gpz carb woes

[virus]

ive been doing more work on the gpz750 today, and at the moment when I set the tank to prime when on the side stand the carbs overflow back out the air box side of the venturi after filling the bowls, this only happens on carbs 1+2, 3 tends to stop with a full bowl, and 4 is always bone dry.

Im guessing I need to seperate the carbs and give every passageway a blast with carb cleaner, then set the float heights on them all? or is this all down to the fact its on the sidestand?


Also, what could cause it to backfire through the carbs when I try to start it?


Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[Finglonga]

Check the needle valves for crap stopping them closing causing the fuel to keep flowing.
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Andy Sez....
F.Y.Y.F.F.

[Ichy]

No4 is probably dry because the lower carbs are flooding. Your needle valves will be stuck or the floats are knackered. You have nothing to lose so give the float bowls a tap with the handle of a hammer. Misfire is either due to a air leak or the poor fuel control.
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https://www.metacafe.com/watch/1972097/how_to_behave_on_a_forum/

[prawny1]

Setting your float hieghts is a good idea, just make sure the needles arn't worn at the same time.

Do your carbs still flood if you prime them with the bike upright?

I know most of the blokes with older jap bikes turn the fuel off when the bikes on its side stand as a matter of course to prevent flooding, but the fact your tap has a prime position suggest its vacuum operated and should be fine left in the on position unless somethings leaking inside the tap.

As far as the backfiring goes it could be down to badly adjusted points/timing (assuming it runs with points) or tight valve clearances maybe.

[virus]

Vac tap, only floods when on prime. flood when upright, and its CDI ignition.

Will get the valves checked out soon, I hate working on 16v engines.

Cheers
John
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[prawny1]

[Grav]

The Float Needle Valve isn't closing properly. This is usually caused by crap in the fuel sticking it open. After cleaning the carbs thoroughly, reset the floats, fit a filter on the main fuel line and it should cure it.
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Dark Lord Of Custard

snigger.....

[prawny1]

[Ichy]

Don't split the carbs, its more trouble than its worth and won't help at all with the problem. Just use carb cleaner to clean around the needle valve and check its seating correctly. Carb repair kits cost about £12 per carb so it may be worth looking for another set if you can't sort it.
____________________
https://www.metacafe.com/watch/1972097/how_to_behave_on_a_forum/