lt1bird Posted November 11, 2014 Report Share Posted November 11, 2014 Guys, this misfire is driving me crazy... 485 trinity setup... runs great at 1/4 throttle up... for the life of me I cannot fix the what im calling a misfire... at 1/8 throttle it seems to sputter a lot....I lean it out and you can feel it get a big boggy as you would think, but the sputter is still there....seems to be there if im rich or lean...does not matter..again, everyplace else seems just fine...If it were ignition I would think it would do it under more of a load as well... any help would be awesome, im lost at this point and ive built a bunch of these LOL Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 11, 2014 Report Share Posted November 11, 2014 Clean carbs (blow out jets and look through orfices) Clean the PV's Check ignition components Look for air leak Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 11, 2014 Author Report Share Posted November 11, 2014 (edited) carbs are clean, no power valves as they are blocked off. Ignition...its all new, timed etc but ill put a timing light on and see if its misfiring via the spark plug wires... you don't think jetting would do this? air leak...guess I could check the reed block gaskets etc... Edited November 11, 2014 by lt1bird Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 12, 2014 Report Share Posted November 12, 2014 Jetting could definitely be the culprit. I assumed it was dialed in, but you said it's doing the same thing when you richened and leaned it out? What's the whole motor set up? Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 12, 2014 Author Report Share Posted November 12, 2014 (edited) its a 485 with trinity PV cyl's... blocked off.... stock porting....155psi compression... setup for pump gas...ignitec ignition...24 total timing... 38mm keihin carbs.. pipes are midrange pipes... v force reeds, 158 mains 65 pilots #6 slides DEQ needles Ive tried leaner slide, richer slides....different needle dia etc to try and clean up 1/8 throttle... im starting to wonder if there is a leak in the exhaust.. so its sucking air in at lower throttle settings... think that could do it? whole new setup so its never been dialed in... well, 1/4 throttle up was and I rode it like that for a little bit...now im making a big effort to make it smooth... and its just not good.... don't get me wrong...you can ride it like this but it should not be doing that at 1/8 throttle, you should be able to put along at 1/8 throttle steady cruise without is misfiring/sputtering... Edited November 12, 2014 by lt1bird Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted November 12, 2014 Report Share Posted November 12, 2014 Try different diameter needle or dek ,might have to redial in main after changing needle Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 12, 2014 Author Report Share Posted November 12, 2014 The needle in it is the leanest dia I can find... That's why I went to the 7 slide to lean it out more Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 12, 2014 Report Share Posted November 12, 2014 ^that Have you tried a 60 maybe 58 pilot? What type of porting? If it's got block offs and they did a fairly high exhaust, you may be hard pressed to try and get some low end. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 12, 2014 Author Report Share Posted November 12, 2014 (edited) The porting is stock.... the PV block off plates I cut to fit so they matched the port perfect...full open. Even with the power vavles installed it was going the same thing....maybe a bit worste.. I have tried pretty much all the pilots from 50 up... Edited November 12, 2014 by lt1bird Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted November 13, 2014 Report Share Posted November 13, 2014 A d-series is def not the leanest diameter ,usually when u have exhausted al jetting options needle taper/diameter is the culprete , sometimes odd set ups require odd needle selection,have you pressure tested the motor Quote Link to comment Share on other sites More sharing options...
special06shee Posted November 13, 2014 Report Share Posted November 13, 2014 Who cut the domes? I had a motor do exact same thing yours is doing. Ended up being a shit ass dome design. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 13, 2014 Author Report Share Posted November 13, 2014 tim from titan made them...they were exactly what I wanted... positive quish unlike the negitative squish angle on the trinity domes. The DEQ needle.... the Q is the diameter, and its the leanest I can find.... that's why I went to a leaner slide...the leaner slide most definatly leaned out the idle as well... so the slide leaned from idle to 1/4 throttle... and it still seems to misfire like its rich... even the EGT seems to drop when it starts to miss at 1/8 throttle... drops to 290-300C from high 300's This is the second motor ive had do this...I had a 535 do the same thing... but I never spent much time to fix it.....whole different motor, pipes etc... with power valves... im just wondering if im being to picky? maybe a built in issue with the stock cylinders? I would imagine not many quads would be staying at 1/8 throttle lol I might take a day and go trhough the setup and check for leaks, comprssion, leakdown etc... check timing... just to make sure.... Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 14, 2014 Report Share Posted November 14, 2014 I know you keep saying "stock" but most of their "stock" stuff has some work done unless it's ordered Raw. Did your builder order the cyls untouched? Quote Link to comment Share on other sites More sharing options...
m671054 Posted November 14, 2014 Report Share Posted November 14, 2014 What about a reed issue maybe? Just tossing it out there. Not even sure if its possible Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 14, 2014 Report Share Posted November 14, 2014 It's possible. Quote Link to comment Share on other sites More sharing options...
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