i need help with my engine. ever since it went down, the engine is really starved for power in the higher RPMs.... I have cleaned the carbs, and the airbox/filter and it didnt seem to do much good. Could there perhaps be something worng with the fuel pump, or the spark iginition system. It has only happend since i layed my bike down and I am really lost. the bike runs OK in the lower RPMs, but then the throttle dosent respond and the bike luches and the power is On/off.... oh and a low rumbly sound.... (my spark plugs are new, so I dont think its running on 3 cly.) please help as I want to get my bike up and running again, has anyone had this kind of problem... if so how did you fix it? thanks aaron
Ok, we'll start from the top. Firstly a few more questions for background information. 1. What model FZR is it? (Does it have EXUP?) 2. How bad was the bike-laying-down incident? 3. Does the bike idle properly? Ok, just working with my logic here... if the bike is starving for power in high rpm and it does have an EXUP valve, it's possible one of the cables has snapped or the valve has been wedged closed (or partially open). If the EXUP valve is working (or it doesnt have one), then it's back to basics really. Fuel, Air, Fire. Fuel: Is the fuel filter clean and flowing properly? Are there any kinks in the fuel lines? Is the fuel pump working properly? Any other blockages in the fuel system? Air: Air filter clean? Carb slides not sticking or gummed up? Carbs cleaned and balanced recently? Fire: Spark plugs all operating correctly? (remove each one and test it in it's proper lead) Properly installed? If it's none of them, then it's time to start thinking about a lack of compression. Things like a valve not seating properly would also cause a lack of power, although i would've assumed it would also make the bike idle quite rough aswell.
1. 2kr 1989, Yes, there is a valve but no mechanism that is moving it, it sort of just flutters 2. 45-50kph, slid on the left side for about 10 feet into a low curb, when i picked it up, it ran like crap and wouldnt rev AT ALL... couldnt go over 80kph on the way home. i cleaned the carbs really good, but i noticed cyl 4 was slighly sticking, and i dont know how to fix that. my airbox had melted int he past and dosent fit properly on the carbs.... I tried to balance the carbs witht he help of a friend, but it was too hard because she said it was jumping all over the place (perhaps a slight vaccum leak?) I cheked those boots that connect the carbs to the engine and they have a few little cracks in them, but only on the outside, none of the cracks go all the way though. i tested my fuel pump by running 12 volts to it and seeing how the pressure trigger was working, but it seemed ok.... I also have a new inline fuel filter that I am going to put on tommorw. oh, and i also have new spark plugs that are only 3 weeks old. so that's the lowdown... I was doing OK before, but now I am starting to run out of ideas of what it might be. I will be compression testing tommorow if I have time. and bombermax, that would be great if you could take a look at er'. I work late during the week, but perhaps saturday eve.. or sunday anytime. thanks all. Aaron
I bought my bike with what sounds like a similar problem to what yours has now and it turned out to be airbox-carb rubbers. Does it sound like it gets starved at around 8k revs, even though the EXUP is fine? And does it not go over 80km/h? (and have you already told us that there isnt a good connection there?) My money is on the rubbers, it might be time to get the hot water jug out to soften them and try re-sealing them before you check for further issues...
ok... thanks for the tip. tommorow I will try to do that... btw is it fesable to put the airbox on the carbs before they go on the engine? and arent you not supposed to get carbs wet?
Of everything you've said... i'm thinking a few things need to be done. Firstly, the EXUP valve needs to be either repaired or removed. If it's not fuctioning properly then you'll be lacking power down low, and probably crippling the bike up the top end. Either wire the valve completely open or remove the valve all together. As has been suggested, an air leak may also be possible. If the bike had a sudden jolt or impact then it could quite easily break the seal the rubbers had formed. Let us know how you go with all the suggestions so far, and with a bit of luck and a bit more hard work i'm sure you'll get it running again properly. <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->
Wire up the EXUP fully open. It will run like a lame duck below 6000RPM but at least wont cause any problems when in it's usefull rev range. But they are definitely a much better engine when the EXUP is fully functional. The EXUP motor sits below the rider's seat on the left hand side and connects to the EXUP valve with two cables..
ok, so I did a compression test today and here are the results, cyl 1: 122 cyl 2: 127 cyl 3: 125 cyl 4: 125 so they are all within 10% of each other so that is a good sign. Things I am replacing are - airbox (anyone have one?) - carb boots - clutch plates - head gasket Hopefully once all these things are done, then it will run OK. So how do I "wire open" my exup valve? right now the cables are running to nothing in that little casing on the exaust, and the valve is just fluttering.
New head gasket is around $30 from yamaha although I have one here (new) for sale once I sell my bike. Rotate the cable attachment disk on the exup valve fully clockwise and lock it into that position with a bit of wire.
