Sf1 36mm PHF carb tuning

Looks like whoever lined the tank didn't follow the directions. Tanks must be cleaned with their (Por15) "marine clean' and thoroughly dry before treatment. Product needs to cure for several days. I just did mine. Remains to be seen if proper procedure is successful. Once the tank has seen rust, cleaning/lining it would seem the only way to mitigate more of same, given the propensity of water accumulation from the ethanol (water attraction) in modern fuel.
 
3CBRG said:
Looks like whoever lined the tank didn't follow the directions. Tanks must be cleaned with their (Por15) "marine clean' and thoroughly dry before treatment. Product needs to cure for several days. I just did mine. Remains to be seen if proper procedure is successful. Once the tank has seen rust, cleaning/lining it would seem the only way to mitigate more of same, given the propensity of water accumulation from the ethanol (water attraction) in modern fuel.
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I never used to line my tanks, I use Evaporust, filled to the brim and let it do its thing for a couple weeks. Then I rinse with metal prep and a handful of drywall screws, rinse with hot water and then rinse with methyl hydrate to absorb all the water and let dry in the sun for a day. Since my painter started using Pour 15 liner I bought some for myself and lined four tanks this spring, very easy to use and it seems to work fine. I showed my painter the pile of crud that came out of the tank and he is going to remove the liner with some form of solvent and then acid and do it all over again. He is a very thorough guy, he thinks he lined the tank then the next day masked in the filler spout and petcock bungs and painted the tank. The masking was on the tank when I got it last Tuesday. I suspect the masking off the tank slowed the cure and the product never fully cured properly. When I have lined my tanks I left the filler cap off for weeks and the petcocks out.

Jim
 
sfcpiet said:
Needle should be "K" series, K-something.

piet
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Found this on the web

Original setting for LAVERDA 750 SF1, SF2, SF3 (Dell'Orto PHF 36):

Pilot jet 55

Choke jet 70

Main jet 140

Needle jet 265 AB

Needle K2, 2nd  position

Float height  18mm +/- 0,5mm

Looks like I need to find some K2 needles
 
If the tank is in good condition internally why line it??? Foreign shit in the tank is asking for trouble as you just found out. If the tank internal is an issue then line it.
Have never lined a tank yet but when I was thinking about it on the carbon tank I made I did alot of research and Casswells epoxy based liner came out tops.
In the end Boba convinced me that the West System epoxy he uses and the same as I used was impervious to ethanol based fuels even thought our fuel in West Oz isn't ethanol based.
Several years later having fuel sitting in the tank it's still good.
 
I've never lined a tank either, ands I don't think I ever would, considering some of the failure stories I've heard on here and through other sources. If any of my tanks ever spring a leak I'll weld a patch in.
 
Many years ago I had a badly rusted Triumph tank that kept blocking the taps and carbs, so I did the Killed Spirits thing. That's dilute Hydrochloric Acid, then water and nuts shaken and rinsed dozens of times and then the liner, CREME, that's all there was back then. At was a disaster, the excess wouldn't flow out and set in a big lump. The coating came away, I eventually cut a section out of the bottom and had it sandblasted. I hear the later coats are better.A mate did the brazing, that was the first time we did the car exhaust into the tank thing to stop explosions.
 
Pilots are 55 standard on all big Laverda motorcycles. ( and some small I think?)
SF1 plugs would be NGK B8ES. I've used them for 40 years. Some use other makes.

Petrol is hydrophile, with or without ethanol.

Paul
 
140 main is too lean and you risk holing piston on any flat out run, 145 are safe.  60 slides are also leaner than standard 50, but will work ok with your big pilot jets. Bike will be cleaner with smaller pilots and the 50 slides, road bikes spend most of their time at small throttle openings. These parts are expensive so leave it as is.
As said K2 needle is correct. On tuned motor the K2 is more restrictive than about 155 main jet, needing a needle thinner at the tip for mj larger than that but that doesn't concern your bike.
B8ES are the sparkplugs, if running really hard B9ES.
 
I found a pair of K2 needles in my stash of Dellorto parts, fitted them and then fired up the bike with fresh gas and set the idle and air screws.
I took the SF1 out for an hour ride today at various speeds, in town and on the freeway. At stop the idle was about 2100 rpm then it would fall to 1200 / 800 and stall if I did not ease on the throttle. I do not believe I am getting an air leak from the manifolds. The carb bodies are new and Wolfgang had provided new internals but I think the slides are the old ones and I suspect they are too sloppy and I am getting air leaks past the slides at idle.

I did a plug chop after a twenty minute spin on a back road at 70 km/hr, pulled in the clutch and hit the kill switch. Both plugs were a bit sooty, definitely rich. Maybe they were sooty from the intown running prior to the plug chop. Tomorrow I will take a fresh set of plugs with me and fit them prior to a mid speed plug chop.

I stopped at a friends bike shop and aimed a thermometer at each header noting the temp was going up and down by 10 ~ 20 degrees F from side to side which he thought was a sign of worn slides.

If I were to purchase a new pair of slides what size should I get for general riding, mostly in and around town with occasional day runs at highway speeds.
 
Canuck750 said:
I went back out to the shop and pulled the carbs off, after removing the float bowls I was shocked to see a pile pf grey crud in each bowl. I had just got the gas tank and side panels back from my painter and he had also sealed the tank with Por-15 tank sealer. The tank was clean inside and rust free but my painter swears by a thin coat of Por-15.
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I swear at POR-15 ......... even if you fix your messy problem it will eventually shit itself from age and then this little mess will seem minor. I would swear at your painter as well.

Properly cleaned and then either electrolysis  or coated with an aircraft grade epoxy is about the only safe way to go.

Jim
 
Not a good idea to fit old slides to new carb bodies! They's simply wear the carb bodies!

Get some new 50/- slides and fit 50 or 55 pilots. The idle prob you describe sounds like 'hunting' and can surely be a result of worn slides (they literally catch on the worn edge of the slide and then drop as vacuum reduces. Can also be (as described previously) having the mixture screws a little lean. The grey shite is another matter - I would steer well clear, as Jim says! Sounds like it may be too late for that if your painter is going ahead trying to fix his stuff-up.

Be aware that plug colour is a whole new story with unleaded fuel. Sooty is kinds the way they'll look with anything but hard full throttle (ie main jet) running. The only plug chops I have ever done are full throttle max revs, clutch in, but that was back in the unleaded days. if you fit the new 50/- slides, reduce your pilot jet size and go with 145 mains, then tune your mixture screw, you shouldn't need to do a plug chop.
 
Canuck750 said:
I found a pair of K2 needles in my stash of Dellorto parts, fitted them and then fired up the bike with fresh gas and set the idle and air screws.
I took the SF1 out for an hour ride today at various speeds, in town and on the freeway. At stop the idle was about 2100 rpm then it would fall to 1200 / 800 and stall if I did not ease on the throttle. I do not believe I am getting an air leak from the manifolds. The carb bodies are new and Wolfgang had provided new internals but I think the slides are the old ones and I suspect they are too sloppy and I am getting air leaks past the slides at idle.

I did a plug chop after a twenty minute spin on a back road at 70 km/hr, pulled in the clutch and hit the kill switch. Both plugs were a bit sooty, definitely rich. Maybe they were sooty from the intown running prior to the plug chop. Tomorrow I will take a fresh set of plugs with me and fit them prior to a mid speed plug chop.

I stopped at a friends bike shop and aimed a thermometer at each header noting the temp was going up and down by 10 ~ 20 degrees F from side to side which he thought was a sign of worn slides.

If I were to purchase a new pair of slides what size should I get for general riding, mostly in and around town with occasional day runs at highway speeds.
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If your tickover is irratic it can be a partially blocked pilot jet ( you over compensate with tickover adjustment and it goes on to next circuit) or ignition cutting in / out - a coil can give symptoms like this and also sooty plugs. I had a dicky coil on a Guzzi that would play up after a downhill run ( soot up plug) then would feel like fuel starvation, then would suddenly clear, took me a while to sort .Jason
 
Piranha Brother 2 said:
Not a good idea to fit old slides to new carb bodies! They's simply wear the carb bodies!

Get some new 50/- slides and fit 50 or 55 pilots. The idle prob you describe sounds like 'hunting' and can surely be a result of worn slides (they literally catch on the worn edge of the slide and then drop as vacuum reduces. Can also be (as described previously) having the mixture screws a little lean. The grey shite is another matter - I would steer well clear, as Jim says! Sounds like it may be too late for that if your painter is going ahead trying to fix his stuff-up.

Be aware that plug colour is a whole new story with unleaded fuel. Sooty is kinds the way they'll look with anything but hard full throttle (ie main jet) running. The only plug chops I have ever done are full throttle max revs, clutch in, but that was back in the unleaded days. if you fit the new 50/- slides, reduce your pilot jet size and go with 145 mains, then tune your mixture screw, you shouldn't need to do a plug chop.
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Thanks!  I have ordered a new pair of 50/ 3 slides and 145 mains, hopefully this will improve the running.
 
It is entirely possible that you've got more of that crap tank sealant still stuck in the pilot jet system. But try the new slides first. Luckily it's not a big deal removing and refitting carbies!
 
I got the new 50 slides and installed them with new 145 main jets, idle is still erratic so I stripped the carbs once again and back into the ultrasonic cleaner they went, blew out all the passages and air seems to flow trough all passages.

Wiggling the choke cables caused idle to jump, I don't like cable operated chokes and change all my bikes out to flip lever chokes, so I ditched the choke lever and splitter cable and installed a pair of flip levers, I think only the left side will be easy to use so the right will probably remain off, I have been told by Ducati guys that on bevel twins an operable flip choke on the front cylinder will suffice with the back carb also fitted with a flip choke but not used. With the flip chokes that seemed to help.

Idle is still poor, the idle will suddenly climb way up. I disconnected the plug leads one at a time and the right carb is much smoother, the idle screw is wound in about half way, the air screw about 1 -1/4 turns out. Left carb on its own requires the idle screw wound all the way in to run but just barley. Air screw on the left is 1-1/4 turns out.

I pulled the intake manifolds off and resealed them, these are the newer Dellorto carbs that take a rubber boot to the alloy manifold, I don't think there are any air leaks.

I stripped the left carb down again and after checking everything again I found this return valve is missing the check valve, just a wide open passage. No idea how that happened or when the ball went AWOL.



Am I right to assume this missing check valve is what is causing the very poor idle on the left carb and causing the idle to suddenly climb way up?
 
That little check valve is part of the accelerator pump system. It's the pump's intake tube through which it sucks fuel from the float bowl. The built-in ball check valve is there to stop to stop back flow. Without it, the pump won't work. But I don't think it would have any effect on the idle circuit.

If your accelerator pumps are still operating (some folks disable them), then you'll need a new intake valve to make it work properly. It's part number 8557, available from most Dellorto parts suppliers.
 
Dellortoman said:
That little check valve is part of the accelerator pump system. It's the pump's intake tube through which it sucks fuel from the float bowl. The built-in ball check valve is there to stop to stop back flow. Without it, the pump won't work. But I don't think it would have any effect on the idle circuit.

If your accelerator pumps are still operating (some folks disable them), then you'll need a new intake valve to make it work properly. It's part number 8557, available from most Dellorto parts suppliers.
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Thank you for clarifying that, I did remove the pump levers so this is likely not the cause of the idle issue, I need to keep looking.
 
Are you absolutely certain that those choke plungers are sitting properly on their seats? The rubber bung in the bottom of the plunger is sitting correctly? It takes almost nothing to allow mixture to leak through the choke system and over-ride the mixture screw system. Look down the holes, swap plungers to the other side. Swap that dodgy pump jet missing the check valve to the other side. After all you have been through I would be swapping carb bodies side to side to determine that it is definitely carb related, which I agree it does sound like.

 
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