420 RACING Posted August 27, 2004 Report Share Posted August 27, 2004 I have the same problem with 33's that flat spot is a bitch, same as everyone elses. I'll tell you what there should be some happy people when there is a cure for this common problem with these 12 ports!! Quote Link to comment Share on other sites More sharing options...
23champ Posted August 27, 2004 Report Share Posted August 27, 2004 Don't get me wrong, the motor runs great,and I am satisfied with the performance. Its my fault the motor isnt running to its fullest potential. Jetting is very critical, especialy on a race ported motor. I know I can fix the problem through jetting so I'm not to worried. All it takes is time. Trial and error. Quote Link to comment Share on other sites More sharing options...
BansheeBrian Posted August 27, 2004 Report Share Posted August 27, 2004 Anyone try a pilot larger than 50? Just wondering. I'm running 50 pilots 175 mains airscrews out 1 turn and needles in the center notch on the 35's. I know that I'm rich on the needles at the moment but as 23Champ mentioned this is a trial and error issue.Those carb spring drive me insane but if I remember Holyman or someone used zipties to hold em'.Well...back to the garage for some more tinkering. Quote Link to comment Share on other sites More sharing options...
ssbanshee Posted August 28, 2004 Report Share Posted August 28, 2004 what gearing and tires you guys running in the sand Quote Link to comment Share on other sites More sharing options...
Oilsmoke Posted August 28, 2004 Report Share Posted August 28, 2004 (edited) I run a 14/44 and 21x12x8 9 paddle haulers I geared down where i ride it very steep sand and very deep. I need more paddle I think . Edited August 28, 2004 by Oilsmoke Quote Link to comment Share on other sites More sharing options...
PlaynSand Posted August 28, 2004 Report Share Posted August 28, 2004 I don't have a stroker or 12 port " I wished I did" But when I was running my stock carbs I had a lot of trouble getting them tuned in , I finally did but it was a lot of trail and error. After I put the 33 pwk's on it made a world of difference , lowend is stronger and midrange is unreal and revs out forever on topend , so I do think I found the ideal size of carb for my engine. My real question is do any of you think that maybe the 35's my still be choking your 12port strokers down ? Causing all of these erratic jetting problems . Has anyone tried some 38's or larger?? Well I bet someone will find the right combo in time . Quote Link to comment Share on other sites More sharing options...
bkabina Posted August 28, 2004 Report Share Posted August 28, 2004 I am going to try some 38's.I have 35 pwks now with 160 mains needles in the second clip down,and 58 pilots,just shy of 3000ft.It is the 12 port stroker,after a plug chop the plugs were still wet.The only thing I use the motor for is drag racing and It comes off the line faster than my friends 520 kurtz t rex and I smooth power the whole way to the finish.I decided to try trail riding with it the other week.So I took off the wheelie bar and put on the in frame pipes ( Shearer in-frames I run Grand River Suicide's for drag's )We hit the trails and even done some hill climbs with no problems.I have instant power off Idle through the middle and keeps going all the way to the top smooth with no problems.After some pretty hard running down a dirt road I checked the plugs again.Still wet.Rode some more,After we were done riding we took it easy on the way back just cruising.After we got back I checked the plugs and they were still wet and black as hell.I don't know if this will help any of you guys but that is how my bike is.If you have any questions feel free to pm me and I will help any way I can.Later Steve Quote Link to comment Share on other sites More sharing options...
Oilsmoke Posted August 29, 2004 Report Share Posted August 29, 2004 38 are a stock size for a 250cc MX bike my 385 cut in half is 192.5 this is 77% of that vol. But I don't think the 12port is that much more efficient than a 250MX machine. Pure Drag Racing I would use a 38 but for my needs 35 is what I plan on making work.I will use the Mikuni TMX35mm it will match my intake track the best. Quote Link to comment Share on other sites More sharing options...
23champ Posted August 29, 2004 Report Share Posted August 29, 2004 I don't have a stroker or 12 port " I wished I did" But when I was running my stock carbs I had a lot of trouble getting them tuned in , I finally did but it was a lot of trail and error. After I put the 33 pwk's on it made a world of difference , lowend is stronger and midrange is unreal and revs out forever on topend , so I do think I found the ideal size of carb for my engine. My real question is do any of you think that maybe the 35's my still be choking your 12port strokers down ? Causing all of these erratic jetting problems . Has anyone tried some 38's or larger?? Well I bet someone will find the right combo in time . I think for all around ridding the 35's are plenty, maybe even a bit large (when just idleing up a hill and nail it it will bogg a bit. from to much fuel and not enough air. at low rpm the 35s are so big it doesn't have enough air velocity). <[don't think thats spelled right, but I've been drinking quite a while, so it looks good to me]. But if you clutch it and get some r's behind it, it will come alive. If all you do is drag race I would go with some tappered bore lectrons. Like a 38 in and 40 out. Those carbs are bad ass. I have a 46mm straight bore on my CR500 hillclimber. It probably gave it another 3 to 5 hp if not more...... KILLER CARBS Quote Link to comment Share on other sites More sharing options...
BansheeBrian Posted August 29, 2004 Report Share Posted August 29, 2004 When I rode today the slight bog was still there but not as bad. When I turned in the airscrews the bog almost disappeared. This motor wants air! Quote Link to comment Share on other sites More sharing options...
BakoBanshee Posted August 29, 2004 Report Share Posted August 29, 2004 When I rode today the slight bog was still there but not as bad. When I turned in the airscrews the bog almost disappeared. This motor wants air! Doesn't turning in the air screws mean less air? Quote Link to comment Share on other sites More sharing options...
Banchetta Posted August 29, 2004 Report Share Posted August 29, 2004 I haven't read the whole 5 pages of this thread, but I can tell you guys this. I got more hp on the dyno w/ my stroker w/ the 35's than the 26's, 28's, and 33's...bottom and top...I also had a dead spot that I couldn't get rid of. Dave at Noss gave me a set of heads to try out...My squish was way off w/ the stroker, I was running a spacer plate w/ 158psi...I put Daves head on and boosted my compression to 185psi and problem solved.....I think the strokers need a little more compression to match porting and stroke...What is everyone else using for compression on there strokers? Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted August 29, 2004 Report Share Posted August 29, 2004 I haven't read the whole 5 pages of this thread, but I can tell you guys this. I got more hp on the dyno w/ my stroker w/ the 35's than the 26's, 28's, and 33's...bottom and top...I also had a dead spot that I couldn't get rid of. Dave at Noss gave me a set of heads to try out...My squish was way off w/ the stroker, I was running a spacer plate w/ 158psi...I put Daves head on and boosted my compression to 185psi and problem solved.....I think the strokers need a little more compression to match porting and stroke...What is everyone else using for compression on there strokers? ive got 180 pounds. still got the bog, but mine has a spacer plate. maybe thats what our problem is?? im runnin 35mm pwk, v force, boss intake, rocket pipes. jetting at 175 mains, 50 pilot and needle who knows where. it runs the same no matter where the needle is. Quote Link to comment Share on other sites More sharing options...
Banchetta Posted August 29, 2004 Report Share Posted August 29, 2004 My shee ran best w/ 162 mains, 42 pilot, and needle 2nd clip from the blunt end...I ran a little larger main in California, but the pilot was still spot on....I noticed a huge difference going from a 45 pilot to a 42. I still had a dead spot at 5500rpms though and drove me nuts. I don't know if the head/domes did the trick or the compression, but it was worth every penny. Quote Link to comment Share on other sites More sharing options...
Oilsmoke Posted August 29, 2004 Report Share Posted August 29, 2004 Locogato I wouldn't think it's the spacer plate because there are other that don't have the bog. My Doesn't have that problem but I run Mikuni Quote Link to comment Share on other sites More sharing options...
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