Carbs on their way out - SV650.org

yorkie_chris · 17-01-11, 07:01 PM

Sad day, my carbs have expired. With economy going down to 40mpg and it starting to sound a little rough I tried to balance the carbs, only to find that all the possible adjustment is done.

So, time to modify with some roller bearing linkages. Sure I had some really small ballraces around somewhere....

17-01-11, 07:05 PM

I didnt realise that could happen

yorkie_chris · 17-01-11, 07:10 PM

I am quite surprised at the rate of wear. They've always been lubed with non-sticky PTFE lube too. Hoped parts like this would last longer, bah.

That is actually the spigots on the carb arms (70k) that are worn too, the linkage bar and hence bushings inside it are pretty new (50k?).

17-01-11, 07:12 PM

Totally with you.

17-01-11, 07:15 PM

Not worth buying some used carbs then?

Sid Squid · 17-01-11, 07:48 PM

Similar problem with my ZX6 at about 110,000, a bit of wear in the bodies around the spindles, would run OK off tickover, but wouldn't idle right whatever I did. Bought a set from ebay for £12, perfect and unworn.

Jayneflakes · 17-01-11, 08:53 PM

Personally, I would love to see the work you put into a Carb refurb, the idea that you could rebuild plain bearings with tiny races and the like does sound fascinating. Please don't tell me that you were joking, it will make me cry today!

andrewsmith · 17-01-11, 09:04 PM

YC i think Harry may have a set for sale.

How long did they last BTW?

Sid Squid · 17-01-11, 09:24 PM

A repair for worn carb bodies/spindles with rollers of any kind is unlikely to be practical, there is rarely enough material to be able to enlarge the holes enough. The procedure ordinarily involves fittng bushes, these can be thin enough to not require a much enlarged hole, and don't need the seals a roller or ball bearing would.
A bush of suitable material will wear much better then the original whatever you use - originally the spindle runs directly in the light alloy of the carb body.

embee · 17-01-11, 10:16 PM

Old SU carbs and the throttle bodies we used to make at Jaguar used what were referred to as "DU" bushes, a code used by the manufacturer Glacier for the material and construction.

See here , so if you do need to recon a carb spindle at any time, if it's a very rare or irreplaceable old item for example, then these are the kiddies. They run with a hard brass spindle pretty successfully but will work fine with plated steel.

17-01-11, 07:01 PM	#1
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Carbs on their way out Sad day, my carbs have expired. With economy going down to 40mpg and it starting to sound a little rough I tried to balance the carbs, only to find that all the possible adjustment is done. So, time to modify with some roller bearing linkages. Sure I had some really small ballraces around somewhere.... __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat

17-01-11, 07:05 PM	#2
hongman Guest Posts: n/a	Re: Carbs on their way out I didnt realise that could happen

17-01-11, 07:10 PM	#3
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Re: Carbs on their way out I am quite surprised at the rate of wear. They've always been lubed with non-sticky PTFE lube too. Hoped parts like this would last longer, bah. That is actually the spigots on the carb arms (70k) that are worn too, the linkage bar and hence bushings inside it are pretty new (50k?). __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat

17-01-11, 07:12 PM	#4
hongman Guest Posts: n/a	Re: Carbs on their way out Totally with you.

17-01-11, 07:15 PM	#5
Jordy Guest Posts: n/a	Re: Carbs on their way out Not worth buying some used carbs then?

17-01-11, 07:48 PM	#6
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	Re: Carbs on their way out Similar problem with my ZX6 at about 110,000, a bit of wear in the bodies around the spindles, would run OK off tickover, but wouldn't idle right whatever I did. Bought a set from ebay for £12, perfect and unworn. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

17-01-11, 09:04 PM	#8
andrewsmith Member Mega Poster Join Date: Apr 2010 Location: Newcastle upon Tyne, Just south of salad dodging country Posts: 7,750	Re: Carbs on their way out YC i think Harry may have a set for sale. How long did they last BTW? __________________ RIP Reeder 20/07/1988 - 21/03/2012. Always missed squire!!! Every year we meet old friends, gain some new ones, lose old ones and you always remember them all. “Live as if you were to die tomorrow. Learn as if you were to live forever.” Mahatma Gandhi

17-01-11, 09:24 PM	#9
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	Re: Carbs on their way out A repair for worn carb bodies/spindles with rollers of any kind is unlikely to be practical, there is rarely enough material to be able to enlarge the holes enough. The procedure ordinarily involves fittng bushes, these can be thin enough to not require a much enlarged hole, and don't need the seals a roller or ball bearing would. A bush of suitable material will wear much better then the original whatever you use - originally the spindle runs directly in the light alloy of the carb body. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

17-01-11, 10:16 PM	#10
embee Member Mega Poster Join Date: Jul 2003 Location: Warwickshire Posts: 2,801	Re: Carbs on their way out Old SU carbs and the throttle bodies we used to make at Jaguar used what were referred to as "DU" bushes, a code used by the manufacturer Glacier for the material and construction. See here , so if you do need to recon a carb spindle at any time, if it's a very rare or irreplaceable old item for example, then these are the kiddies. They run with a hard brass spindle pretty successfully but will work fine with plated steel. __________________ "Artificial Intelligence is no match for natural stupidity"

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
How do I get the carbs off?	BigBaddad	SV Talk, Tuning & Tweaking	9	31-03-10 10:25 AM
carbs	dirtydog	For Sale - SV's and SV related items	3	11-08-08 09:39 PM
NT carbs	Stig	Idle Banter	2	01-12-07 09:55 PM
carbs help	addicted to rage	SV Talk, Tuning & Tweaking	10	16-11-07 02:02 PM
Set of carbs	POGS69	For Sale - SV's and SV related items	2	11-06-07 05:03 PM