swooshdave Posted March 15, 2008 Report Share Posted March 15, 2008 Sorry Mike I was thinking you were wanting to build a top spec KT250.................here in the UK there are several experts able to make worthwhile changes on old twinshocks, and having been quoted only Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 16, 2008 Author Report Share Posted March 16, 2008 The steel bash plate (bashed) and the two frame rails (also bashed) it is welded to between the lower engine mounts weigh 2.5 lbf. The frame sprang apart pretty noticeably after doing the cuts. A square foot of 3/16" aluminum plate is about 2.6 lbf so there may prove to be no net savings by converting to a frame that is open under the engine. cheers, Michael Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 16, 2008 Author Report Share Posted March 16, 2008 When I pulled the rear dampers I noticed that the swing arm would barely move unless I gave it a very strong push. When I removed it I found several problems. The center tube in the frame is .060"/1.5mm narrower than the space between the rubber silentbloc bushings. When the pivot spindle is tightened up the frame is drawn together, pushing the center bushing of the silentblocs in until they take up that clearance on the center tube. This removes the offset of the center bush on the outside of the swing arm and means the face of the swing arm rubs on the frame and wears as pictured below. I made a couple of small press tools to try and remove the silentblocs but they wouldn't budge with the vise, and I don't have a press. I'll probably just use a hole saw to cut the rubber out and then a small grinding point to cut through the outer case of the silentblocs. After the hacksaw attack: http://www.eurospares.com/graphics/trials/KT250nobottom.jpg Detail of dented frame tube: http://www.eurospares.com/graphics/trials/...ottomdetail.jpg Smeared/worn metal at the swing arm pivot: http://www.eurospares.com/graphics/trials/...0silentbloc.jpg cheers, Michael Quote Link to comment Share on other sites More sharing options...
swooshdave Posted March 16, 2008 Report Share Posted March 16, 2008 On sale! 12 ton(ne) press Are you going to go with bronze bushings? Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 17, 2008 Author Report Share Posted March 17, 2008 Hi Dave, When I get a press I'm going to go for 20 ton minimum, as a friend occasionally runs into a crankshaft with a lot of interference that will have his 20T press straining. It will do it, but you know it is working pretty hard. Finding space for it in the garage will be the issue. If you use a small drill you can get most of the rubber removed between the outer housing and the center bush of the silentbloc, and the center will then easily press out with a vise. A little bit of careful grinding split the housings and they are now out. I've got a piece of aluminum turned to the 28mm ID of the swing arm and probably tomorrow I'll bore that for a good fit on some .75" shafting and put them into the swing arm and see how well things line up. Doing a test with some scrap aluminum is better than screwing up some bearing stock. Other than that I didn't do much with the KT today, spending the time instead doing some welding on the upper wheel yoke of my English wheel. It was nice to not have that screw up either. cheers, Michael Quote Link to comment Share on other sites More sharing options...
swooshdave Posted March 17, 2008 Report Share Posted March 17, 2008 (edited) I assume to go old school you will use something like Oilite? Have you considered some of the new plastics that are more durable and also self-lubricating? Perhaps Delrin? I have an uncle in the high tech plastics biz and I can get some recommendations. We used some scraps when making some suspension pieces for my Corvette. Amazing stuff they have nowadays. 20 ton(ne) Edited March 17, 2008 by swooshdave Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 17, 2008 Author Report Share Posted March 17, 2008 No, Oilite isn't as sturdy as SAE 660 bearing bronze as it is porus to hold the oil, so it should be saved for light duty stuff. I've got the 660 on hand too. Some plastics are neat materials, but you need to have a good idea of when to use the different ones. Delrin/acetal is probably a good choice for something like rear set lever pivots (or use the Oilite). Teflon is not a good choice as it has problems with cold flow when under pressure. If you run the 660 bronze on a hardened and hard-chromed shaft and get it some grease now and then it will last a very very long time, especially if you can have a pretty good amount of surface area. cheers, Michael Quote Link to comment Share on other sites More sharing options...
mcman56 Posted March 17, 2008 Report Share Posted March 17, 2008 While making a 1/4" skid plate, I used a 20 ton press for the press brake and barely had enough power. Searching for an inexpensive but more powerful press, I found one at Grizzly. The arbor plates are just channel and there are no markings on the bottle jack but it works well. It has a lot of power so looking back I wonder if there was an issue with the 20 ton press. http://grizzly.com/products/30-Ton-Shop-Press/H6228 Quote Link to comment Share on other sites More sharing options...
swooshdave Posted March 17, 2008 Report Share Posted March 17, 2008 While making a 1/4" skid plate, I used a 20 ton press for the press brake and barely had enough power. Searching for an inexpensive but more powerful press, I found one at Grizzly. The arbor plates are just channel and there are no markings on the bottle jack but it works well. It has a lot of power so looking back I wonder if there was an issue with the 20 ton press.http://grizzly.com/products/30-Ton-Shop-Press/H6228 I'll see your 30 and up you to 50! 50 ton(ne) Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 22, 2008 Author Report Share Posted March 22, 2008 Things were just too sloppy at the swing arm pivot with the nominal (but slightly undersized and then slightly worn under the silentbloc bushings) 12mm pivot bolt, so I've reamed the center section of the frame out to a nice fit for 1/2". The outer support plates are still sloppy on that so they are going to come off and have new ones made and welded back on. I've got the new steel bushings blanked from some 7/8" Thomson linear shafting (just the regular case-hardened shafting, not the stuff that is also chromed though that would probably be better for longevity) and bored/reamed for the 1/2" shaft. They'll get faced to length after I decide what I'm doing with the rest of the parts and make the bronze bushings. cheers, Michael Quote Link to comment Share on other sites More sharing options...
swooshdave Posted March 22, 2008 Report Share Posted March 22, 2008 Whoever gets the bike after you is going to wonder "wtf" when they see this non-metric stuff. Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 22, 2008 Author Report Share Posted March 22, 2008 That's my goal, to become a "dreaded prior owner." My bike wasn't exactly pristine when I got it and I had to deal with some DPO issues. I'd be happy to go metric on everything. An English friend of mine living in Spain was getting a used lathe and I reminded him to be sure he got all the threading change gears so he could cut both inch and metric (I presumed he was getting a metric machine). He replied "why would I want to cut an inch thread?" But all the cool MilSpec aircraft types of fasteners are inch, and they are a lot nicer to use than "commercial/industrial" metric stuff as you can get the grip length you want without having to chop 3/4 of the excess threads off. If I get it fixed right any future owner is not likely to have to deal with any of the stuff I've changed, as it won't be a problem for them. Anyone who wants a stock bike needs to not buy something from me. I've not owned many new bikes (only 4 that I can recall) but most of them didn't stay stock for very long. There are just too many stock parts that benefit from being replaced, and I'm far from the only one who did that replacing "back in the day." I am definitely spending time making plans for a new frame. Getting the original frame useable is the goal right now. I do have a spare motor and could pick up another without much trouble and I might end up with the lightly modified stock bike to loan out to friends and a "trick" one for me to ride. At least until I get my XTY400 built. But there is no assurance I'll like that once I've built it. I have to admit that I was sorely tempted by a 1976 325 Alpina basket case that I saw on the local Craig's list yesterday. But it was soooo incomplete that even at $200 I was able to resist buying it just for the motor. A 325 Bul would probably be much more to my preference than my KT, but I know that I'm not outriding the KT. Buying yet another bike (when I'm trying to at least hold the line if not cut back) is something I don't need to do. cheers, Michael Quote Link to comment Share on other sites More sharing options...
michaelmoore Posted March 27, 2008 Author Report Share Posted March 27, 2008 I cut the outer pivot support plates off today. http://www.eurospares.com/graphics/trials/KTdamagepivot.jpg shows the heavy scarring on the insides of the plates from the ends of the swing arm. http://www.eurospares.com/graphics/trials/KToldweld.jpg In the middle of the photo you can see a weld that was there on the 3/4" frame tube when I got the bike. It is pretty much at the top of the doublers they added for the pivot plate and footpeg mount. I think I've seen at least one other KT with a weld in that area so it might be a spot to keep an eye on. cheers, Michael Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 27, 2008 Report Share Posted March 27, 2008 Hi Michael Had a KT many years ago, and although I had a lot of fun and did my first trial on it, my main memories are that the front end was never right. The stearing was unpredictable and the forks were also poor. The Kt, when used on the road used to pop and bang on the overrun, and I was advised by the dealer to open the plug gap to 75 thou ! I can also remember on wet days putting my hand on / near the engine and getting sparks jumping several inches. Most riders did away with the two stroke tank and went to pre mix. I'm pretty sure that I still have the original hand book somewhere which I thing was A4 size and fairly comprehensive. Ross Quote Link to comment Share on other sites More sharing options...
swooshdave Posted March 27, 2008 Report Share Posted March 27, 2008 Hi MichaelHad a KT many years ago, and although I had a lot of fun and did my first trial on it, my main memories are that the front end was never right. The stearing was unpredictable and the forks were also poor. The Kt, when used on the road used to pop and bang on the overrun, and I was advised by the dealer to open the plug gap to 75 thou ! I can also remember on wet days putting my hand on / near the engine and getting sparks jumping several inches. Most riders did away with the two stroke tank and went to pre mix. I'm pretty sure that I still have the original hand book somewhere which I thing was A4 size and fairly comprehensive. Ross Can we assume the bike wasn't new when you rode it? How would you describe the condition (showroom, used, thrashed) and did that have anything to do with the "issues"? Quote Link to comment Share on other sites More sharing options...
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