Engine stalls with throttle

[Aeschere]

Hello again,

Sorry for the amount of questions but I keep running into things.
Last night I went for a 1.5 hour drive without any problems. This morning I could drive away easily but after about 3km the revs went down, the bike slowed and eventually the engine stalled.

When using max choke I got it to run idle but the revs went from 4k to 1k and everything in between. The moment I used the throttle a bit the revs went down and the engine turned off again.
During the walk home I could start it after a few minutes, ride a couple hundred of meters in 1st gear before it stalled again. This is making me think that the bike has been sitting still longer than the dealer made me believe and that there was some gunk in te carbs that came loose when I started using the bike again and is now clogging up the jets.
Is this fair to assume and should I pull the carbs or could there be another reason for this behavior?

Thanks once again!

[threepot]

I had very similar after buying my bike. Turned out to be a blocked fuel filter into carburettors..The small cone shaped one in the 't' piece.

[Sin_Tiger]

I had very similar after buying my bike. Turned out to be a blocked fuel filter into carburettors..The small cone shaped one in the 't' piece.

Start at the tank. Check the nylon strainers on the petcock inlets. Check the fuel in the tank for crud that might have moved (clean it out) . Then as TP says 

[London_Phil]

With my petcock, I found that when trying to drain tank, it trickled out then stopped with 3/4 of a tank in, the flow difference after removing the internal strainers was amazing. Try also opening the petrol cap, to see if you have an airlock due to a blocked breather or cap poppet valves. Start from top and work down , I think.
Good luck.

Regards, Phil

[Aeschere]

Thanks for the suggestions. Went to work today.

Removed the side panels..found out the screw heads were glued to the fairings and the screws were still in the tank. The panels are fixed with velcro and double sided tape :(


Removed the tank...found out the low gas sensor wasn't connected
Removed the fuel tank filter...looked clean. The reserve filter is a little bit bent but that shouldn't interfere with gas flow


Removed the carbs...the screws on the bottom (can't think of the name for those cups. Edit: float chambers!) were a bit to tight so I could only remove one without damaging the screws, looked very clear

Removed the fuel hose filer...was clocked with a black blob of something...cleaned it out. Sure hope that was what was causing the shutdown.


Found out a hose from the air box to the engine was just laying on the engine...attached it. What is it for? Edit: Found it, it's the breather hose...not much of a big deal when it is loose.


Reassembled everything but forgot the way the fuel hose is supposed to run, if anyone got pictures of the best way, that would be great.

Turned the petcock to reserve to let the carbs fill, tried starting...the startermotor is turning but nothing is starting up. Thought it might be the battery so I hooked it up to my car and tried again...no success :(

Since I don't have a workshop and need to work in front of my house I am calling it quits for today and will try again tomorrow. Any suggestions on what might be the problem this time?

All in all it was a busy day with a lot of disappointments. Finding out all kinds of things are wrong with the bike but I guess that's the life of someone trying to ride older bikes...

Edit: Also found a loose bolt underneath the rear suspension. Just a phillips screw but couldn't see where it came from.

[JayDub]

That nice of the previous owner!
most people dispose of the tiny filter and fit an in-line one instead,either below the petcock or as I did, on top of the air box, which is where the fuel pipe originally runs.  Its best to remove the carbs and strip them all to make sure the jets are all clear, and the diaphragms are not holed or split, even though the blocked filter was probably the culprit, also check the rubbers connecting the carbs to the head, they don't last very long and crack/split easily.  The thick hose attached to the air box is the crank case breather, there should be another thinner pipe at the bottom which has (or should have) a plug in the bottom end, this is a drain which you need to empty, but not very often, Make sure that when you refitted the carbs that the throttle cable is seated properly, or the throttle valves will be half open.

[London_Phil]

Those internal filters are collapsing, I suggest removing them. They just pull off.
Fit an inline filter.

[Aeschere]

Phil, do you mean the filters from the petcock or the inline filter at the carb side?

I will get a battery charger first thing tomorrow to make sure the power is sufficient. It seems to be a bit low since the start motor turns slower and slower. Then I guess I will check the routing of the fuel hose to make sure that the carbs are getting fuel and give it another try.

[Sin_Tiger]

Those internal filters are collapsing, I suggest removing them. They just pull off.
Fit an inline filter.

The filters on the main and reserve pipes, they collapse under higher flow once they get warm. I'd advise binning them in favour of an external filter also. You can see what's going on and do something about it at the roadside without taking everything apart. The house runs upward from the inlet T between the carbs over the top of the air box with the U at the tank end, really hard to get it wrong  :icon_wink:

Try this as a suggestion for an external filter (http://www.hein-gericke.co.uk/benzinfilter-gross-90-anschluss.html) , cheap enough to have a spare under the seat.

The breather hose from the air box to the casing will make a difference if left off.

[London_Phil]

The filters attached to the petrol tap assy on the inside of the tank. One at the top of the brass tube, and one fitted into body for the reserve position

[threepot]

Re crankcase breather hose..I've fitted one of these,after reading about the damaging effects recirculating crankcase gasses can have on your engine? Toxic and corrosive.My bike is running lovely .....tt600 coil conversion,New camchain,castrol power oil,and even the split airbox mod!

[JayDub]

most people dispose of the tiny filter and fit an in-line one instead

That Bixxer, believe it or not - is what I was trying to say... in my own (unclear) way  :icon_wink: 

[Aeschere]

It's alive!

Recharged the battery and checked the fuel hose position. Turned out the engine wasn't getting fuel since the floater chamber was completely empty.
Just did a 15km round and the bike handled great. Still needs some work (need to check the valves) but a happy owner once again! :)

Edit: Guess TP was right straight away so a special thanks to him for pointing me in the right direction