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Topend Rebuild; how does it sound?


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Just rebuilt my topend with a driveline 392 kit and wanted opinions on how it sounds initially. Sounds a bit rich at the air screw but other than that, crispy to my ears and it seems to rev out well in neutral. Haven’t ridden it yet so load may change that. Driveline suggested a 320-340 main for my elevation and yearly temp range. They were very specific with the needle clip position so i doubt that needs to be changed.  The excessive smoke when revving is just from the assembly oil.

Engine mod list:

Driveline 392 Assassin topend (as cast), FMF Fatty pipes w/ T5 silencers, +4 timing, VF4 reeds, Chariot billet intake, Stock carbs (320 main, 30 pilot, Stock needle at 4th clip), Uni pod filters (one stage), a Noss trixx coolhead w/ 20cc big bore domes, and Sunoco 110 race gas with klotz benol @ 32:1

videos:

 

Edited by Steven66
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13 hours ago, Keno said:

Well, it runs.  I imagine they recommended rich jetting for break in.  I'm sure Ayesully will chime in soon, he's the resident stock carb jetting expert.

cant tell if sarcasm or not but dont matter because bill and lane taught me everything I know basically so what ever they tell him trumps anything I say lol

Edited by Ayesully810
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25 minutes ago, Keno said:

Not really sarcasm.  You seem to be the one helping most with jetting issues these days.

hahaha i must just be used to skeeters zingers all the time.  

btw steven66 i just listened to the video sounds good! i like he idea of toomey silencers on FMFs.  should run really well. you will love it 

Edited by Ayesully810
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2 hours ago, Ayesully810 said:

hahaha i must just be used to skeeters zingers all the time.  

btw steven66 i just listened to the video sounds good! i like he idea of toomey silencers on FMFs.  should run really well. you will love it 

Preciate it. I am having a low power off idle issue though. Right now with the 30 pilots and 1.5 turns out, it feels like a dog compared to my buddy’s stock port and cylinder build with the exact same exhaust setup. He’s running 27.5’s @ 1.5 turns and 290 mains. When the main starts to work, this 392 is amazing, it’s just the off idle power. It actually feels worse than my old dune port setup with T5’s and the same pilot settings. Any advice? 

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adjust the air fuel screw in/out it will tell you what you need.  If it feels like its running rich turn that air fuel screw out another full turn see what happens.  Race fuel you will probably be able to jet leaner than pump fuel.  If it starts fine right now do a plug chop on the main get that dialed in. those numbers are pretty spot on though my old DL 4 mil with stockers on pump was 350 main 35 or 37.5 pilot vito needle same spot,  obviously driveline can direct you as well via email or what ever ur using. Bill scheel helps run that joint too hes on fb 

Edited by Ayesully810
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5 minutes ago, Ayesully810 said:

adjust the air fuel screw in/out it will tell you what you need.  If it feels like its running rich turn that air fuel screw out another full turn see what happens.  Race fuel you will probably be able to jet leaner than pump fuel.  If it starts fine right now do a plug chop on the main get that dialed in. those numbers are pretty spot on though my old DL 4 mil with stockers on pump was 350 main 35 or 37.5 pilot vito needle same spot,  obviously driveline can direct you as well via email or what ever ur using. Bill scheel helps run that joint too hes on fb 

I’ve done a couple runs with the air screw at different spots and the off idle lack of power is still there. Unusual to me since I just checked my buddy’s bike and it’s actually running 30 pilots as well at 1.5 turns and it has a very linear and smooth power curve. I started to think I had a leak somewhere but I’ve already tested all areas and didn’t see any. There’s a gremlin somewhere I know it

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28 minutes ago, Steven66 said:

I’ve done a couple runs with the air screw at different spots and the off idle lack of power is still there. Unusual to me since I just checked my buddy’s bike and it’s actually running 30 pilots as well at 1.5 turns and it has a very linear and smooth power curve. I started to think I had a leak somewhere but I’ve already tested all areas and didn’t see any. There’s a gremlin somewhere I know it

if its really rich and sputtery before it starts to make power lean the needle out a clip see if it helps.   if you leak tested it already dont let that worry you 

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17 hours ago, Ayesully810 said:

if its really rich and sputtery before it starts to make power lean the needle out a clip see if it helps.   if you leak tested it already dont let that worry you 

I ended up raising the needle clip position up one to the 3rd slot and it cleaned up a lot of the lack of power but it still has a little hesitation. I’m going to raise it one more position and see what that does. If it still doesn’t feel the way it should, I’m considering pulling the Dynojet needles out of my buddy’s bike to see how they feel. He’s got instant power that rises linearly and pulls all the way until max rpm

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