GS550 carb rebuild questions

[StevieB]

Hi just got a few questions regarding cleaning and rebuilding CV carbs on a GS550e. Firstly thanks to everyones help in figuring out my original issue with a fuel tap. The advice and links on here are so helpful - thanks.

After replacing my fuel tap as it wasn't giving a decent fuel flow from the vacuum I was hoping for an easy start. However I couldn't get it started. Fuel now in carb bowls, spark on all cylinders but all plugs dry. Suspect no fuel through carb jets.

Followed brilliant carb cleaning and rebuild guide from this site. Managed to get them all apart without damaging anything and only having to saw slots in a couple of screws. Have discovered a lot of red debris sludge which think has gradually got into the Jets and now stopped fuel flow. One of the float posts has been previously snapped and welded - good repair!

My couple of questions are:- conflicting information - do you measure float height with or gaskets?

 

Pilot screws were previously capped - do I reset to noted original settings from factory (all different) or set to manual figures?

[StevieB]

And most importantly need advice on source of O rings for carb internals, fuel connecting pipes, vents pilot jet plugs and chokes. Bit dubious about Eblag or Amazon, Fowlers and Robinson Foundry are for individual seals, was hoping for a complete rebuild kit.

[Poldark]

The caps on the idle mixture screws were just there to comply with US environmental standards; they pull out easily.  There's no way the original factory settings would still be correct; our fuel formulations have changed in the past forty years, and yours will be different too.  Carbs were generally jetted too lean from the factory.  If running everything mostly stock, go one size larger jets.  If running higher flowing air intake or exhaust, you may need to go two or more sizes larger.  Of course this could all vary on local atmospheric conditions, fuel formulation, and vehicle regulations.

[BigT]

CycleOrings.com for the O rings

It's a bit hard to tell, but are you confusing the pilot jet with the pilot screw? The pilot jet is what you're showing in the pics, they need to have the rubber caps over them

The pilot screws are on the top front of the carbs

[BushcrafterQC]

Hey i found this guide for the Gs550 carbs. I'm strugling with mine. cant get the bike to start anymore. hope this helps! 

https://drive.google.com/file/d/1oqEjoQyS9F3xSr2-15yDZILxt7KzQje7/view?usp=sharing

[StevieB]

Thanks for the advice on the carbs and spares.

The guide from Bushcraft was the one I followed - brilliant.

Other websites and manuals say measure float height with gasket. Think set + .5 mm without gasket, will then be close to limit with gasket.

I think my photos confused things - pic inside bowl was to show old gasket and debris that I think caused jet blockages and prevented bike from running.

The other pic was to show welded float post - I thought quite a good repair.

So far I have totally stripped the carbs (drilled out pilot screw blanking plug and fitted self tapping screw to remove blanks).

Also rubber pilot jet plugs removed as not much left of them - totally had it - don't think they were sealing.

Plan to get all them cleaned and reassembled once I get all the spares.

Will update with progress and photos.

Cheers

 

[TonyGee]

ive always done it from the gasket face, (no gasket) 

[StevieB]

Thanks will set with no gasket.

 

[StevieB]

Started the cleaning process, being thorough so will take a while.

Just one issue so far - one of the choke plunger outer dust seals is torn. Can't find a parts list or diagram that details them.

Anyone know of a part number?

I know mikuni bs32 cv's not just used on the gs550.

[BushcrafterQC]

On 4/10/2021 at 5:17 PM, StevieB said:

Started the cleaning process, being thorough so will take a while.

Just one issue so far - one of the choke plunger outer dust seals is torn. Can't find a parts list or diagram that details them.

Anyone know of a part number?

I know mikuni bs32 cv's not just used on the gs550.

Did you find the dust seal anywhere? mine are torn also

[StevieB]

Still rebuilding between working shifts. Set float heights and now measuring fuel level on each carb. Couldn't find dust seal for choke anywhere. Glued it back together with vulcanising  puncture glue - seems to work and added an o ring between spring, carb choke plunger and screw in retainer to totally seal against dust. Seems to operate without restricting choke plunger movement.

Will update with photos next week when I start rebuilding.

[BushcrafterQC]

2 hours ago, StevieB said:

Still rebuilding between working shifts. Set float heights and now measuring fuel level on each carb. Couldn't find dust seal for choke anywhere. Glued it back together with vulcanising  puncture glue - seems to work and added an o ring between spring, carb choke plunger and screw in retainer to totally seal against dust. Seems to operate without restricting choke plunger movement.

Will update with photos next week when I start rebuilding.

I ordered these seals http://www.nichecycle.com/ncs/categories/carburetor/oe-style-replacement-parts/48-5040-mikuni-bs34-choke-plunger-dust-seal-by-ncs.html

they are for the bs34's, not shure at all if they fit, i'll let you know if they do.

[StevieB]

Continuing the carb rebuild.

Saved the link for choke dust seals - thanks bushcrafter.

The repair to mine is good - vulcanising glue sorted it - but added an additional o ring between the spring and brass housing to stop any dust.additiinal dust o ring

[StevieB]

Everything back together - thought going well - found out original fault - the passage way between float bowls and choke feed, and choke feed tubes totally blocked. Used old tip from Dezza on here with cellulose thinners to dissolve the old sealant blockage.

Cleaned everything, replaced seals, gaskets, needle valves and set up float height and fuel heights with clear tubing from fuel in bowls. All spot on and each carb needle valve stopped fuel flow at correct height.

Ganged all carbs together, set up mechanical balances.

Refitted to the bike, and now fuel is pouring out of airbox drain from no3 and 4 carb.

Obviously not seating, no amount of tapping stopped the flow.

Drained the oil, no fuel evident.

Not sure of next step - was thinking take carbs out and fill with fuel first - but think angle they need to be tilted to will spill fuel anyway.

Bit stuck?setting fuel heightsetting fuel height

 

[Gixer1460]

Off bike float valve checking really needs to approximate fitted conditions in bike (sorry if obvious!) Carbs to be set at intake angle and with a 'decent' quantity of fuel in a remote tank / header / can / bucket / whatever, needs to be connected to the inlets and be positioned about 2 -3 feet above the carbs. Yes, its higher than when fitted, but a little excess is better. A good float valve/s should hold against this head of fuel at least for 6hrs to be called good!

[StevieB]

Hi thanks for the advice.

Tried taking bowls off in in situ to check floats seating - virtually impossible on inner carbs. Taken them out again - one job I really hate - not much clearance even with airbox unbolted.

May have found fault - no3 carb float pivot point and pin have damage marks and may have restricted float movement. Will smooth them off and try again.

I shall check all carbs needles seating as u suggested over a few hours.

Will try n fit with bowls full of fuel so floats should stay seated. And there was fuel in engine - oil drained.

When I set the float heights before got them exact as diagram (22.4mm). With this setting and fuel in each carb set totally level I got the specified fuel level of 5mm.

If the carbs are set to in bike positiin (roughly 5 degrees down, fwd) then the fuel height will vary from front to back. So where would u measure the fuel height from?

Only thing I'm not sure about but will be testing on the bench all carbs together before refitting to the bike.

I know gotta be patient as things take time but just wanna ride it!how I set float height

 

[Gixer1460]

The 5 degrees or so fitted angle will not make a huge difference in fuel levels - you've followed the book, thats good enough!

Edited April 30, 2021 by Gixer1460

[StevieB]

Cheers - will dress out damage on float internal pivot and pin after work tomorrow. Never noticed it before, think been mangled by someone in the past - pliers or vice. Hoping this may have been the cause of float sticking.

Will then leave carbs sitting with fuel feed attached overnight.

Hopefully no leaks!

[StevieB]

Still having issues with the carbs - can't get the fuel to stop leaking past the float needles.

Carried out the leak test with fuel reservoir about 18" - 2' above the carbs, they're set at approx angle as on the bike.

Fuel can be seen slowly and steadily dropping (takes hours) and exits from one of the air intake tappings.

They were new valves and seals. Also tried advice on YouTube fixing leaking valves. Polished the inside of valve Bush and sides of needle valve to reduce friction. Thought stop valves sticking. Letting it sit overnight with end of fuel pipe blanked off - to simulate on bike with fuel tap off.

Think the only way forward is to bite the bullet and get genuine Suzuki valves and needles.

Lost count of how many times I've had the bowls off to try and resolve the leak.

Fuel seeps out of lower right (in zoomed in photo) air tapping.

[TonyGee]

its hit and miss with after market float valves, genuine is the way to go if you can afford the bloody prices 

[fab]

have you weighed your floats?, you may have a crack or hole in it or has it been repaired

if its heavier than the others it could have a problem closing up and sealing 

[StevieB]

Thanks - examined floats - no leaks when submerged - no damage. The floats seal intermittently, can be sealed or unseated by tapping each bowl. So think just a bad seal from aftermarket parts.

And yes agree the prices of genuine parts are high and don't really want to pay that - but unfortunately don't have much choice. Had enough of trying to get cheap ones to  seal. True what they say u get what u pay for. Never had this issue before but never done a leak check before fitting.

If cheap ones don't seal effectively then they could have  always be letting fuel leak from between fuel tap - fuel tube into carbs - explain why it's never been a good starter.

Hopefully next  post will be on finished projects not advice section - cheers.

[Dezza]

Are you 100% sure the leaks are coming from the valves themselves? I ask as sometimes the new o'rings that seal the valve seat / carb body join can be a challenge to get to seat properly and if these leak, it can look like there's a leaking valve. It may be worth double or triple checking but I agree with the general consensus that pattern carb components (made of metal) are often of dubious quality.

[StevieB]

100% sure, leak checked valve seats and o rings first. And intermittent leak which could be seated/unseated by tapping bowl.

Would never be able to trust floats to not leak, learnt my lesson on quality of parts. Won't be ordering pattern parts on critical items again.

Ordered genuine parts from Fowlers (ouch!) - back order - typical.

Cheers

[StevieB]

Carb rebuild update

 

Received genuine Suzuki float needles from Fowlers. Leak checked them on the bench - fuel level initially dropped them stabilised when height of fuel in fuel feed (initially 2' above carbs).

Figured either residual air in carbs or increased head of fuel had to balance against designed pressure operation of float valves.

Anyway as stabilised for a few hours fitted blank to fuel feed to simulate petrol tap off - no leaks after 24 hours.

Finally fitted to the bike and first run carried out.

Main thing it started with no fuel leaks from carbs.

However nothing ever runs smoothly straight away!

Bike runs from choke to fully warned up - but it has an erratic idle, if you rev the throttle and release it doesn't idle straight away.

Get the idle speed adjusted around 1200 rpm and it will increase occasionally to 2500.

I was thinking the completion of this project has taken forever - been a couple of months to get fuel issues sorted. So researched on here for advice - Satansams gsx750 revs super high post has given me hope (6 months plus!) and some pointers to try:-

Carbs cleaned and rebuilt as per guidance - happy with them!

Haven't adjusted mixture screws away from 2.5 turns yet or balanced carbs.

was thinking possible air leak from carb rubbers/manifold or Airbus or sticking CV slide (CV membrane definitely good) but when tested them for operation before fit one did stick - reseated cap and sorted - recheck them. Thinking of investing in carb vacuum gauges.