Meatballs Posted June 25 Share Posted June 25 Hi and thanks for adding me to the group. I have a 1978 V75a, is it ok for the oil pump to be disconnected and run on pre mix? Pump already disconnected before I bought the bike I wasn’t sure if the oil was spraying directly into the internals. What is petrol/ oil ratio? What is the correct spark plug? Thanks Quote Link to comment Share on other sites More sharing options...
NE0 Posted June 25 Share Posted June 25 Welcome in Meatballs......Ah the V75A..the Ol Yamaha Step-thru, haven't seen one of those in ages!!.. and the earlier one of course, which you've ALL seen before... ....on the membership pages! As regards to your problem, It's far better to run on the oil pump (as designed by the yamaha boffins) than on premix. You can get it to run on premix of course, but fouling the plug and running too lean are just some of the issues you get when trying to match a pumps performance. With todays modern fuels and additives ,You tube is the place to go to, to look up ratios for two strokes from people who have found the best ratios and mixes that work, with their two strokes..... but it would be better, in my opinion, to get the pump working again! Having said that, the reason for the pump not working may be down to availability of parts or spares. Afterall, 1976 is rapidly approaching 50 years old. Trying to source fifty year old parts is going to be an issue, as we all know! I've got a 78 DT175MX and an older Honda 400/4. There again the DT was a popular bike and many, many were sold and spares, albiet pattern parts, are readily available for this popular bike, the Yamaha Step-thru? I'm not so sure there's a massive following or indeed an abundance of spares. The Honda C90 Step-thru sold in bigger numbers and there may be even a small following? Let us know how you get on, but I'd bet the reason for going to Premix by the previous owner may have been related to the above instead of him seeking better performance!! According to google, this page:- https://www.motorbikespecs.net/index.php?flag=2&model_id=2147607&make=Yamaha details the V75A specifications and the spark plug recommended is an NGK BPR6HS Hope thats of some help... Quote Link to comment Share on other sites More sharing options...
Meatballs Posted July 4 Author Share Posted July 4 Hi and thanks for the reply. I will look into getting the oil pump working. One other thing, do you know what the fuel tap positions are? It shows “on” , “res” , and “pri”. It seems to start and run better when on “pri” Quote Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted July 4 Moderator Share Posted July 4 Not a clue... Possibly Prime? A kinda choke thing? Quote Link to comment Share on other sites More sharing options...
finnerz89 Posted July 4 Share Posted July 4 Prime. For starting after you've run dry Quote Link to comment Share on other sites More sharing options...
Meatballs Posted July 4 Author Share Posted July 4 1 hour ago, Snakebite68 said: Not a clue... Possibly Prime? A kinda choke thing? 1 hour ago, Snakebite68 said: Not a clue... Possibly Prime? A kinda choke thing? Arhh ok. Thanks 1 hour ago, finnerz89 said: Prime. For starting after you've run dry Thank you Quote Link to comment Share on other sites More sharing options...
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