DUCATI TT and F1 FORUM
 
It is currently Tue Aug 22, 2017 10:41 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 21 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Thu Nov 11, 2010 8:21 pm 
Offline

Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Has anyone fitted TM 41's to a TT2?
I think F1's may have a bit more room than a TT2?
Graeme


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Thu Nov 11, 2010 10:56 pm 
Offline

Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Hello Steve,
Is the "float need"le jet too big or too small in the TMs as they come standard?
Sorry I don't understand this bit
graeme


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Fri Nov 12, 2010 7:55 am 
Offline
User avatar

Joined: Sun Aug 08, 2010 4:37 pm
Posts: 360
Images: 6
Location: Ottawa, Ontario, The Great White North
graeme wrote:
Hello Steve,
Is the "float need"le jet too big or too small in the TMs as they come standard?
Sorry I don't understand this bit
graeme

Hi Graeme:

The TM41s seem to be used in snowmobiles and other 2-strokes, so they usually come with a very large float needle jet. I struggled with flooding (especially on the front carb) until I moved down to a 2.0 - and then eventually a 1.8. Shannon's f1 - in a lower state of tune - had TM38s which worked well too. If you end up with a set, let me know and I'll send you my set-up data.

_________________
Steve Munro
loudbike
http://www.loudbike.com
http://www.vintagemotorcyclesforsale.com


Top
 Profile Personal album  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Sat Nov 13, 2010 8:12 pm 
Offline

Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Thanks Steve,
My TT has PHM 40's with the clamp type fixing to the manifolds.
How can the TM41's or TM38's fit to my clamp type manifolds?
Did you have to turn a pair of adaptors?
My manifolds have been flowed and filled to match the heads, which have also been filled to match the manifolds. So I don't want to replace the manifolds if I can make adaptors to blend the TM"s to the manifolds.
I will ask the boffin who flowed the heads for his recomendation re 41mm V 38mm as to which size he would recomend for my engine. Either way I would have to make adaptors.
Graeme


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Sun Nov 14, 2010 6:01 am 
Offline

Joined: Sat Nov 13, 2010 6:40 am
Posts: 28
Hi Graeme, I am running the 'black top' 40PHM's on my '90 900SS with twin cables right back to an aftermarket Domino throttle pull, & never thought of it as being heavy, thought its not light either....

If you have a pantah style splitter & single cable back to the pull that might be part of the problem, though they work fine on Dellorto 36's in my experience.

BTW the most beautifully carbed Duc I have ever owned was an 88 model 750 running on 36mm Dellortos.

Andrew K


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Mon Nov 15, 2010 12:15 am 
Offline

Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Thanks Andrew,
Twin pull Domino with 2 Venhill cables. I tried 2 standard Pantah cables also.
This thing carburates very well, it's just very stiff.
I've taken both carbs off the manifolds and had the cables as straight as possible which didn't make any difference. So it has to be the carbs I would think.
Graeme


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Mon Nov 15, 2010 6:17 am 
Offline

Joined: Sat Nov 13, 2010 6:50 am
Posts: 1
hi graham
if you are running a quick action throttle it may make the pull very heavy


Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Mon Nov 15, 2010 9:14 pm 
Offline
User avatar

Joined: Sun Aug 08, 2010 4:37 pm
Posts: 360
Images: 6
Location: Ottawa, Ontario, The Great White North
Phil's got a point (sort of..). Although as I think back, The Original loudbike bevel racer had 40mm Dellorto's and a Domino quick-action - and the effort was only slightly higher than on my GT once I found a good set-up. As I recall, the Domino didn't come with a nylon washer to isolate the hand grip from the throttle housing and I had to scrounge one up. As well, I spent some time finishing the surface of the cam as it was dragging on the housing. I use plenty of graphite in the throttle housing and on the clip-on OD and liberal amounts of cable lube. Fran McDermott's TT runs 41mm Malossi's with a quick action and I'd say that effort on his throttle was acceptable as well.

I know it's all basic stuff, but when you twist the throttle can you detect drag anywhere? Have you tried it with the housing apart? If it's truly at the spring, then you might want to explore some different ones as there are at least a half-dozen varieties of spring rate.

_________________
Steve Munro
loudbike
http://www.loudbike.com
http://www.vintagemotorcyclesforsale.com


Top
 Profile Personal album  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Mon Nov 15, 2010 10:57 pm 
Offline

Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Hello Gents,
The Domino is about 1/4 pull. I fitted a throttle off a 900 SS and it was only slightly less effort.
I have a nylon washer that I made between the housing and grip.
Take the cables out of the Domino and it has no friction.
But pull the cables at the throttle end and each carb slide is stiff and I can hear and feel the resistance.
I have the lightest springs, and even cut them down to the point that the slides didn't close from high revs, then had to buy new light springs.

I'm sure it's the slides in the carbs.
Removed the pumps and that definately removed the "lump" in the action, but still heavy.
Maybe I need to lap them a little with very light paste? (don't realy want to do that for obvious reasons)

Maybe I bought a bad pair of black top PHMs ?
After a ride the first summer on a hot day, the rear float stuck down at a fuel station and flooded the carb, then proceded to fill the bottom fairing with fuming hot fuel. I came out of the servo to see the bike sitting in a pool of fuel.
The 2 posts either side of the float axle/pin had expanded and squeezed the float so it couldn't rise.
Once it cooled down it was free again. I filed the float shaft tube to give it more clearence between the posts and never had the problem again. The front carb was the same.

I'm definatly looking for any assistance from you gents, but I have tried all the usual things and sort of feel that it's time to give up on these carbs. But they do fuel well and maybe there is something stupid I'm missing.
Graeme


Last edited by graeme on Thu Dec 16, 2010 5:02 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Heavy 40mm Dell'Ortos' What else will fit?
PostPosted: Tue Nov 16, 2010 10:21 pm 
Offline

Joined: Thu Oct 14, 2010 7:30 am
Posts: 133
You could check the slides/slide bores for shiny spots to see if the slide or bore is out of round. If so some light sanding can provide some clearance. The coating[zinc?] on the slides is pretty thick and sometimes uneven. I've burnished graphite into slides on Amal carbs to improve the action and it may help on Dello slides.Are the cables making any sharp bends or is the tank lying on the rear cable? It happened on my F1 and a spacer under the tank mount made it much easier.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Template made by DEVPPL