zykezz Posted September 22, 2015 Share Posted September 22, 2015 Hey, as Blackhat and Cynic recommended i had a cylinder rebore and a new wiseco piston + a new bearing. Now the problem is that at 7500 rpms there is a rattle (metalic klicking) in the engine in any gear and it starts at the same time, all the time, strange thing is that i had this rattle with the old piston but it was not that loud. I am guessing this rattle comes from the powervalve, but i cant find the cause. I opend the valvesystem and the the piston is not touching the valve as was my first guess + i did grind it to fit the new piston before i assembled the engine. So does anybody have an idea what could it be. Oh and forgot that the rattle starts when there is need for torque like uphills and riding in dirt with high gear. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted September 22, 2015 Moderator Share Posted September 22, 2015 Sounds like pinking to me but that is a bit oldskool for a 99dt unless someone has messed with the timing at some point. Might be advisable to get it checked. 1 Link to comment Share on other sites More sharing options...
zykezz Posted September 22, 2015 Author Share Posted September 22, 2015 (edited) Maybe i should change the main jet for a bigger one ?Cynic that is a strong possibility because i have the original 240 jet in it . Edited September 23, 2015 by zykezz Link to comment Share on other sites More sharing options...
Moderator Cynic Posted September 23, 2015 Moderator Share Posted September 23, 2015 Pre ignition has little to do with the jetting, if you hadn't rebuilt the top end I would have said that you need a decoke but that doesent apply.Pinking is caused by the ignition firing to early, an engine sparks and starts the burn while the piston is still on the up stroke and is timed so the bang expands as its pushing the piston down. What happens with pinking is the burn starts early and the piston is rattling in the bore trying to push against the burn. Will rapidly wear out your engine.Check your ig timing, (something I rarely suggest). Link to comment Share on other sites More sharing options...
zykezz Posted June 28, 2016 Author Share Posted June 28, 2016 Hello, long time no reply, sorry for that had much to do Things i have done on the bike but still rattles and has some new anomalies like cutting out and stuttering above 8500 rpm. Checked the ignition, it was spot on New crank seals and KOYO bearings new carburetor, from china that actually works and fits directly - http://www.aliexpress.com/item/Super-Performance-OKO-KOSO-PWK-Carburetor-CARB-Motorcycle-RACING-PARTS-Scooters-dirt-bike-ATV-28mm-30mm/32372691367.html?spm=2114.13010608.0.56.wjhFwD - does the same thing with both carbs and with all jet sizes . new airfilter, new sparkplugs , new ignition coil Bike starts fine and revs really good to 11k rpm if its on neutral but if driving the rattle starts at about 7500 - 9000 rpm and along side it stutters. Im running out of ideas what to check and change. i can make a video of it on friday, if it helps. With regards. Zykezz Link to comment Share on other sites More sharing options...
zykezz Posted July 17, 2016 Author Share Posted July 17, 2016 Hello, got to the bottom of my problems, took the cylinder off and found a surprise as you can see on the photo. The strange thing was that the piston had no damage on it and the engine started really good. Could i buy a new piston and re-bore the cylinder because there is a wössner piston up to +2.5 so the new bore would be 58.5mm or i would have to find a new cylinder ? The current bore is 57.25mm in diameter Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 17, 2016 Moderator Share Posted July 17, 2016 oops, can see lubrication/heat issues too with the scoring either side of that badly damaged port. Can't see how the piston is undamaged unless it was like this when re assembled. Not sure how useable that barrel is, the top of the exhaust port has an important part to play in the way a 2 stroke runs. I think I might be looking for another barrel. Link to comment Share on other sites More sharing options...
slice Posted July 17, 2016 Share Posted July 17, 2016 Have to agree with Cynic that looks cracked and too far out to be any use. 1 Link to comment Share on other sites More sharing options...
zykezz Posted July 17, 2016 Author Share Posted July 17, 2016 Thanks guys, well i guess its back to work and make some money then, to buy a new cylinder and a piston, any of you guys know where can i get one and sends to Estonia. or might a re-sleeving be an option Link to comment Share on other sites More sharing options...
slice Posted July 18, 2016 Share Posted July 18, 2016 You can resleeve 4 strokes, done that, but not sure about smokers tho! Link to comment Share on other sites More sharing options...
zykezz Posted July 18, 2016 Author Share Posted July 18, 2016 Hello, i searched the internet and the re-sleeving would not be an option be cause it would be to expensive. i found a cylinder and a head on the internet that is marked 4BL but i have 3MB will the 4BL fit my bike with the head that comes with it ? , Link to comment Share on other sites More sharing options...
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