Texaco350 Posted December 28, 2009 Report Share Posted December 28, 2009 Hi all, I just rebuilt my motor over the Christmas break, and I'm hoping someone can help me in sorting out what jet's to use. The current setup is as follows: Carb: Main Jet 280. Pilot 25 (Stock) Needle clip on last position. Also V force reeds. Engine: New crank with +4mm Stroker, Cylinders overbored to 65mm with Wiseco pistons ans rings. My problem is when I open the throttle beyond 1/4 it boggs and starts banging and misfireing, I moved the clip on the needle down to the last and when reving the engine i pull out the choke, it definately made a small difference so I think i need bigger mains? does this seem correct?? what size do ye think I should begin with if my thinking is correct?? Would i also need to increase my pilot jet's?? it seems to tick over nice a smooth as it is with the stock 25's and run smooth to just beyond 1/4. The air screw is at approx 1.75 turns out. Any help would be greatly appreciated. Oh my elevitation is about 350 - 500ft above sea level and the current temp over here in IRE is between 4 and 10C. Quote Link to comment Share on other sites More sharing options...
GNR101 Posted December 28, 2009 Report Share Posted December 28, 2009 Hi all, I just rebuilt my motor over the Christmas break, and I'm hoping someone can help me in sorting out what jet's to use. The current setup is as follows: Carb: Main Jet 280. Pilot 25 (Stock) Needle clip on last position. Also V force reeds. Engine: New crank with +4mm Stroker, Cylinders overbored to 65mm with Wiseco pistons ans rings. My problem is when I open the throttle beyond 1/4 it boggs and starts banging and misfireing, I moved the clip on the needle down to the last and when reving the engine i pull out the choke, it definately made a small difference so I think i need bigger mains? does this seem correct?? what size do ye think I should begin with if my thinking is correct?? Would i also need to increase my pilot jet's?? it seems to tick over nice a smooth as it is with the stock 25's and run smooth to just beyond 1/4. The air screw is at approx 1.75 turns out. Any help would be greatly appreciated. Oh my elevitation is about 350 - 500ft above sea level and the current temp over here in IRE is between 4 and 10C. i would say your lean.. i would say u would need around 320 sized mains 27.5 pilot but.. depends what pipes you have and airfilter/s lid on or no box Quote Link to comment Share on other sites More sharing options...
GNR101 Posted December 28, 2009 Report Share Posted December 28, 2009 and do a plug chop test. if you ride it around tomuch and your lean.. your new build will be u/s Quote Link to comment Share on other sites More sharing options...
dragbanshee Posted December 29, 2009 Report Share Posted December 29, 2009 I would say lean also! I dont know what the temperture is there, but if its cold you need to richen it up as it gets colder. Still don't know what you're running for filter, assume you are running box with no lid, then you would need to be atleast 290-300 mains. I would be running the needle between 3rd & 4th clip from blunt end. As for the pilot, mine always started up and ran fine with the 25s and sounds like you may be fine on the air screws, but not all motors are the same. Just to make sure, did you get the slides back in the right carbs? The cutouts of the slides go to the rear of the bike, yep it happens alot! If you have messed with the TORS, let us know. Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted December 29, 2009 Author Report Share Posted December 29, 2009 i would say your lean.. i would say u would need around 320 sized mains 27.5 pilot but.. depends what pipes you have and airfilter/s lid on or no box I was thinking the same, thanks for the info, I'll get some bigger jets in the new year, no store open for parts here in IRE until the 4th Jan. I'm using FNF fattys and a K&N filter. The filter is still in the box with the lid on, wonld ye recommmend removing the lid or the whole box?? the reason I left it on was we do alot of trail riding and its fairly muddy. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted December 29, 2009 Author Report Share Posted December 29, 2009 I would say lean also! I dont know what the temperture is there, but if its cold you need to richen it up as it gets colder. Still don't know what you're running for filter, assume you are running box with no lid, then you would need to be atleast 290-300 mains. I would be running the needle between 3rd & 4th clip from blunt end. As for the pilot, mine always started up and ran fine with the 25s and sounds like you may be fine on the air screws, but not all motors are the same. Just to make sure, did you get the slides back in the right carbs? The cutouts of the slides go to the rear of the bike, yep it happens alot! If you have messed with the TORS, let us know. Ya the slides are back in the right carbs, I double checked yesterday, its about 4 degC here at the moment, nice and fresh. The only thing i did with the TORS was remove it when cleaning the carbs and checking the float height, i put it all back together and sync'ed the carbs again after, its a pain to do anything with that in place. I might remove it altogether later in the new year. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted December 29, 2009 Report Share Posted December 29, 2009 Def up that pilot,chuck the tors,check your coil,did you adjust the bottom of the ports for the crank?Ohm out your plug caps to rule out ignition,pressure test it to rule out air leak,with the lid on I cant see you in the 3s at all Quote Link to comment Share on other sites More sharing options...
AKheathen Posted December 30, 2009 Report Share Posted December 30, 2009 welcome to bhq.......so, what did you do to get the 4mill done? porting? cut domes/head, or spacer plate either on the top or bottom of the cylinders? definately rule out any leaks first, if you haven't done a leakdown yet.if it checks out good, then start climbing up on the mains. with the popping/missfire, i would say you are at least 2-3 sizes lean on the mains, with the lid on. did you install a billet plate that bolts in your airbox to run the filter? if so, then you acn just remove the lid, but remember that you need to go up 2 more sizes on the mains when you pull the lid. so, 40f, ~400ft, fmf fatty, and we need to know about the 4mill setup and premix ratio, and can get you closer...... Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted January 15, 2010 Author Report Share Posted January 15, 2010 welcome to bhq.......so, what did you do to get the 4mill done? porting? cut domes/head, or spacer plate either on the top or bottom of the cylinders? definately rule out any leaks first, if you haven't done a leakdown yet.if it checks out good, then start climbing up on the mains. with the popping/missfire, i would say you are at least 2-3 sizes lean on the mains, with the lid on. did you install a billet plate that bolts in your airbox to run the filter? if so, then you acn just remove the lid, but remember that you need to go up 2 more sizes on the mains when you pull the lid. so, 40f, ~400ft, fmf fatty, and we need to know about the 4mill setup and premix ratio, and can get you closer...... Sorry took so long to reply, Crazy busy since the holidays. I purchased a 4mm stroker kit,(crank, spacer plate, wisco pistons.) bolted it all up and like I said at the beginning it wouldn't run, she just kept bogging and missfiring. Anyhow In relation to your question's the spacer plate goes in under the head's and I have no leaks. New K&N filter fitted to modified air box, (Alot of holes drilled and the inside of the cover removed) My mains were 280's, Pilots 25's. Mix is currently 16:1 (Run in Mix according to manual) I purchased a jet kit which arrived the beginning of the week but was the wrong one, the only bigger size than what I had were 340's. I replaced the 280's with the 340's, replaced the needle's ( Mid clip position) and started it, not too smooth on idle, boggs at 1/4 to 1/2 then revs free??? (Just bogged previously, wouldn't rev out) tried needle height adjustment but no good. Have I bigger problems?? cabr sync is ok, idle screw 1.5. I don't know alot about 2 stroke and I'm now thinking is my problem due to porting or am i still lean? has anyone any info on porting?? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted January 15, 2010 Author Report Share Posted January 15, 2010 Def up that pilot,chuck the tors,check your coil,did you adjust the bottom of the ports for the crank?Ohm out your plug caps to rule out ignition,pressure test it to rule out air leak,with the lid on I cant see you in the 3s at all Hey there, sorry for not getting back to ya earlier. I gt a jet Kit on Monday, but as always the shop ordered toe wrong one so the only thing i could change were the mains, 280's to 340's. Synced the carbs, idle screw 1.5 out, it will rev out now but still boggs and bangs between 1/4 to about 1/2,+ or -. I am now thinking have i a bigger problem. I replaced the stock needles with the ones in the kik ( seem about 3-4mm shorter) and put the clip in the centre position. I have moved the clip to all positions both rich and lean and it seems to make little or no difference. Should my cylinders have been ported to match the +4mm stroker kit or should she still run away happy without porting?? Can anyone give me some info on porting 2 stroks as I;m new to them. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted January 16, 2010 Report Share Posted January 16, 2010 try putting the stock needles back in on the middle setting. the needles in the kit are usually pretty lean, and may cause that bog there. how does it run wot warmmed up? the 340 may work fine, but it's best to buy jets not in a "kit" or buy a collection of jets that they sell on ebay, which have every size main up to 390, which would be the only kit. if it seems to run good wot, then do a proper plug chop to see where it's at. as the temps and/or elevations change, you will ned to change to a different size. there is a ton of info on jetting pinned in this section that you should read. Quote Link to comment Share on other sites More sharing options...
volcrano Posted January 16, 2010 Report Share Posted January 16, 2010 Sorry took so long to reply, Crazy busy since the holidays. I purchased a 4mm stroker kit,(crank, spacer plate, wisco pistons.) bolted it all up and like I said at the beginning it wouldn't run, she just kept bogging and missfiring. Anyhow In relation to your question's the spacer plate goes in under the head's and I have no leaks. New K&N filter fitted to modified air box, (Alot of holes drilled and the inside of the cover removed) My mains were 280's, Pilots 25's. Mix is currently 16:1 (Run in Mix according to manual) I purchased a jet kit which arrived the beginning of the week but was the wrong one, the only bigger size than what I had were 340's. I replaced the 280's with the 340's, replaced the needle's ( Mid clip position) and started it, not too smooth on idle, boggs at 1/4 to 1/2 then revs free??? (Just bogged previously, wouldn't rev out) tried needle height adjustment but no good. Have I bigger problems?? cabr sync is ok, idle screw 1.5. I don't know alot about 2 stroke and I'm now thinking is my problem due to porting or am i still lean? has anyone any info on porting?? Thanks in advance. [/quote holy shit stains 16:1 mix????that right there has seriously leaned out your air/fuel mix.do a 32:1 mix at least.the more oil the leaner the air/fuel mix.less oil the richer.what oil?klotz supertechniplate is the shit.r50 is a plug fouler.change ur ratio to 32:1,install bigger pilot.if that dont help,close the gap on spark plug slightly and see if that helps or makes worse.make sure the carbs are really synched good.the closing of the spark plug gap is a somewhat test to see if u have a weak ignition.is the black brain box to the tors on the left side frame disconnected?+4 timing might help too,but that and pilot is more for bottom but does have affect on midrange.seems odd changing all clips makes no difference.was it better or worse before u changed the needles themselves???? Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted January 16, 2010 Author Report Share Posted January 16, 2010 try putting the stock needles back in on the middle setting. the needles in the kit are usually pretty lean, and may cause that bog there. how does it run wot warmmed up? the 340 may work fine, but it's best to buy jets not in a "kit" or buy a collection of jets that they sell on ebay, which have every size main up to 390, which would be the only kit. if it seems to run good wot, then do a proper plug chop to see where it's at. as the temps and/or elevations change, you will ned to change to a different size. there is a ton of info on jetting pinned in this section that you should read. Thanks for the help, I'll give another read through the links for jetting. She's the same warmed up. The reason I didn't try a plug chop is I was afraid of doning damage, I was trying to get a clean rev before doing that. I'll try the stock needles and see. I thought the ones in the kit might richen it up due to they being shorter than the origionals. Thanks again. Quote Link to comment Share on other sites More sharing options...
Texaco350 Posted January 16, 2010 Author Report Share Posted January 16, 2010 holy shit stains 16:1 mix????that right there has seriously leaned out your air/fuel mix.do a 32:1 mix at least.the more oil the leaner the air/fuel mix.less oil the richer.what oil?klotz supertechniplate is the shit.r50 is a plug fouler.change ur ratio to 32:1,install bigger pilot.if that dont help,close the gap on spark plug slightly and see if that helps or makes worse.make sure the carbs are really synched good.the closing of the spark plug gap is a somewhat test to see if u have a weak ignition.is the black brain box to the tors on the left side frame disconnected?+4 timing might help too,but that and pilot is more for bottom but does have affect on midrange.seems odd changing all clips makes no difference.was it better or worse before u changed the needles themselves???? The reason for the 16:1 is the manual said to use it for the break in period. If i went 20:1 would that be a bit better while still playing on the safe side?? Could my problem be due to porting or should my shee run fine as is?? I can't seem to get Klots over here at the moment so I'm using Shell, its supposed to be the best available and all my mates use it with no problems. I haven't disconnnected the TORS but I'll try that also. The carb sync seem's to be spot on. I think it was worse before I changed the needles but I'm going to put the stock ones back in and double check. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted January 16, 2010 Report Share Posted January 16, 2010 well, the thing about premix ratios, and what the manual says, is that it is based on low end oils, and stock jetting. the factos are 1: a higher grade oil is made to run in smaller amounts and has higher viscosity and protection, with more burn-off resistance, and 2: the larger the jets, the more premix, ergo more oil, than the 200 mains almost 2x as much, which also means viscosity of changing it now could make the difference of as much as 2 jet sizes. i would do the 32:1, find a good oil, and pick some more mains up Quote Link to comment Share on other sites More sharing options...
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