Carbs probably need ultrasonic cleaned. Do you access to one?Hello guys..
I am having some bad problems with my zxr400 (L model 1997).
Before all.. I used this bike for years without an issue but At some point the bike sat in the garage for a couple years because of my health conditions were not good at all. But after that bad part of my life.. now that I am again on the live side some time ago I took her out and was running very rough.
So I went for a full carb clean, new plugs and so on.
Found float levels all messed up(never touched them before) and put into manual specs so perfect at 11mm.
Begun to run kinda ok.. but very difficult to start (before the forced stop she used to roar to life in a button click, now it seems to slooowly coming to life almost struggling...).
The main problem is.. when cold the bike runs fine.. very very smooth. After warming up..you ease a bit more on the throttle (staying at city rpm so 5..6000.. ) and the bike feels bogging like mad, like its flooded and running on 2. Sounds like a twin and has problems taking more revs.
It feels like some years ago when 2 of my idle jets were clogged after winter stop.. the bike was rough, sounded like a twin and low power, but this time they are clean..
Maybe something stuck in carb passages? I cleaned them with carb cleaner and blasted them with compressed air more than once..
To be honest the only thing I've found bad after those couple year in the garage was the air filter like rotten and falling apart. Maybe some airfilter sticky parts clogged some carb passages?
If you go wide open the bike launch but feels not so fast as it used. Going down it struggle to keep idle and bogs a lot.
Anyway.. to solve the problem I did:
Replaced air filter with new oem unit, correctly oiled.
full carb rebuild with new rings, new gaskets and so on.
Cleaned jets ans all passages..
Checked boots and did alignment.
No big differences
New plugs, also tried the fuel pump mod suggested online (zxr400 by default has the pump running only from cranking, so not priming the carbs before crank.. this leads to a lot of cranking if bowls are empty), no difference
Tried swapping coils with cbr 600 ones with mod suggested on zxr400 forum and done by many users.no big difference.
Bike is fully oem, no modification.. only carb trumpets are a little shorter because oem become hard as rock and deformed and replaced with some I made with lathe and milling machine.. but did years ago and never had a problem with that.
The last winter I did also a full engine rebuilt.
Replaced all sealings, did the valves, pistons, checked barrels, new rings, new everything. Engine is now almost brand new.
But problem is still there.
I dont really know where to look at... I dont want to surrender, we did together so many nice rides..
Here no one knows those bikes so i dont really know who to ask..
Anyone has an idea??
ZXR400 weird problem
Hello guys..
I am having some bad problems with my zxr400 (L model 1997).
Before all.. I used this bike for years without an issue but At some point the bike sat in the garage for a couple years because of my health conditions were not good at all. But after that bad part of my life.. now that I am again on the live side some time ago I took her out and was running very rough.
So I went for a full carb clean, new plugs and so on.
Found float levels all messed up(never touched them before) and put into manual specs so perfect at 11mm.
Begun to run kinda ok.. but very difficult to start (before the forced stop she used to roar to life in a button click, now it seems to slooowly coming to life almost struggling...).
The main problem is.. when cold the bike runs fine.. very very smooth. After warming up..you ease a bit more on the throttle (staying at city rpm so 5..6000.. ) and the bike feels bogging like mad, like its flooded and running on 2. Sounds like a twin and has problems taking more revs.
It feels like some years ago when 2 of my idle jets were clogged after winter stop.. the bike was rough, sounded like a twin and low power, but this time they are clean..
Maybe something stuck in carb passages? I cleaned them with carb cleaner and blasted them with compressed air more than once..
To be honest the only thing I've found bad after those couple year in the garage was the air filter like rotten and falling apart. Maybe some airfilter sticky parts clogged some carb passages?
If you go wide open the bike launch but feels not so fast as it used. Going down it struggle to keep idle and bogs a lot.
Anyway.. to solve the problem I did:
Replaced air filter with new oem unit, correctly oiled.
full carb rebuild with new rings, new gaskets and so on.
Cleaned jets ans all passages..
Checked boots and did alignment.
No big differences
New plugs, also tried the fuel pump mod suggested online (zxr400 by default has the pump running only from cranking, so not priming the carbs before crank.. this leads to a lot of cranking if bowls are empty), no difference
Tried swapping coils with cbr 600 ones with mod suggested on zxr400 forum and done by many users.no big difference.
Bike is fully oem, no modification.. only carb trumpets are a little shorter because oem become hard as rock and deformed and replaced with some I made with lathe and milling machine.. but did years ago and never had a problem with that.
The last winter I did also a full engine rebuilt.
Replaced all sealings, did the valves, pistons, checked barrels, new rings, new everything. Engine is now almost brand new.
But problem is still there.
I dont really know where to look at... I dont want to surrender, we did together so many nice rides..
Here no one knows those bikes so i dont really know who to ask..
Anyone has an idea??
I am having some bad problems with my zxr400 (L model 1997).
Before all.. I used this bike for years without an issue but At some point the bike sat in the garage for a couple years because of my health conditions were not good at all. But after that bad part of my life.. now that I am again on the live side some time ago I took her out and was running very rough.
So I went for a full carb clean, new plugs and so on.
Found float levels all messed up(never touched them before) and put into manual specs so perfect at 11mm.
Begun to run kinda ok.. but very difficult to start (before the forced stop she used to roar to life in a button click, now it seems to slooowly coming to life almost struggling...).
The main problem is.. when cold the bike runs fine.. very very smooth. After warming up..you ease a bit more on the throttle (staying at city rpm so 5..6000.. ) and the bike feels bogging like mad, like its flooded and running on 2. Sounds like a twin and has problems taking more revs.
It feels like some years ago when 2 of my idle jets were clogged after winter stop.. the bike was rough, sounded like a twin and low power, but this time they are clean..
Maybe something stuck in carb passages? I cleaned them with carb cleaner and blasted them with compressed air more than once..
To be honest the only thing I've found bad after those couple year in the garage was the air filter like rotten and falling apart. Maybe some airfilter sticky parts clogged some carb passages?
If you go wide open the bike launch but feels not so fast as it used. Going down it struggle to keep idle and bogs a lot.
Anyway.. to solve the problem I did:
Replaced air filter with new oem unit, correctly oiled.
full carb rebuild with new rings, new gaskets and so on.
Cleaned jets ans all passages..
Checked boots and did alignment.
No big differences
New plugs, also tried the fuel pump mod suggested online (zxr400 by default has the pump running only from cranking, so not priming the carbs before crank.. this leads to a lot of cranking if bowls are empty), no difference
Tried swapping coils with cbr 600 ones with mod suggested on zxr400 forum and done by many users.no big difference.
Bike is fully oem, no modification.. only carb trumpets are a little shorter because oem become hard as rock and deformed and replaced with some I made with lathe and milling machine.. but did years ago and never had a problem with that.
The last winter I did also a full engine rebuilt.
Replaced all sealings, did the valves, pistons, checked barrels, new rings, new everything. Engine is now almost brand new.
But problem is still there.
I dont really know where to look at... I dont want to surrender, we did together so many nice rides..
Here no one knows those bikes so i dont really know who to ask..
Anyone has an idea??
1 - 11 of 11 Posts
Carbs probably need ultrasonic cleaned. Do you access to one?
Any chance you can borrow an ECU to verify with a comparison? Mine started going bad and had similar issues. If it's not plugs, coils, carbs or engine, only thing left is the brains.
I swapped out the ecu from another bike.
I swapped out the ecu from another bike.
This evening after work I come home and really a disaster, I really struggled to come home.. over 6000 rpm was going ok, not so powerful as it should but at least running "round" not feeling like running on 3 or 2. under that rpm was clearly running on 2.
So I decided to take it apart again, disconnected carbs from bike, and made pump fill bowls until self shutting down because of closed float needles. from the engine side of carbs no visible spills. so seems the float valves close kinda ok.
I took out the spark plugs and thats the result:
![Wood Finger Font Recreation Eyewear]()
cylinder 1 and 2 are almost ok , 3 and 4 are really really black. and on cylinder4 carb rubber boot i've found fuel, it was literally wet.
tomorrow I'll take the carbs apart in every single bit and try to check all the passages to see if I notice something.
but seems weird being that..because when cold runs great, and when begins doing that thing.. if I bring her over certain rpm everithing seems to work, it just feels a bit heavy because too rich. maybe at lower rpm is so rich that tends to foul plugs and cause that problem.. point is, why so rich all of a sudden?
So I decided to take it apart again, disconnected carbs from bike, and made pump fill bowls until self shutting down because of closed float needles. from the engine side of carbs no visible spills. so seems the float valves close kinda ok.
I took out the spark plugs and thats the result:
cylinder 1 and 2 are almost ok , 3 and 4 are really really black. and on cylinder4 carb rubber boot i've found fuel, it was literally wet.
tomorrow I'll take the carbs apart in every single bit and try to check all the passages to see if I notice something.
I have a place not so far away that could do that, if tomorrow I will not find anything.. I'll try getting them ultrasonic cleaned and see the results..Carbs probably need ultrasonic cleaned. Do you access to one?
Not at the moment, here is a very rare bike, so no one has one.. so I would have to buy one.Any chance you can borrow an ECU to verify with a comparison? Mine started going bad and had similar issues. If it's not plugs, coils, carbs or engine, only thing left is the brains.
I swapped out the ecu from another bike.
but seems weird being that..because when cold runs great, and when begins doing that thing.. if I bring her over certain rpm everithing seems to work, it just feels a bit heavy because too rich. maybe at lower rpm is so rich that tends to foul plugs and cause that problem.. point is, why so rich all of a sudden?
I would have the carbs cleaned in the ultrasonic cleaner first. Rebuild the carbs again, replace the spark plugs and go for a test ride. If it's still idling rich (it seems to me the float bowl needles aren't closing all the way), I would look for raw petrol/fuel like you did before. Sometimes, after carbs sit with/without fuel; they need to be cleaned in the ultrasonic cleaner about 3 to 4 times before all the old fuel in the smaller passages are removed.This evening after work I come home and really a disaster, I really struggled to come home.. over 6000 rpm was going ok, not so powerful as it should but at least running "round" not feeling like running on 3 or 2. under that rpm was clearly running on 2.
So I decided to take it apart again, disconnected carbs from bike, and made pump fill bowls until self shutting down because of closed float needles. from the engine side of carbs no visible spills. so seems the float valves close kinda ok.
I took out the spark plugs and thats the result:
View attachment 24096
cylinder 1 and 2 are almost ok , 3 and 4 are really really black. and on cylinder4 carb rubber boot i've found fuel, it was literally wet.
tomorrow I'll take the carbs apart in every single bit and try to check all the passages to see if I notice something.
I have a place not so far away that could do that, if tomorrow I will not find anything.. I'll try getting them ultrasonic cleaned and see the results..
Not at the moment, here is a very rare bike, so no one has one.. so I would have to buy one.
but seems weird being that..because when cold runs great, and when begins doing that thing.. if I bring her over certain rpm everithing seems to work, it just feels a bit heavy because too rich. maybe at lower rpm is so rich that tends to foul plugs and cause that problem.. point is, why so rich all of a sudden?
What @Slorg442 mentioned is possible if the ECU/Igniter isn't sending a strong enough signal in combination with the pickup coil (the magnet[?] that picks up the signal from the ignition rotor) and the coils. This could be tested with a multimeter/DVM to measure the primary and secondary outputs on the coils. But, if it was a coil problem, it would be on cyl. 1&4 or 2&3 not 3&4.
I'm going to stick to my guess with it being fuel related and say it's the carbs.
Thank you for your help,I would have the carbs cleaned in the ultrasonic cleaner first. Rebuild the carbs again, replace the spark plugs and go for a test ride. If it's still idling rich (it seems to me the float bowl needles aren't closing all the way), I would look for raw petrol/fuel like you did before. Sometimes, after carbs sit with/without fuel; they need to be cleaned in the ultrasonic cleaner about 3 to 4 times before all the old fuel in the smaller passages are removed.
What @Slorg442 mentioned is possible if the ECU/Igniter isn't sending a strong enough signal in combination with the pickup coil (the magnet[?] that picks up the signal from the ignition rotor) and the coils. This could be tested with a multimeter/DVM to measure the primary and secondary outputs on the coils. But, if it was a coil problem, it would be on cyl. 1&4 or 2&3 not 3&4.
I'm going to stick to my guess with it being fuel related and say it's the carbs.
I had the same feeling, thats why yesterday I did that test.. even if I felt disappointend seeing that there were no noticeable leaks as I was expecting.
This is the real hope.. that some internal passage has been clogged as happened to my pilots...
Anyway I think I will do exactly like that and write then here the results.
Good point on the coils.. I thought about removing from the list because I had this problem with oem coils (which are 2 serving 2 cylinders each) and also had with cbr600 coils which are separate coils (even tho the signal from ecu are still only 2).. and also with 2 different sets of plugs.
You are right, 3 and 4 work on different ignition channels, so if was a signal problem it would have lead the bike to totally cut out instead of running on 2.
This should kick ignition from list.
But just to be sure I'll swap coil 1 and 2 with 3 and 4 even if as you I still think the problem relies in carbs.
At first I thought about diaphragms but when I did the alignment a while ago they were working flawlessy.. and the rubber itself is in pretty good shape
I cant help with any advice, wish i could. Have you joined the facebook zxr400 pages? Lots of advice and parts for sale on there.
im in the uk and happy to post things to italy if it helps you out.
you buy them and ship them to me, i will then ship them to you in italy if the seller wont. As long as you pay the shipping im happy to be a mail forwarder if it helps you out
im in the uk and happy to post things to italy if it helps you out.
you buy them and ship them to me, i will then ship them to you in italy if the seller wont. As long as you pay the shipping im happy to be a mail forwarder if it helps you out
Hello guys, bit of an update.. today after work I fully disassembled my carbs looking for.. I don't know what I was looking for..lets say I was looking for something..anything.
checked kinda everything and all felt in good shape (gladly since there were fully rebuilt like 15 kilometers ago). SO I begun chasing ghosts..
tested all passages with compressed air and spray.. the only thing I noticed is about the choke.
beside the brass shaft are a bit worn, blowing on their rubber seal they seem to hold air.. so I tried to test the fuel stopping capabilities.
end part of the choke piston has a rubber insert and a guide needle.
basically when you pull the choke the piston opens uncovering a passage that goes into the bowl on the jet and on a little hole that should rest on the vented part of bowl, I guess to atomize the fuel, and it also uncover abig hole connecting the lower part of diaphragm chamber to the front carb intake.
i sprayed a bit of wd40 inside the choke jet and blowed a bit of air into the jet. I know that that channel works on vacuum and not on positive pressure, BUT doing so.. carb 3 and 4 leaked wd40 after the choke piston wetting the channel.
This can be a hint. I don't know if I am on the right route.. but tomorrow I will think a way to make a sort of transparent pipe to connect to carb and to apply high vacuum.. I'll make the choke jets pick up some liquid from a little bowl or piece of hose.. and I want to see if those 2 carbs would spray fuel without doing nothing. If they will do.. we may have a culprit.
If its only that.. maybe just putting some shims under the spring would push the piston more forcefully and lock better.
Another thing I want to check is the channel which goes from front of carb, to the needle, to main jet to those 5 little holes where the butterfly rest. but the choke route seems more promising..
Speaking of parts..the only 2 that come to my mind are the ecu as suggested (even tho I don't think it can be the culprit) or the carbs themselves (hoping to find some in not worse shape). carbs can be found even here on ebay, but at 250 euro as price tag I would try everything I can before throwing money on some used carbs that can be even worse than mine.
Anyway I appreciate a lot your help, if in need I'll ask you! Thanks a lot!
checked kinda everything and all felt in good shape (gladly since there were fully rebuilt like 15 kilometers ago). SO I begun chasing ghosts..
tested all passages with compressed air and spray.. the only thing I noticed is about the choke.
beside the brass shaft are a bit worn, blowing on their rubber seal they seem to hold air.. so I tried to test the fuel stopping capabilities.
end part of the choke piston has a rubber insert and a guide needle.
basically when you pull the choke the piston opens uncovering a passage that goes into the bowl on the jet and on a little hole that should rest on the vented part of bowl, I guess to atomize the fuel, and it also uncover abig hole connecting the lower part of diaphragm chamber to the front carb intake.
i sprayed a bit of wd40 inside the choke jet and blowed a bit of air into the jet. I know that that channel works on vacuum and not on positive pressure, BUT doing so.. carb 3 and 4 leaked wd40 after the choke piston wetting the channel.
This can be a hint. I don't know if I am on the right route.. but tomorrow I will think a way to make a sort of transparent pipe to connect to carb and to apply high vacuum.. I'll make the choke jets pick up some liquid from a little bowl or piece of hose.. and I want to see if those 2 carbs would spray fuel without doing nothing. If they will do.. we may have a culprit.
If its only that.. maybe just putting some shims under the spring would push the piston more forcefully and lock better.
Another thing I want to check is the channel which goes from front of carb, to the needle, to main jet to those 5 little holes where the butterfly rest. but the choke route seems more promising..
Thank you for your kindness, no I haven't joined because I don't have facebook or other social account. kinda weird uh? I know heheI cant help with any advice, wish i could. Have you joined the facebook zxr400 pages? Lots of advice and parts for sale on there.
im in the uk and happy to post things to italy if it helps you out.
you buy them and ship them to me, i will then ship them to you in italy if the seller wont. As long as you pay the shipping im happy to be a mail forwarder if it helps you out
Speaking of parts..the only 2 that come to my mind are the ecu as suggested (even tho I don't think it can be the culprit) or the carbs themselves (hoping to find some in not worse shape). carbs can be found even here on ebay, but at 250 euro as price tag I would try everything I can before throwing money on some used carbs that can be even worse than mine.
Anyway I appreciate a lot your help, if in need I'll ask you! Thanks a lot!
Litetek has what you may need, including the choke seals which you suspect as bad. He's a good guy, and even spent time exchanging emails with me about ZX7/ZXR750 throttle shaft seals. Anyway, if your choke seals are bad, he's the only one I've seen that offers them.
Thank you a lot for the website suggestion! never heard of it before, just had a look and it has some very interesting items ! thank you a lot!Litetek has what you may need, including the choke seals which you suspect as bad. He's a good guy, and even spent time exchanging emails with me about ZX7/ZXR750 throttle shaft seals. Anyway, if your choke seals are bad, he's the only one I've seen that offers them.
My pleasure. Viton o-rings are higher quality than rubber anyway. He's legitimate.
1 - 11 of 11 Posts
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