GS750EC Carb Rebuild

[joe79]

Hi all,

Here's a brief of a carb rebuild I recently undertook.

Background
The bike was running, but running hot on pods and overflowing. The original owner had obviously had problems setting the carbs, pulling his hair out trying to figure why it would run fine on "Pri" until it overflowed, yet when he put it on "Run" or "Res" it would starve out I die. As a result I got the bike at a cheap price

I decided to strip a clean the carbs as part of the maintanence plan to get her back on the road. So glad I did as it turned out that the primary fuel needle jet on No2 was snapped of in the body. Unfortunatley no amount of work would free it and the body was deemed as junk.

I searched the interwebby thing for a while and finally scored a full set-up of carbs and airbox complete with decent end seals and the rear snorkel that often disappeared as previous owners where incompetant at remounting the airbox.

1.jpg

More to come when I figure out how I can post more than one image in a post....

[joe79]

Part II

So I set about cleaning and rebuilding the carbs





Before bench balancing the units





Before the final build so the before and after photo



After

[hannibal]

They're beautiful! Seriously those things are spotless. Care to share your cleaning process?

[joe79]

They're beautiful! Seriously those things are spotless. Care to share your cleaning process?

Thanks.

Basically they where stripped to component parts before the surface grime was cleaned away with a detergent bath a toothbrush.

Once the loose material was gone, bowls and jetways where soaked with a fuel cleaner additive to loosen / dissolve petrol residues, before each component was run through an ultrasonic cleaner for about 30 min.

I used a heated bath with US cleaning fluid to start and then later runs with normal household detergent. Last runs should be plain water.

Finally, once the bodies where dry a buffing wheel was run over the bodies to clear away the surface zinc alloy oxidation, carb tops, bowls and backing plate where buffed up too.
After that.

[sihi]

Yesterday I dipped my carb in ultrasonic cleaner with dishwasher tablet for 10 minits. I have to say it,s clean but. I probably take it out to early so now it looks like that. Also small white bobbles are in main body tubes . I did few runs first with dishwasher tablet + water than with soap+water last only tap water. I readed that solution is depending on which material you dipping and is very important. I wish to attach more pics but it doesn't allow me. 20150801_233557[1].jpg

[sihi]

20150801_225010[1].jpgsmall bobbles .

[joe79]

Yesterday I dipped my carb in ultrasonic cleaner with dishwasher tablet for 10 minits. I have to say it,s clean but. I probably take it out to early so now it looks like that. Also small white bobbles are in main body tubes . I did few runs first with dishwasher tablet + water than with soap+water last only tap water. I readed that solution is depending on which material you dipping and is very important. I wish to attach more pics but it doesn't allow me. [ATTACH=CONFIG]41273[/ATTACH]

Time for the buffing wheel.

If there's residues in the carb bodies run it through the bath several more times with clean water.

Make sure your tablets are fully dissolved if using them, alternatively use a liquid detergent

10 min is a short run time. Mine had about 30 min each

[sihi]

I have no idea what
went wrong

[joe79]

I have no idea what
went wrong

Nothing went wrong. If that material is detergent grains put it back through the bath. If it's not its surface oxidation that's all. Run over the bodies with a polishing wheel. Make sure you wear a mask. Zinc is nasty stuff.

How mine came out the bath.

[sihi]

Good to know. But after bath do you protect body with any lubricant like silicon in spray or something

[joe79]

Good to know. But after bath do you protect body with any lubricant like silicon in spray or something

I haven't. My aim was clean internals. Don't see why you couldn't

[sihi]

I haven't. My aim was clean internals. Don't see why you couldn't

Can you post what kind of buffing wheel you use?

[joe79]

Can you post what kind of buffing wheel you use?

http://www.moorespeedracing.co.uk/motorcycle-tools/professional-aluminium-stainless-steel-polishing-kit.html?gclid=CI2_j53IiscCFWHlwgodH5gDtA

Other makes of polishing kit are available. Don't really need to much soap as you're just taking the oxidation off.

[joe79]

Result Of The Carb Clean

Parts List
Replacement Carb Bank & Airbox assembly (2nd Hand)
New Air Filter & Gasket
New Airbox Carb Rubbers
New Carb Jets, Needles, Gaskets & 'O' Rings
New Carb Rubbers & 'O' Rings

Additional Works
Carbs stripped, cleaned, rebuilt and bench balanced
Valve Gaps checked and reset
General cleaning

[sihi]

My is now in that condition