low power, slight hiccup thru the carbs, and one fouled plug? - Ducati Monster Forums: Ducati Monster Motorcycle Forum
 
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post #1 of 7 (permalink) Old 06-19-2007, 09:57 AM Thread Starter
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low power, slight hiccup thru the carbs, and one fouled plug?

Okay, so it's time to figure out just what is wrong with my bike. (2000 M750, aftermarket high pipes, aftermarket dynacoils & pod filters) I bought the bike used & untaken care of, for the most part. It has a hiccup throught the carb(s) that is very noticeable at idle, and sometimes when shifting. I don't want to say backfire, because it's not a big pop, just a cough.

The bike is very underpowered, so much that I thought maybe a belt was off by a tooth...checked that last night & the belts are in correct position. The vert. cylinder's plug is fouled pretty bad & exhaust smells like gas. Horiz. cyl. plug looks almost perfect. This makes me think ignition timing is either weak or retarded on the vert. cylinder, since (I hope) both carbs would be adjusted fairly close to one another, and might explain the hiccupping thru the carbs.

Any suggestions? swap the coils to see if the fouling follows the coil? I don't have a compression tester, but can get one...how do you adjust ign. timing? or at least check it?

thanks all.
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post #2 of 7 (permalink) Old 06-19-2007, 03:47 PM
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

When is the last time the bike had a major service? If you don't know then it needs one, including timing belts. Do a compression check first. After the service if it still runs poorly I would consider a look see if the carbs have been re jetted.



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post #3 of 7 (permalink) Old 06-19-2007, 04:16 PM Thread Starter
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

it had the 12k service...Pretty sure the receipts show new belts, and they weren't bad looking when I checked their position last night. If I check valve clearances, that should take care of "service" requirements that would have anything to do with this, correct?

any idea what the compression PSI should be?
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post #4 of 7 (permalink) Old 06-19-2007, 10:27 PM
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

The 2000 750 was still carb-ed, right? How many miles has it got on it? My guess is that the needle jets are worn out and it's running rich...

big
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post #5 of 7 (permalink) Old 06-20-2007, 11:19 AM
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

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Originally Posted by bigiain
The 2000 750 was still carb-ed, right? How many miles has it got on it? My guess is that the needle jets are worn out and it's running rich...

big
+1 Change the fouled plug and run the bike 'till it fouls again. If it does you can be pretty sure the needle jets are ovaled.
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post #6 of 7 (permalink) Old 06-20-2007, 03:32 PM Thread Starter
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

cool, thanks. It has 20k miles on it, roughly. I will be doing a comp. check, just to rule that out, then I'll pull the carbs off.

any reccomendations on a kit from anywhere in particular? dynacoils, pod filters & high pipes are the mods.
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post #7 of 7 (permalink) Old 06-20-2007, 09:57 PM
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Re: low power, slight hiccup thru the carbs, and one fouled plug?

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Originally Posted by NODNARB
cool, thanks. It has 20k miles on it, roughly. I will be doing a comp. check, just to rule that out, then I'll pull the carbs off.
Thats a little earlier than I'd expect for ovaled out needle jets, but not outrageously so - I find I need to replace mine every 50,000km or ~30k miles.

Quote:
any reccomendations on a kit from anywhere in particular? dynacoils, pod filters & high pipes are the mods.
I'm a big fan of the FactoryPro kits, they seem really well though out in areas like including a full set of stainless steel allen headed bolts to replace the mild steel phillips head screws that tend to seize in and you end up mangling the heads when you try to remove them...

Having said that, I hear people are usually perfectly happy the the DynoJet kits too (keep in mind DynoJet use a different jet numbering scheme to everybody else, so comparing FactoryPro or Mikuni jet sizes with DynoJet sizes directly doesn't work - I've seen a conversion chart somewhere out there on the web though...)

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