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Okay so just for fun the 1993 in the shop was run on the dyno today as the first bike since setting the dyno back up. All systems go and runs went without a hitch.
Except... the bike only made about 25rwhp. Double checked the settings because I must have hooked something up wrong , swapped the ignition pickup to the rear cylinder to test for a bad ignition. Both runs look fine just no one is home. A little background on the bike is in order, it was a cheap bike that everyone loves to find and yes it had all the trademark issues.

Compression and leakdown tests were done and both were good.
full tune done and the valves probably had not been done in a looonnng time.
carbs sync'ed and the fuel screws set on a gas tester (1 screw was falling out)
air filter plugs etc all good. not running on one at any point, sounds fine just weak.
I was shocked as the bike sounded much better than it looked and was shaping up to be another good bike finding a good home, by ear it sounds normal and good.
Air fuel on the dyno showed a little rich down low rpm but gets better as the rpms climb, certainly not bad enough to cause a 2/3 loss of power.

Well that's how my day ended tomorrow I see if my finding is correct but for now what do you think?
975043
 

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seems like the carbs are suspect. things are working as you say but no power. wrong jetting or reduced jet sizing due to coating of ? on the bores of the jets.... I would look into the carbs.

Fred
 

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i've had a few recently that have been sitting for some time where the needles have been stuck in the needle jets with fuel residue. i think it's the yellow die they put in our unleaded. a friend who used to work at the refineries said that the raw die is so concentrated in the drums it's black. in the carbs it's dark green.

years ago when we were doing bimota we had an sb6 dyno rather low that the owner was pissing and moaning about. turned out he'd adjusted all the free play out of the rear brake. not sure why it didn't just melt it though.
 

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Discussion Starter #8
Well I made no progress on it today as I need the okay to do more work on the bike,costs and all. I assume I will be back on it next week but I have the 94 that needs a cylinder fixed and its fresh carbs installed first.



975077


The 94 needs dyno time and for me to re-install the horizontal top end and make sure tyhe oil consumption problem is gone. then I will have time to re-visit the carbs on the 1993.

Brad the slides will lift if you manually move them or blow air in the hoses well on the right side the air will move it on the left it igf not budging. I am going to guess a pinched or holed diaphragm.
jimc2
exhaust is clear and seems to flow well at 8000rpm on the dyno buy who knows if the carbs dont fix it that is one step before I touch the motor.
 

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Discussion Starter #10
As usual it is not the fault of Ducati, Mikuni or the rubber tree plant that gave us the diaphragm. More likely the fact the carbs were cleaner than the rest of the bike and there are other hints to the prior owner/mechanic like the cases holding 2 extra quarts of oil, 7 chrome studs and one updated stud that seems to be slightly further exposed than the rest. A 8mm bolt holding the sidestand bracket to the case because they could not get the rest of the broken steel bolt out of the case. I could go on....
 

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Discussion Starter #12
Stages of bike ownership

first owner= love and care
second = love and some care
third = love
fourth =cool bike for cheap, abuse and no care
fifth =look a running motorcycle
sixth = look a non-running project bike
My customers = Hey look how cheap I got this bike for, followed by its going to cost how much to fix it? lol
 

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I felt that ,when I found this low mileage 97 900ss/cr only 13000 miles had not been started in 12 years I'm the third owner.It needed allot of TLC and knowledge of how to finesse this beauty back to life.After some time and money I'm nearly there.I didn't expect like it this much.
 

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Discussion Starter #14
Where to start

Who ever hacked this bike should really take up a new hobby, I should not complain as this is all billable hours to fix screw ups.
Today's chores was to tackle the carbs first as I already knew the slides were not opening. BUT THAT'S NOT ALL....
If you have a bad gasket, don't change it just add some goo.
If you are missing a o-ring or two don't worry leave them out.neither o-ring in the diaphragm chamber.
shims on the needle? mix it up, put one on top and the other side put it on the bottom.
Pilot jets? well it is a 1993 so it might be a 37.5 but then some like a 40. so to get there use a 37.5 in one carb and a 42.5 in the other.
at least the needle jets are fine.

That's not even mentioning the broken off bolt in the tank latch and in the engine cases from the side stand.

975363


well at least it survived the dyno runs without a problem and the gains were worth the effort. I was only surprised at how decent the fueling was with both slides fully closed at 7,000rpm


975364
 

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Where to start

Who ever hacked this bike should really take up a new hobby, I should not complain as this is all billable hours to fix screw ups.
Today's chores was to tackle the carbs first as I already knew the slides were not opening. BUT THAT'S NOT ALL....
If you have a bad gasket, don't change it just add some goo.
If you are missing a o-ring or two don't worry leave them out.neither o-ring in the diaphragm chamber.
shims on the needle? mix it up, put one on top and the other side put it on the bottom.
Pilot jets? well it is a 1993 so it might be a 37.5 but then some like a 40. so to get there use a 37.5 in one carb and a 42.5 in the other.
at least the needle jets are fine.
.... wuhl hell fire ..... partz iz parts, right? ....

.... damned fussy ass I-talyun thing ... if'n it wuz a HARLEY it wooda run jist fine !! .....

.... whuts this werld comin' to .... everthing iz jist goin tuh hell in a hand basket I tell ya whut !!




(some people's children! they go out and buy a junior mechanic's tool set at Harbor Freight and suddenly they're master technicians. makes me wonder what else you're in store for!!!!)

.... wuddya mean I caint put 30wt in the forks? .... hell I put it in the brakes too !!! .... it's all jist oil ... !!!

:rolleyes:
 

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I'm starting to wonder if the previous owner of my 900 is the same person that did this one. Mine also had a mis-matched longer head stud - he proudly explained that he changed it, taking a stud from a salvage monster motor. Why would anyone go through the trouble and then only change one.... I should've walked away then but I was already there with a rented van...

He couldn't explain why the engine would cut out when you turn on the choke, even though he "cleaned the carbs". I found out that he had mixed up the choke jet and the screw that holds the jet block to the carb body. Sure they have the same thread size, but one would think the lack of a hole could be a bit of a tip which is which. Of course all this work done without replacing a single o-ring or gasket. Cheaper that way, just like the self tapping screw from home depot used to hold on the oil cooler.

Anyway, I'm guessing the electrical system will not look much better on that bike. Watch out for the old "twist and tape" trick.
 

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Anyway, I'm guessing the electrical system will not look much better on that bike. Watch out for the old "twist and tape" trick.
what no wire nuts?
(near sickening...I'll spare you details of a recent encounter with a neutered -via electrical bastardization- sportbike)
 

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All I can say is----Other peoples children----it would be hard to fuck them up that bad without trying lol
 
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