DIABLO BANSHEE Posted September 29, 2004 Report Share Posted September 29, 2004 I just recently installed a cool head with 19cc domes,i checked the compression,it was at 170 psig on each cylinder.i have a mid range port that was putting out 58hprw before the cool head was installed,i adv.my timing +4 deg.will this be ok or should i go back on the timing.also i'm running t5's and rad valves 4th clip on needles and 320 mains,after the mods i started up the bike and reved it a couple times and i pulled the plugs it looked like i was running alot leaner now.any ideas? Quote Link to comment Share on other sites More sharing options...
sredish Posted September 29, 2004 Report Share Posted September 29, 2004 As far as the timing, that's fine, that's where I and many others run ours. 170 is good compression, and I'm sure you know, that is a 110 octane machine, anything less and you'll be looking for a new top end. My philosophy with jetting is, use my gut feeling. If this looks good or that looks good, but my gut tells me something's up, I follow my gut. If you feel it's running leaner, then do something to change that. Worst you can do by going richer is ruin a plug. Now, you can't tell anything by firing the bike up and revving it a few times. When you get out and ride it, it will have a much much harder load on the bike and this will lean your bike out more. Also, the ONLY way to tell how lean/rich the main jet is, is by getting it up to 5th or 6th gear holding the throttle pinned Wide Open Throttle and kill it. The 5th or 6th gear will put a heavy load on it and the WOT will be pulling straight from the main and this will give you a true and accurate reading as to how the main jet is running. Were the plugs new, if so, they won't color much, if any, until they're heated up good for about 15 or 20 minutes. My suggestion is to go out and run the bike and pull plug readings properly. If all you've done is increase the compression and advance the timing, and the bike was running right before, then you'll probably be alright, in some cases, a slight change could be necessary, but you'll have to run the bike like I said above to really know. Good luck. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted September 29, 2004 Report Share Posted September 29, 2004 It will run a little hotter with higher compression and advanced timing. If it does seem to be a little lean after running it jet up. It may have been lean before but more noticable now since you have added more heat. Quote Link to comment Share on other sites More sharing options...
DIABLO BANSHEE Posted September 29, 2004 Author Report Share Posted September 29, 2004 (edited) thanx for the help guys,i'm on it as far as the 110 0ct. goes,i think your right about running lean prior,i ride sand mountain alot which is 4-5feet and i live at sea level i have to check i probably havent returned the jetting to sea level after that last ride.thanx again Edited September 29, 2004 by DIABLO BANSHEE Quote Link to comment Share on other sites More sharing options...
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