Guest ptedward Posted January 22, 2014 Share Posted January 22, 2014 Greetings VF braintrust! I have a 1985 VF750F which I had running but now it barely idles at 1500 with full choke and as soon as you twist the throttle the slightest it stalls - then when you fire it again it reves up to 3000 and quickly falls to 1500. I thought it was the fuel pump or relay and got different ones of each - that did not seem to be the problem. The fuel pump moves some fuel ... Any thoughts? I am wondering about whether CDI's are calling for fuel (if that is indeed part of their role)? Thanks for any advice! Ted from Alberta [Ps - the roads are dry up here and even though it is cold I would still ride!] Link to comment Share on other sites More sharing options...
Member Contributer JeffInFranklinTN Posted January 22, 2014 Member Contributer Share Posted January 22, 2014 Check to see if you are getting spark at all four cylinders first. Must be a white/blue spark. Orange or reddish spark is not good. How old is the battery? Can you load test it? Check battery connections.(must be clean and tight) Including the negative cable at the engine. Frame grounds from the wire harness must also be clean and tight. If all four have good spark, move on to fuel... Are you sure the float bowls are full of fuel? Has this bike been sitting for a while without being started/ran? Usually if it will only run with the choke on, the jets in the carbs are dirty and the carb rack must be removed for a cleaning and rebuild. (if you want it done right) Does your bike have a fuel filter? Could be clogged. In case you don't know.....one spark box runs the tach and the other spark box runs the fuel cut relay. (if you do have a fuel pump) If you only have spark on two cylinders...you can switch out the connectors on the spark boxes to see if the dead cylinders have spark now. If the tach was working and quits working when you switch connectors you have found your problem. More often the solder joints where the wires connect inside the spark box can crack but can be repaired by resoldering them. One spark box has a yellow wire for the tach and the other has a blue wire for the fuel cut relay. Swapping them around will not hurt anything. Link to comment Share on other sites More sharing options...
Member Contributer Burns Posted January 23, 2014 Member Contributer Share Posted January 23, 2014 give the carbs a very thorough cleaning... if that doesn't resolve it, I'd take a look at the pickup coils. Link to comment Share on other sites More sharing options...
Member Contributer RollinAgain Posted January 23, 2014 Member Contributer Share Posted January 23, 2014 It's probably the carbs but it wouldn't hurt to also check for any air leaks especially around the carb boots. How does the air filter look? Rollin Link to comment Share on other sites More sharing options...
Member Contributer JeffInFranklinTN Posted January 24, 2014 Member Contributer Share Posted January 24, 2014 Odd...post a question asking for help and then don't come back to check for replies....Maybe he figured out the problem...hope he's okay. Link to comment Share on other sites More sharing options...
Guest Posted January 24, 2014 Share Posted January 24, 2014 Hey guys, thanks for the info - I didn't expect alot of response, next time I will check sooner!! I took the carbs off - it is possible the boots are leaking, the clamps were loose on three of the four. I will do a thorough cleaning this evening. Thanks guys!! Ted Link to comment Share on other sites More sharing options...
Member Contributer JeffInFranklinTN Posted January 24, 2014 Member Contributer Share Posted January 24, 2014 Hey guys, thanks for the info - I didn't expect alot of response, next time I will check sooner!! I took the carbs off - it is possible the boots are leaking, the clamps were loose on three of the four. I will do a thorough cleaning this evening. Thanks guys!! Ted Ahhh, that was going to be my next question..."if the carbs had been off?" IF YOU ARE NOT BUYING NEW BOOTS YOU SHOULD TRY THIS.... Here's a quote from a member on the "other" v4 forum. "3 parts rubbing alcohol to 1 part oil of wintergreen, I put in a small jar large enough to cover 4 boots and put a lid on, left for 48 hours and their like brand new, magnandy on v4mb has a post on it, its amazing the difference, you should try it, testing some bad blinker stem now" After treating your boots with this they will not stay "soft" but it should enable you to install them easier and get a complete seal. (I'm assuming you re-used the boots that were already there) Link to comment Share on other sites More sharing options...
Guest Posted January 24, 2014 Share Posted January 24, 2014 IF YOU ARE NOT BUYING NEW BOOTS YOU SHOULD TRY THIS.... Here's a quote from a member on the "other" v4 forum. "3 parts rubbing alcohol to 1 part oil of wintergreen, I put in a small jar large enough to cover 4 boots and put a lid on, left for 48 hours and their like brand new, magnandy on v4mb has a post on it, its amazing the difference, you should try it, testing some bad blinker stem now" After treating your boots with this they will not stay "soft" but it should enable you to install them easier and get a complete seal. (I'm assuming you re-used the boots that were already there) Thanks for the tip! They were ridiculous to get off ... I will try your tip - but I guess I won't be putting back together tonight though! What is "oil of wintergreen" by the way? Link to comment Share on other sites More sharing options...
Member Contributer JeffInFranklinTN Posted January 24, 2014 Member Contributer Share Posted January 24, 2014 LOL Sorry I don't know. I just recently found about this myself. I would think you could pick it up in a grocery store. Edit: Google says Wal-Greens and other pharmacy stores carry it. Link to comment Share on other sites More sharing options...
Member Contributer RollinAgain Posted January 25, 2014 Member Contributer Share Posted January 25, 2014 I've never heard of "Oil of Wintergreen" either but it sounds like if you put some on your nipples before riding it will keep you warm on a cold day LOL !!! BTW...A heat gun or hair dryer will help soften the boots for easier removal. Letting the boots soak in hot water for about 5 minutes will make them much easier to put back on. Rollin Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted January 25, 2014 Member Contributer Share Posted January 25, 2014 I use to soak mine in warm transmission fluid and then after installed I would coat them in silicon grease mixed with graphite. Looked brand new . Link to comment Share on other sites More sharing options...
Guest Posted January 25, 2014 Share Posted January 25, 2014 I use to soak mine in warm transmission fluid and then after installed I would coat them in silicon grease mixed with graphite. Looked brand new . Great advice ... Thanks to everyone for the helpful tips ... I will let you know soon if I got things running - carbs are cleaned now and ready to put back - I just need some cotter pins for the choke arms - I kind of wrecked them getting them out -oops. I won't get to it tonight - going out to a Robbie Burns night tonight --- gotta celebrate part of my heritage! Have a great weekend folks Ted Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted January 26, 2014 Member Contributer Share Posted January 26, 2014 Irn Bru and a Big Mac???? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.