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NX650 fuel tank hose routing? Engine dies when idling and when braking at stops...

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Hey guys!

 

As I've bought and rebuilt an NX650 with a XR650L engine, I now seem to have trouble with air line routings and such...

 

So I wanted to ask - maybe someone can tell me what are the two hose nipples under my fuel tank? There is one smaller than the other. The biggest one seems to be fuel ventilation, as below the fuel tank cap there is a little hole, which dirrects air through the biggest hole under the tank - but what is the smallest nipple under the fuel tank??? What should be connected there - where sould it be routed?

Thanks

 

EDIT: So the problem actually is engine dying when idling and also when I ride - when I brake to stop at intersection. The thing is that it most often happens when engine is not fully warm, but it happens also when engine is fully warm - just not that often. When I did the rebuild I also cleaned carburetor. Now all the hoses are routed correctly. Also I did adjust pilot screw as per manual. Basically, when engine is warm it idles fine, and then suddenly dies, like if I had turned the key (can hear starter motor spining for a second). The same hapens when braking to a stopage - engine dies like I would have turned the key. Also, when engine dies while braking, not always I can get it to start right away - sometimes I need to try to start it for about 3-5 seconds. 

 

What could cause this?

P.S. There was some minor scratch on the needle, so I thought that it could be a problem - I wanted to buy it at dealers, but it is discontinued.

Edited by RadekSkylark

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lot of times the hole under cap is for a drain like if you over fill tank it has somewhere to go!

 

Yes, now I know that - the big nipple is for excess drainage and the small nipple is for fuel tank ventilation. 

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My guess is the auto decomp mechanism on the cam is shagged..Read the following,,It's to do with a 600,,Forget that,,Both

bikes run the auto mechanism on the cam..I am not saying it is the problem for sure..More,,consider it as the possible issue,,

 

http://www.advrider.com/forums/showthread.php?p=16753137

 

I know nothing of hose routing on NX650..I did post over at ADV when you wanted to know whether the motor sounded normal.

It did apart from that odd click near the end of the vid as I mentioned..That odd click if it was nothing else may be a sign of something

not being right with the auto mechanism. NX..XRL..XR are all basically the same engine,,all run the auto decomp on the cam..On the 600

it can be removed,,others,,dunno,,may affect the starting as you  have no kickstarter so need to rely on the battery..The auto may be needed

to get the engine spinning fast enough using the battery to enable a start..Without it the compression may be to much for the battery to handle..

Edited by Horri

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Thanks for replay!

 

The strange CLICK was me stepping on a plastic box :) Not the engine :)

 

If it would be auto decompressor system wouldn't the problem be constant???

 

Thank

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Did you read the thread I posted..All I can go on is what I think it may be by reading lots of stuff .The symptoms are the 

same to me..I can't say whether it should or shouldn't be constant..His seemed to be an occasional problem,,yours seem to be the same.

To me 1+1=2....Your bike cuts out..his bike cut out...It could be electrical,,CDI partially shagged..I don't know..I offer advice

not certainty. You could buy a new CDI and test it..If that doesn't fix it then the next in line to me is the auto decomp.

 

Ok about the box..Had me wondering that's all..

Edited by Horri

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Did you read the thread I posted..All I can go on is what I think it may be by reading lots of stuff .The symptoms are the 

same to me..I can't say whether it should or shouldn't be constant..His seemed to be an occasional problem,,yours seem to be the same.

To me 1+1=2..Ok about the box..Your bike cuts out..his bike cut out...It could be electrical,,CDI partially shagged..I don't know..I offer advice

not certainty. You could buy a new CDI and test it..If that doesn't fix it then the next in line to me is the auto decomp.

 

Yeah, I read that thread - thanks for that. I understand that no one can tell for sure. The thing is that english is not my native language and that thread really was the first, in quite a while, that I couldn't make much sense of... As from what I could understand from that thread is that for him the problem was engine rattling, choking and wanting to stall (and stalling occasionally), for me the problem is that it just dies like if I had turned the key... 

 

I'll keep in mind the auto decompressor system, of course, I'll start with things that dont require engine disassembly...

The thing that concerns me the most is that the engine has only died when idling or getting close to idle (low motorcycle speed and/or low engine speed), so it seems that it must be something with carburetor - pilot jet, pilot screw adjustment or something like that....

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Yep,,Ok..Best to wait for ScottNelson to turn up..He had some issue with a 650L engine that sounds exactly the same,,

My understanding is that he sold that bike to someone else and he fixed the problem somehow..He will be able to send you

hopefully on the right path to the fix..

 

Latvia..Very nice place from my understanding..Heard something on the radio the other day about people cycling through

there,,Said it was great and very cheap with friendly people..Good luck..

Edited by Horri

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Yep,,Ok..Best to wait for ScottNelson to turn up..He had some issue with a 650L engine that sounds exactly the same,,

My understanding is that he sold that bike to someone else and he fixed the problem somehow..He will be able to send you

hopefully on the right path to the fix..

 

Latvia..Very nice place from my understanding..Heard something on the radio the other day about people cycling through

there,,Said it was great and very cheap with friendly people..Good luck..

Yeah, I hope he'll chime in :) Cause I'm pretty much out of any simple solutions by now...

 

Yeah, we had some kind of cycling tour here. Many people on bicycles riding around and stuff ;) 

 

For a European country Latvia is pretty cheap - cheaper than UK, Germany, France and any other big countries. Mostly people are kind, but I believe that people are that way all around the world, though there are always those who want to f**k everything up ;) 

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Hey guys!

 

As I've bought and rebuilt an NX650 with a XR650L engine, I now seem to have trouble with air line routings and such...

 

So I wanted to ask - maybe someone can tell me what are the two hose nipples under my fuel tank? There is one smaller than the other. The biggest one seems to be fuel ventilation, as below the fuel tank cap there is a little hole, which dirrects air through the biggest hole under the tank - but what is the smallest nipple under the fuel tank??? What should be connected there - where sould it be routed?

Thanks

 

EDIT: So the problem actually is engine dying when idling and also when I ride - when I brake to stop at intersection. The thing is that it most often happens when engine is not fully warm, but it happens also when engine is fully warm - just not that often. When I did the rebuild I also cleaned carburetor. Now all the hoses are routed correctly. Also I did adjust pilot screw as per manual. Basically, when engine is warm it idles fine, and then suddenly dies, like if I had turned the key (can hear starter motor spining for a second). The same hapens when braking to a stopage - engine dies like I would have turned the key. Also, when engine dies while braking, not always I can get it to start right away - sometimes I need to try to start it for about 3-5 seconds. 

 

What could cause this?

P.S. There was some minor scratch on the needle, so I thought that it could be a problem - I wanted to buy it at dealers, but it is discontinued.

 i had a wire broken inside the insulation from vibration. sometimes would run , other times not, and intermittent. had to follow each wire and bend until i found one that bent at a sharp angle without creating a loop. that was it in this case, looked perfectly good on the outside but broke inside. sometimes a dirty kill switch will do this too if you have one. easily cleaned and cheap.

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Yep,,Ok..Best to wait for ScottNelson to turn up..He had some issue with a 650L engine that sounds exactly the same,,

My understanding is that he sold that bike to someone else and he fixed the problem somehow..He will be able to send you

hopefully on the right path to the fix..

Apparently getting the jetting spot on and making sure that all of the electrical parts are clean and working was all that was needed.  I never did hear if the bike got to the point of running perfectly.  I just know that the guy who bought it eventually stopped asking questions, and the bike ran beautifully on the Baja trip that he bought it for.

 

Turning the idle up helps prevent it from dying when at idle.

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Apparently getting the jetting spot on and making sure that all of the electrical parts are clean and working was all that was needed.  I never did hear if the bike got to the point of running perfectly.  I just know that the guy who bought it eventually stopped asking questions, and the bike ran beautifully on the Baja trip that he bought it for.

 

Turning the idle up helps prevent it from dying when at idle.

 

Yes, thats correct - when I raise idle speed to about 1500-1600rpm it doesn't stall that much.

 

I'll try to check few things today and then I'll post how it goes. Maybe you all will be able to help me out a bit more ;)

 

Thanks alot to everyone for input!!!

Edited by RadekSkylark

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So I adjusted the choke cable and the problem got better. But engine is stilll stalling the same occasionally...

But now I tried to adjust the PS (pilot screw) - I turned it out 2,5 turns as per manual, adjusted TSS (throttle stop screw) to 1400rpm, then I turned out PS and at 3 turns it started to stumble a bit (at 3.25 it stumbled alot). When I turned in to ~1,75-1,5 turns out, engine speed raise to ~1,6k-1,7k rpms... but the things is, it kept that way until the PS was seated - the engine didnt die, because of the TSS adjustment which seems to allow enough fuel and air into the engine. I even was able to rev it a bit with PS seated... I also did a little test run with it seated - occasionally when at idle or braking to idle it would drop below 1300rpm (which I adjusted the TSS to), and then would stumble if throttle got opened or would die while idling...

So the question is - how can I adjust it correctly? The pilot jet is #48 Keihin, which comes like that from factory...

Thanks alot!!!

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Ideas needed!

 

After I adjusted choke cable on my NX650 two weeks ago it didn't stall as much and run a little bit better. But still, rpm's are unstable and fluctuate in range of 300rpm. Not horrible, but not cool either. The main problem is occasional stalling, though. When engine is warm, bike won't stall idling. But when I ride it, it will occasionally stall when braking to a stop. 

 

In detail: Around 20% of the time when riding in gear and then pressing clutch in, and slowly braking to a stop, revs will drop to ~1500rpm (which is idle) for 1-2seconds and then will drop down to 1100-1200rpm, and will be there for few seconds or till I start opening throttle again. As I understand, this seem to indicate rich mixture (or am I wrong?).

Also around 20% of stops done fast (hard braking with alot of front fork travel) end up stalling. So, I ride, depress clutch and brake hard, at that point rpm's start to drop to around 1500-2000rpm, and somewhere at that point engine stalls, mostly when still braking (beeing in motion). Also I've noticed that at these moments only around 50% of time I can already start the engine up. Other 50% of time when I try to start it it wont start - sometimes it will crank and wont start for few seconds (1-3sec) just like if it had been flooded. Sometimes it just wont crank - I just press the start button and nothing happens for few seconds (1-5sec), then it'll start up just fine.

 

Also, today I discovered that when standing still and idling, if I hold front brake and compress front forks fast (like when doing a fast stop), engine will drop rpm from 1500 to ~1000rpm like if it would want to stall... The question is, why this could be happening - does it want to stall because of over flooding or because it cannot get enough fuel? I think this is the same case as the one of stalling while braking hard to stop.

 

Just to add - I've tried another used carburetor which has been cleaned and seemed to be in normal working order. Also I've tried another choke cable and insulator. My insulator had a crack underneath it - but there where no cracks from inside, so I don't think there was a problem with it, cause the spare one I tried had just a tiny crack from underneath and also no cracks from inside - no difference.

 

1) What could cause the problem of RPM's fluctuating in the range of 300rpm?

2) What could cause the stalling issue?

3) Also I got a problem of huge fuel consumption (~9liters/100km = 26,5MPG) - what could cause that?

 

Hope someone will suggest something. Thanks for everything!

Edited by RadekSkylark

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Sounds like there are a few issues, lets start with fork travel changing rpm. This can only be two things, a worn wire shorting out or more likely a throttle cable routing issue. I would have someone push down on the handlebars in a bouncing motion while you watch the carb end of the cable for movement. Its probably getting pushed by your speedo cable or front brake line up near the handlebars somewhere. You may just be able to reroute the cable.

As for the dying at idle, what elevation are you at? For the pilot screw, turn it out 2.5 turns, adjust idle screw (tss) to proper rpm, turn the pilot screw in until you reach the highest rpm then turn it back out until it loses 100rpm. Now use the idle screw (tss) to set the idle back to proper rpm.

If after this process the pilot screw is less than 1 turn out you need to go down 1 pilot jet size.

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Sounds like there are a few issues, lets start with fork travel changing rpm. This can only be two things, a worn wire shorting out or more likely a throttle cable routing issue. I would have someone push down on the handlebars in a bouncing motion while you watch the carb end of the cable for movement. Its probably getting pushed by your speedo cable or front brake line up near the handlebars somewhere. You may just be able to reroute the cable.

As for the dying at idle, what elevation are you at? For the pilot screw, turn it out 2.5 turns, adjust idle screw (tss) to proper rpm, turn the pilot screw in until you reach the highest rpm then turn it back out until it loses 100rpm. Now use the idle screw (tss) to set the idle back to proper rpm.

If after this process the pilot screw is less than 1 turn out you need to go down 1 pilot jet size.

I understand that by worn wire you mean a wire loosing connection (ignition wire) and thus spark plug not giving spark at one moment?

 

I will try to check throttle cable but I really doubt that this is the problem, because rpm's drop below idle speed. Throttle cam is stopped by throttle stop screw and it only can go one way - higher rpms...

 

I'm at sea level (pretty much). I've tried to adjust pilot screw, but something is incorrect - I seem to have rich mixture always. I can turn pilot screw totally in and still rev engine (and I have confirmation that my #48 Keihin pilot jet is definitely not too big). So I cannot really get it adjusted...

 

Thanks

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I misunderstood about the throttle change with fork travel. I had it in my head that it was revving on compression, now that i reread it i get what you are saying.

Its getting fuel somehow. If the pilot isnt too big, has the clip been moved down on the needle? Maybe its that scratch you found on the needle letting fuel by. are you just assuming that because it is a stock 48 pilot that it cant be too big? Usually the process i described above is how to determine pilot size so i am curious how you have determined that yours isnt too big.

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I misunderstood about the throttle change with fork travel. I had it in my head that it was revving on compression, now that i reread it i get what you are saying.

Its getting fuel somehow. If the pilot isnt too big, has the clip been moved down on the needle? Maybe its that scratch you found on the needle letting fuel by. are you just assuming that because it is a stock 48 pilot that it cant be too big? Usually the process i described above is how to determine pilot size so i am curious how you have determined that yours isnt too big.

A guy from Australia who is helping me out with ideas said that it is definitely not too big, he has had bigger in tha same engine without a problem (stock engine). 

 

I just checked the fuel level in the bowl by adding a clear hose to the bottom of the float bowl (drain nipple) and raised it in the air to see whats the fuel level. Level is somewhere at the float bowl gasket, thus normal. When compressing front forks level rises ~8mm (pretty much to the bottom of venturi)... so this may cause the problem of engine wanting to stall under hard acceleration.

 

Today I assembled my own insulator back onto the bike. After adjusting pilot screw for the first time bike does what it is supposed to do - starts to die at aroudn 0,75 out, and also starts to stumble at around 3,25-3,5 out. It seems to be the best on 2,5 out. It stalled twice while idling, though. Went for a quick 10km ride and it didn't stall.. rpms where just dropping few times below 1500, like I've already described.

 

Will try 2 turns out and see how it goes later. I don't mind revs going up and down, the only thing I'm concerned about is stalling and fuel consumption.

Edited by RadekSkylark

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So today did more riding (after changing to a iridium spark plug as a member on advrider sugjested (which had helped him with similar problem) - it was better... 

 

The problem still exists, though. Will try to change spark plug wire and ignition coil in week or so. 

 

Today measured real fuel consumption - 8l/100km (30MPG). Not cool. Don't know what could cause that. Will try and put in my mates jet needle (from his spare carbureto) and see if that helps. If that doesnt will also check the size of main jet on mine and on his spare main jet (both were #148, but maybe mine is drilled to a bigger size).

 

Any other ideas on what could cause excesive fuel consumtion?

 

P.S. Idirium spark plug did make things better to some extent, but the problem is still there...

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Swapping needles sounds like a good idea. I was wondering if your jets had been drilled out also but im still thinking pilot jet more than main. You are definately right that a 48 pilot shouldnt be too big but as i said before, the standard adjustment procedure seems to point at either the pilot being too big or the needle allowing fuel from the main jet to be getting through while at idle.

Jets are cheap. I would put in two new jets and your friends needle and try the adjustment procedure again. Its worth the $8 to know what jets you actually have.

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