| Author | Message | ||
     The4ork |
i put those stage3 XB heads cyls and pistons in the bike, and i just cannot figure out why its got no balls.... seems like its hesitating in the mid and high rpm range... no backfires or pops but it just seems gutless, like its not wanting to rev up plugs look nice and brown so its not fuel... could it be timing? gonna go grab some food and run some errands while it cools off, and gonna look in the manual how to set the timing and see if its off. just thought i'd post, maybe there is something i overlooked... | ||
| Oldog |
No the heads them selves do not require alteration of timing, check compression pressure, IIRC 60 1st revolution +120 2nd roll +150 3rd roll +170 max teh exception to that statement would be if the CR is increased and detonation is an issue. | ||
| The4ork |
turned it 3 times and getting about 125 on both | ||
| Mmmi_grad |
You need to up your accelerator pump setting at least. I would start these questions to the people who sold you the heads, they should know the formula you need. Absolutely recheck timing, it always needs to be right. Rule of thumb though is no power no pops is usually a rich condition. With those heads I would be worried about the acceler setting, carb. (Message edited by mmmi_grad on November 22, 2009) | ||
| Rick_a |
Was the throttle wide open? It should be closer to the 190-200 psi range. The stock jetting will not work. That's most likely the issue. Plug color means nothing unless the engine is killed at the specific rpm range you're trying to read. If it's running more compression, it's recommended to use about 7-8 degrees less total advance, and to reach total advance at around 3000 rpm. Use the premium gasoline as well. The dyno is your friend. My engine has gone through 3 versions now. The final timing is always set on the dyno after selecting the main jet that makes the most power. The timing curve, low speed jet, and needle are always done on the road. The bike should easily stomp the stocker everywhere. Did you follow any break-in procedures before you ran it out? Tuning is everything. My first build...doing an XB head swap, cams, Mikuni carb and higher compression...only netted a 7hp gain initially and ran fairly poorly. After several hours on the dyno it gained 21hp total and ran almost too well...the power delivery was more violent than anything short of a 1098 Ducati. | ||
| The4ork |
i did the compression test with the throttle closed. will recheck with it wide open... the carb has a dynojet kit in it, with a 48 pilot and 185main currently.... I'll have to double check my needle too make sure it's set right... I don know anything about how that adjustment affects the performance... it has good throttle response but it just feels like I'm pulling a trailer when I give it wide open | ||
| Guell |
your 185 main is too small for those heads | ||
| The4ork |
i have a 170, 185, 190, 195 i put the 195 in it during the build, and had the power issue, tried going back to a 185 and didnt notice much of a difference | ||
| The4ork |
FIXED IT!!!! busted out the instructions for the dynojet kit that came with the bike when i bought it, it was already installed so i never payed much attention to it... anywho, still have the 185 jet in it, and i took the needle out and placed the E clip where it told me and put the shims where it told me according to the instructions and put it back together... took it out of the driveway and shifted into second, went down the street and opened the throttle all the way (expecting it to be slow like it was...) and the thing burned the hell out of the rear tire. needless to say, after i was done Sh*tting my pants  i had a huge grin on my face  that feels so much better. im sure it will require more tuning, i'll prabably need to size the jet up to the 190 or 195, and play with the needle shim a bit. im a total noob at this carb tuning so for me its trial and error... but if any of you guys with more experience can lead me in the right direction that would be great! | ||
| Brinnutz |
What did you do as far as the head temp sensor? I'm curious. | ||
| The4ork |
i just left the head temp sensor in there and tucked the wire away... as far as i know its not needed on the S1 | ||
| Rich |
What did you do with the stock heads? I need a set. | ||
| Sloppy |
If you change the combustion rate (rate of time to full cylinder pressure) then an ignition change is in order. Ported heads, new combustion design, cam, compression ration, etc. can all affect this. But if it's running well, call it good - otherwise it will require dyno time... | ||
| The4ork |
Rich i still have the stock heads/cyl's/pistons and they are in good shape. however they are NOT thunderstorm heads, but standard lightning heads. lmk if your still interested, as they will be going to ebay soon... phelan said he'd help me out to post on ebay for maximum exposure, apparently they are upgrades for sportsters | ||
| Oldog |
Congrats on the alteration.. sounds like it went well after you sorted it out.. | ||
| Phelan |
They are an upgrade to 883's and 1200's, '88-'03, excluding '98-'03 XL1200S, which has a dual-plugged version of the same head. The heads are not much different than standard '88-'03 1200 heads, other than the extra material in the combustion chambers to yield a 10:1 CR over the factory 9:1. | ||
| Rich |
I'm interested, I'll pm you. Thanks. |
