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T3 VHB30 carbs. Worn out?

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Jimble View Drop Down
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    Posted: 04 Apr 2018 at 11:24
Cutting a long story short a knowledgeable acquaintance who has never owned a Guzzi suggested the carbs on my T3 could be worn/worn out. They are the original pair fitted back in 1978, the bike has only done 36k miles, was stood for 20 years up to 2014 and has done little since to be honest.
What should I be looking for, can measuring the slide and body dimensions be helpful?
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Barry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Barry Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 11:43
"worn out" - What prompts that conclusion? If stood for a long while, then the carb surely could do with a little TLC - and that's relatively easy to do yourself with these carbs, not least because a superbly illustrated how-to is available here: http://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

Pretty much everything is available for rebuilding / servicing these carbs (from Eurocarb, to offer but one source), and the fact that so many of them continue to do sterling service on Tonti roundheads (and some Loops?) speaks volumes.

As I understand it, and I'm not a mechanic, the significant item that can be "worn" and sadly not replaceable (due to unavailability) is the slide itself.  Unless someone has been particularly brutal with the carbs in the past, then 36K is small potatoes, and you might reasonably expect a lot more miles out of them.

You could readily service them yourself, or get someone else to do so (perhaps getting them cleaned at the same time), or you could potentially replace with new 'round body' PHF30's, readily available from your regular Guzzi parts supplier.

Me, I'd be looking to establish what "worn out" really means, and work from there. Like as not, they just want some love, some perishables replaced, and careful set-up.  For my money, I reckon an inspection/estimate would, in the first instance, be a lot cheaper than a pair of replacements (which would still need setting-up for your particular machine).



Edited by Barry - 04 Apr 2018 at 11:48
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jpc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 11:50
As above Thumbs Up

180K miles on mine, experience beats "knowledge".

Slides, being flat-faced, wear out even less than round ones.

At most replace needles & needle jets, if at all, at that modest mileage.
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Ken-Guzzibear View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 11:54
To be fair spares for the flat slide carbs are running out they are well past sell by date .... The easy replacement are the round slide carbs as fitted to the T5850's and, with different jetting many 750's PHF I think but easy to check the ones with small triangular pump fitted do give a bit more go to the 850/1000's well worth swapping especially if you use your bike, by ALL means keep the flat slide carbs to pop on for and shows/authenticity ...not worth wearing them completely out. It IS the slides that wear quite badly they are the very parts you cannot get!
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Barry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Barry Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 12:06
Originally posted by Ken-Guzzibear Ken-Guzzibear wrote:

spares for the flat slide carbs are running out


That's not been my experience, Ken. I have been able to get *everything* I need for these carbs, over the past couple of years, with the exception of the afore-mentioned slides. Eurocarb, and Gutsibits have been able to get me - without exception - any and all of the parts I've wanted. Granted, since they are a discontinued item, that situation won't always be the case. But then my T3 is a discontinued item in its entirety. (o;
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 12:14
Originally posted by Ken-Guzzibear Ken-Guzzibear wrote:

. It IS the slides that wear quite badly

Ken, I'm really puzzled by that statement !

Unless perhaps another "improvement" was carried out by removing the breather box that brings some oil fumes to the carbs.

The VHBs do have an accelerator pump in the main jet well, what is there to improve ? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 12:43
Both of my Loops are fitted with VHB's.As was my Laverda GTL.They have given me no problems apart from having to abrade/polish out the indentations in the slides caused by the throttle stop screws.These indentations can cause erratic tickover but the fix is easy.Eurocarb have slides in stock for the 27-30mm range and for the smaller range as well as jets,gaskets etc.I'm staying with VHB's untill I encounter a real problem.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cyclobutch Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 13:04
They surely aren't worn out. Worst case might be the jets opened out by impurities running through them in the fuel. Swap out the jets for new every 30k-40k miles and keep on riding. Swap the 'choke' (enricher) plungers every 10k-20k miles.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranton_rambler Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 17:20
I'm also running VHB's on both of mine - 29's on the loop, which has done 46k miles, and 30's on the Spada which has done 35k miles.
No issues with starting, idling or fuel consumption.
When I bought the Spada it had been standing for 15 years so I stripped both carbs, cleaned and fitted new seals. They do like to be balanced properly in my experience. I use a pair of Davida gauges.
A common issue is fuel leakage past the cold-start plungers. Easily fixed by new plungers from Eurocarb.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jerry atric Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 19:16
50,000 miles on my VHBs, they are fine. The only thing on my Cali that is really past its sell by date with no available spares is the plonker on the seat
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 19:26
folks the vthou is 250k miles plus.....As has been said parts are available and slides will be fine for a few k miles Your bike your choice .... Not bothered about winning prizes ...the Vthou simply works ..... Not going to get into any argument about how this or that simply the round carbs work better ....got my info from Guzziology, followed that advice it is usually good advice ....

Edited by Ken-Guzzibear - 04 Apr 2018 at 19:30
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnno Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 20:12
Oh Ken I got round and square carbs they both work sound but then again I ain't done 250 000 miles on my bikes Ken when we out riding it's been a few years now
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Post Options Post Options   Thanks (0) Thanks(0)   Quote theone&onlymin Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2018 at 20:54
I may have .

Still on the VHB30's


Still rockin'

Cheers
Min


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Ken-Guzzibear View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2018 at 11:41
Johnno free ride in weekend at The Rockbar 13-15th bands Fri & Sat night...camping or local hotels see flyer on my facebook page mate My vhb's have been refurbished but off the bike as the round un's work better better acceleration and holds m way speed better especially 2 up and fully loaded ....I actually found the info in Guzziology, Ray has put the newer ones on his Spada, one other advantage is much lighter throttle pull due, I am told, to the effect of vacuum on the flat slides .... the old carbs work fine and will do so for oodles of miles ....nowt wrong with 'em at all .....

Edited by Ken-Guzzibear - 05 Apr 2018 at 11:47
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2018 at 14:21
When I overhauled the VHBs on my old T3 Cali the best bit of information I picked up was to spend as long as it takes to get the float height right.
After that all the adjustments worked beautifully.
Before that it was a nightmare! An experienced Guzzi man told me they were “worn out”. They weren’t.
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