richiedan40 Posted September 29, 2015 Posted September 29, 2015 hi guys I,m back after a bit of an absence , not absinth ! had to do my test again due to the dvla having lost some of my licence details , ah well , all done and 600 spondulies lighter. any how , my old yam pre divvy xj600 1989 , is playing up , and I,m great at pulling things to bits and stickin em back together but when it comes to intermitant stuff ?????? so can you please help......bike fires up great , 1st time every time I get her out , she rattles a bit from the clutch but basically runs great. pulls like a train and no smoke. shes done 30000 mile but ive restored her to a certain extent. now , heres the difficult bit...if I do roughly 15 mile or so or slightly less if ridden hard she starts miss firing and then runs on 3 cylinders , 2 cylinders if I try to go further. let it cool down for half an hour and shes back on 4. if I really open her up , 7-8,000 revs it seems to briefly hit on four cylinders again but briefly. now , I love the old girl , shes ugly but great fun ....we all know one of them eh ? I just want her running right again , surely cant be much , I was thinking coil , electronic ign box ? any ideas lads I,m desperate here. how do you test these items if it is them , please can you help . cheers Richie. ps , I know this is a yam site but any one needs help with a brit bike. I,m availlable
Tommy xs Posted September 29, 2015 Posted September 29, 2015 Hi Rich I agree with you're theory either the coils, maybe hairline crack opening when warm or as you also hit on the ecu can have an intermittent fault as I've had in the past, you should be able to find on eBay, l assume you've already tried the easy stuff first like plug, leads, caps. I think the only way to test ecu is to try another if you can borrow one but I think its best to have a spare if possible anyway as the do tend to start breaking down around the thirty year old mark. With the coils you could try switching them over to see if she still dies on same cylinders. 1
slice Posted September 29, 2015 Posted September 29, 2015 As above really, do the easy stuff then work your way towards the expensive stuff.
robrow Posted October 11, 2015 Posted October 11, 2015 I would be tempted to suggest the same as above, my pre divvy has yet to have this specific one, although might be worth looking at fuel tap and filters..?I have just stripped a running pre divvy as a donor for my cafe, and have a ruck of bits left over, some of which (inc engine) will be finding themselves onto a kart chassis, if you are nearby, you are welcome to try borrowing a few bits to cure her.
Moderator drewpy Posted October 11, 2015 Moderator Posted October 11, 2015 I had my fz cut out today and my quick diagnosis was vacuum in the fuel tank. confirmed when I stopped and undid the cap and she started right away I popped off the cap and found that i put the one way valves in the cap the wrong way as there was a little cut out which aligned with recess of the cap body. easy fix 1
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