michaelmoore

From the AHRMA rulebook: Tony, do you not see any problems with your statement when ARHMA runs an event (including Nationals) that caters to amateur riders including kids on Yamaha 60 minienduros and people who've never ridden a trial before (and may be doing it on some early 70s enduro bike that they dragged out of a shed)? AHRMA events are "national" only in that they cover most of the nation, not in that they are aimed at "National" level riders. If you are running a pro-type "National" then you need to have a way to exclude people who don't fit that caliber of event, which I suspect will be about 80% of the AHRMA trials riders. The AHRMA events I've ridden over the last 5-8 years sure seem to be aimed at "family/fun" kind of riders, though I'm sure that if Bernie Schreiber or Lane Leavitt want to show up and ride the 1 line they'll be welcome. Difficult riding at that kind of event needs to take place in a section where someone can ride a line appropriate to their skill level. The loop needs to be set for the very lowest denominator rider. If you don't, then you might as well just refuse their entry as taking their money and pointing them at a loop they may not be able to navigate is pretty close to fraud (in my view). cheers, Michael

Note the smoke coming off the rider's right boot heel: cheers, Michael

It does no good to have sections that novices can ride (and Modern Classic Novice appears to generally be the largest class at AHRMA events) if they can't make it from section to section on the loop. After I get warmed up I can usually clean any MC3 section, I just can't do it consistently. I've seen spots on the loop at different events that have had me not feeling very comfortable about riding them. When I see the majority of other MC3 folks having a lot more trouble riding the sections then I do, I suspect they are going to be even more uncomfortable about hard spots on the loop than I am. And let's not forget the people who ride the 4 line. They've got to get around the loop too. Difficult obstacles need to be appearing in the sections, not on the loop. cheers, Michael

Here's the old one: If Miller made that filter to fit the OEM carb, then an OEM filter boot might also have problems mating up to the Mikuni. cheers, Michael

I discovered that the OD of the VM26 Mikuni bellmouth is just a bit less than the nominal (unstretched) ID of the Miller air filter's integral boot. I made a small adapter to press onto the bellmouth to increase the OD to the point that the boot has to be stretched to fit. It wasn't a big project, but without it the airfilter wasn't staying attached, even when clamped. I thought it was worth mentioning in case someone else had to deal with this same combination of parts. cheers, Michael

I've got a 441 project that has been "resting" for quite a while. Compression plates will ruin any squish clearances that you might have. Instead, try to find a flat-top piston that you can dish in the middle. I bought an OEM XL350 Honda piston with a flat top as the bore size is in the right range. Wristpin sizes don't match so I'll have to deal with that. Megacycle Cams does a trials cam for the unit singles. I'm not sure they have it in the catalog and I don't have it handy to give you the part number on it, but you might look into that. I'm going to start with a 26mm Mikuni on my XT400 Yamaha project bike, and sleeve down the intake as mentioned above. The 441 frame is really heavy. ETA: I am welding up the combustion chamber a bit around the edges so there will be some squish area with the flat top piston. The center of the piston crown looks thick enough to take a bit out to make a central bowl in it. cheers, Michael

1978/70 KX125A4 and A5 clutch cover clutch throwout mechanism The 1974-79 KX250 diagrams show the arm on the front of the clutch cover instead of the top. cheers, Michael

A couple days ago I was talking to a friend who is building up a Monark 125MX with a 6 speed Sachs engine. I asked him if he'd gotten one of the shifter kits and he told me that the person who was building the engine claims that if you open up a little the slots in the gears for the selector bar that resolves the "box o' neutrals" issue (presuming you've also got the shifter mechanism properly adjusted). That will add a little backlash, but makes it easier for the selector bar to move into the gear instead of bouncing off because it doesn't perfectly hit the opening. That's hearsay, but the person who is doing the work has a good reputation for being competent. cheers, Michael

The new VMX that arrived yesterday has an article on the Wassell, and says that Wassell took over the Dalesman (frame by Jim Lee). Some were also sold as Penton Mudlarks and Tyrans. cheers, Michael

Bob Ginder at B&J Racing http://bjracing.com/kt250.html cheers, Michael

Bob Ginder at http://bjracing.com/ can fix you up with some of that. There are also a few KT enthusiasts making some replica parts that are listed at http://members.tripod.com/kawasakiKT/index-4.html Your local Kawasaki dealer may still be able to supply the odd piece here and there. cheers, Michael

There are a couple articles on the KT250 site http://members.tripod.com/kawasakiKT/index-4.html I think Bob Ginder sold the last of his big bore kits a few years ago. IIRC the big bore kit sold by the Tryals Shoppe was a 310. I have some suspicion, since a spacer plate was needed under the cylinder, that they might have used a piston from a Suzuki RM370A (piston port) or something like that, but since I don't have one of those pistons falling readily to hand and foot I've never been able to check that. I found a piston from a watercraft that seemed a perfect match with the KT piston other than bore until I found a couple of ports in the piston skirt that appeared to not be in places that the KT ports would appreciate. But the skirt length, bore, deck height, etc all seemed right on. When I look at how much flywheel a 325 Bultaco has compared to a KT250 it appears that even with an add-on weight a KT330 would be pretty light on the flywheel mass. I'd like to have more flywheel on it as a 250. cheers, Michael

IIRC, Doug Domokos used an electric motor to keep the front wheel spinning for the gyro effect when he set a world record of 140+ miles in a wheelie. FWIW, the current director of Product Engineering at Segway once had a KT250. But I don't think that Tony Foale has ever mentioned to me anything about entering a trials event on the KT. I've told him that when I get both the Bultaco and the KT running that he'll have to schedule a trip out here so he can ride one of my bikes in a vintage trial. cheers, Michael

Hello Arie, If you need a piston there is a Wiseco piston for the early Honda MT250/CR250 that is commonly substituted. KT250 rod kits seem to be pretty rare these days, but you can use the later KX250 rod kit with a spacer under the cylinder (the rod is several mm longer). I can't think of any real problem areas in the motor beyond the normal wear items. A few people are making some replica parts and listing them at the KT/KX Page. There is some information at my website on porting and pipe modifications I've done to my bike. Some of the USA vendors are not against the idea of shipping overseas, so don't let that stop you. cheers, Michael

I don't know if the KT geometry is as bad as some say, because in some places it is nearly identical (according to published numbers) to the Sherpa T. But the KT frame is just a hodgepodge of little brackets and gussets and tubes when compared to the T frame. Smith must have been laughing up his sleeve after foisting that off on Kawasaki, unless of course it was Kawasaki that added all the complication. I'll see about taking the fork clamps off the Kawasaki and sticking it on the frame fixture so I can take photos of both of them with a common "known dimension" feature in the picture. That makes it a lot easier to scale them and overlay with a graphics program cheers, Michael

Since I had the Sherpa T and KT frames handy I shot some photos of them and uploaded them to http://www.eurospares.com/newadd.htm so that it would be easy to compare the two. cheers, Michael

I should mention that I'm retired and I've got the time to fiddle with things. I'd prefer that I NOT need to fiddle on the Bultaco, but oh well . . . On the Bultaco I'm not doing anything more than fixing damaged parts. New rings or straightening a swing arm, there's really not a lot of difference when you get down to it. Once it is back together and hopefully pretty much "right" I can leave it alone, and I'll do the fiddling on the KT250 which needs it more than the Sherpa T does. Rider/developers like Peter Gaunt are what I'd like to emulate. Since I lack the native talent to be a top-class rider I'll have to look more to the developer side of things. The KT frame is really crying out for replacement. cheers, Michael

I've had my share of PITA POS bikes (and tools) and I'm tired of them. So I'm trying to get to where I have bikes (and tools) that don't make me swear at them. I may still swear at myself, but that's different. This bike seemed to be in not too bad of condition but there's a lot of stuff you can't find until you take things apart, and I've learned that you really need to take things apart unless you get a bike from a friend where you know the history of it, or it is very obviously a super low-mileage vehicle. I've got the tools and equipment to check this stuff, so I may as well make use of them. Once I find out that something is wrong I now have trouble turning a blind eye on the issue because I've got enough experience of that being a bad move on my part. Fix it now before it gets too bad, or fix it later and spend twice as much time and effort becuase it is really hammered. I'm trying to go with the former plan. Now that I've found how easily the parts of a trials bike bend I'm definitely going to try and keep in mind to not ride quite as spiritedly out on the loop! cheers, Michael

I was just down in the garage and I did my first prying at a triple clamp. Wow, I never thought a cast aluminum triple clamp would be so easy to bend! I put one side of the lower clamp in the mill vise, oriented the clamp so the two holes for the stanchions were vertical (so I could try and pull only in a horizontal plane so I would put as little extra twist into the clamps as possible) and then put a fork leg in the other hole and clamped it up. With an 18-24" lever arm it is not a question of "brace yourself and pull", but rather a "I wasn't even pulling hard yet and I hope I didn't overbend things." In any event, the front axle is now almost parallel to a line across the fork tubes. It is about .020" high on one end. That's not at all perfect, but the fork tubes are almost dead on in the same plane now (a couple thou off over 3" and I've got to measure to see if the axle is out instead of having it glaringly obvious to a visual inspection. Based on how easy these parts have been to bend my guess is that a very sizeable majority of old dirt bikes that are in use today are probably bent more than just a little bit. Before I go back to fiddling with wheel lacing/truing/alignment I'm going to disassemble the front wheel, clean the remains of the hub paint off and lube up all the spoke nipples so they'll have a chance of resisting corrosion in the future. It will be interesting to see how much difference this all makes to the offset of the rear rim. cheers, Michael

http://vintage.bravepages.com/ktshopmanual.html is the KT250 shop manual and the wiring diagram should make things clear for you. cheers, Michael

Bent lower triple clamp. The rear fork leg is weighted so it sits flat on the 1-2-3 block: and the front fork leg doesn't touch but at a corner: Of course, the bend is magnified when it finally gets down to the axle, much less the contact patch, which are 20-30" away. I have another set of clamps (199?) but the stem threads aren't great and my thread file isn't having much luck cleaning it up. I was able to get the stem out of that set, but the one in the 159 clamps has yet to budge. It would be convenient if I could just swap the stems over (presuming the 159 stem isn't bent along with the lower clamp). I'm starting to wonder if a DPO was using this as a MX bike. It sure seems to have seen greater than normal loads. cheers, Michael

Here's a mockup of what I did to straighten the swing arm.. Pry/clamp on the free (right) end of the arm. I put the frame on the fixture and aligned the pivot shaft at right angles to the sides of the base. There is .004" variance in height from one end to the other so I'm going to take that as meaning that the frame is plenty straight enough. Triple clamps are next on the list to look at as I have some suspicions about the lower one or the stem being bent. cheers, Michael

I've had to work hard to overcome my natural inclinations for bodging things. Taking short cuts often seems to result in false economies where I end up having to fix even more stuff down the road. I want to put this bike together right, and then hopefully not have to do anything other than normal maintenance to it for a long time. Bent frames/swing arms, wheels out of alignment, knackered swing arm pivot bushes don't qualify as "right" for me. They may be fine for other people's bikes but I'd prefer to not have them on mine. If I can improve on the original spec and make things "righter" then that pleases me. cheers, Michael

Before you can decide whether or not to have it welded you have to identify the alloy to determine if it is actually weldable. If it remains "mystery footpeg aluminum" then you are probably best off avoiding welding on it and risking a failure. cheers, Michael

I've gotten it down to about .025" over the 6.7". With my crude levers and clamps I managed to overbend once so I decided that getting 90% of it out was going to have to be close enough. Another couple of big Kant-Twist clamps need to be on the shopping list. C-clamps just swivel and gyrate around when trying to use them to clamp objects while they are moving. It did take a pretty fair bit of movement for things to start bending and staying bent. It seems like the axles will now lay in the same plane and parallel, but the triple clamps look to be a little off to one side. I've not got those clamped up with the pinch bolts but I did use the top caps to pull them into the top clamp. I'll try loosening the top caps and see if I can twist things a bit there. If that doesn't work, then the top clamp will have to come off while I look at that area. The righthand gusset at the steering head shows a little bulge in the middle of the back edge, which could just be from being hit by something at some time, or due to a bit of movement between the top and front tubes causing it to buckle. I've seen that same problem on some other frames that lack triangulation of the steering head and count on the gussets to stiffen things up. Putting a little bit of a right angle rib on the outside (open) edge of the gusset would help it resist that kind of distortion. Since all the steels have the same modulus of elasticity they are all equally stiff. Using 531/4130 vs mild steel with all the tube sizes the same gets you a frame of equal stiffness, but one that will bend a bit farther before taking a permanent set. I've seen mention (Morley?) of works riders from the UK taking lengths of 531 in their luggage when going to Spain so that it could be used in their personal bikes. Where the Bultaco has a 28mm round swing arm the KT250 has a 28x 36 ellipitical tube. Top tubes are the same OD at 36mm and the subframes are 20mm vs 3/4". Bultaco could have gone to a 44 x 1.5mm top tube, saved 6% in weight and increased stiffness by 50%. That could be carried through on the rest of the frame. I've seen triangulated space frames on roadracers that were lighter than trials frames and immensely stiffer in both bending and torsion. I guess it took a few more years before the trials frames designers started doing something other than the same thing they (or someone else) had been doing for 20 years. Oh yes, the side stand needs some attention as it is pretty bent up, probably from someone doing what Dave describes, standing and starting the bike while it was leaning on the stand. Back to the garage to look at the forks and clamps! cheers, Michael