daveyrev3 Posted October 7, 2008 Report Share Posted October 7, 2008 hi im dave from middlesbrough been riding trials for 6 years now and had a sy 250 scorpa but recentley bought a 2004 beta rev3 and noticed that it has a slight rattle from the cylinder head i think its the piston and been told that its not that bad and that they can be ridden for months like that... the bike rides perfectly and hasnt let me down but just not sure about the noise can any 1 help?? Thanks dave Quote Link to comment Share on other sites More sharing options...
tombo46 Posted October 7, 2008 Report Share Posted October 7, 2008 I have had the same thing that you described, started about a month after I bought the bike new (Gas Gas 300). doesnt seem to affect the riding, just annoys me alot so im interested to know whats wrong. mine only happens when the bikes hot though, is it the same with yours? Tom Quote Link to comment Share on other sites More sharing options...
zippy Posted October 7, 2008 Report Share Posted October 7, 2008 I did a rebuild on my 2000 Sherco 2.9 but got a little cheap and reused my piston. (still looked nice) Now she runs sweet got the low end grunt back, throttle response is great. Only problem..... that pesky rattle. It rattles right from start. not just when hot. So with the piston slap my nice new rings won't last as long. but that is the price I pay. Quote Link to comment Share on other sites More sharing options...
benj Posted October 8, 2008 Report Share Posted October 8, 2008 coinsidentally i too think i have this problem from another post of mine, i should be getting the top end back today as the shop is matching up a c or d size piston to stop this problem, i tried just new rings and the small end bearing but its the play in the piston that i believe is causing the rattle so hopefully will all be sorted, Quote Link to comment Share on other sites More sharing options...
daveyrev3 Posted October 8, 2008 Author Report Share Posted October 8, 2008 I have had the same thing that you described, started about a month after I bought the bike new (Gas Gas 300). doesnt seem to affect the riding, just annoys me alot so im interested to know whats wrong.mine only happens when the bikes hot though, is it the same with yours? Tom na mine starts the rattel from the min u kick it off. have you checked your coolent. the bike will rattle wen hot if the coolent level is down!! Quote Link to comment Share on other sites More sharing options...
peterb Posted October 8, 2008 Report Share Posted October 8, 2008 Hi davey, I used to be in the Guisborough MCC also, a few years back. The rattle you describe is the piston that has either worn, or has deformed which can happen when the motor is drowned and the sudden cooling thermal shock deforms the piston. Usually a new piston kit fixed the problem. New rings never fix this problem for long. Hi Tombo, it is very, very, very unusual for a new GG to have any piston slap after a month from new, the piston bore clearence is extremely tight which is why it is best to run these motors in gently over the first 8 hours of use. Is your bike a std 08 or a Raga 300? Reason I ask is that the Keihin set up on the Ragas are not, in my opinion perfectly set up from new and they tend to run lean from 1/4 throttle onwards which produces the pinging noise when under load as you snap the power on, are you sure it is piston slap that you have and not the sound of a lean carb? The Keihin main supplied is 122, best to run with a 125 and try a slightly richer needle type GJH, in lieu of the JJH. If it is a DellOrto carb, it can be quite normal for these carbs to come out from the DellOrto factory with the float height incorrectly set lower than spec - I have seen many, they tend to run lean because of this. Make sure the float arms look parallel with the carb body/bowl mating surface when the carb is upside down. (There is a measurement of 18.5mm but looking parrallel is fine). The jets are otherwise fine on this carb. Bye, PeterB. Quote Link to comment Share on other sites More sharing options...
copemech Posted October 9, 2008 Report Share Posted October 9, 2008 Not to mention, even on a new bike there must be some clearance for things to move and operate properly! SOME noise is simply normal and acceptable! You really need to compare apples to apples to get a feel for things like this. Even some normal varience is possible in anything, any bike. Quote Link to comment Share on other sites More sharing options...
tombo46 Posted October 9, 2008 Report Share Posted October 9, 2008 Thanks for the reply pete, ill take a looksy at it. how can I adjust the float height if I need to (on a dellorto) All the best Tom Quote Link to comment Share on other sites More sharing options...
benj Posted October 13, 2008 Report Share Posted October 13, 2008 just an update on mine, ive just fitted a size e piston from the original size a and all noise has gone, ran sweet as a nut all weekend, i cant inagine that the piston rattling in the cylinder bore is gonna be any good for the long term so i'd say try a new piston sonner than later. Quote Link to comment Share on other sites More sharing options...
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