariel is now shorter ) and it did help a lot,much better response to throttle but still fading out but now at higher revs! decided to switch fuel off and run it low so it would lean out and it improved through the rev range. now, im im on the top clip at the mo so im going to remove the plastic spacer/washer thing so itll lean out more,got loads of adjustment either way cos the clip will be in the middle! thanks again bud,sterling stuff.

[1992divvy]

taggy,thanks for that mate but already sussed that the po put 400 slides in for some reason! not sure of headers but they are 4-2-1 stainless and at the mo got a cut down zx10 can on as its a little quieter than my art pro! no real change whichever one i use cos they are both free flowing! did baffle the art can but it made no difference.

[Clanky]

Glad you're making progress mate. Here's a link to a good discussion on the needles:

viewtopic.php?f=8&t=3378&p=37844&hilit=jet+needle

If its any consolation to you while your struggling away one of my float bowls leaked when I ran the bike up today, bit the bullet and got four new carb repair kits. Fortunately for me the seller is in my town but they do have a shop on eBay, cheapest source of kits I have found in case you ever need any:

http://www.ebay.co.uk/itm/YAMAHA-FZR600 ... 5d3205512f

Let us know if you get to the root of the problem it may help someone in the future.

[1992divvy]

hi,ooops sorry to hear that! still easy fix for you! ripped them carbs out again today,getting good at it now...tank out carbs off and out in about 6 mins! done the needles,just removed the plastic spacer and a washer and re-clipped at 2 out of 7, so leaner but not stoopid threw it all back in,said a small thank you and hit the go button and bugger all! spun over fine coughed and popped but would not catch,now i think it may be my fault as when i pulled the carbs i block the two overflows so when i stand em up fuel dont piddle everywhere. anyhow when i refitted them i forgot to 'loose' what was in the carbs and i think it all shot into the inlet! tried again a few hours later and it sounded better ( no choke obviously!) and tried but didnt catch,about 5 seconds AFTER i stopped cranking sodding big bang from zorst made me bloody ears ring . so ive left it alone for tonight,ill give it stick again tomorrow. did look at the link and its not a bad price but mine seem to be good at the mo. good luck with yours,let you know how mine is...del.

[Clanky]

Sorry to hear that things didn't work out today. Sometimes better to just walk away and do something else to gather your thoughts.

Mine is up and running nicely now but when I first went to start it up this afternoon it cranked well but I got nothing. Had a brew and then it hit me, I left the bloody fuel tap in the off position Primed it a few times and problem solved, celebrated with another cup of tea and a quick test ride.

I'm sure you'll get this fixed in time.

[1992divvy]

well i went out today with low expectations as to how things were going to pan out but it suprised me by starting up with no fuss and running reasonably sweet! so i did the usual thing and put it together,added a bit more fuel and wheeled it out to the road,nervously swung me leg over,switched on,hit the button and prodded the gear lever. now this was the moment,as i let the clutch out,that it usually all goes wrong,but not today! shot up the road with a little bit of a grumble( think it was still a little cold)but so much better.went down the road turned around,give it some beans and actually had to change gear! whooopi it works! just a bit of fine tuning to do but it needs a run of at least 5 miles to be sure and ive got to tax it first! many thanks to clanky for the dimensions and helping me find that the slides were wrong! when i get five mins ill write the settings up once im happy with the way it runs.easy bit now,repairing and spraying the plastics,got to make it look good now it works . del.