750 GTL - Best Carbs? - With Free Choice

Haggis

Haggis

Hero member
Location
UK
Hi All

I'm working on a basket case GTL which is totally without carbs.

Any thoughts on what is best to bolt on?

Priorities are function - torque and smoothness, together with easy access to jets, needles, etc for dialing in. Originality (VHB) not so important. No need for outright WOT power.

Cheers, Paul H
 
Also might be affected by availability of the carb type you decide on.
Finding decent VHBs might be like trying to find rocking horse poo.
 
Did a very successful job on a GTL - used 32mm D/O's from a Jota - acceleration was excellent -  can use the triple type inlet stubs too with some easy mods - Regards - Phil
 
If originality does suddenly become an issue, 30mm VHBs from Guzzis often turn up on eBay.  Some of the brassware needs swapping and the accererator pump should be ditched, I never got to grips with that on my GTL.  Even bored out a pair to 31.5mm for my asthmatic-at-higher-revs long-stroke (original looks being paramount), have yet to try them.

piet
 
Dual throat Weber.

Or if you're going for a rat bike look, put a different carb on each cylinder.  :D

OK, I'll be serious. Like Vince said, you can't go wrong with round slide Mikunis. They perform well, are reasonably cheap (especially if you can find a good second hand pair), brassware is readily available, and they're simple to tune.

Keihins are probably just as good as Mikunis (I'm not as familiar with them).

Dellorto carbs are OK, but expect to pay twice as much as an equivalent Mikuni if you're buying new. If you can scrounge a set from a Laverda triple (ask Red), then you'll need to buy a pair of cable tops for them.

Stay away from Amal because they're ludicrously overpriced rubbish. Any 2nd hand ones will be fucked.

Many years ago I put a pair of second-hand VM32 Mikunis off a Suzuki 500 Titan on my old Triumph Bonneville. I had to make up an adaptor to fit them to the Triumph head, but once they were on there, they worked brilliantly. Even the Suzuki jetting was good! The lack of accelerator pumps didn't have any deleterious effect.

With the old Amals it was a snivelling, coughing, backfiring heap of shit that was hard to start and wouldn't idle. The Mikunis transformed the bike into a torquey, smooth running, lovely thing to ride. It would start easily, idle perfectly, didn't piss fuel everywhere and never backfired. The idiot I sold it to put the Amals back on. The tosser didn't want Japanese carbs on a pommy bike.  ::)
 
Dellortoman said:
Dual throat Weber.

deleterious
Click to expand...

:D I had dual throat Dellorto's on my Z900 ........... oops, I forgot I was talking to a Tasmanian named Dellortoman .......... sort of makes sense.  :LOL: :LOL:      ;)

Deleterious ............ are you wearing google out?
 
"I had dual throat Dellorto's on my Z900 " Did you get it to run perfectly, Chris?
Back in the days when I lived every day in motorbike workshops I came across numerous Kawa and Honda fours that had these, and they never seemed to be quite right through the range, forever getting fiddled with. I saw an SF with them/one and it was flat through the midrange. I never got involved in setting them up myself.
As for the best carbs for a GTL, it really is hard to beat found slide Mikunis, so in one definition they are the best.
On my racer which was my roadbike with same carbs, it?s Keihin FCR are bloody brilliant. The air adjustments in addition to fuel jetting are fantastic. Are they needed for a GTL Laverda? Not necessarily.
 
Tippie said:
"I had dual throat Dellorto's on my Z900 " Did you get it to run perfectly, Chris?
Back in the days when I lived every day in motorbike workshops I came across numerous Kawa and Honda fours that had these, and they never seemed to be quite right through the range, forever getting fiddled with.
Click to expand...

Err, no. Smooth as silk low down, mid range was always the issue ..... but back then, mid range was just a blink in time as it was mostly always WOT everywhere  :D

I always put the midrange issue down to the Bonniville cams, and, or, the Kerker 4/1.

My daughter is in your neck of the woods Tippie, she sent me some pictures of the ?hairpin turns? edit ?bobby pin turns? looks like good riding country, when you can. The pictures were the roads with rocks as falling off the cliff bollards in the clouds.
 
two into one manifold and a 45mm SU from a metro.
advantages
constant velocity
never out of balance
very light throttle (its a butterfly)
fuel temperature sensitive fork in float bowls (richer when hotter/weaker when cooler)
easily tuneable to your 750
massive torque
superb fuel economy
great looks and a talking point
Carb from metro will cost a tenner.
you can even use a pancake filter (wa hey)
and install Paddy Hopkirk stickers
convinced?
CLEM
 
A sidecar bloke in west oz mounted a std Holden six carb (solex?) to a homemade manifold of tube cut at 45deg, so right angle bends, to his gold wing engine. Bike ran like a dream, barely needed adjusting the carb.
 
Tippie said:
A sidecar bloke in west oz mounted a std Holden six carb (solex?) to a homemade manifold of tube cut at 45deg, so right angle bends, to his gold wing engine. Bike ran like a dream, barely needed adjusting the carb.
Click to expand...

SU
 
Neither of those on any of my Red Motors. I couldn't remember so googled it and bingo, Stromberg. Till I went 192 with the works, M22 4 speed and a 350 Holley.
 
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