fuel starvation

[Bixxer Bob]

just about to go recover a steamer - done120 miles, stopped and won't start, suspected fuel starvation (but not my diagnosis). I'm told fuel is getting as far as the carbs, or at least itscoming out of the filter.  Is this common?  Cheers, BB

[Mustang]

what filter ...................

OEM filters are :
1. inside the tank on the petcock pipe
2. an itty bitty nylon cone filter inside the pipe at the junction between #2 & #3 carb this is the one that clogs

on mikuni carbed bikes the nylon filter on the petcock pipe  is known to suck flat and prevent fuel from flowing , mrs m's bike did this from new , but it would always restart after stopping , she got to know when it was happening and would switch to reserve before it would die . switching to reserve would let the fuel flow again.
needless to say , but guess which filter is missing from her bike now  :D

the other thing that will prevent fuel from flowing is a plugged cap vent on the tank .......rare but does happen , try it with the cap open and see if it dies when running .


and the #1 thing that will prevent it from running ,,,,,,,,,,,,,
is it really gas they see coming out the line or is it water , a plugged tank drain lets all that water sit right where the petcock pipe is ,


if its not one of those three things it isn't likely to be fuel starvation

[Bixxer Bob]

ok Mustang, thanks for the ideas. Not had a chance to touch it since we got back due to today's celebrations.  It was only runing on 2 yesterday, deffo fuel coming from 2 carbs; he couldn't get the drain out of the 3rd. Before pulling it apart gonna check all coils are good, but it dies when opening throttle so pretty sure uts carb somewhere. I could vaguely remember about the cone filter butdon't know yet which carbs he drained and of course by now the fuel will have trickled through if it's only part blocked. He has a nylon in line filter but know thats not blocked.  Anyway, lots to check I think.  I'll keep you posted.

[Bixxer Bob]

got to her today. Non-original filter in fuel line. Not running on middle pot. Checked coils by swapping, deffo not coils. Removed Mikuni carbs, middle carb pilot jet blocked. Stripped all three and cleaned thoroughly, reassembled, still same prob ie dies when opening throttle then comes in with gusto when needle jet takes over at about 3k revs. Am guessing some crap we didn't find.  Here we go again......

[Mustang]

make sure the blanking cap is on the right hand air snorkel .if not that's how it will run

[Bixxer Bob]

Thanks, cap is in place but will check everything seals ok. middle pot was still cold after second try. swapped 2 and 3 plugs and now all three are hot, but miss is still there. New set of plugs tomorrow as well I think.  Its a bugger whenyou are chasing 2 faults...

[Bixxer Bob]

just checked the cap, tis ok. miss is now regular but most of rev range. new plugs tommorow and if that doesn't work, carbs off again I guess.

[metalguru]

Just a thought, try the coil primary 0.63 ohms and secondary windings 10.5K-ohms impedence a good replacement for these are the stick coils from a superfour, just requiring minimal rewiring.
Pick up coil=530 ohms
Hope you got a spanner for the middle plug as they can be tricky.
Bet its a lump of poo floating about in the middle bowl!!

[Mustang]

if you found the #2 pilot was clogged , my bet is the rest of the passageway in #2 pilot circuit is crudded up , this is where the Sea Foam works wonders , try dumping whatever you guys have across the pond that is similar in the tank proceed to the last paragraph

not knowing the history of the bike ........but if it's the first time out this year after sitting around for a couple months  it just needs a good shaggin........

take it out for a spin and make it run in the 3500 rpm range it will spit and sputter but they generally come into it after a few miles of being made to run off the pilot circuit , use the choke if you need to to keep it from stalling . ride the wheels off it for about an hour or so , sometimes thats all it needs to wake them silly mikunis up after they been sitting .

[rybes]

but if it's the first time out this year after sitting around for a couple months  it just needs a good shaggin........

 :shock: i like my bike but thats takin things a bit too far. plus if Camilla caught id get a slap id feel for months  :lol:  :lol:  :lol:

[Bixxer Bob]

Carbs have been off 3 times now, no idea where the crap is coming from.  Anyway, after soaking one brass tube from float area to intake bellmouth with brake cleaner for 15 mins to clear a blockage, anda new set of plugs, its at least running on all 3 again. Better but not perfect. Idle screws were all over the place too ranging from 1 1/2 to 2 turne out. set them all to 2 turns.  He's off thrashing itnow to see if it clears  :roll:

[metalguru]

Sounds like some mucky petrol has been added, or the inside of the fuel pipe is deteriorating, may be a good idea to fit a min 50micron filter to the fuel supply pipe, the same as fitted to the Girlies will do the job just right but just a pattern will suffice. Possibly replace the fuel pipe with silicon.

BTW the degreaser I use is Swarfega traffic film remover only available to trade outlets, will remove skin too!

[Bixxer Bob]

I buy TFL at the local motorfactors :lol:

It's back and running ok now. Not perfect, but nothing a new air filter and a carb balance won't fix. That tube was so badly blocked I'm not convinced the problem has 'just' happened, I think its been in the offing a while.  Anyway, thanks for all the input guys.

[pegleg]

if you found the #2 pilot was clogged , my bet is the rest of the passageway in #2 pilot circuit is crudded up , this is where the Sea Foam works wonders , try dumping whatever you guys have across the pond that is similar in the tank proceed to the last paragraph

not knowing the history of the bike ........but if it's the first time out this year after sitting around for a couple months  it just needs a good shaggin........

take it out for a spin and make it run in the 3500 rpm range it will spit and sputter but they generally come into it after a few miles of being made to run off the pilot circuit , use the choke if you need to to keep it from stalling . ride the wheels off it for about an hour or so , sometimes thats all it needs to wake them silly mikunis up after they been sitting .

Just to add to Mustangs excellent advice.
I drained my tank, first added a full bottle of Redex petrol treatment, then 10 litres of fuel so it all mixed properly.
Then spent the afternoon giving her a good spanking.
Might be worth a try at the first sign of any running problems.