lt1bird Posted June 13, 2009 Report Share Posted June 13, 2009 This is posted in the egt question as well: Did some reaserch and this is what i found for exhuast gas temp... should be roughly 1100 at wot 1000 just before the pipe comes on higher rpm cruze like 1/2 throttle 200 at idle well, mine is about 180 at idle, about 842 while 1/4 throttle cruzing at WOT ist 1000 Took it out on the hwy for a run and at wide open throttle it was about 950-1000 then as i roll off the throttle(1/2-3/4) I see the egt shoot up to 1290--1300.....guess what happens next? You guessed it.....just as I start to pull the clutch in I can feel it tighting up/seizing....still stalled but it was very very close.....Guess ill put richer needles in before I do that run again..... I dont think the needle clip postion will fix that problem whats your guess? since its happening right at 1/2-3/4 ill probably need a diffrent needle length....im running a cen.....Guess ill try a Richer DGN as I have some... any opinoin on this? Are they prone to seizing while rolling off the throttle??? like my buddie pete says....If its go tits or wheels its gonna give you trouble" Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted June 14, 2009 Report Share Posted June 14, 2009 Maybe you need a thinner diameter needle. That way you have a little more fuel at the 1/4 throttle range. Something like a cel. The first letter is the taper. It controles the fuel in the upper end of where the needle meters fuel. Diameter is the bottom end of the spectrum. Go look at duncan racing international web site they have a great keihin jetting guide. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted June 14, 2009 Report Share Posted June 14, 2009 Sorry LT1 can you remind me what carbs and needles are in it? Quote Link to comment Share on other sites More sharing options...
lt1bird Posted June 14, 2009 Author Report Share Posted June 14, 2009 CEN needles, 38mm keihn carbs I did try the CEl needles they seem to work very good...had just a little bit of low end sputter just off idle, thats why im using a CEN needles now as that change cleaned up the sputter.... bike acutally runs pretty darn good. It leaned out at about 3/4 throttle not down low...... thats why im looking at changing to the DGN needles as they are richer in the 3/4 throttle range..... Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted June 14, 2009 Report Share Posted June 14, 2009 CEN needles, 38mm keihn carbs I did try the CEl needles they seem to work very good...had just a little bit of low end sputter just off idle, thats why im using a CEN needles now as that change cleaned up the sputter.... bike acutally runs pretty darn good. It leaned out at about 3/4 throttle not down low...... thats why im looking at changing to the DGN needles as they are richer in the 3/4 throttle range..... I think you meen den. That would be richer in the 3/4 range. Wouldn't a dgn also be a longer needle witch would be like raising the clip position leaning it out. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted June 14, 2009 Report Share Posted June 14, 2009 The Keihin carbs are known for lean spots on the needle. So you need to richen them up. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted June 14, 2009 Author Report Share Posted June 14, 2009 I need to do more reserch on the need length.....DEN and CEN both have the same length but the taper is greater on the DEN. Im a bit confused on that....I just look at the chart and go richer or leaner per the chart....But within each group there seems to be diffrent lengths as well...Guess I need to look at that closer....The differnt legths....just changin clip positions would change the length as well...Guess Ill measure the gap between the clip positions and see what they are.... Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted June 15, 2009 Report Share Posted June 15, 2009 Here is the Keihin Jetting Guide I was talking about. http://www.duncanracing.com/techfaq/Tech_k...n-jetting.phtml Quote Link to comment Share on other sites More sharing options...
okbeast Posted June 15, 2009 Report Share Posted June 15, 2009 I'm running a CEL in my 35pwks on a 421 cub. I know alot of people run them and are used to the jetting and like them. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 15, 2009 Report Share Posted June 15, 2009 On your CEN needle, where is your clip? If you your not in the top or bottom postion then dont worry about a longer or shorter needle. Just move your clip down one position (down towards taper = Richer, Up towards bunt end = Leaner) Quote Link to comment Share on other sites More sharing options...
okbeast Posted June 15, 2009 Report Share Posted June 15, 2009 I'm very curious how or why you think it is doing this "light seize" or w/e you talk about? lol Quote Link to comment Share on other sites More sharing options...
lt1bird Posted June 15, 2009 Author Report Share Posted June 15, 2009 Im not sure one clip position will be enough....im in the second to the top clip position....I know I can drop it down but the clip position only really effects only very little at 3/4 throttle....The Neddle taper effects it a bunch at 3/4 thottole where it was lean. My egt was real fine when wide open.....when i slowly rolled off the throttle to 3/4 throttle I could see the EGT start to go real high...about 1300F which is bad......Just as im about to pull the clutch in i could feel it start to tighten up/seize....rpms were dropping fast......similar to running out of gas..... I did lots of other testing around town......all was good....I just could not do a 3/4 thrttole run around town, thats why i hit the hwy...... thats when I saw it spike..... Checked out the engine....everything look fine....no scoring etc..... Funny, I did the same thing many months ago when it was cold out....Got it running then went for a quick rider and did not warm it up.... went WOT, and I could feel it doing the same thing....siezing...... My engine is very tight....Now I warm it up to 130 degrees before i set out.... Thank god for the EGT gauge otherwise i might have thought ignition etc..... Quote Link to comment Share on other sites More sharing options...
okbeast Posted June 15, 2009 Report Share Posted June 15, 2009 Sorry but I just see how you're feeling it tighten up, guess i've never had one jetted that far off. And I think moving the clip will have quite a bit of affect with the mid-range to top. Think about how far it moves it with the cilp compared to the diameter of the needle. And 2nd from the top is almost as lean as it goes, Why not just try moving that instead of getting a new needle, doesn't really make sense? Quote Link to comment Share on other sites More sharing options...
lt1bird Posted June 16, 2009 Author Report Share Posted June 16, 2009 I know what you mean........I already have the needles so thats not a probelm. If you look at the chart for the needles you will see that the taper effects the mixture the most at 3/4 throttle.... the lenght not so much. Thats the only reason I was going to change the needles...based on the chart..... Im guessing your correct on the clip position....It would move it more that the taper thats for sure. I think between the needle clip and the too lean of main jet it is simply just to lean. I moved my main jet back to 158 from 142, ill try the richer needles and let you know how they work....if drivebiltiy suffers than ill put the DEN back in....leave the clip in the center. Yes, the feeling of it siezing is most notable! just like you run out of gas/bog..... If it were electrical my EGT would not have shot up.... Quote Link to comment Share on other sites More sharing options...
okbeast Posted June 16, 2009 Report Share Posted June 16, 2009 Oh ok, well I wouldn't associate running out of gas/bog feeling with a seize feeling. And going from 142 to 158 is quite a big jump. What carbs again? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.