junker Posted August 20, 2008 Share Posted August 20, 2008 I have been rebuilding an 1988 FZ600 ( with Mikuni Round Slide type carburettors) from the oil pan up (not literally) and have gotten to the carbs along with other persisting problems. I have yet to properly synchronize them due to the inability to buy one of the manometer things, and i haven't gotten around to loading the bulky bike in my truck and hauling it to the shop to have them do it yet. But in my limited understanding, the carbs should have a good cleaning after sitting for god knows how many years, (probably it's entire lifespan). I pulled the suckers off (gently and meticulously) and prepared a clean workspace (family members want to kill me for dripping gas all over their spare room floor) and began dissembling... I got the float bowels off, and sprayed them with carb cleaner, removed jets, sprayed them, replaced them, disassembled the diaphragm and cleaned all related parts.... basically i cleaned the whole Shebangey-Bang and put it all back together. I got it to run, and now, a day later i noticed the half tank of gas i put in, is now a small sloshing puddle in the morning. I swiped my fingers over the bottom half of the carbs & got a slippery gas residue. After running it today, the gas came dripping out of the (what i believe to be) overflow tubes and an air jet on the outer lip of the intake mouth... I have pictures upon request of the carbs and what i think are these air jets that the gas came out of, email me @ [email protected] and ask for the pics, i cant figure out how to put them in threads on this forum... Is it possible i accidentally adjusted something in the float bowl? Is anyone Familiar with Old FZ600 Carbs? Link to comment Share on other sites More sharing options...
junker Posted August 20, 2008 Author Share Posted August 20, 2008 also, the yama-haha! schematic dosen't really help crap; it only shows one side of the carbs and dosent even really give correct names for each labeled part.... so yes, i have already tried to study the carbs via that route and got slapped with a dead end Link to comment Share on other sites More sharing options...
fosdyke Posted August 20, 2008 Share Posted August 20, 2008 also, the yama-haha! schematic dosen't really help crap; it only shows one side of the carbs and dosent even really give correct names for each labeled part.... so yes, i have already tried to study the carbs via that route and got slapped with a dead end Hi If you haven't already - check and recheck the float height on the carbs. If these are ok then make sure that when the floats reach the right height they shut off fuel flow from the tank - you can do this by blowing down the fuel line whilst operating the the floats. One other thing to check would be to make sure the floats don't have holes in - never come across it myself but have heard of it from other people. Good luck Link to comment Share on other sites More sharing options...
junker Posted August 21, 2008 Author Share Posted August 21, 2008 How Do I check the float height? And if i CAN blow air through the fuel line with the floats all the way up, how do i adjust them to shut off? What if the float height is correct, does that mean that there is a leak somewhere in a gasket or something? Can replacing screws have this effect, i had to replace the old screws with new brass ones i bought from The Home Depot, they were the exact same size and shape, just new and not as easily stripped is all. What about a plugged jet, the bike is now hard to start and will only rev to 4.5K and if i twist throttle beyond that it acts very strange, lurching RPM levels and will sometimes even stall out. Could this be related? Should i completely tear down the carburetors again and completely STERILIZE each and every part? I FEEL LIKE STABBING SOMETHING!!! I HATE CARBURETORS! Link to comment Share on other sites More sharing options...
fosdyke Posted August 21, 2008 Share Posted August 21, 2008 How Do I check the float height? And if i CAN blow air through the fuel line with the floats all the way up, how do i adjust them to shut off? What if the float height is correct, does that mean that there is a leak somewhere in a gasket or something? Can replacing screws have this effect, i had to replace the old screws with new brass ones i bought from The Home Depot, they were the exact same size and shape, just new and not as easily stripped is all. What about a plugged jet, the bike is now hard to start and will only rev to 4.5K and if i twist throttle beyond that it acts very strange, lurching RPM levels and will sometimes even stall out. Could this be related? Should i completely tear down the carburetors again and completely STERILIZE each and every part? I FEEL LIKE STABBING SOMETHING!!! I HATE CARBURETORS! OK one thing at a time: 1. Check float height - remove the bowl and using a ruler measure the height of the floats when they are closing the needle valve (ie in the up position), and compare to the workshop specs. To adjust you have to bend the brass tab that stops the floats from dropping. 2. Needle valve not shutting off fuel flow when floats are at correct height (ie you can blow air down the fuel intake) - you need to 'carefully' (do this over a table and some paper) remove the needle valve it will be attached via a wire to the float assembly. Examine the needle end it should taper to a fine point - if it doesn't then you will have to get a new one. Otherwise clean (carefully) replace and check to see if you can still blow air through the fuel intake. Repeat this process for each carb. 3. Don't worry about the screws - brass are often used so as not to damage the carb body. 4. If you have a blocked jet you will need to clean it out - try blowing through it - if it is a removable jet (some are hidden) unscrew and look through it at a light source (not too bright!) you should see a perfectly round hole - if not blow through it small end to large using your mouth - I tend to find this clears most stuff. If not DON'T use wire, but soak in carb cleaner overnight and try again. 5. Poor performance is almost certainly linked to this - sorting carbs is a bit like doing black magic - but I find persistance usually pays off. Good luck PS sorry don't have float heights for this model - do you have a workshop manual? Link to comment Share on other sites More sharing options...
junker Posted August 22, 2008 Author Share Posted August 22, 2008 For Some reason I don't feel like stabbing anything anymore... Thank You. No I do Not have a work Shop Manual Yet, I Am pretty busy with work (Landscaping Industry is going down the tubes with housing market in America). On My Days that I am Free after work i have been trying to tinker around with things that I know how to do and that don't require any specs from Yamaha, The Auto Parts Store dosen't sell any for an FZ and I am going to order one from themotorbookstore.com tonight. Do You know where get carb gaskets and O-rings for older bikes? Yama-haha! only wants to sell me the ENTIRE carb for $300!!! I just want the little rubber gasket My local dealer is a retard with hill-billy ties and he orders from the same site i could go to and charges double! Link to comment Share on other sites More sharing options...
grizzlydan Posted August 22, 2008 Share Posted August 22, 2008 To check the float height, hold the carburetor so the float hangs down, then tilt back until the valve needle is just seated (the small rod in the end of the needle valve shouldn't be compressed). Measure the distance from the carburetor body (without the float chamber gasket) to the top of the float. The float height should be 20.0mm +/-1.0mm(0.787+/-0.020inch). Again that's what it says in the manual. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 22, 2008 Moderator Share Posted August 22, 2008 For Some reason I don't feel like stabbing anything anymore... Thank You. No I do Not have a work Shop Manual Yet, I Am pretty busy with work (Landscaping Industry is going down the tubes with housing market in America). On My Days that I am Free after work i have been trying to tinker around with things that I know how to do and that don't require any specs from Yamaha, The Auto Parts Store dosen't sell any for an FZ and I am going to order one from themotorbookstore.com tonight. Do You know where get carb gaskets and O-rings for older bikes? Yama-haha! only wants to sell me the ENTIRE carb for $300!!! I just want the little rubber gasket My local dealer is a retard with hill-billy ties and he orders from the same site i could go to and charges double! Clymer do a manual for your bike, its 29 dollars, see it Here I sent you a link to this site earlier, you can also look at a diagram of the carb or any part of the bike and see the cost of available parts at the bottom of the page, a luxury we dont have here in the UK. BTW while were on the subject of carbs it seems that there is a model just for California and one for everywhere else, be sure you know which yours is! Link to comment Share on other sites More sharing options...
junker Posted August 24, 2008 Author Share Posted August 24, 2008 Does anyone know if the; what look like jets in the mouth of the carbs are removable? Either way, does anyone know their function? The schematic, like i said only shows one side of them. Link to comment Share on other sites More sharing options...
junker Posted August 25, 2008 Author Share Posted August 25, 2008 Clymer do a manual for your bike, its 29 dollars, see it Here I sent you a link to this site earlier, you can also look at a diagram of the carb or any part of the bike and see the cost of available parts at the bottom of the page, a luxury we dont have here in the UK. BTW while were on the subject of carbs it seems that there is a model just for California and one for everywhere else, be sure you know which yours is! thank you man, i haven't ever checked my messages... lol i have now though Link to comment Share on other sites More sharing options...
junker Posted August 25, 2008 Author Share Posted August 25, 2008 Ok ppl, thank you all for all your help, tonight i have removed the carburetors again, cleared all of the blocked main jets (3 out of 4), inspected all of the diaphragms (were all a-ok) and adjusted the troublesome float height, I also noticed that the throttle butterflies were completely out of whack- one open while one's closed - I adjusted them to the best of my visual ability and perhaps they will function temporarily until i get them properly synchronized. I have not attempted to start it, despite my overwhelming urge of curiosity, it is too dark and these friggen gigantic mosquitoes want me for dinner. Tomorrow will be the day of truth, no work scheduled, so first thing in the morning I'll gas her up and see if she runs Crossing my fingers Link to comment Share on other sites More sharing options...
junker Posted August 25, 2008 Author Share Posted August 25, 2008 OK one thing at a time: 1. Check float height - remove the bowl and using a ruler measure the height of the floats when they are closing the needle valve (ie in the up position), and compare to the workshop specs. To adjust you have to bend the brass tab that stops the floats from dropping. 2. Needle valve not shutting off fuel flow when floats are at correct height (ie you can blow air down the fuel intake) - you need to 'carefully' (do this over a table and some paper) remove the needle valve it will be attached via a wire to the float assembly. Examine the needle end it should taper to a fine point - if it doesn't then you will have to get a new one. Otherwise clean (carefully) replace and check to see if you can still blow air through the fuel intake. Repeat this process for each carb. 3. Don't worry about the screws - brass are often used so as not to damage the carb body. 4. If you have a blocked jet you will need to clean it out - try blowing through it - if it is a removable jet (some are hidden) unscrew and look through it at a light source (not too bright!) you should see a perfectly round hole - if not blow through it small end to large using your mouth - I tend to find this clears most stuff. If not DON'T use wire, but soak in carb cleaner overnight and try again. 5. Poor performance is almost certainly linked to this - sorting carbs is a bit like doing black magic - but I find persistance usually pays off. Good luck PS sorry don't have float heights for this model - do you have a workshop manual? P.S. - ONe of the button shaped top covers that house the diaphragm spring was apparently crushed in (perhaps a previous owner acted upon the need to destroy something that i was feeling) Until now i figured it wasn't a hinder to the function of the carb, but when i manually lifted the diaphragms and that one slammed shut faster than all the others i realized it needed to be repaired, which i did Link to comment Share on other sites More sharing options...
junker Posted August 25, 2008 Author Share Posted August 25, 2008 Ok Everybody! Thanks for all the advise and guidance! I started her up today and she runs GREAT! Better than i had her going back when i thought she was good!! I'm going to make a video of it soon, I'm trying to log progress for anyone else who might have a similar project along the way. For the first time, i actually got it to move more than 10ft on her own! I now realized that i had to adjust the clutch lever, big time, the bike kept wanting to go even with the lever all the way in... that was scary! I adjusted it and it ran great all over my yard!!! I think i woke the neighbors up! My neighbor has a YZF i think, definitely a Yamaha... I always thought he hated me because of my dog, but he was giving me thumbs up and watching me and crap...LOL Next Project; getting the battery Revived Next, Next Project; getting front turn signals Distant Future Project; Getting Her Inspected and On the road!!! Thanks a lot guys, you are a major help to me... I try to give back what knowledge i have on the forums but i'm afraid it pales in comparison to the help you all have given me... Thank You Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 26, 2008 Moderator Share Posted August 26, 2008 Ok Everybody! Thanks for all the advise and guidance! I started her up today and she runs GREAT! Better than i had her going back when i thought she was good!! I'm going to make a video of it soon, I'm trying to log progress for anyone else who might have a similar project along the way. For the first time, i actually got it to move more than 10ft on her own! I now realized that i had to adjust the clutch lever, big time, the bike kept wanting to go even with the lever all the way in... that was scary! I adjusted it and it ran great all over my yard!!! I think i woke the neighbors up! My neighbor has a YZF i think, definitely a Yamaha... I always thought he hated me because of my dog, but he was giving me thumbs up and watching me and crap...LOL Next Project; getting the battery Revived Next, Next Project; getting front turn signals Distant Future Project; Getting Her Inspected and On the road!!! Thanks a lot guys, you are a major help to me... I try to give back what knowledge i have on the forums but i'm afraid it pales in comparison to the help you all have given me... Thank You Always good to see some success, well done junker . Now what about that other thread...The one about lights cutting out the engine...That fixed now? Link to comment Share on other sites More sharing options...
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