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Carb Cleaning Vs Rebuild

B

bill_face

Forum Apprentice
Hello there.

I've got a 1979 GS550 that takes ages to start from cold & more recently was running underpowered.

I did a carb rebuild a few years ago when i first got the bike (it was a non-runner that had been in a garage for many years). I never got it to start quickly but it was running better. I would like to do a basic carb cleaning as a starting point, without replacing o-rings etc (mainly becuase I haven't got any). Does this make sense or is a rebuild always necessary? If so is there a guide any where (for VM carbs)? I've only found a rebuild guide

Cheers

Phil
 
To clean them properly, you do need to pull them apart. member Nessism has put together complete kits for CV and VM carbs for cheap enough. Don't know about shipping to UK, though.

Are your valve clearances in spec? Meaning, have you checked them? and when? Tight valves can lead to hard starting, among other much worse things.
 
https://gsarchive.bwringer.com/

VM tutorial on the right side
Follow it to the letter
And, adjust your valves

The problem with rebuild kits is twofold:
1. The parts are typically inferior to the original parts
2. They give you the idea that just swapping in new parts is good, when really, cleaning the carb body is the key to success.
 
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Chances are high that a good cleaning, and replacing the soft parts like float bowl gaskets and O-rings, will get you down the road. The carbs must be fully broken down, the carb bodies and jets, cleaned in carb solvent of some sort, then the carbs can be reassembled with the new soft parts. The most often worn part is the float needles, so check them over carefully. Also, the rubber coated fuel tee and fuel transfer tubes may need to be replaced (if they are shrunk and/or cracked.) Overall, not a huge investment.

Realize before beginning, that most new owners short cut the rebuild process. Then the bike doesn't run right, and they have to start over, wasting more time. It's best to bite the bullet and do the job right the first time.
 
I read this around here all the time. It seems, according to most on this site, it's never a good idea to clean carbs, always completely disassemble and rebuild... That ruins my theory of trying the cheapest, simplest things first then go farther "IF" needed.
 
Thanks for the input everyone,

How often do carbs need rebuilding? I'm not a new owner, I rebuilt them around 4-5 years, since when I have had a hard starting problem (it didn't start at all before that)

I was just going through my box of bits and came across a set of Cycle O - Rings (i think i got a set resent as the post to UK took an unexpectedly wrong time last time), so apart from the time involved I have nothing to lose from rebuilding. Time is an issue atm...

Valve clearances were good last time I was in the engine

Cheers

Phil
 
bill_face said:
Thanks for the input everyone,

How often do carbs need rebuilding? I'm not a new owner, I rebuilt them around 4-5 years, since when I have had a hard starting problem (it didn't start at all before that)

I was just going through my box of bits and came across a set of Cycle O - Rings (i think i got a set resent as the post to UK took an unexpectedly wrong time last time), so apart from the time involved I have nothing to lose from rebuilding. Time is an issue atm...

Valve clearances were good last time I was in the engine

Cheers

Phil
Click to expand...

Yeah, but how long ago was that and how many miles ago?
 
It's been something like 10 to 15 years since I've seen the inside of my GS850's carbs.

Ride the thing once in a while and the carbs will be fine pretty much indefinitely.

Ignore it for three or four weeks in warm weather, a little longer if it's cool, and they'll gum up and you're back to square one.

When I've had other work to do that's going to take longer, I remove and completely drain the carbs. In the winter I use Stabil or similar, and usually drain them to get through the worst bits of winter.
 
One of the joyful things about this site, is the collective learning and sharing of the importance of clean carbs, and how to obtain them. It truly isn't difficult, or expensive, to do a proper clean and refresh, including new O-rings and gaskets. On many other motorcycle sites, people think that a "rebuild" involves buying some "carb kits" from eBay or Amazon, and slamming in them in. On the GSR, the Collective, knows better, and isn't shy to tell the newbies! I hope this trend continues, since it separates this forums above most others...
 
Righy-o. Consensus reached. I'll rebuild them

The VM Carb rebuild guide over at BikeCliff says I need a can of Berrymans Carb Dip. Seems to be a State side solution (i'm in the UK). I can get it here but its ?40+ ($50). Is there a UK equivalent or is that how much it costs?
 
bill_face said:
Righy-o. Consensus reached. I'll rebuild them

The VM Carb rebuild guide over at BikeCliff says I need a can of Berrymans Carb Dip. Seems to be a State side solution (i'm in the UK). I can get it here but its ?40+ ($50). Is there a UK equivalent or is that how much it costs?
Click to expand...

I am in The Netherlands, bought a 0.75 Gallon/2.8 Liter can years ago for about ?40 per liter.
There is a Yamaha product that works well but not like Berryman in my experience.
Best stuff i found in 20 years.

Expensive, but it will last for many cleanings/years.

Always open to alternatives though !
 
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A ultrasonic cleaner is a substitute for the dip.
a bit more expensive, but can be used for cleaning other things, like grimy bolts and such.
And, no smelly dip!
 
Some years ago while working on a Bible camp bus that was left sitting with a full tank of fuel for seven years, I found, quite by God's grace,that hot water alone will clean a LOT out of the whole fuel system. Then I did a little experimenting and found that an excellent addition is TSP (tri-sodium-phosphate) with cold water. TSP can be found as a paint remover in crystalline form. It used to be (fifty or more years ago) used with boiling water to clean engine blocks inside and out for rebuilding in all the reputable shops.
Soaking for a little while and a toothbrush does wonders. Rinse well with cold water, dry with air, and follow with aerosol carb cleaner through the jets. I used that approach when bringing the GS 1100 back to life after 7 or 8 years. Adjusting valves and carbs made it start and run well (that is after going completely through the electric system).
​
 
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