bikerbill2021 Posted December 13, 2017 Report Share Posted December 13, 2017 Hey all So this is going to be a bit of a read, but I'm going to be as in depth while keeping it to the point as I can. TL;DR: Bike will not accelerate, idles and free revs fine, fires up first kick or so, but under load and past 1/4 throttle acts as tho there is a rev limiter. Have tried multiple approaches to diagnosing problem which range from playing with jetting to swapping parts from a known good bike, and have had very little success Now before we start, here is the bike and mods/repairs done 96 Banshee Fresh top and bottom end with all new seals/gaskets, stock bore/stroke, head milled and new jug MX style ported by HJR, welded crank, compression at the moment cold was around 120, which seems very low for a fresh motor with porting/head work, however I haven't even been able to break the motor in, so that may have something to do with it Jetting WAS set at 330 main, 27.5 pilot and #3 on the needle as per recommendation of Kevin at HJR, temp ATM is 60-75 degrees with elevation at 1200 ft above sea level (Phoenix AZ) I will dive into this below as part of my diag Running AVGAS with Lucas semi synthetic at 32:1 Toomey T5s K&N style pod filters with outerwares (at the moment not installed for diag) Brand new V force 4 Reeds, some generic boost bottle I had lying around (figure'd it couldnt hurt, unless it has a hole in it causing all my problems, then It will become a shooting practice target) NGK B8ES gapped to .025, stator/flywheel pick up set at .018 No TORS, No parking brake, none of that, I went through the wiring harness to check for problems/continuity and remove all the BS that goes alone with that, there is nothing related to that on this bike aside from a bare, parking brake-less clutch perch. Timing plate advanced +4 Bike has LED lights on it, two spots and a small bar on the bash guard wired into the stock wiring, no rectifier/battery, etc. I cant see how that would affect anything due to the lighting circuit being separate of the ign circuit, just adding to give as much info as I can Stock other wise Ok, so, now onto what I've (attempted) to do to try and figure out this problem. My friend lent me his great running 98 to swap parts from, which is similar to my bike mod wise minus the port/head work, his jetting is 290 on main, 27.5 pilot, and #3 on the needle, just for a base reference, I will refer to this bike as the "Swap Bike". Also, I did all this in steps to try and rule out any issue, I did not swap/change/adjust all at once, just to clarify Carbs are spotless clean, choke tube is in place between them, synced properly via "peep hole" on side of carb, slides properly installed with angled/swept edge oriented towards rear of bike Tried riding around with choke popped out on first setting, bike ran worse, so my thinking is too rich on the main. Pulled the plugs just to see, plugs were soaked. I played with the jetting and needle position and leaned the main all the way down to a 280, which is less then the swap bike had in it, it seemed to climb the RPM range a bit better, but still hit that wall and would not accelerate properly/spit sputter etc. Also swapped sliders/needles from swap bike, as my needles looked aftermarket (different color/strange part number then swap bike), no change there. The swap bike had 380 mains in it when we first picked it up years ago, aside from fouling up the plugs and not liking the higher elevations up north, it still screamed like a banshee should, which made me question the jetting on mine Tested and swapped 3 different stators, and 2 different flywheels, as well as putting timing back to 0, no change My coil was new, but tested and swapped anyways, no change I had a Dyna FS CDI kicking around, tried swapping that, no change Reeds are new, but inspected anyways/checked if installed right, no problem found Checked and cleaned ground point for harness, as frame was painted recently for strip down, as well as previously stated inspected/cleaned/rewired/tested/ and removed unnecessary tors/parking brake wiring from harness, no change, even added a ground point from head bolt to ign coil bolt, no change Inspected toomeys for possible clog, no problem found kicked bike over with plugs out to see if possible coolant leak internally (had an issue with the head leaking first time around putting motor together, turned out to be a bad gasket), no problem found Kicked bike over with plugs out and installed in caps, have nice blue spark Im sure I'm forgetting more I've done, but I have searched multiple forums/threads, and checked off as much "common sense" stuff as I could find, with no success This bike is racking my brains guys, Ive never had a machine give me such a head ache, and I work on VWs for a living! Please, any help would be great, I don't want to, but I'm getting to the point where I'm going to take it to my local bike shop, and as a mechanic, that is about as low as it gets for me Thanks Pics for clicks Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted December 13, 2017 Report Share Posted December 13, 2017 (edited) Even though the junk is off carbs and P brake , is the TORSbrain box unplugged ??(a must ) Left frame rail by tank , three wires Edited December 13, 2017 by Larry's Shee Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 7 hours ago, Larry's Shee said: Even though the junk is off carbs and P brake , is the TORSbrain box unplugged ??(a must ) Left frame rail by tank , three wires There is nothing TORS or parking brake related on this bike, no brain, no parking brake sensor/brain, nothing, everything has been removed related to that system, wiring, tors carb mechs, parking brake mech, everything Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted December 13, 2017 Report Share Posted December 13, 2017 Covering bases . Check pick-up gap at flywheel . Not re-reading post. Ground at frame , no paint at frame. Run a ground from engine to that point. There's actually a thread about this. Did you swap coil? Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted December 13, 2017 Report Share Posted December 13, 2017 Covering bases . Check pick-up gap at flywheel . Not re-reading post. Ground at frame , no paint at frame. Run a ground from engine to that point. There's actually a thread about this. Did you swap coil?Check plug gapEnvoyé de mon SM-G935W8 en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 (edited) 40 minutes ago, Larry's Shee said: Covering bases . Check pick-up gap at flywheel . Not re-reading post. Ground at frame , no paint at frame. Run a ground from engine to that point. There's actually a thread about this. Did you swap coil? 21 minutes ago, ClaudeMachining said: Check plug gap Envoyé de mon SM-G935W8 en utilisant Tapatalk Pick up gap .018, checked and cleaned ground at ground point, no paint on ground point, as well as attempted moving ground to different ground point, no change. Also added additional ground from engine to that ground point, as well as a ground from head bolt to bolt to ign coil mount, referencing from that thread previously, no change. Tested my new coil, old coil, and Swapped coil from known good bike, no change. plug gap .025 NGK B8ES Edited December 13, 2017 by bikerbill2021 Quote Link to comment Share on other sites More sharing options...
gusto Posted December 13, 2017 Report Share Posted December 13, 2017 Slides aren’t in wrong are they? it does sound electrical though. Have you tried a Yamaha Cdi from the parts bike? Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 16 minutes ago, gusto said: Slides aren’t in wrong are they? it does sound electrical though. Have you tried a Yamaha Cdi from the parts bike? slides are in correctly, Ive had that issue before as so many of us have, but ive ensured the taper is towards the back of the bike. I had the Dyna FS CDI swapped in and it made no difference, may try the CDI from my buddies, but I was chatting with my local shop, and he seemed pretty certain that it was fuel related. Said to remove the emulsion tubes that the needles ride in and clean them out, then drop down to a 270 or even a 260 main. I conveyed my concern about being too lean, but he said he sees banshees come through all the time with mods similar to mine with similar jetting. Ill give it a try Quote Link to comment Share on other sites More sharing options...
gusto Posted December 13, 2017 Report Share Posted December 13, 2017 that seems real low on the mains. You’ve done a full leak down I assume? speaking of fuel, is it fresh? Filter at petcock clean? keep us updated, I’m stumped Quote Link to comment Share on other sites More sharing options...
Keno Posted December 13, 2017 Report Share Posted December 13, 2017 Can you link to a video of it running so that we can hear what it sounds like when trying to accelerate? 1 Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 1 hour ago, gusto said: that seems real low on the mains. You’ve done a full leak down I assume? speaking of fuel, is it fresh? Filter at petcock clean? keep us updated, I’m stumped Fresh 100 LL AVGAS picked up last week, no fuel filter on bike, however I run clear lines and see no junk in them or the bowls, also petcock is new. I thought maybe the AVGAS was the issue, but theres guys on here that run it on stock bikes with no problems, and I run it in my YZ250 to reduce detonation, and it runs great albeit different motor, but still I have not done a leak test yet, however I replaced all seals when I went through the motor, stator side I've inspected and looks fine, crank side cant see, but its not smoking excessively so I'm thinking that side is good as well. That will be the next step 18 minutes ago, Keno said: Can you link to a video of it running so that we can hear what it sounds like when trying to accelerate? I will attempt to get a video here in a bit, I'm gonna head to my local shop and chat with him, pick up some mains, Emulsion tubes were clean, no problems there, cleaned them out with cleaner and compressed air for good measure Quote Link to comment Share on other sites More sharing options...
ZillaFreak Posted December 13, 2017 Report Share Posted December 13, 2017 What are the specs of the milled head? Who milled it? Is it just milled, not cut? Have you tried premo gas? Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 16 minutes ago, ZillaFreak said: What are the specs of the milled head? Who milled it? Is it just milled, not cut? Have you tried premo gas? I had Kevin Herr of HJR racing mill the head for me, I wanted to run AVGAS so he said he would mill it for that, didn't give me any specs sadly, on the invoice it just stated "Banshee Head Milled AVGAS". By premo gas you mean premium I.E. pump gas such as 91-93? Or straight race fuel? Ive only ran the AVGAS in it for the time being Quote Link to comment Share on other sites More sharing options...
ZillaFreak Posted December 13, 2017 Report Share Posted December 13, 2017 I mean pump gas (91). If the head is "milled" for AVgas, and you are only getting 120psi there is something no adding up. Either the head was fucked up or your gauge is fucked up. Quote Link to comment Share on other sites More sharing options...
bikerbill2021 Posted December 13, 2017 Author Report Share Posted December 13, 2017 1 minute ago, ZillaFreak said: I mean pump gas (91). If the head is "milled" for AVgas, and you are only getting 120psi there is something no adding up. Either the head was fucked up or your gauge is fucked up. gauge is a cheapy one from o'rielys, so its most likely not very accurate. Also I haven't even been able to break this motor in aside from some heat cycles and what ive been doing now, so im not sure if that would have anything to do with it I was thinking this too however, I would think my compression would be much higher with a milled head, the AVGAS being a higher octane/burning slower would make sense in it acting the way it is, but ive read that people run AVGAS in stock banshees with no issues, which makes me circle back and doubt the issue Quote Link to comment Share on other sites More sharing options...
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