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+--- Thread: CARBURETTOR Problems In Low RPMs (/showthread.php?tid=76202)
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 02-08-16
(29-07-16, 07:34 PM)darrsi link Wrote: Gotta remember the age of these bikes so unless you buy new then all carbs are gonna look grubby, it's what's going on inside that counts though.
For the record, a new set of carbs is £611, but you do get a free delivery :lol
Yeah that's exactly what I'm afraid of, the inside could be worse than the outside! Green accumulated petrol gunk :rollin
That's very kind of them, FREE DELIVERY!
It would be the most absurd thing I could do as the bike costed less than that! It was a salvage bike which I bought as a project bike, was about to finish a big mod when the running problem accrued and it has delayed the works for the whole summer as I don't have the heart nor time to continue until I sort out the heart of the beast!
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 02-08-16
A small update but maybe the culprit has been found!
Since I just finished 30K and didn't get the bike's history when I bought it I decided to rule out the valve clearance. When I got the bike it had 22K on the clock and I had no idea if the clearance was checked or not. So on Sunday I decided to open up the engine and check, all measurements well within specs and timing markings spot on so that has been ruled out.
During the weekend I took the jets out and soaked them in carb cleaner over night, I also took the carbs to a local shop and used an air nozzle connected to their compressor and blow out all the passages because so far I've been used canned air but obviously provides less air pressure. Nice air flow through all the passages.
After a night's worth of soaking in carb cleaner I still noticed dark spots on the outside of some jets so I decided to soak them another night but this time in Pepsi. Next morning the jets were amazingly shiny!
My intestines must be super clean as well, haha! Very happy with my new inexpensive carb and stomach cleaner I put the carbs back together, added some fuel and realised that the fuel level was all over the place!!!
I haven't touched the tangs on the floats since the last time so WTF was going on?!? I opened up the carbs again, bent the tangs all the way up (towards the needle valve) and still I would have way too much fuel on carb 1 & 3
When I took the carbs apart for the second time few months ago I replaced the O-rings and the needle valves. They were aftermarket ones as they were much cheaper but the holes were much bigger and they were marked 2.0 rather 1.0 like the originals. Are they faulty then or is the size of the fuel inlet holes too big for the floats to handle? I wouldn't imagine the size would matter, does anyone have experience of these?
http://www.ebay.co.uk/itm/CARBURETTOR-FLOAT-NEEDLE-VALVE-WITH-SEAT-YAMAHA-FZS600-FZS-600-FAZER-98-03-NEW-/272231399564?hash=item3f6241808c:g:zmEAAOSwqv9V6uV1
Re: CARBURETTOR Problems In Low RPMs - Dave48 - 02-08-16
Dont know if this helps but I recently ordered 4 carburettor overhaul kits from M & P direct. They came in packaging showing maker "Tourmax"made in Japan suitable for FZS 600 1998-2001. ref no 7245384 Vergaser (German for carb) Rep STZ CAB-Y73. Cost for four inc p&p £42-95.
Fitted fine & bike running well. Cant say I noticed any markings on actual needle valve assemblies but my eyes are as old as the rest of me-dont ask! I can understand variation in size of main,pilot,starter jets but why would there be a need for different sizes of the needle valve?
Sounds like you have an over supply of fuel on 2 carbs-maybe recheck condition of "O" rings,floats, & float heights on offending carbs.
Re: CARBURETTOR Problems In Low RPMs - Dave48 - 02-08-16
2 further thoughts:
1. You did tighten the needle valve seat retaining screws when you changed them?
2.Float height for 2000 on models should be 3.5mm above float chamber mating surface ( Its 4.5mm on earlier models) 2000 on carbs are marked 5DM1 01
Earlier models are 5DM1 00.
Only mention this in case carbs have been replaced by previous owner. I know its a bit of a long shot but in diagnosing faults you cant assume anything. :eek
Dont mean to teach anyone to suck eggs but it seems you have ruled out a lot of the obvious things mentioned by others. Good luck!
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 02-08-16
(02-08-16, 04:24 PM)Dave48 link Wrote: Dont know if this helps but I recently ordered 4 carburettor overhaul kits from M & P direct. They came in packaging showing maker "Tourmax"made in Japan suitable for FZS 600 1998-2001. ref no 7245384 Vergaser (German for carb) Rep STZ CAB-Y73. Cost for four inc p&p £42-95.
Fitted fine & bike running well. Cant say I noticed any markings on actual needle valve assemblies but my eyes are as old as the rest of me-dont ask! I can understand variation in size of main,pilot,starter jets but why would there be a need for different sizes of the needle valve?
Sounds like you have an over supply of fuel on 2 carbs-maybe recheck condition of "O" rings,floats, & float heights on offending carbs.
The only reason I could think of is to get a faster fuel flow when racing, if the throttle is pretty much wide open most of the time then the bowls would fill up faster with the bigger needle valves. The "O" rings are just a few months old and fine, the floats have been left submerged in fuel and came up without a drop inside so they don't seem to be leaking, the tangs on the floats are bent way much to my liking and compared to how they were originally.
I remember that it was a massive pain to get the fuel level right, both with the original and the new needle valves. One minute I almost had it and after a minor adjustment it changed drastically like something was leaking. Could there be a crack in the carb body?
Re: CARBURETTOR Problems In Low RPMs - Dave48 - 02-08-16
Its a possibility. I think you may need to go back to basics & recheck everything to do with the fuelling,from the supply pipe from pump to the inlet rubbers,item by item. Dont assume anything just work from first principles. Even recheck work you have previously done yourself. You will get there!
Re: CARBURETTOR Problems In Low RPMs - Bretty - 02-08-16
So did the bike come to you with these problems, or did they develop while you've had it?
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 02-08-16
(02-08-16, 04:43 PM)Dave48 link Wrote: 2 further thoughts:
1. You did tighten the needle valve seat retaining screws when you changed them?
2.Float height for 2000 on models should be 3.5mm above float chamber mating surface ( Its 4.5mm on earlier models) 2000 on carbs are marked 5DM1 01
Earlier models are 5DM1 00.
Only mention this in case carbs have been replaced by previous owner. I know its a bit of a long shot but in diagnosing faults you cant assume anything. :eek
Dont mean to teach anyone to suck eggs but it seems you have ruled out a lot of the obvious things mentioned by others. Good luck!
1. Of course I did and last time I opened the carbs I took the floats out and checked if the needle valve seats were sitting in it's place properly
2. According to the markings on the side these are the correct carbs but it's true, you can't assume anything when you buy a used bike without any history at all
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 03-08-16
(02-08-16, 06:43 PM)Bretty link Wrote: So did the bike come to you with these problems, or did they develop while you've had it?
It hasn't been idling very well after a rusty tank incident. Carbs have been cleaned, floats leak tested, O rings replaced, and new needle valves fitted. After a lot of struggle adjusting the fuel level it seems to have changed over a period of few months and sometimes the valves don't seem to be closing properly as the level is randomly too high. The new needle valves have a harder spring, bigger rubber needle and the seats have a bigger hole and are marked 2.0 instead of 1.0 like the old ones. Apart from the obvious differences they seem to be same. My logic thinking tells me that a harder spring would make it easier for the floats to close them but maybe I'm wrong. I did a leak test with the bowls off and not a single drop of fuel was spilled. But when adjusting the fuel level I had to bend the tangs on the floats quite a lot towards the valve to be able to obtain a "useable" fuel level.Does anybody have experience of these aftermarket needle valves? Or any other brand? Here's a link http://www.ebay.co.uk/itm/CARBURETTOR-FLOAT-NEEDLE-VALVE-WITH-SEAT-YAMAHA-FZS600-FZS-600-FAZER-98-03-NEW-/272231399564?hash=item3f6241808c:g:zmEAAOSwqv9V6uV1
Re: CARBURETTOR Problems In Low RPMs - His Dudeness - 03-08-16
The Fazer carbs really shouldn't need any tweeking. If I was you I'd put everything back to factory settings. Or for the sake of an easy life just get another set of carbs. They aren't very expensive
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 03-08-16
(03-08-16, 06:55 PM)His Dudeness link Wrote: The Fazer carbs really shouldn't need any tweeking. If I was you I'd put everything back to factory settings. Or for the sake of an easy life just get another set of carbs. They aren't very expensive
Yeah I've done everything I can because I wanted to find the problem. The bike has been to two shops without good results hence me still working on it. Few weeks ago I thought about a set of second hand carbs and tonight after having set the fuel level almost perfectly and the bike still idling like a retard I've decided to formally give up and get another set of carbs!!! :'(
I spotted a nice set of 2003 version, they should be compatible with the 2002 bike, right?
Re: CARBURETTOR Problems In Low RPMs - darrsi - 04-08-16
(03-08-16, 10:53 PM)7uckyDog link Wrote: [quote author=His Dudeness link=topic=20641.msg238595#msg238595 date=1470246937]
The Fazer carbs really shouldn't need any tweeking. If I was you I'd put everything back to factory settings. Or for the sake of an easy life just get another set of carbs. They aren't very expensive
Yeah I've done everything I can because I wanted to find the problem. The bike has been to two shops without good results hence me still working on it. Few weeks ago I thought about a set of second hand carbs and tonight after having set the fuel level almost perfectly and the bike still idling like a retard I've decided to formally give up and get another set of carbs!!! :'(
I spotted a nice set of 2003 version, they should be compatible with the 2002 bike, right?
[/quote]
02/03, same bike.
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 06-10-16
Update and a surprising twist!
So after my last post I got a second hand set of 2002 carbs. They were filthy on the outside and had gunk and cracked o-rings on the inside. Went through the carb fixing process again and slapped them on the bike.
The engine idles much better! I was so happy! Went for a ride and discovered that now I have a problem in the high RPMs, WTF!?!
It behaves like a ignition retardation when trying to overtake quickly. The engine sputters and looses power of the throttle is twisted quickly. But if I ease it in slowly then I can get through the whole range. I've swapped the TPS sensor (but they're both used) and there's no change. There are new plugs, new caps and the spark looks good.
What's going on!?! Has anyone had any issues with the ECU?
Re: CARBURETTOR Problems In Low RPMs - Fazerider - 06-10-16
(06-10-16, 05:46 PM)7uckyDog link Wrote: It behaves like a ignition retardation when trying to overtake quickly. The engine sputters and looses power of the throttle is twisted quickly. But if I ease it in slowly then I can get through the whole range.I'd guess that's one or more of the carb slides jamming because of the sudden large pressure difference, rather than rising smoothly.
You may be able to feel that if you try raising them one at a time by hand, though obviously that's a carbs-out job.
Re: CARBURETTOR Problems In Low RPMs - 7uckyDog - 06-10-16
Well I checked the slides, the membranes and anything else just in case before putting the "new" carbs in.
But it would be an easy job to swap them for the older ones to rule it out I guess.
I'm inclined to try another ECU, does anyone know if I could use with ease from the same model and if it has to be the same year?
Re: CARBURETTOR Problems In Low RPMs - BBROWN1664 - 06-10-16
Sounds like a fuel related problem.
Everything is fine unless you open the throttle too quickly.
I would have a look at the sizes of the jets in the original carbs (assume they are standard) and the new carbs. I suspect you have got a set someone has re-jetted. The ECU would not cause that sort of problem.
Re: CARBURETTOR Problems In Low RPMs - bikemad - 06-10-16
On my bike I had carb problems blocked green/brown crust after cleaning them still not starting or firing ?
Found out O rings knakerd thus flooding tried a 2nd set that was on donor bike it ran but not brilliant but it ran,so I took them apart but not the best condition the screws only just came out of the float bowls ! so as my originals are clean I swapped the seats & O rings.
Bike started ran but died after warming up ? I realised too rich pilot screws set at OEM so two & three quarters of a turn out it runs ok now don't need choke to start either bike has a K & N filter.
I still get a slight hesitation around 2000rpm otherwise it pulls like a train I'm considering a dyno jet kit
Re: CARBURETTOR Problems In Low RPMs - oberonspacefruit - 07-10-16
If you do end up getting the ngk spark plug ends, dont get the angled ones as theyre not long enough to comfortably pop out of the top of the rocker cover so you hace to turn them sideways, which is hard if youve clipped some off your leads. go for the straight ones, they will fit better.
Re: CARBURETTOR Problems In Low RPMs - darrsi - 07-10-16
(06-10-16, 11:07 PM)bikemad link Wrote: On my bike I had carb problems blocked green/brown crust after cleaning them still not starting or firing ?
Found out O rings knakerd thus flooding tried a 2nd set that was on donor bike it ran but not brilliant but it ran,so I took them apart but not the best condition the screws only just came out of the float bowls ! so as my originals are clean I swapped the seats & O rings.
Bike started ran but died after warming up ? I realised too rich pilot screws set at OEM so two & three quarters of a turn out it runs ok now don't need choke to start either bike has a K & N filter.
I still get a slight hesitation around 2000rpm otherwise it pulls like a train I'm considering a dyno jet kit
They don't need a dyno jet kit.
Been there, done that, had to change back to OEM for it to run right again.
Re: CARBURETTOR Problems In Low RPMs - bikemad - 08-10-16
(07-10-16, 05:04 PM)darrsi link Wrote: They don't need a dyno jet kit.
Been there, done that, had to change back to OEM for it to run right again.
Ok thanks I'll forget that then