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air box
Nov 11, 2012 23:42:05 GMT 1
Post by Deleted on Nov 11, 2012 23:42:05 GMT 1
hi there, would drilling some holes in the air box make the bike run a bit leaner? what reasons for doing it? thanks in advance , ken
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Post by midlifecrisisrd on Nov 12, 2012 9:05:43 GMT 1
Drilling holes in the lid is common. Done it on my YPVS to allow more airflow than the original hole allows. More flow will alter the mixture.
Steve
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air box
Nov 12, 2012 10:15:58 GMT 1
Post by Deleted on Nov 12, 2012 10:15:58 GMT 1
thanks steve, after putting the needles to the leanest clip setting its still fairly rich, my airbox already has a couple of holes in the top but they have duct tape over them , i might take it off and see if it leans it out a bit more, does that sound fair enough or do i need to change jets , everything is standard with the 1981 350lc carbs, 220 mains, 22.5 pilots, ken
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air box
Nov 12, 2012 15:02:39 GMT 1
Post by skaterboy on Nov 12, 2012 15:02:39 GMT 1
i was running standard jetting on my bike and believed it was too rich. I changed the main jets to 180 and ran the bike for several months. But alas like all LC's another issue failed head gasket caused a coolant leak into a cyl which then ran lean and melted the top of the piston. On taking it apart the other piston was fine and showed a good cloour. So in fact if the headgasket had not expired it was running fine with 180 mains.
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air box
Nov 12, 2012 17:48:11 GMT 1
Post by midlifecrisisrd on Nov 12, 2012 17:48:11 GMT 1
thanks steve, after putting the needles to the leanest clip setting its still fairly rich, my airbox already has a couple of holes in the top but they have duct tape over them , i might take it off and see if it leans it out a bit more, does that sound fair enough or do i need to change jets , everything is standard with the 1981 350lc carbs, 220 mains, 22.5 pilots, ken Think they all run rich. You can only try and see what the holes do. Do you have a genuine Yam air filter in it? Reason I ask is that I fitted a "hi flow" filter and it ran richer than the genuine one so went back to it. Steve
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air box
Nov 12, 2012 18:49:25 GMT 1
Post by marddy on Nov 12, 2012 18:49:25 GMT 1
i was running standard jetting on my bike and believed it was too rich. I changed the main jets to 180 and ran the bike for several months. But alas like all LC's another issue failed head gasket caused a coolant leak into a cyl which then ran lean and melted the top of the piston. On taking it apart the other piston was fine and showed a good cloour. So in fact if the headgasket had not expired it was running fine with 180 mains. My just restored 4L0-01 has 220 mains. Pistons are 4th O/s Wisecos. Yet to even start running-in. FYI, I have 4 holes in the air box top...have taped it. Should I change it to 180 mains? Then, any reason why Yam gave 220s??
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air box
Nov 12, 2012 21:39:48 GMT 1
Post by copper99 on Nov 12, 2012 21:39:48 GMT 1
Interesting topic...back in t'day, a friend and myself had standard 250LCs, he drilled his bikes air box , got a bit more induction roar out of it but it was never as crisp or quite as fast as my standard air box'd bike, despite mucking around with re-jetting.
What benefits HP wise can you supposedly get from doing this mod?
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air box
Nov 12, 2012 22:04:11 GMT 1
Post by Deleted on Nov 12, 2012 22:04:11 GMT 1
thanks for the replies, i have a genuine air filter but is dry. my engine is bored out to 2mm ,so is nearing the end of its life although ive only done a couple of hundred k's on it since rebore , im wondering if im placing to much emphesis on plug colour,? the plugs are very dark but arent wet or fouled, its idling well at around 12-1300 rpm ,pulls from a stand still without having to play with the clutch and revs up to 9500 with only the tiniest hessitation around 2500 rpm, it doesnt have that hold onto your pants kick at 6000rpm but still is fun, i will take the tape off and see how it goes but i think thats the last i will do asfar as tuning goes, i also have to take into account that im nearly 130kg ,the more i think about it ,imagine how quick it would be if i was 50-60 kg lighter, lol
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air box
Nov 13, 2012 22:43:27 GMT 1
Post by midlifecrisisrd on Nov 13, 2012 22:43:27 GMT 1
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Post by bare on Nov 14, 2012 4:09:20 GMT 1
Yama Traditionally jetted their engines Rich. Saving the owners from destroying their motors and consequently large Warranty costs for Yamaha. Slightly rich costs extra fuel and a couple of Hp.... BFD. Lean it out ONLY if willing to buy/pay for a rebuild. Yama San wasn't Stupid.
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Post by Deleted on Nov 14, 2012 4:43:16 GMT 1
doesnt really matter now, thing blew up yesterday, looks like the little end bearing failed and the conrod broke and most of the bottom of the piston disintergrated, case is ok, will need a new right hand barrell,pistons,conrods ,gaskets etc, was getting heaps of oil, wasnt thrashed, could have been worse i suppose, the hardest thing will be finding a right hand barrell thats not to far gone, such is life
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Post by midlifecrisisrd on Nov 14, 2012 8:54:45 GMT 1
That's a nightmare
Hope you get a barrel ok
Steve
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air box
Nov 14, 2012 13:16:18 GMT 1
Post by Deleted on Nov 14, 2012 13:16:18 GMT 1
thanks steve, looking like you have to buy a pair, will wait and see, sooner or later something will come along, ken
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air box
Nov 17, 2012 19:46:28 GMT 1
Post by 47x on Nov 17, 2012 19:46:28 GMT 1
wat a bummer ken. :'(gutted for you m8!!
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air box
Nov 17, 2012 22:38:16 GMT 1
Post by Deleted on Nov 17, 2012 22:38:16 GMT 1
thanks all, well good news , i scored a right hand barrell so now its just a matter of going thru the motions, the barrell was going to be the hardest bit,
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air box
Nov 17, 2012 22:48:10 GMT 1
Post by marsbar350 on Nov 17, 2012 22:48:10 GMT 1
sorry about your trouble ken got any ideas on the cause glad your getting sorted
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Post by Deleted on Nov 18, 2012 0:24:04 GMT 1
hi andy,it looks like either the conrod or small end failed , not quite sure, was getting plenty of of oil ,the left barrell and piston looks as good as the day it was made,also have found out the company that did the rebores are a bit hit and miss ,all i can say is it was getting oil, wasnt thrashed,there wasnt even any sign of anything wrong, just stopped all of a sudden, nothing dramatic only going about 15-20 mile an hour, all gudgen pin clips still in place. thanks again to andy and steve for your kind offers, i will get a couple of photos up when my wife sorts out the computer, ken
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