lorenzo Posted February 14, 2011 Author Report Share Posted February 14, 2011 Just a brief update on this: The jetting, as far as I could see, was completely as stock and although I can't be certain the middles weren't drilled out slightly, the pilots were also as they left the factory, which means the dyno guy simply replaced the damaged diapragms then dropped the needles by one slot, about an hours work all told, and that's including the regular struggle I have getting the airbox back on the carbs, so I think it's prety safe to say I've been a bit ripped off by Dynopro racing of Runcorn. Anyway, thanks to the generousity of the good folk of PB forum, I've finished where the dyno guy started and hopefully I've made a better job of it. One size up on the pilots and also larger mains too, along with performance needles in their centre slot (3 of 5, so that's one lower than the stock needles were before), and the pilot screws back to 2 turns out, it feels like I'm at least pretty close. Certainly low down feel from the engine is much better. Where before it would feel limp when pulling from low revs it's now smooth from just over 2k onwards, and a really linear feel to the way the power comes in, all the way up to silly revs. I also found it was really easy to stall if you pulled away at less than 1500 rpm, this is no longer the case. I've not taken it as far as the rev limiter yet, over 11krpm as it's starting to rain is asking for trouble, but it certainly feels like it revs a bit quicker than before. The most noticable thing is that there's no really obvious steps in the power, it's really quite smooth. Pick up from a neutral throttle is where it was being caught out before, and this too feels like it's improved, certainly blipping up and down the box and matching revs is really easy to do, but as I say, the weather prevented any real in depth testing. I've a trackday coming up round Oulton on the 26th of Feb, which is going to be the big test, mainly of the bike, but also of my ability to not start crying like a baby when I get too cold. At some point too, just for my peace of mind, I may get it onto another dyno, not for power so much, just so I can make certain that the AFR is looking good right across the rev range. Once again, many thanks to everybody for their help. Link to comment Share on other sites More sharing options...
lorenzo Posted February 17, 2011 Author Report Share Posted February 17, 2011 And now I've got a lovely new manual cam chain tensioner fitted too. Marvelous. Link to comment Share on other sites More sharing options...
Thom_1991 Posted February 21, 2011 Report Share Posted February 21, 2011 How bad a job is it mate? Link to comment Share on other sites More sharing options...
Thom_1991 Posted February 21, 2011 Report Share Posted February 21, 2011 Looks like the needles are too rich and the main jets are leaning off at the end. It goes like this. Pilots to about 1/4 throttal Needles from 1/4 to 3/4 throttal Mains till full throttal Isn't the print out a full throttle run though, so how do you know about fuelling on less than full throttle? Link to comment Share on other sites More sharing options...
lorenzo Posted February 22, 2011 Author Report Share Posted February 22, 2011 How bad a job is it mate? Which, doing the carbs or the tensioner? Neither are tough, probably the hardest bit is getting the airbox back on, one side always pops off when you're pushing the other side down. The tensioner is awkward to get to so you can't use an allen socket on it, just a normal allen key, and you have to do it in tiny little 30degree turns, but it's not tricky. Actually adjusting it is a peice of piss once it's fitted, you can get a spanner onto the end of the adjust easily, most of the faff is taking the tank, the airbox and the cam cover off so you can see the cam chain. In terms of the carb fiddling, it's easy to do, but then again I guess I was quite lucky that no screws rounded etc when taking bits off the carbs, I know it's happened in the past on other carbs I've stripped just to clean. Actually swapping stuff on each carb is very simple, but on my bike you take the seat off, lift the tank, take the airbox off, undo some hoses, undo 5 electrical connectors, side fairing off, undo the idle adjuster cable bracket, undo the 2 throttle cables and the choke cable, then undo the carb inlets, so it's always a 30 minute job to get the carbs off, minimum. I tried adjusting the pilot screws with just the tank lifted up but I was having a lot of trouble, and when quarter of a turn is critical I decided it was best to take the carbs off (but left them under the tank so the cables stayed put, just turned them upright) and adjust them when I could see what I was doing. The fuelling at part throttle, which is where I was having the most part of the difficulty with, is fairly simple. Not only do the pilot jets take care of the lower end of the rev range on a full throttle run (which you can see is lean from the printout) but you can also learn how it's fuelling at a closed throttle and part throttle too. At low revs on the dyno run, up to 4k say, the fact that the throttle is fully open is irrelevant, these are CV carbs and the slides are only going to be opening a bit, and hence you'll only be pulling air from the pilot jets at these revs, and you can see that it's lean. This is also reflected in the symptoms of a surgey feeling coming from a closed to a neutral throttle, hence I went one size up on the pilots. Another symptom of a lean bottom end is the fact that the bike runs much smoother when it's very hot and the tickover picks up: Just before the fan cuts in the tickover is about 400rpm higher than it is when the bike's at about 75deg and the note smooths out a bit. Half a turn extra on the pilot screws has sorted this (so I'm now 2.5 turns out on the larger pilots). When it was on the original pilot jets and the screws were still 2 turns out another symptom was that as I pulled the clutch in comign to a set of lights etc, at about 3krpm perhaps, the revs would drop to about 2.2krpm, then hang and take about 20 seconds to drop back down to idle. I thought this was an inlet leak, but further reading has told me that this is also a typical condition of lean running. Obviously, this is more or less all theoretical at the moment, although i've done the changes and my seat of the pants dyno says everything's improved, I'm going to get it back onto a dyno and get an AFR for it once again, just so I know what's going on with it now. The one thing I'm glad I didn't have to do is the float heights, both dynojet and factory pro say that I should keep the floats as per stock: Having to do that would then throw another variable into the mix and although I think I've got a half decent grasp of the fuelling from the jets, floats are just going to mess my head up a bit I think. Link to comment Share on other sites More sharing options...
ccmhunt Posted February 23, 2011 Report Share Posted February 23, 2011 Have a great time this weekend, report back how it all went......wish that I was in the the track but we don't start up again for another two months Link to comment Share on other sites More sharing options...
hipringle Posted February 23, 2011 Report Share Posted February 23, 2011 I,m gutted ,looks like the weathers gona be nice for him. Link to comment Share on other sites More sharing options...
lorenzo Posted February 23, 2011 Author Report Share Posted February 23, 2011 If I was you I'd be gutted too. Literally. It's the only way you're ever going to lose weight. Link to comment Share on other sites More sharing options...
hipringle Posted February 23, 2011 Report Share Posted February 23, 2011 If I was you I'd be gutted too. Literally. It's the only way you're ever going to lose weight. True but the kind lord spared me your looks, its a good job or I wouldnt be here to type this. Link to comment Share on other sites More sharing options...
lorenzo Posted February 23, 2011 Author Report Share Posted February 23, 2011 True but the kind lord spared me your looks, its a good job or I wouldnt be here to type this. I know, you're lucky to have me, I'm fighting those playboy girls off as I type. Now, Anoushka, get those nipples out of my face, I'm busy here... Link to comment Share on other sites More sharing options...
hipringle Posted February 23, 2011 Report Share Posted February 23, 2011 FFS never in my lifetime. aanyhoo, just try & imagine them corners for the weekend on track then add 20 mph that should bring you up to speed or thereabouts Link to comment Share on other sites More sharing options...
lorenzo Posted February 26, 2011 Author Report Share Posted February 26, 2011 Right people, I would say my fiddling about with the carbs was a success, I've just got back from a day round Oulton and it was fantastic, really smooth, really clean pick up, so a very big thankyou to all who've helped with getting it to this state, thanks very much once again. I still intend on getting it dyno'd so I can get another AFR run, just to see how things have progressed and what can be done to improve things further, but to be honest it's as good as it ever was previous to my exhaust swapping, it's lovely. Link to comment Share on other sites More sharing options...
ccmhunt Posted February 26, 2011 Report Share Posted February 26, 2011 Right people, I would say my fiddling about with the carbs was a success, I've just got back from a day round Oulton and it was fantastic, really smooth, really clean pick up, so a very big thankyou to all who've helped with getting it to this state, thanks very much once again. I still intend on getting it dyno'd so I can get another AFR run, just to see how things have progressed and what can be done to improve things further, but to be honest it's as good as it ever was previous to my exhaust swapping, it's lovely. congrats...glad to her of it, and still jealous. Still two more months until we are warm enough to be on the track. Link to comment Share on other sites More sharing options...
lorenzo Posted February 26, 2011 Author Report Share Posted February 26, 2011 It could be argued that it needs 2 more months for us to be on track too, it was freezing today, about 6 or 7 degC I guess, and really wet in the morning. The highlight, although a little childish, for me was having a drag race from about 45mph with madmike off this forum, hitting the meat of the pwer about about 9500 and, on cold tyres as we'd just come out the pits, spinning the rear up! Completely unintentional, but great to know it can do it! Link to comment Share on other sites More sharing options...
ccmhunt Posted February 26, 2011 Report Share Posted February 26, 2011 It could be argued that it needs 2 more months for us to be on track too, it was freezing today, about 6 or 7 degC I guess, and really wet in the morning. The highlight, although a little childish, for me was having a drag race from about 45mph with madmike off this forum, hitting the meat of the pwer about about 9500 and, on cold tyres as we'd just come out the pits, spinning the rear up! Completely unintentional, but great to know it can do it! we have 4" fresh snow, roads have 1" ice, and high today was -7 deg C..... Link to comment Share on other sites More sharing options...
lorenzo Posted February 26, 2011 Author Report Share Posted February 26, 2011 we have 4" fresh snow, roads have 1" ice, and high today was -7 deg C..... No such thing as bad weather, only the wrong clothing.... Actually no, that's pretty horrible. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.