etohio Posted December 30, 2013 Share #1 Posted December 30, 2013 I have what I think is a strange problem with my 88 Venture. I bought it non running and rebuilt the carbs. I replace every rubber part with new Yamaha rubber including the diaphragms. It ran and runs great and I get between 34 on the low to 43 on the high for mileage. The problem is that when it is below 40 degrees it will not start or it does start and you can not give it any gas or it will die you just let it lope for a minute and warm sum and it is ok. It will never and I mean never start at any time with the choke on. When I rebuilt the carbs I had to force the choke plungers out of their cylinders all 4 of them. I did not do anything to the chokes other than clean them and did not replace any of their rubber. I did make sure that they seated all the way down with choke off. Did I miss something? The only rubber I remember is on the bottom of the plunger I think. I checked the price of new plungers and they are $65 each. Thanks, Link to comment Share on other sites More sharing options...
bongobobny Posted December 30, 2013 Share #2 Posted December 30, 2013 Yes! One carb has a choke diaphragm that may be ruptured. Forgot which carb it is but may cause your problem... Link to comment Share on other sites More sharing options...
etohio Posted December 30, 2013 Author Share #3 Posted December 30, 2013 I was thinking of loosening two or 3 of the choke actuating levers and seeing if I could narrow the problem down. It's just an idea. The other thing is that 2 of spark plugs are on the rich side. So I was thinking there might be a leak in the choke circuit. Link to comment Share on other sites More sharing options...
dingy Posted December 30, 2013 Share #4 Posted December 30, 2013 I have what I think is a strange problem with my 88 Venture. I bought it non running and rebuilt the carbs. I replace every rubber part with new Yamaha rubber including the diaphragms. It ran and runs great and I get between 34 on the low to 43 on the high for mileage. The problem is that when it is below 40 degrees it will not start or it does start and you can not give it any gas or it will die you just let it lope for a minute and warm sum and it is ok. It will never and I mean never start at any time with the choke on. When I rebuilt the carbs I had to force the choke plungers out of their cylinders all 4 of them. I did not do anything to the chokes other than clean them and did not replace any of their rubber. I did make sure that they seated all the way down with choke off. Did I miss something? The only rubber I remember is on the bottom of the plunger I think. I checked the price of new plungers and they are $65 each. Thanks, Maybe some help, about half the price you had for air cut offs http://www.ebay.com/itm/YAMAHA-XVZ12-XVZ13-VENTURE-ROYALE-TDM850-YFM250-YFM350-YFM400-AIR-CUT-OFF-VALVE-/291030017020?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item43c2bda3fc Gary Link to comment Share on other sites More sharing options...
etohio Posted December 30, 2013 Author Share #5 Posted December 30, 2013 The part I was referring to for $65 was the starter set. Does the small diaphragm set that was referred to have affect on the choke circuit? Evidently I do not understand the choke circuit on these carburetors so any help would be gratefully accepted. Link to comment Share on other sites More sharing options...
OrlinEngh Posted December 30, 2013 Share #6 Posted December 30, 2013 The first gens I had as soon as they would crank over I would put the choke to half way or less to let them warm up, It would take a couple of minutes before they were warmed up. If it was above 50 didnt need much to choke them to start if any. Orlin Link to comment Share on other sites More sharing options...
Peder_y2k Posted December 30, 2013 Share #7 Posted December 30, 2013 Nowhere did I read that the carbs have been synched, or the pilot screws adjusted properly, or, that any SEAFOAM or other similar fuel system treatment had been used. -Pete, in Tacoma WA USA Link to comment Share on other sites More sharing options...
etohio Posted December 30, 2013 Author Share #8 Posted December 30, 2013 carbs were sync and pilot adjusted as best I could. The bike runs great and I have no problems except for the choke. When I bought it the choke mechanism would not move because all 4 plungers were frozen in there cylinders. I rebuilt the carbs per a very good set of instruction found on the net ( http://www.venturers.org/Tech_Library/index.php?action=article&cat_id=001010&id=366 ) after cleaning and replacing O rings it started up and I sync with carb tune. As it is now if it is over 40 or 50 degrees it starts right up and runs great just don't touch that choke handle! Link to comment Share on other sites More sharing options...
Peder_y2k Posted December 31, 2013 Share #9 Posted December 31, 2013 OK, if you can't use the choke/enricher function without compromising cold starting, then the slow speed fuel mix is rich, and the enrichment makes it so rich the spark plug can't ignite it, so the pilot screws need to be adjusted to lean the mix, by turning 'in' 1/4-1/2 turn to begin with. Give it a try and see what happens. -Pete, in Tacoma WA USA Link to comment Share on other sites More sharing options...
Marcarl Posted December 31, 2013 Share #10 Posted December 31, 2013 Check to make sure that all the choke plungers (enrichment valves, start circuit) are returning to the in position, could be that one is hanging up, and that could be to misalignment of the leaver off the shaft or the shaft itself. Link to comment Share on other sites More sharing options...
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