Yamahappyuk Posted August 11, 2012 Share Posted August 11, 2012 hello , i`ll keep it short ~ after trying to adjust my timing via a strobe light ( as i have no dial guage ) , i see three marks on the rotor close together and 1 on the baseplate / engine , do i set my timing to the first mark and it advances to the others when revved ? ( someone has been messing around in there and it was the only thing i haven`t looked at but i knew something was awry as bike was running weird ) motors back together with another 1mm oversize piston but i need to reset this timing ... thx in advance / Pete * Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 12, 2012 Moderator Share Posted August 12, 2012 the long central mark is the one, the shorter marks are the + or - tolerance marks so actually anything between the marks is deemed ok...increase the idle speed to around 3000 rpm Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 yeah thankyou for clarifying that AirHead , after visiting my local bike mechanic this evening , we found tdc roughly first and it appears there is no mark on the engine , well there is but on the opposing side of the timing rotor marks when at TDC ( sort of above the front clamping bolt area ) , the baseplate has a line roughly in the centre of one of adjustment bolts ( the top one) , anyway we found 1.8 mm BTDC with a micrometer dial guage and marked the engine case and set the baseplate accordingly , strobed at 3000 revs like you said and reset the air screw and idle , now shes much happier and more relaxed at tick over ( think i will try a 9`s plug also ) ... if i can stop the float bowl overflow issue am sure everything will be ok , have changed the needle assembly twice for new ones and even all the carb has been swapped with new internals , i set floats to 21mm and still fuel escapes from pink overflow pipe ... any ideas on this ? Happy Biking / Pete * Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 14, 2012 Moderator Share Posted August 14, 2012 Pete i take it you set the 21mm float height with the spring loaded pin uncompressed? Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 apologies for mixing up 2 topics AirHead , yeah the pin is just actuating the spring , i tip it on its side and have checked so many times its beyond a joke now , i will check the breather stub , is a good idea K Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 14, 2012 Moderator Share Posted August 14, 2012 It happened to me once after fitting a new float valve, just a few drips though usually when coming to a halt, it aventually went away...just doesnt seem to do it any more. is the reed block sealing well...have you tested that? Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 everything is brand new yammy , all gaskets and pipes , this has all been checked again after holing a piston and cleaning all the ally debris out , i will run it now and see what happens , maybe it will settle down as you say . i`ll upload some pics too ... can i just add , looking at Venturas ? recent photos , i dont like the idea he has used pink overflow pipes as carb oil feed ... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 14, 2012 Moderator Share Posted August 14, 2012 you misunderstood me perhaps, are the reeds sealing well as a one way valve? Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 ahhh yes , sorry , i have 2 sets and could see one assembly was deformed so i fitted the ok ones which looked flat against the housing Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 14, 2012 Moderator Share Posted August 14, 2012 going away from the the fuel overflow so what was the cause of the holed piston? incorrect (advanced) ignition timing? Main jet too small? Both? What? Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 timing was the issue i think , someone meddling pfff , was a brand new piston and had run in for 1000 plus miles , main jet is standard 130`s i think it is ( needle is on the centre clip position ) bike was running ok at moderate revs but then on other occasions was terrible , could not keep any decent pace up hills without full throttle even though it was not revving high , was all i could do to keep going ... i changed carbs and all the internals then holed the piston . Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 14, 2012 Moderator Share Posted August 14, 2012 I would recommend a bigger main jet myself they dont cost much, I know the original was 130 but I dont trust modern petrol that much myself it's certainly not the same as it was in 1979...buy a 135 and a 140, fit the 140 first and if it doesnt bog down all well and good ...if it does then try the 135...thats what I'd do. Pistons are expansive...jets arent. If you do this dont buy pattern jets either, genuine ones from allens is the way to go Link to comment Share on other sites More sharing options...
Yamahappyuk Posted August 14, 2012 Author Share Posted August 14, 2012 i agree about fuel , is all chemicals now thats true ya , i`ll look into a larger jet , be careful out there , bye for now ... Link to comment Share on other sites More sharing options...
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