Suzuki XF650 wont fire up after fuel system clean.

[xe0n1]

Hey all, new to the forum and need some advice.

I brought a bike from my work (a huge hire company / workshop)who had a old 1997 suzuki XF650 11k miles on the clock that has been sitting for nearly the last 3 years. I am used to tinkering with newer sportbikes (injection / ECUs) so this is a new one for me

For starters I pumped the old fuel out of the tank and put a few ltr fresh fuel with line cleaner. She started but only on full choke and would die instantly with any gentle throttle. I just about rode her a hundred yards or so from her resting place into the workshop so she works.

Fair game the carbs need cleaning. Pulled them out and a mechanic mate cleaned them. I cleaned the tank out so it's mint and made sure the lines where clean.

Put back together again all the same and she won't start.

The plugs are clean and sparking 100% confirmed as she fired up when spraying starter in the air box, fuel is 100% flowing through the tap so the carbs must be getting petrol, you can feel the compression coming from the exhaust.
But worryingly there is no smell of unburnt petrol from the exhaust can...

She also has a brand new battery and I have ensured the fuel tap is set to "prime".

I'm stumped, all the guys at work are pretty flat out at the moment so I am having to do this myself but its pretty handy as its a full size workshop.

Thanks for reading and apologies for the essay!

Cheers :@)

Here is a few pics.
Before


After a steaming down.


Partly stripped.






Right side carb view (not the best pics sorry)



Left side.

[Brummbär]

Most carburetor cleanings are not carried out completely and thoroughly.
Did your mechanic remove the jets completely to clean them from both sides?
The carburetors were just thrown in an ultrasonic bath?

[momoxf]

Brummbär, the engine worked before...so why should cleaning lead to a completly non working engine. I think the mechanics made a failure when they reassembled everything.

xe0n1:
Did you check if all the pipes are correctly connected on the carb? So is the fuel pipe really connected to the correct contact at the carb?
How did you make sure that the carb definetly gets petrol? Did you open the drainage to check?

[coon]

If you leave it standing on primary it will flood the engine. You only use primary to flood the carbs.

Check the Oilglass, you will see if it has filled with fuel.

[Lebowski]

Are you dead sure, coon? Because the "needle valve" (Nadeldüse) should prevent the carb from overflowing. Imho the "PRI" position works exactly the same like the "ON" position with vacuum. You could turn the petcock on "PRI" forever without having any overflow (under the condition that everything is working as it should!).

Please correct me if I'm wrong.

Cheers!

[dodo]

that´s true, but as you said before only if the "needle valves" are completely leakproof...

you should turn the fuel valve at on/res if the bike stands arround a longer time to avoid overflooding the engine caused by minimal leakages at the needle valves... also at "pri" the fuel "presses" because of its weight on the needle valves and in the other positions there is no pressure from above cause of the closed "underpressure-fuel-valve" these are pretty little valves and they can not resist any pressures for a longer time...


@ts:
you should check everything again, it can´t be that there isn´t anything wrong with sparks, fuel and compression and it doesn´t run. I think something is wrong with the fuel supply, this is the most probable reason in my opinion, how said, for example wrong carb-cleaning or mistakes at the rebuild...

[xe0n1]

Still no Joys

I took the carb out again and it was sent to a motorbike garage to be looked over, ALL ok with exception to one of the jets is slightly larger than the other?, he said it looks like either someone has "drilled it out, OR put a larger one in"...... would this cause my problems?

Accelerating is difficult, anywhere between 3 and 4k revs is very sluggish to go through and it feels like the bike is rocking forwards and backwards if that makes sense?

Could the odd sized jet cause this?, Apparently the bike mechanic was able to clear it with the choke?, I have noticed that when riding if you pull the choke up a fraction and it goes above the 4k rev range it picks up ok, but the min you drop bellow/change gear it rocks backwards and forwards again trying to get past that range?. It feels almost like the engine is being starved of fuel.....

[Brummbär]

How many turns the idle mixture screws were turned out?
They need 3 and a little more.
Look at #6