gasgas Posted October 31, 2005 Report Share Posted October 31, 2005 (edited) Did a search but cldnot find a satisfying answer. Finally i want to split the cases of my 2002 pro gasgas, as i have this gear shifting problem. The problem is back shifting from 3rd to 2nd. And a grinding noise when in 4th. But now my question. Can i leave the clutchside untouched/intact, so waterpump/clutch, when i do the splitting. So basically i only have to remove the flywheel, and i can split it? What about the crankcase fit to the bearings? Is it a loose fit, or cold/warm pressed fit? Ps: i am editing this topic to make it more interesting(hopefully) for everybody. From now on, i will be making pictures of the stripped down engine and asking everybody to join in, to make some comments. The reason for the strip down stands: i am having trouble shifting down from 3rd to 2nd gear. Edited November 4, 2005 by gasgas Quote Link to comment Share on other sites More sharing options...
lineaway Posted October 31, 2005 Report Share Posted October 31, 2005 Try WWW.trialspartsusa.com this is Jim Snells website. He had made a DVD available to gasgas owners in the usa. The video covers a complete rebuild of the pro motor which is a must have for anyone attempting to properly adjust the shift cam of the pro. Good luck! P.S. yes you do have to remove the clutch. Quote Link to comment Share on other sites More sharing options...
n.wales_sherco_lad1 Posted October 31, 2005 Report Share Posted October 31, 2005 the grinding nosie when you go into 4th is natural on a gasser. Quote Link to comment Share on other sites More sharing options...
arieltt Posted November 2, 2005 Report Share Posted November 2, 2005 You've got me thinking now R2W. I'm not sure that you do need to remove the clutch and crank pinnion to split the cases. The flywheel needs to come off (extractor is about a tenner from BVM) to get to the screws behind it, the cases can come apart leaving all the shafts attached to the drive side crankcase so the clutch can stay attached. You are right though. It comes off easily enough and in one bit. Tony Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 4, 2005 Author Report Share Posted November 4, 2005 (edited) The last couple of days i am having a email conversation with Heath, better known as r2wtrails, about my progress in splitting the cases of mine Pro. I wld like you all to know how far i am at the moment, and will add some pictures along the way of the whole journey. At this moment i took the cilinder off the cases, removed the clutch, but am stuck with that little primary gear on the crankshaft. The %#% thing won't come off, and as don't want to kill the cases i am forced to ask my neigbour nicely for a tiny extractor, to do the job. I am convinced now, after talking to Heath, that i better do a complete overhaul since i separate the cases anyhow. I also have the feeling seeing al the oil and carbon on the piston, that i am in for new crankseals. here some pictures taken today. Edited November 4, 2005 by gasgas Quote Link to comment Share on other sites More sharing options...
arieltt Posted November 4, 2005 Report Share Posted November 4, 2005 A familiar sight....I had my Pro engine to bits before Heath got his hands on it. New seals didn't cure the problem that time. Hopefully the new version combined seals/bearings that Heath fitted will have done the trick. Fortunately the bits aren't too expensive. Looks like you've got a fair bit of blow-by on the rings. Was it burning a lot of oil before you stripped it? A lot of red gasket goo as well. Good luck. Tony Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 4, 2005 Author Report Share Posted November 4, 2005 (edited) Tony, the red gasket sealer is my work , i always pressure test the topend, and one way or the other i always find leaks around the inlet. So to be sure i use liquid gasket. The blowby is the product of the rings not sealing due to carbon build up. I found my engine not smoking to much, but looking to this rather fresh piston, he is 8 months old, i must say that i am rather shocked by the sight. The rings had never the chance for sealing properly, so i think i replace the rings and just clean up the piston(piston still in specs). Edited November 4, 2005 by gasgas Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 5, 2005 Author Report Share Posted November 5, 2005 Today i splitted the cases, and as promised they just pop apart with a gentle tap with a rubber hammer. Suprise, suprise, the pro has got a 6 gear box but only 4 opposite gears to use? How do they do that? I am still puzzled by that, but will find out soon. Btw the $## primary gear won't come off, i even made some kind of a extractor, used lots of heat but it is sitting tight. Maybe i have to visit the dealer for it. Will he be happy to see me, doing all the hard labour myself Well, i order my parts there so he better be happy. Here a pic of that 4 gears 6 shifter. Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 7, 2005 Author Report Share Posted November 7, 2005 (edited) You wanted to know but were afraid to ask, here is the answer. the text is a little bit difficult to read. The first and 4th gearing using a lot of teeth, and this will explain the grinding noise in 4th gear. No signs of shattered teeth(although the pictures suggest otherwise) or excessive wear. So all in all i am happy with the gearbox. What i will do is smoothing the shiftdrum slots as it is very rough cut. It will definately smooth out the shifting. 1st gear:red line 2nd:green 3rd:blue 4th:purple 5th:yellow 6th:brown Edited November 7, 2005 by gasgas Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 8, 2005 Author Report Share Posted November 8, 2005 With arrows i show you all the places i have deburred and smoothed. The shiftdrum is responsible for smooth shifting as the dogs ride tru the slots. I also chamfer the edge of the skirts of the piston. By making an angle here the skirt doesn't push away the oilfilm on the cilinder but rides over it, thus creating less drag. It is mainly done with race egine but it can't hurt a trials engine in my opinion. Have a look at the picture. I used this oxidewheel and a sharper/pointed wheel to get into the edges of the drum. Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 9, 2005 Author Report Share Posted November 9, 2005 This morning i went to the dealer. It was my first time there, and i must say i was pleasantly suprised by their enthusiasm. Nice guys who liked to help me. I have seen otherwise, but oke, different story. I showed them my problem with the pinion gear that i cld not get off, and they told me that, they waited till the customers were gone and that they just hammered it off. No fancy tools there When i promised i wld not cry when they start hammering i was allowed to watch and even help a little. It was my task to catch the crank when it popped out of the crankhalf. So said so done. After some hammering the gear let loose. I love it when things come together, or seeing how pros do the job Well the right case half definetly showed some leaking oil, as you can see in the picture. Plus you see the crank with a loose first gear lying next to it. It is time for resembling after i cleaned the whole bunch. Oooo i also noticed one bad bearing, which i will replace. The small bearing of the outgoing assy is bad, the rest all the bearings feel oke, which is nice to know. Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 10, 2005 Author Report Share Posted November 10, 2005 (edited) Today's report. I just made some pictures of a job i did in februari this year. When installing a new piston, i saw that the cilinder was overlapping the case halves. So in fact this is big obstruction of flow tru the transfer ports. Since 2 stroke benefit of a good flow i took out the dremel again, and got rid of the overlapping cilinderbase. here are the pictures of both cases versus the cilinderbase. You can see where i took away some alu to get a smooth transition. Btw if somebody wants to see a special part pls let me know, possibly i can make a picture and show it. Starting tomorrow it is assembling time Edited November 10, 2005 by gasgas Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 12, 2005 Author Report Share Posted November 12, 2005 Todays report, a bit of happiness and sadness . First the happy part. I finally were able to remove the small bearing from the left case in which the clutchshaft is running. The little $$# was very hard to remove without the proper tools. Which i don't have. But with some creativity i succeeded. The sad part. Never hit a bearing on the inner race. You know it i know it, so why did i do it anyway? Perhaps i thought that for just one little hit it cld not hurt. So i destroyed a new crankshaft bearing, which set me back a 15 euros. I heated up the case halves with our kitchen oven, 160 degrees celsius, and took the bearing out of the freezer, minus 18 degrees celsius. Thought it wld just pop in, but my o my, he did not . Taken by the suprise i immediatly started hitting the outer race(offcourse) but then when it moved deeper, i did not have a proper tool(again) to hit anymore on the outer race so i continued on the inner race. Well, that moved it deeper, no question, but after that the bearing rolled rather oddly. Like it sort of had this grooves in it . I will call the shop tomorrow to send me one more. Learned of that bearing i did the other one nicely So now the left case is ready, with two new bearings in them and the right will have to wait another 24 hours. Later ... Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 17, 2005 Author Report Share Posted November 17, 2005 Report of last night. Both mainbearings are now seated. The last one just popped in, with the freezer/heating trick. No hammering what so ever. The seal was more trouble as this fit is just too tight to let it drop in by itselves. With all bearings placed i put the gears back in. Without fitting the crankshaft yet, i putt the cases together to check on the shifting. Strange thing occured the shafts wldn't turn, like they were jammed. After some disassembling and again assembling i found out that the cases were not sealed together properly. It didn't really show a gap or so but a tap with the hammer putt things right. Scary how tight the tolerances are. An other funny thing i discovered is the tolerances between a new bearing and old bearing. The old mainbearings (it is a 6205 C4) just slips on and a new bearings needs a tap with a hammer . Later...again Quote Link to comment Share on other sites More sharing options...
gasgas Posted November 19, 2005 Author Report Share Posted November 19, 2005 Hi everybody, the engine is back in one piece, and doing a leak down test showed no signs of any leaks whatsoever. My first impression of the engine when i first put it back and tightened all the bolts was that it just felt incredible tight. Like everything was dragging. Offcourse news seals create a lot of drag, but i cld not imagine it wld feel tight like this. I had my doubts about everything but since the crank sits in the bearings with a slip fit i cld not be that the bearings where out of true. or something like that. Anyway started the baby this afternoon, after getting me some fresh petrol mixed with 1% bio synthetic 2stroke oil, and let it idle for a couple of minutes rode it around checking the shifting. I really felt happy when i realised that the shifting was cured. With distinct claks it shifted up and down tru the gears. I also changed the carb setting and went for a 36 pilot(from a 33) and a 118 main(from a 112) to compensate a little for the cold wheather around here, needle 2nd clip from top. Tomorrow i will do some training with the new engine and see how things go. Right now i feel satisfied knowing that i really did a good job. Shifting is cured. New bearings are installed. New rings pupm up the compression. New cranksseals must do a good job keeping the gearoil away from the piston. Here a few last piccies Quote Link to comment Share on other sites More sharing options...
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