charlie_pank Posted June 4, 2004 Share Posted June 4, 2004 I've got a problem with my (V-twin) bike when it's hot (oil temp 130 deg. C). If you blip the throttle from idle then it takes a second to respond, and in about 60% of cases, it stalls. It also often backfires into the airbox. If you increase the revs gently from idle it's fine. I've done a couple of experiments: 1. Remove HT lead from cylinder 1 Result: Same problem but more pronounced 2. Remove HT lead from cylinder 2 Result: Same problem exactly 3. Swap over spark plugs Result: Haven't had a chance to test yet. Extra info: The engine is fuel injected so no carbs to fiddle with. It is aircooled and due to the configuration of it, cylinder 2 runs hotter than cylinder 1. Given all the above info, and the fact that the HT lead for cyl. 2 is close to the cooling fins of the head of cyl. 2 and pretty much out of the airflow (HT Lead for 1 is in the airflow, as is the head.) I think that when the HT lead for 2 gets really hot, it doesn't carry the current very well and so the cylinder is not always firing. Can anyone help me to confirm whether or not my diagnosis is correct? Edited to add - the ignition is fully electronic with 1 coil per HT lead. After I've tried it with the swapped plugs, if I still have a problem, I'll swap the coils over. It there a good way to check that the coil and HT lead are working properly? Thanks C Edited by - charlie_pank on 4 Jun 2004 08:48:11 Edited by - charlie_pank on 4 Jun 2004 09:03:33 Link to comment Share on other sites More sharing options...
John Howe Posted June 4, 2004 Share Posted June 4, 2004 For what it is worth, I had a heat related misfire over 4,500 revs on the Seven - replacing the crank position sensor cured the problem. JH Deliveries by Saffron, the yellow 222bhp Sausage delivery machine Link to comment Share on other sites More sharing options...
charlie_pank Posted June 4, 2004 Author Share Posted June 4, 2004 I'm hoping it's not a sensor failure as I won't be able to diagnose that myself. Just out of interest, how do you know it was heat-related? Link to comment Share on other sites More sharing options...
John Howe Posted June 4, 2004 Share Posted June 4, 2004 It only happened when the car was hot... JH Deliveries by Saffron, the yellow 222bhp Sausage delivery machine Link to comment Share on other sites More sharing options...
charlie_pank Posted June 4, 2004 Author Share Posted June 4, 2004 😬Is the crank position sensor heat-sensitive? Did you replace any of the wiring to the sensor as well? In my case I suspect that it's the resistance of the HT lead at the high temperatures that's causing the problem, I was curious to know if you thought your problem was a resistance/temperature one too. Link to comment Share on other sites More sharing options...
Graham Perry Posted June 4, 2004 Share Posted June 4, 2004 Ammo's the V twin man 😬 Link to comment Share on other sites More sharing options...
charlie_pank Posted June 4, 2004 Author Share Posted June 4, 2004 Where is Ammo when you need him? Link to comment Share on other sites More sharing options...
shn7 Posted June 4, 2004 Share Posted June 4, 2004 Charlie, Sounds like it could be one of the HT leads leaking current to me. Try going out somewhere very dark and looking around the leads for any signs of arcing. I had a similar problem years ago on an Alfasud having fitted electronic ignition. Amazing display of mini-lightning Steve. Link to comment Share on other sites More sharing options...
Adam Posted June 4, 2004 Share Posted June 4, 2004 I know nothing about how the bikes ecu works, but in general .... many ecus that control fuel from a speed/load lookup table, using MAP as load, will use throttle position to sense "snap throttle" responses etc. Im just thinking that back-firing is caused by a lean fuel mixture (isnt it?) and so maybe the ecu isnt seeing the rapid throttle movement and under fueling. No sure how the hot oil temps fit into this theory though. If you do have an ecu controlling the fueling, check the throttle pot. Link to comment Share on other sites More sharing options...
charlie_pank Posted June 6, 2004 Author Share Posted June 6, 2004 Hi Steve, think you might be right, I'll go and lurk in a gloomy garage and try and have a look! Charlie'n'Kermit The plan is: There is no plan S5EVN Link to comment Share on other sites More sharing options...
shn7 Posted June 6, 2004 Share Posted June 6, 2004 Charlie, Make sure your garage is well vented Steve. Link to comment Share on other sites More sharing options...
charlie_pank Posted June 7, 2004 Author Share Posted June 7, 2004 *cough** splutter - well it wasn't that! Took it down to the dealers this morning (head hung in shame at not being able to fix it myself). They reckon that the throttle bodys need balancing. - so nothing to do with the ignition then! So they're taking it next tuesday to sort it out. Funny thing was the bloke said "also need should have a look at what that noise is", "what noise" says I. So he goes and gets the keys for his monster (exactly the same model as mine), starts it up, and it sounds so much quieter and smoother and without the high pitched whine from the clutch casing. (I'd never heard another one running so had no idea they should sound like that!). Hopefully when I get it back next Thursday it will be like a new bike! I'm a bit cheesed off that by implicatoin, the place that sold it to me in Feb probably hadn't done the full service they claimed, but hey ho, there was no way for me to tell. These people in Edinburgh seem friendly enough so far, they even told me a few weeks ago that all they would do for an 9k service is change the oil and filter and advised me not to bring it to them 'cos I'd be better of doing it myself. I'm also encouraged by the fact that I've had a chat with the guy who will be working on it, and seen that he has exactly the same bike as me... fingers crossed... Link to comment Share on other sites More sharing options...
shn7 Posted June 7, 2004 Share Posted June 7, 2004 😬 😬 😬 so your garage isn't vented very well then. 😬 😬 😬 Hope they get it sorted for you. Steve. Link to comment Share on other sites More sharing options...
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