Starwriter Posted October 10, 2013 Report Share Posted October 10, 2013 Yep, time to split the cases, but, don't do it upside down. After you have everything ready to split, with the crank gears removed, put a ratchet strap from 1 end of the crank, over the head, between the spark plugs to the other end of the crank. Just tighten it snug. Don't get carried away. Then lift the top case off, leaving the trans in the lower half. While it's apart, flip the top half over, remove the ratchet strap, lift the crank slightly and replace the crank seals. Check to see if the crank pins are welded. If they're not, do a complete teardown and send the crank to be trued and welded. If it's a stock crank and it is already welded, make sure the pins in the crank bearings are located properly when you put it back together. Also, make sure you remove the steel strap behind the clutch basket that ties the top and bottom case halves together. Quote Link to comment Share on other sites More sharing options...
nightmarebanshee Posted October 10, 2013 Report Share Posted October 10, 2013 and to add to what star said ^ make sure you clean everything first...the last thing you want is dirt and grime falling into everything....made that mistake the first time i split the cases on a bike a long time ago Quote Link to comment Share on other sites More sharing options...
Tommygunn Posted October 10, 2013 Author Report Share Posted October 10, 2013 (edited) Thanks for all the tips. I'll be sure to keep everything clean. I've also read on here of a few people drilling a 1/8 inch hole in the side of the case and using a punch to knock it out. I'm a machinist so I could ream it to .125 and make a plug to press in very tight. bad idea? Edited October 10, 2013 by Tommygunn Quote Link to comment Share on other sites More sharing options...
Tommygunn Posted October 10, 2013 Author Report Share Posted October 10, 2013 Or I could thread it and put a threaded plug there so if it ever happened again, it would be a quick fix. Quote Link to comment Share on other sites More sharing options...
03DMshee Posted October 10, 2013 Report Share Posted October 10, 2013 Dont overthink this nor try to take the "easy" route...just think because of this your gonna split the cases and answer about 50 questions you might have had about what is really under your seat...you might have an issue in the motor you dont even know about and you can rectify it before your doing the same thing in the near future..i know it seems like a lot of work but it really isnt and you will thank everyone in the end... Quote Link to comment Share on other sites More sharing options...
Starwriter Posted October 10, 2013 Report Share Posted October 10, 2013 ^yeah, what he said. Besides, you're a machinist? Mod the trans while it's apart. Mill out 3 dogs of all the gears that have 6 dogs. Machine the shift drum for a ball bearing on the left end, mod the shift shaft and the shift star. It will shift sooooo much nicer. Quote Link to comment Share on other sites More sharing options...
troyzstang Posted October 10, 2013 Report Share Posted October 10, 2013 I also agree. Split the cases. I recently bought a used complete 421 cub and tore it down to go through it. So glad I did. One of the crank bearing were shot. Could have cost me a lot more then the bench time to tear it down. Better safe them sorry Troy Quote Link to comment Share on other sites More sharing options...
Starwriter Posted October 10, 2013 Report Share Posted October 10, 2013 Just found my notes on the shift drum bearing. It's a # 6902 bearing. Just machine down the shift drum for a press fit and press it on. Leave some space between the side of the bearing and the face you just machined into the drum. Quote Link to comment Share on other sites More sharing options...
Tommygunn Posted October 11, 2013 Author Report Share Posted October 11, 2013 Is there a write up on this anywhere? I could machine the parts, I'm just not sure what i'm looking for. This may sound stupid but what are the "dogs"? Quote Link to comment Share on other sites More sharing options...
Starwriter Posted October 11, 2013 Report Share Posted October 11, 2013 This is one that I did. I am not a machinist, but I get by. There are 3 dogs on the corresponding gear. So, stock is 3 dogs going into 6 dogs. By cutting out 3 of the 6 dogs, you allow more time for the dogs to engage. This does not weaken the trans or have any bad side effects. Quote Link to comment Share on other sites More sharing options...
Tommygunn Posted October 14, 2013 Author Report Share Posted October 14, 2013 Gotcha. Thanks. Looks like i'm going to split the case and do that. Thanks for all the help Quote Link to comment Share on other sites More sharing options...
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