Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 42 Posts

·
Registered
Joined
·
24 Posts
Discussion Starter #1
Got this bike from a collection and to be honest not even sure when it last ran. The curator said all it needed was a carb rebuild but it's needed a few more things such as front caliper rebuilds, fork seal & wiper replacement which I've done so far.

I've just rebuilt the carbs and for the life of me cannot get enough slack for the front cable so the carb slide is sitting way too high in the carb- about 4mm above the pencil mark in the pic which is where it should be all the way down. The 6mm adjuster is all the way down and I've assemble and reassembled the slide/needle/cable mechanism so many times I'm surprised I haven't broken the pump arm. Very odd.

I dismantled and lubed the cable and cable splitter and after putting it back together- still no play. I thought I would maybe go for Tommaselli Daytona 2C throttle kit and GT cables but saw you need a separate starter and kill switch which would not look good.

I guess I need to start the search for a new cable.
990133


990136
 

·
Registered
Joined
·
2,302 Posts
Have a look at the parts book; the Darmah had a curved cable guide into the twistgrip originally and a cable to suit, so you probably have the wrong cable. You could carefully remove some of the outer sheath to give more free play. BTW make sure that there is free-play on the choke cables when they are fitted, so that the choke plungers are fully seated.
 

·
Registered
Joined
·
24 Posts
Discussion Starter #4
Thanks Duccout. Yes, been thinking more about it and think I'll take the cable off the bike, lay it out and do some comparative measurements to the OEM part (if I can find those details-parts book doesn't specify measurements) with a view to perhaps trimming the sheath on one of the cables. I have the curved cable guide into the twist grip and it looks very original. Recollecting the assembly process, I don't think I have done anything incorrectly- I thought there may be something awry in the splitter connection...but took it apart, cleaned it, re-lubed and it all looks good in there. It may be simply a case someone replaced that one piece of cable in incorrectly. I have the snap on/off choke lever versions, which I renewed, so at least those are not an issue.

990174


990175


990176
 

·
Registered
Joined
·
413 Posts
Please ignore below - it crossed with your earlier post! Seems you have the situation in hand ... :)

As Colin: as standard, Dramah's have a 3 cable (1-into-2) arrangement - see below. If someone has changed the throttle into a twin pull, that might explain why the front cable ain't right -?

FWIW, I've added the original part numbers: 954 is the back, 955 is the front. The full set is/was 0801.54.960.

[
990182
ATTACH=full]990181[/ATTACH]
 

·
Registered
Joined
·
24 Posts
Discussion Starter #6
Cable off the bike....
990279


Throttle end. Interesting not having a cap, but, not necessarily problematic.
990280


Knowing that I wasn't having an issue with the rear carb I measured and compared the available cable end (outside of the sheath) in each cables. The rear measured 9cm whereas the front (which was too tight, no freeplay and the slide did not make it all the way down) only had just nearly 8cm....which makes total sense as to why I was having a problem. Cannot overcome a simple lack of length.

Rear Cable
990283


Front Cable
990285


Double checked the splitter junction box- and each cable's end (nub/ferrule?) sits in the same place within that brass connector.
990286


So my solution will be to carefully remove about 1cm of sheath from the front cable and go from there. My only concerns is:
-where did that 1cm go?
-how did anyone run this bike with this set up?
 

·
Registered
Joined
·
2,302 Posts
The answer is that either the PO fitted a cable from another model, or an aftermarket cable that was made wrongly. Aftermarket cables are a nightmare, years ago I bought a pair of spare cables for my 750 made by a well-known UK company called Venhill, and kept them in my tool kit for years. When the bike needed new cables, I unwrapped the spares and they did not fit! Years later I bought a pair of cables for my 900 and tried to fit them and they did not fit either, so I called the seller and he told me that he got them from Venhill! I only buy cables made by the Italian company 'Old Racing Spare Parts'
 

·
Registered
Joined
·
24 Posts
Discussion Starter #8
Good to have a recommended cable vendor. Over here (US) Motion Pro is a the go-to custom cable maker, but even then, unless you can send them the original, sometimes their items needed a little tweaking.

My point is/was: I think I'm learning that when you buy a bike from a 'collection', it may look the part, but you have to be prepared that it maybe never ran while in their ownership. This bike came with a very complimentary hardcover Falloon Report, but it didn't quite tell the deeper story.

990343


In other news I trimmed back the plastic and got ready to carefully attack with a hacksaw blade. After 1 minute my ADD got the better of me and I brought out the Dremel. No inner cables were harmed in this episode.

Chopped off this much....
990342


Reassembled with carbs on bike and managed to get 1/8 play in both carb cables. Took a while to get the accelerator pumps primed and working. One other worry I had was that the cable nub at the throttle end was sticking out of it's proper place on the plastic throttle inner and catching on the inner of the control switchgear. Such a situation could lead to a stuck throttle. I think I cured it. Anyone else have this problem? Still feels a little rough.

Anyway...it started fine....no-one warned me how loud these Conti's are and then, HUGE, loudest backfiring I've ever heard in my life with flames out of the right hand exhaust (not out of carbs). Being 10pm at night I had to stop. Live in a dicey area where there's tons of late night gunplay. Didn't want anyone to think I'm now part of that.

Wondering if it's excess fuel sitting in the pipes. Praying that it's not an issue with the stock Bosch electronics that still inhabit the bike.

The previous, previous owner referred to backfiring when cold.....so I made sure I got #6 plugs in.

990344

Note: Despite the PPO's rebuild of all the brake 'cylinders' (pretty sure he means calipers)....sometime between November and January one of the front calipers quietly released all of it's hydraulic fluid contents onto the front Campagnolo ruining it's original paintwork. I think it was just annoyed of being in the living room rather than on the road.
990345
 

·
Registered
Joined
·
2,302 Posts
You will have to see what happens with the backfiring, it is usually caused by a rich mixture which allows unburnt fuel to ignite in the exhaust pipe, so the tickover screws may need adjusting. I know what you mean about the Contis; a few years ago I was sitting on a wall at a petrol station having a break, when an explosion happened in the station, making me jump out of my skin! It wasn't an explosion, just some guy starting his Hailwood Replica.
 

·
Registered
Joined
·
260 Posts
Just FYI, I wasted a fair bit of money on new throttle and choke cables from Bevel Heaven. Not one of them fit. I then had them modified locally and they made them just a little too short...!!

So after rebuilding my carbs from the ground up a year later, and also wanting to use an elbow on the rear, I took the whole assembly to the cable guy and made them up with him right there and then. That was really the best solution. I was able to get the exact amount of slack I wanted on all cables, and even better, I was able to get them the exact length I wanted so that they now come out of the tank and around to the throttle in perfect unison.

Regarding the backfiring... If your the pipes are 100% air-tight all the way along, then they can handle unburnt fuel without blowing up.

Tighten your pipes everywhere. Use fresh gaskets on the headers and tighten them up there before doing the rest so that it sits completely square in the head. I don't need it here, but in some cases one might need to use a heat-capable sealant on the crossover. Prior to taking that advice, I would get backfires and bangs and I always thought they were due to tuning issues. Now it never happens.

Some related pix:

990419


990420


990421
 

·
Registered
Joined
·
24 Posts
Discussion Starter #11
Cheers Robax. Much appreciate the pics.
Hope you don’t mind a few questions?

Carb finish looks great. How did you clean yours?

I did a chemical dip, (Berrymans) looked great, then did 2 hours in my mini heated ultrasonic tank- with some stuff they call Simple Green over here but everytime I do the tank they come out dull and grey even when I’ve used typical dish soap.

Backfiring is only coming out of the front/horizontal. Just to be sure I’m recleaning that carb again- but good to know about sealing the exhaust. I think that’s my task today. What did you use as a sealer? Do you have a special tool for those exhaust nuts?

Also
1- it doesn’t backfire with the choke on
2- With the choke off the backfire disappears when I screw in the airscrew a lot.

My throttle still very notchy feeling. Seeing the 2 cable pull which looks tidy. How are you doing the kill/electric start?
 

·
Registered
Joined
·
260 Posts
I've got a long series of videos in a playlist here on YouTube.

I go into loads of minute details.. down to the tiniest o-ring. There's also a follow up where I calibrate the pumps, which I didn't do in that series. Was well worth it.

The finish is vapour blasting. I tried many types of cleaner, including aluminium brighteners but they all just make the metal go dark. Ultra sonic doesn't really clean anything. It can shake off some crusty bits in areas you might not be able to reach, but it does nothing to the metal. My engine is vapour blasted as well. It's the best looking finish for parts like the carb bodies.

Obviously tell the person not to do the inside of the slide barrel. He'll put bits of foam in there and anywhere else necessary. I also told him to go lightly overall.

See this stuff from Permatex or something similar for the exhaust. I haven't used it, but I understand you can rub it off with your fingers when you want to repeat it. You'd put it on during assembly of course, not afterwards. And just wipe off the excess.

Depending on whether your pipes are genuine or not, it's easy for them to not be dead 'square' in the heads when they are first tightened up on the contis and the crossover. Genuine pipes have the calibration crimp marks up by the flange bolt end... and are more likely to fit right. Check the gasket for blow-by.. it'll be sooty where that's happening.

Yes, I bought one of those special wrenches. They're all over. You need to tighten the nuts more than one could by hand, and any other tool is highly likely to break a tooth. My one's not that great though. It's the one that is a single flat piece of steel, cut by laser or something like that. It works but I have to use a rag around the handle because it's extremely painful to use with any significant pressure. I also would prefer one with more tangs. look for one that goes more than half way around and that has a proper handle.

Have no kill or electric on the 900SS.. just the kick and the key.

Also.. I'm not sure I mentioned in the carb series, but I ended up getting the lightest of the 3 available springs for the slides. I also used some small pieces of brass tube to shim all of the cables so that they don't tilt and instead come out straight from the carbs and the throttle and choke as well. I think that's a little overboard for most, but I was looking to maximise the calibration accuracy of the whole system. It worked well and it all feels nice.

The cables I got off Steve where the teflon ones, but the ones I had made locally were just generic. They feel just as smooth however. I think that is largely due to laying it all out carefully and then finishing it off with the lighter springs.

Note that the slides aren't all that smooth out of the box anyway. You'll feel that by lifting one with your finger all the way up. The way it hits the pumps makes it feel uneven. Perhaps the notchy feel is due to that?
Rob
 

·
Registered
Joined
·
24 Posts
Discussion Starter #13
Rob, thank you so much for taking the time to answer all my questions and making those videos. Invaluable.

Delved up into fifth video then couldn't resist jumping forward to the Accelerator Pump Setting. Awesome stuff.

Overall, the footage has inspired me to strip the carbs again and get them vapor blasted. It just so happens a good friend of mine has his own v blaster so it's not a hard decision. I have to wait for the exhaust nut wrench and new exhaust gaskets to arrive anyway. Got the Permatex red so I'm planning to ensure the exhaust is well sealed.

I like that 40º elbow for the rear carb, and since I am now familar with reducing cable sheaths I would like to do the same thing. Can you tell me where you sourced it? Apologies if you mention it after Part 5.

But here’s something that’s been right under my nose the whole time regarding the backfiring issue. Notice how the reducer on the right hand carb is extended out- I’m wondering if this is a standard practice to distance the carb from the head to solve some issues or is this what might be causing the backfiring? I didn’t it touch it as I trusted it was positioned correctly. Funny how one does that only to find that the trust is almost always misplaced.

990493
 

·
Registered
Joined
·
2,302 Posts
No! Those plastic sleeves are supposed to be pushed all the way in! No wonder the bike was backfiring. Actually, it is quite common for the carb to start to creep off the manifold and they have been known to fall right off. The sleeve needs pushing back in and it may be reluctant to move if it has been in that position for a while.
 

·
Registered
Joined
·
260 Posts
heheh like Duc says.. no!

They're cheap so you may as well get fresh ones. Otherwise bash that one in. New ones are a real tight fit into the carbs, but not so tight onto the manifolds. Use silicon grease to keep it removable and just make sure it's tightened up.

You'll enjoy redoing the carbs. I had fun doing mine. The worst part was having the wrong piece or failing to get a part that I wanted to replace. I did end up setting them up entirely as original and then did a lot of testing of different jetting later. The outcome was that I found I could tune the engine to run nicely with any jets. The real difference was in the power delivery. Leaner is weaker, but smoother, whilst richer delivered more power for a rougher feel. There's a long series on AFR testing where I come to that conclusion.

People will tell you the accelerator pump is unnecessary and is better removed. That video demonstrates quite the opposite. It's well worth calibrating and made a big difference. I don't think I mentioned in the video that mine were set to about half of the correct delivery. I think whoever did them in the past must have taken the values from the PHF specs.

I got that elbow from Gowanloch in Sydney. I called and asked about the part. There are three different angles - 40, 50 and 90 degrees. I believe I purchased the 40 - Look up 'Dellorto 9330' on Google.

I let the rear throttle cable go up inside the middle of the tank, across the frame to the other side and then out the front of the tank. The cable length allows it to form a nice curve without hitting the underside of the middle of the tank. The front cable joins the rear just before leaving the tank. I don't know how the factory did it, but I found this the best method.

I've got plenty of photos if you need anything.
Rob
 

·
Registered
Joined
·
260 Posts
Oh.. note that the elbow has it's own 5mm cable adjuster and matching nut. You need to get those along with the elbow. The elbow itself has a 6mm nut on it. They're all Dellorto parts. The dellorto.co.uk site is a good place to put it all together regardless of where you end up buying.
 

·
Registered
Joined
·
324 Posts
Agreed, doing the carbs is fun. The only thing I did not touch was the accelerator pump setting. There's a tiny dab of red paint from the factory on the pump setting screws so I just left them alone. Rick's custom carb shop shown below. Note my usual pizza boxes, ice cream tubs and old socks have been replaced with yogurt pot and a Tupperware container. Beer and good tunes help.
990520
 

·
Registered
Joined
·
2,302 Posts
Rob, the accelerator pump setting was different according to what model of 900SS the carbs were intended for: if the bike was fitted with Lafranconi or Silentium silencers and air filters, then the pump calibration was a lot less. Some markets had 900SS 's supplied with the Silentiums but no air filters. My 900S2 came with 40mm carbs and air filters so when I changed to Contis and K+N filters I reset the pumps to the delivery listed for early 900SS.
 

·
Registered
Joined
·
260 Posts
There's only one value provided for each model carb in the Ducati Dellorto Maintenance Guide, with no reference to filters or pipes. It's 8cc +_0.5 over 20 strokes of the slide for the PHM 40 and half that for the PHF. I've not found other specs for this after a lot of searching.

The screw adjustment controls the total volume. The slide controls the point at which the pump starts working and the jet controls the duration of the squirt. i.e. a larger jet for a quick bike and a smaller jet for a slower one.

With that in mind, it could be the case that the Silentium/filtered and smaller-jetted bikes had a smaller pump jet.

The easy test is just to wind it on as in the start and end of my video. Mine went from crappy to happy with this adjustment. Well worth doing.

Rick... mine had the paint as well, so in the initial rebuild I maintained that calibration. But after discovering the bogging I decided to double check and found it all wrong. After confirming the results I mixed up a little clear epoxy with red enamel for the screws. That made the paint suitably gluggy and any spilled fuel doesn't take it off.
 

·
Registered
Joined
·
24 Posts
Discussion Starter #20
I've yet to ride mine, but I for one will be testing what amount of cc's the accelerator pump is putting out....

off topic but found this fantastic original parts catalogue on ebay....arrived from France.
990631


990633
 
1 - 20 of 42 Posts
Top