guzziriders.org - moto guzzi forum Homepage
Forum Home Forum Home > Technical > Big Block Tonti
  New Posts New Posts RSS Feed - plastic inlet manifold
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

plastic inlet manifold

 Post Reply Post Reply Page  12>
Author
Message
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Topic: plastic inlet manifold
    Posted: 31 Jan 2019 at 09:16
As my G5 has 36mm carbs fitted, with matching manifolds, fitted by a previous owner, I am thinking of returning it to 30mm carbs as, with std. Spada/G5 heads and valves, I cannot see how the big carbs can do much good.
I realise the original square slide 30mm carbs are "hen's teeth" these days and likewise the original cast ally manifolds.
So it'll be round top, round slide 30mm carbs, and I see that suitable plastic manifolds are available from Gutsibits. Howevere they warn that they are not the same angle as the original parts and that "clearance may need to be made for air filters".
Does anyone have experiance of using these plastic manifolds ?
What air filters fit best ?
How does the carb top/cable entry position work out in relation to Spada/G5 petrol tank  & taps ?
Back to Top
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2019 at 10:31
Looking at the plastic manifolds on Gutsibits site, they now look to me to be a very similar angle to the Lemon manifolds I have, so filter position and carb top will be similar to what I have at present, though mayby the 30mm carb has smaller overall dimensions and there will be a little more space all around.
 Comments from those who have the PHF30mm carbs, retro fitted are still welcome.
Back to Top
Jools View Drop Down
Falcone
Falcone
Avatar

Joined: 19 Aug 2016
Location: Milton Keynes
Status: Offline
Points: 92
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jools Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2019 at 13:58
I bought some of the 'plastic' manifolds from Gutsibits myself to do the VHB30-to-PHF30 conversion - which I never got around to doing. 

The angle between the original VHB and PHF manifolds is considerably different, a quick comparison just now on my own G5 would suggest around a 25 degree difference, the VHB types being angled inwards (towards the centre of the bike) considerably more than the PHF type. 

However, if you've got the 36mm carbs and manifolds already fitted, you're already there as the angle will be the same as the 'plastic' manifolds, and any modification/replacement of the sidepanels will already have been done. Replacement 30mm PHF's should fit straight onto your existing manifolds too if I'm not mistaken - a pity as I'd like to have bought your alloy ones from you!! (I've gone the whole hog and am replacing the pistons/heads/carbs on my own G5 for Le Mans types).
Jools

V1000G5
1972 T150V
1961 Royal Enfield Constellation
1971 Suzuki ACC50
erm... 1963 Philips Panda
(and other assorted detritus)
Back to Top
Ken-Guzzibear View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 13 May 2014
Location: Sileby Leics
Status: Offline
Points: 5415
Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2019 at 15:29
Done this on mine .... 
I have alloy intakes needed stepped inlet studs as they are different sizes
The inlets are shorter as are the rubber joints
I have Cone type K&N filters with a Le Mans breather box
It does need the inner edge of the side panels cutting out with a dremel to allow them to fit you have to taake most of the inner edge away but it is not noticeable from the side 
You will need new throttle cables I use those from Cali 2 they do form a long loop but that is no bad thing had them on mine since 2008 ish never an issue at mot and not had to replace a throttle cable 
Yes the PHF round carb with the triangular pump make a noticeable difference to the pick up and top end
The same carb different jets are fitted to the 750 bikes Eurocarb were brill with the rejetting advice too
You can get parts for these
Hope this helps 
The Older i Get, The Better I Was
Back to Top
chilly View Drop Down
Senior Member
Senior Member


Joined: 03 Aug 2014
Location: St Neots
Status: Offline
Points: 328
Post Options Post Options   Thanks (0) Thanks(0)   Quote chilly Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2019 at 19:57
Had to cut my side panels on my T3 + could only fit sponge pod filters with those plastic manifolds,they have a slower bend then standard, K&Ns wouldn't fit on the nearside carb it hit the frame :<( 
Back to Top
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2019 at 10:43
Thanks for your response guys.
It sounds as if I was right, and the plastic manifolds are the same shape as the lemon ones, and that the 30mm carbs do not provide any significantly greater space for the air filters.
I already have cutaway side panels and its still a struggle to find room for the quite small K&N type filters. So Gutsibits plastic manifolds will not be any advantage to me.
I would really prefer to have a pair of original ally elbows as fitted to round barrel Spadas & T3s etc, as, having grown up with Phil Irving's "Tuning for speed" I do not like the idea of mis matched carb/manifold/inlet tract internal diameters.
Obviously with a G5 I'm not exactly "Tuning for speed", but what works for speed in these stakes, usually works for smooth running and good economy as well.
So that's a reason why I want to replace the big 36mm carbs. I know that the G5 inlet tract is approx 33mm rather than 30mm, but its still a step and the 36mm carb is bigger than the motor needs.
I know that Dellortos from (I think) a 750 Ducati might be 32mm which would be dandy, but they were hard to find when we talked about them in the '80s.
I have thought about making a pair of manifolds. If I could find stainless steel "elbows" with the right ID I could probably do it.
But then I thought "What else might be available ?"
And remembering "Allen's Carburettors" as suppliers of Mikuni carbs to suit all sorts of bikes, ancient & modern, I had a look.
On their website at www.allensperformanceparts.co.uk I found "New Moto Guzzi VM32 kit" and there they were, pictures of a G5 ! with 32mm Mikunis munted on newly manufactured ally manifolds, but sadly/worringly no price mentioned! However, new Mikuni carbs are notably more affordable than new Delorttos, so I have emailed them for details.
I've got to admit that Mikunis will look a bit odd hanging out on each side of an old G5, but if they fit and work well, it could be the way to go.
Back to Top
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2019 at 10:50
OOPS!
Back to Top
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2019 at 16:37
Ow !
Over £600 for the complete kit !
Carbs are cheap enough, but obviously getting the manifolds cast has been an expensive job.
Back to the drawingboad for me.
Or, has anybody got a pair of T3/Spada ally manifolds they can spare ?
Back to Top
Chris A View Drop Down
Falcone
Falcone


Joined: 15 Dec 2018
Location: France
Status: Offline
Points: 19
Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris A Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2019 at 21:42
Dellorto PHBH conversion kit ...much cheaper
Back to Top
Ken-Guzzibear View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 13 May 2014
Location: Sileby Leics
Status: Offline
Points: 5415
Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2019 at 22:33
i bought used parts ..... carbs needed a few bits but works fine ...you asked for someone who had done it ...needs cone filters not the oval ones been on the bike over 10 yrs 
The Older i Get, The Better I Was
Back to Top
Gfiver View Drop Down
Falcone
Falcone


Joined: 26 May 2017
Location: Somerset
Status: Offline
Points: 52
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gfiver Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb 2019 at 07:38
Thanks again.
When I asked "Who's done it" it was to gather info, not necessarirly be told exactly how.
But, the concentric conical filters, I had forgotten them, (35 years ago) What I have is those oval things, and too small diameter to the carb, and they keep slipping off no mater how I fit the hose clip, and they were sold as the right ones !
I'll look up the conical ones. Does anybody know the K&N part number?
Back to Top
Mike H View Drop Down
Senior Member
Senior Member
Avatar

Joined: 21 May 2014
Location: East Anglia
Status: Offline
Points: 6094
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb 2019 at 18:49
Originally posted by Gfiver Gfiver wrote:

... What I have is those oval things, and too small diameter to the carb, and they keep slipping off no matter how I fit the hose clip, and they were sold as the right ones !


If it's the same oval things I know, most likely cos of being put onto 36mm carbs, they are intended for 30mm carbs, or at least they do fit onto VHB30 carbs because I've done that (twice) and they never fell off.

However they need the stock inlet stubs to fit properly.

If you can get hold of him you could ask Ray Dunkley / exsmokingbiker if he's got a pair(?)

HTH

"Chicken nuggets don't dance on a Tuesday."
Back to Top
Jools View Drop Down
Falcone
Falcone
Avatar

Joined: 19 Aug 2016
Location: Milton Keynes
Status: Offline
Points: 92
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jools Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb 2019 at 17:22
You could try 'Nick's Euro Bits' for a pair of alloy manifolds - he has a good deal of second hand spares. He's at a lot of autojumbles and on ebay. 
Jools

V1000G5
1972 T150V
1961 Royal Enfield Constellation
1971 Suzuki ACC50
erm... 1963 Philips Panda
(and other assorted detritus)
Back to Top
Pentode View Drop Down
Falcone
Falcone


Joined: 16 Dec 2018
Location: Kimbolton UK
Status: Offline
Points: 23
Post Options Post Options   Thanks (0) Thanks(0)   Quote Pentode Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb 2019 at 18:35
I've fitted Mikuni VM32 carbs on my G5 and the Guzzi on Allen's website is mine 🙂

I spent ages trying to get the VHB30's set up properly, replacing just about every part in them but I wasn't fully happy with the tickover and general running. Having said that, this may say more about my skills as a bike tinkerer than anything else... 

I bought the full kit from Allen's and it went together very easily - granted, I had to make different cables but that's because mine was a non standard set up.

Right from the first start up the tickover was far, far better. On the road running jetting wasn't great so I went to town on this by getting a wide band sensor kit and setting it all up.
As I'd just bought a rather nice new exhaust system I didn't want drill holes in it for the lambda bosses, so I bent up some new down pipes for the purpose of setting the carbs up and brazed the bosses into these.

Working with Dave and Steve at Allen's, it didn't take too long to get the old G5 running really nicely and I'm very happy with the results 🙂 I believe the jetting I've now settled on is what is now supplied with the kit but of course mild tinkering will probably still be necessary. 





The temporary downpipes and lambda sensor. 


Back to Top
red leader one View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07 Oct 2014
Location: Cullercoats
Status: Offline
Points: 3313
Post Options Post Options   Thanks (0) Thanks(0)   Quote red leader one Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb 2019 at 19:43
That looks really tidy.
Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.00
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.047 seconds.