Running like crap

[Dave]

Help
Rhonda has gone off song, it's sort of like fuel starvation exept she comes good above 4000 rpm sometimes, maybe fuel pump needs that many revs to work?. If it's spark it's all 4 pots as the pipes and plugs all look the same. I am thinking vac advance unit (has new hose fitted) but don't know how to test it, idea's please

 

[joedrum]

im not sure dave mines a 1000 and has spring loaded advance thats the one thing i diont like about the 1100s but im sure dan or the many others can post some help. i think some of the 1100s have two advances on them but my memory is not to relieable cant be anything big

 

[mcgovern61]

Dave, the vacuum advance will only make a big difference when accelerating. Many guys pull the hose anyway and plug it. (Not me, I like using it.) Sounds like fuel clog to me.

 

[dan filipi]

Dave, What's the history of the bike?
Have the carbs been rebuilt?

I think your on the right track. I'd check the fuel pump delivery and pressure first then move on to the carbs.
It's easy to blame electrics when it's actually carb problems because they react similar when acting up, usually it's carbs or poor fuel delivery.

 

[Joep]

put a vacuum gauge on the carburator connection and see what it is pulling at idle.. run up to 4 K and see what it pulls then... that will give you a baseline for the vacuum on the system and a place to go from.. without hit and missin' always check the cheap side first!!

 

[AApple]

Carbs....
A fuel pump issue would more likely show up all the time. If the pump is weak, it would be able(maybe) to keep the bowls full at lower rpms, but not at higher rpms, especially if it's having to fill 4 fuel bowls first. Then, after the bowls were full, it should run fine at lower rpms, until the bowls got too low.
The filter could cause it, if it was restricted enough to cause starvation at idle/low speeds, but then the pump would suck it up at higher speed.
Just my observation on mine, anyway. I don't think my fuel pump does a whole lot, as far as pressure/volume. I know it takes a while for the pump to fill the bowls, and fire the thing off if the bowls are empty, unless I turn the petcock on, and let it sit for a while....

 

[scdmarx]

My 82 manual spec for fuel pump pressure states:
2.4psi cranking speed
2.3psi @1100 rpm
2.0psi @5000 rpm

I don't see a volume spec though. Working on cars I have seen good psi showing on a gauge, while there was insufficient volume output. Just say'n.

That said, I'd tend to agree with AApple, that if it is indeed a fuel problem, it sounds more like a carb issue than a delivery issue.

 

[Dave]

Lots of good stuff there guys,cheers.
She cruises perfectly at any revs, idles and starts well only goes bad under load, even small load
Striped and cleaned the carbs when it first started playing up, surprised how clean they was, all fuel passages clear.
Filter is near new.
I can't meassure pressure but will pull the lines off and see how far she can sqirt fuel and also see if it flows freely from the filter.
Gave her a full tank yesterday so should run without the pump so I'II try by-passing it.
Also might try fitting extra long vac hose so I can suck on it while riding, I tried this at idle and about 2000 rpm in neutral and made no difference to the revs but she doesnt play up in those conditions anyway.

 

[dan filipi]

goes bad under load, even small load
.

Have you tried a fresh set of plugs?

Other than that I would say recheck your float levels, check the amount of fuel in the bowls.
Mine was acting like that, turned out one cheap quality needle and seat needed more float pressure to close it so at the correct float adjustment the fuel level would be too high. This was on just one carb which would flood that cylinder during acceleration when the vacuum slides got pulled up.

 

[Dave]

All floats checked, 15.5mm
How soon I forget stuff, raced 2 stokes for all those years and havent suspected the plugs this time.
This has been a deteriating thing since I fitted new spark plugs at last oil change. I keep the old set because I hate throwing out stuff that still works so I'II put em back in tomorrow and try it.

 

[Dave]

Changed plugs, no better
Fuel pump pumps heaps
Suck testing the avdance was interesting, like driving a model T Ford but using mouth co-ordination as well as hands. And it seems fine
Disconected accel pump, problem solved, exept now I need more trottle to start up and to 'blip' between gears and carb #3 is gunna be way out of sync
Funny that the accel pump looked OK when I had it stripped but it must have been flowing fuel non-stop like having an extra jet flooding one carb
At least I (we) found the problem, or have I, used the kill switch a few dozen times while trying to track this issue down. I generally never use the kill switch so there is a chance I have now 'cleaned by use' the switch
At least its going good again

 

[Dave]

Just had a thought, float bowl seal can fail between bowl and pump, this could be the real problem. Can some one give me some links to the various carb kits you all seem to be able to access in the states please. Also if any one is set up to resieve PayPal payments and wants to be a go between I may need you as a lot of companies dont handle international orders because they can not calc the post untill they get to the post office. Thanks

 

[joedrum]

glad its getting worked out somebody will help im sure if parts are a problem . randakks .com is the carb parts guru in the states here

 

[dan filipi]

I have Paypal and can help you out.
Send me a PM and we'll work out the details.

 

[Dave]

Thanks Dan
I will see if they will look after me direct 1st

 

[Dave]

OK, Randakks looks like $200 plus international plus exchange rate should come to about $260 Aussie dollars which is about 1 days pay for me in my current job which the same employer in the US pays about $200US a day so the world yet again proves to be a flat playing surface (yeh I know the media says its round but really, have they ever sailed out to edge to see if ya fall off)
Me, the Harley (yeh I know) and the blonde :heat: (now you lot know why ) are gong on holidays next week so it will be a month or so before I get aroundtothiskitthing but will update when I do :grin:

 

[Smokey66]

Heres something you might not have thought of;PLUG WIRES!If your still running the 30 year old originals,REPLACE EM!I had a similar problem with mine;ran rough,cleared at high rpm,swaped the plug wires and she runs great!Also check those plug boots,they have built in resistors that can also go bad.A couple foot of plug wire don`t cost much,and there easy to change;just screwed into the coils and boots.