badgerkdd Posted January 31, 2016 Share Posted January 31, 2016 (edited) Ok I just need some second opinions etc. on what I think is a fuelling issue? I've fitted a replacement engine to my Gsxr, it ticks over nicely and is not making any worrisome noises. When I ride it and crack up through the revs/ gears it seems to hit about 60/70 mph and seems to run out of revs/ speed and feels sluggish and held back. If on the other hand I ride it gently and accelerate slowly,work up through the gears, the speed will rise to 100 mph and rising ( didn't push it further as it was raining harder and harder, didn't want to bin it). When putting the bike back together, I discovered one throttle cable ( not sure if push or pull) had a slight kink in the outer, but the throttle seems to open and close cleanly, with no hesitation. So my classic car friend ( Brian) and I have a couple of options on what it may be, but I'm open to your greater range of knowledge. We are at: Sticky throttle cable, seems unlikely though Dirt in carbs, cleaned fairly recently but not after old engine developed clatter/ power loss. Possibly, and this is where my friend is heading, the older broken engine used to run quite rich and has lower compression on each cylinder, I dropped the needles to the last ring which seemed to cure the richness, now the replacement engine has better compression and we are thinking maybe the carbs are now running too lean and its behaving like a fuel starvation issue. I'm riding with 1 tooth less sprocket on the front and 1 tooth plus on the rear, don't think that would affect the rev range seriously, but again open to ideas/ experiences. Finally a mate who runs older classic bikes suggested a fresh tank of fuel, redex additive and a good long run as I don't know how long the engine was stood unused in the previous owners garage. Carbs are standard off of a 94 WR model but engine is from a 93 WP model. So Monday or Tuesday, depending on available time I'm going to give the bike a run out, but try running on small increments of choke to add a bit extra fuel. I'll whip the tank off first though to check all cables are clear and check the state of the plug electrodes for colour/ oiliness etc. Now 'Fonts of Knowledge' come forward and enlighten me, please!! Edited January 31, 2016 by badgerkdd added stuff Quote Link to comment
Guest YoshiJohnny Posted January 31, 2016 Share Posted January 31, 2016 Put the needles back to standard setting... Quote Link to comment
Guest YoshiJohnny Posted January 31, 2016 Share Posted January 31, 2016 are you using standard airbox or not? Quote Link to comment
Gixer1460 Posted January 31, 2016 Share Posted January 31, 2016 26 minutes ago, YoshiJohnny said: are you using standard airbox or not? Was going to be my question! Quote Link to comment
gsx Posted January 31, 2016 Share Posted January 31, 2016 Pull the rest of your hair out for the next six months and end up much wiser ! Seriously it's problems like this that make man and machine Quote Link to comment
Sheep Posted January 31, 2016 Share Posted January 31, 2016 Sounds like what i would describe as a flatspot.....i had a bike with a Dynojet kit fitted which did the same.I had an airbox and k&n filter.Turned out they were not balanced correctly.An ultrasonic clean and balance and all was good. Your valve clearances and ignition want to be tip top too....try saying that with false teeth!!!! 1 Quote Link to comment
badgerkdd Posted January 31, 2016 Author Share Posted January 31, 2016 5 hours ago, YoshiJohnny said: are you using standard airbox or not? yeah standard airbox, with K and N filter, I am planning on raising the needles this week, when I got the bike the needles were set to middle clip position ( 3), so I may go back to that, but was going to try the choke trick to get an idea if that is the way to go. 26 minutes ago, gsx said: Pull the rest of your hair out for the next six months and end up much wiser ! Seriously it's problems like this that make man and machine 17 minutes ago, Sheep said: Sounds like what i would describe as a flatspot.....i had a bike with a Dynojet kit fitted which did the same.I had an airbox and k&n filter.Turned out they were not balanced correctly.An ultrasonic clean and balance and all was good. Your valve clearances and ignition want to be tip top too....try saying that with false teeth!!!! My hair is going slowly, I've nothing left to pull out Valve clearances are good, checked them before installing the engine. The needles in my carbs have 5 clip positions, wasn't sure if they were dynojet needles or if 5 clip is standard on WR model carbs? Quote Link to comment
gsx Posted February 1, 2016 Share Posted February 1, 2016 Had a bit of a think about this and as carbs worked before , have you checked your fuel filter in the tank ? Had a similar problem few years ago but had external glass filters so was easy to check Usually the simple things that get over looked Quote Link to comment
badgerkdd Posted February 1, 2016 Author Share Posted February 1, 2016 haven't checked it, it should be ok but yes you are right, sometimes its the simple things. I've been too busy today to have a fiddle around but I'm taking the bike to work tomorrow and will have the opportunity to get the tank off and have a play with carbs, tank filter etc. Quote Link to comment
badgerkdd Posted February 6, 2016 Author Share Posted February 6, 2016 Having had work and life get in the way of fettling, I've just been riding the bike a few times this week but have had a chance to experiment. I took my mates advice and bunged some fresh fuel in and half a bottle of redex, then rode it around for a good hour using all parts of the rev range and gears. Its made quite a difference, I managed to get a lot cleaner acceleration although still a bit wooly in places. After a few miles I pulled on the choke, just a small advance and it did make it a bit happier about cleanly running through the higher speeds and rev range. So early this coming week I will be raising the needles by one groove and then giving her a good run around to see the results. Will post up the result. Quote Link to comment
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