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backfiring and less than optimal power

Old 08-11-2007, 02:20 PM
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backfiring and less than optimal power

here is the specs....

98 superhawk with 24k miles on it...
has a jet kit and owner supposedley said its tuned for colorado specs
PAIR is disabled

Probs are that when started it backfires until its warmed up...even when warmed up it backfires a lot about 20 mph to 0...on occasion there will be a backfire in the carbs...also it kind of stutters while riding at random times...when in 6th gear on the highway going 70-80 its perfectly fine though....mostly stutters around town...

spark plugs have been changed and if anything were a lil white and looked like it was running lean. Im thinking carbs syncing/cleaning and valves...anybody know really whats going on?
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Old 08-11-2007, 11:53 PM
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Well, I'm NOT an expert on working with these things, but this really sounds like the same problem I had for a couple months. Mine was the diaphragm/ vacuum piston on top of the carb. My diaphragm had a 1/4" tear in it (that saying can NEVER be good!). Anyway, bought a new one (not cheap!) and now it runs great. It had the same symptoms tho, power loss, coughing/ missing/ backfiring. It would be worth a look. Just watch tearing into it. There is a spring when you take the cover off that can be a bear! There are a few threads here about it.

https://www.superhawkforum.com/forum...ead.php?t=3414

I don't know if this is the problem, but it sure sounds a lot like what I fought for a couple months, although mine acted up on the highway occasionally also.......I'm sure there are some others that may have a better idea for you. There's a wealth of knowledge here.........good luck!
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Old 08-12-2007, 08:59 PM
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thanks any suggestions are welcome...just trying to narrow it down....how much was it to replace??
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Old 08-13-2007, 09:07 AM
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Sounds like very lean pilot jet...or DPO did some work and somehow skipped a tooth on a cam gear and timing is off a little.
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Old 08-13-2007, 10:10 AM
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The diaphragm cost me $93 with shipping. I imagine you can get it a little cheaper, but I was in a rush to get one ordered so I went with the cheapest of the first three I found. That may not be the problem, just something to look at. Try to narrow down if the missing is related to one jug or the other, then maybe check the diaphragm for that carb. Mine ended up being the front carb. Don't rule anything out tho, it could be any number of things. I may be way off here also......just letting you know what I found when my girl acted similar to what you are describing.
Good luck!
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Old 08-13-2007, 04:28 PM
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Originally Posted by redman View Post
Sounds like very lean pilot jet...or DPO did some work and somehow skipped a tooth on a cam gear and timing is off a little.
i was thinking something with the jet kit...i dont think its timing cause we did a CCT change just recently and everything looked fine on that end.
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