pots Posted April 21, 2009 Share Posted April 21, 2009 hi, im in the process of running my rd in on a complete engine rebuild, ive had some odd smoking problems (another topic) but that seems to be better now since i reset and cleaned the carbs and set oil pump shims at the weekend, since ive done this it is smoking very little how ever ive now gained a top end rattle!! now ive run in many 125 2 strokes and i know the little end bearing starts to rattle very soon after a rebuild but they only rattled on de throttle. this rattle seems to start at about 4500rpm and its there on or off the throttle but it does sound like the little end.im out of touch with 2 strokes, is this normal for a 350 ypvs???apart from that its running fine and i spose theres a slight chance it could be some vibration or something loose but it sound like little end to me. any ideas people???? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 21, 2009 Moderator Share Posted April 21, 2009 Has it had a re-bore? if so can you verify that the ports were chamfered? Link to comment Share on other sites More sharing options...
steve m Posted April 21, 2009 Share Posted April 21, 2009 Could be caused by Detonation Have a look HERE and HERE for more info Just one of the problems we had to be aware of when setting up the TZ and TD Yams jetting and ignition for racing. Pitting/sandblasted look of both the cylinder heads and piston crowns are a sure sign of two stroke detonation. Link to comment Share on other sites More sharing options...
pots Posted April 22, 2009 Author Share Posted April 22, 2009 hi, well i think ive found the prob allthough im going to look into detination all the same.yes its had rebores and i chamfered/polished all sharp edges off myself as im in the precision engineering game.it basicly started when i set the throttle cables up for third time at the weekend whilst trying to sort my odd smoking prob, i sycronised all cables closer than ever and re shimmed the oil pump and it pretty much sorted the smoking , it was also smoking lot less too so i thought right im gonna leave it!so now the little ends start rattling i look in haynes and it says they prob starved of lubrication!!! i mean what is a man to do!!! i just wanna enjoy me kin bike for once and not worrie about somthing else going wrong!!i adjusted oil cable last night to let more through and it sounded better plus it doesnt rattle when its cold hence when its smokey,im gonna rich it up bit more today and let it smoke for while but the damage is prob done wi little ends, il have to change em soon Link to comment Share on other sites More sharing options...
YPVS TONE Posted April 23, 2009 Share Posted April 23, 2009 Was the oil pump bled properly after the engine rebuild ? You say you re shimmed the pump did you just remove shims to reduce the smoking or did you set it up according to the manual with the bike ticking over and the adjust plate on the end of the pump fully out you stop the engine and set the clearance to 0.1mm - 0.15mm or 4 to 6 thou between the raised part of the pulley and the adjust plate ? Tony. Link to comment Share on other sites More sharing options...
pots Posted April 24, 2009 Author Share Posted April 24, 2009 hi tony, i dont know if you saw my previous topic about odd smoking? that was my prob at first, i thought it was sucking in oil through crank seal but turns out now it must of been just excess oil in one exhaust or something because it burns a lot more even plus im building revs up to around 6000rpm now so its proberly cleared it out.i set the pump totaly by the book i added a shim and got it within the sizes, thing is it was smoking lot less after because i syncronised cables even more, i mean it was opening oil pump a bit before carbs opened, took it for long ride and this rattle been there ever since. its between 3500 and 4500rpm on light throttle on and off throttle when the bikes warmed up,first 5 mins from cold its silent lovely!also after i made adjustments it had flooded and it took while to start, iv been worried thinking iv shagged a new conrod or something but i think it would be all the time if it was that and it just sounds so little end to me and iv heard a few little end rattles in me time.ive got new little ends to go in just want to make sure it doesnt happen again.i have since adjusted oil cable again so its running bit more oily to be on safe side.can pump be defective or is it were ive been riding it on tip o throttle every where running it in?? who knows. any ideas?? Link to comment Share on other sites More sharing options...
YPVS TONE Posted April 24, 2009 Share Posted April 24, 2009 Hi Pots It could be where its just burning off the acumulation of oil that has built up in the crankcases and exhaust after the engine rebuild. On my 83 powervalve i find that if i have been pottering about town for a while and then open it up on the dual carriageway you get a cloud of smoke for a while and then it clears itself and the oil pump is set spot on to the book. If yours is an F2 i believe you set the pump on full throttle and the middle one of the three marks should line up with the plunger pin. Tony. Link to comment Share on other sites More sharing options...
pots Posted April 24, 2009 Author Share Posted April 24, 2009 hi tony, my haynes manual says you set the oil pump off the throttle with f and n models tho the revision part says mk2 on full throttle, confusing. i set it off the throttle last week but since ive moved it about again ive just looked and it goes a bit past the full throttle notches anyway so that shouldnt have been the prob.as for smoking now, when its cold it chuffs out loads and when its warmed up you cant realy see anything on tick over, you can smell it tho.spose ive just gotta change little ends again and hope little rattle goes. Link to comment Share on other sites More sharing options...
quickchuck Posted June 29, 2010 Share Posted June 29, 2010 I too have fresh rebuild YPVS on Stan's stage 2. Its got 400miles and really screams, gone up to 8000rpm. But its a bit smokey. Am measuring oil/fuel consumption and its at 5% = 20:1. Will double check the cable adjustment but I figure it should be 30:1 = 3%??? And now Im worrying about this small end risk... What to do? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted June 29, 2010 Moderator Share Posted June 29, 2010 I too have fresh rebuild YPVS on Stan's stage 2. Its got 400miles and really screams, gone up to 8000rpm. But its a bit smokey. Am measuring oil/fuel consumption and its at 5% = 20:1. Will double check the cable adjustment but I figure it should be 30:1 = 3%??? And now Im worrying about this small end risk... What to do? Introduce yourself a little and start a fresh topic all of your own, we don't bite. Link to comment Share on other sites More sharing options...
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