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Green Gouger


dgraf
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I'm going to trim the front downtubes on my KT right below the lower engine mount, at minimum. I may go to a set of plates bolted to the front mounts with a single bolt to the down tubes as on the Gollner frames.

Take a close look at your swing arm pivot for the problems I've outlined in my KT thread. Actually, if your frame's silentbloc bushings seem to be pristine could you measure the length of the central bush? I can't tell if it should be 39.5 or 40mm as both of the bushings on my frame were worn. It isn't a big deal as I'll just make things to fit, but it would be nice to know what number Kawasaki was using in setting things up.

If you run a rear damper with a spring that runs farther down the body past the level of the rear chain be prepared to have to space the left damper out away from the chain for clearance.

In the early 1970s I saw one person refer to the Kawasaki green (as used on the H1R roadracers) as "gator belly green". :hyper:

cheers,

Michael

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If you could do the length of the central tube welded into the engine mount box too that would be appreciated. I'm getting 4.375" (which since the outer support plates seem to be right at 7.5" doesn't surprise me, sometimes inch measurements creep into metric bikes) but the ends of that tube on mine are also obviously suffering from wear. Metric or inch dimensions are fine, I can work with either one.

The problem is that the center bush in the silentbloc bushing is too short, so as you tighten up the nut on the spindle the outer plates are drawn inwards (distorting the frame) until the center bush bottoms out on the tube welded into the frame mount box. On my bike, that doesn't happen until the outer support plates are pretty firmly clamped on the pivot tubes on the swing arm, which means that movement of the swing arm doesn't happen without a lot of extra force being applied.

To get enough thickness to the thrust face of the bronze bushings I'll be making I'll need to cut off the outer support plates and move them over a bit.

Whilst I think of it, my bike came with a glob of weld on the outside of the left pivot to seat rail tube just above the doublers for the outer support plate. I'm now wondering if the extra stress from pulling the frame inwards might have caused a fracture in the past.

I have hopes of getting into the garage tomorrow so I can cut off the outer plates and start fitting up the new ones.

While you have your calipers out you may want to measure at various points on the pivot bolt. The spots under the bushings on my bike are about .002" undersize compared to the part in the center.

cheers,

Michael

Edited by MichaelMoore
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kt06.jpg

I think this photo of a Gollner KT250 used to be on the KT/KX page, but I couldn't find it there any more. You can see the single bolt from the frame to the front mounting plates on the engine. If the frame flexes (which I think it will) that might be a little less stressfull on the engine, or at least it seems that way.

cheers,

Michael

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your plan with bronze bushings sounds t-rick, I 'll get the measurements for you in the evening after work.

My TY250 I remember was a cleaner set up for the bash plate. would love to improve on that area but I need

to get on with installing the shocks and front suspension, rear are w/p gassers,but I still need fork springs. are the ones from john's website the hot set-up?

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Checking the sag in the stock fork springs is on my list of things to do when the bike goes back together. I've seen mention of using aftermarket TY fork springs but I haven't played around with the KT forks as I suspect that just replacing them with a Bultaco fork would be more of an improvement.

If your outer support plates pull in and bind on the swing arm you can probably just insert some small shim washers either between the center bushing of the silentbloc and the center tube in the frame, or instead out at the outer supports, whichever seems most appropriate. If you look I suspect you'll see slop on one or both sides of the silentblock bushing. If the frame/swing arm/bushings had been in great shape I'd probably just shimmed things up. Since they aren't, I'm not going to try and buy new bushings from Kawasaki AND deal with the other damaged parts.

If a 1-2.5mm thick 12mm ID washer fixes things up for your bike, that seems like a pretty easy fix.

Are you keeping the stock exhaust and doing more of a restoration, or are you going to do some modifications? I don't remember if the info on my exhaust on my website includes any dimensions, but I've got the exhaust here at home and I'll try to remember to check and add dimensions if they aren't there. I'm pretty sure the porting changes are documented on my site.

cheers,

Michael

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best I can tell swingarm bushings should be 40mm,the swingarm came out to37.58mm, I'm allowing + or - 1mm for powder coating on s/arm itself. Please don't hold me to it,(my math is horrible) but I see what you mean when tightening s/arm it closes the gap pretty severely. If you can find a kawacker dealer it may be a better option to purchase one,they are cheap and still available(just for measurement purposes) I'll be on line for awhile yet.

p.s. I hope this helps,by the way there may be a good s/arm

at bikeboneyard.com he ahd a few bits left for the kt250

later

Edited by dgraf
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Isn't that "closing the gap" ugly? :wacko: It reminds me of the swing arm on the SF750 Laverda I had, where tightening up the axle pulled the axle plates in a good 1/4" or so.

For your silentblocs you don't need any kind of special hardened shim as spacers so I'd recommend you fill as much of any gaps you spot with whatever 12mm or 1/2" ID washer that falls readily to hand. It is unlikely to be worse than letting the frame be significantly distorted. Even if you only fill 80% of the gap that is going to be an improvement. Make sure that the swing arm proper doesn't end up rubbing on the frame if the center bush is pushed too far to one side or the other.

40mm seems a lot more likely than 39.5mm on the center bush length. But I've seen too many oddball measurements to presume that designers went for the obvious one.

Sometimes motorcycles seem like dancing bears. The amazing thing is not how poorly the bear dances, but that it dances at all. :dunce:

cheers,

Michael

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hey,don't know if you want it or need it,but there is a head and cylinder on ebay for 20 bucks and no one has even bid on it yet! bidding ends in 1day 22hrs. I already have a spare cylinder(just in case)my shocks look kewl but need to be spaced out for chain clearance. To nervous to hack up my exhaust as I haven't got a back

up pipe if something goes awry! thanks for your input.

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I've got a spare cylinder and a spare engine, though that spare engine seems to have spent a lot more time out in the weather than was obvious from the photos on eBay! I recently picked up a NOS spark box, which was easy for me to justify. I may have gotten the last KT250 rod kit out of Kawasaki, but you can use the later KX250 rods if you add a spacer under the cylinder to offset the slightly longer rod.

I didn't use any parts of the stock main exhaust on my new system, only the tail silencer/spark arrestor. But raising the exhaust port to increase the exhaust timing up to near the general trials porting numbers (as you can see on the KT250 page of my website) made a difference with the stock exhaust, so you might want to give that a try.

If you are able to weld you can build a new head pipe. Or if you are able to fit things up and have a friend who can weld that will work too. The welding usually takes a lot smaller portion of the total time than the fitting does.

I'm going to be interested to see how I like the bike after I add some more flywheel mass. I like dirt bikes with heavy flywheels, they seem to fit my riding style.

Are you in the UK or here in the States?

cheers,

Michael

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It looks like the bronze bushing conversion is not going to be a "bolt on" deal (as with the bronze bushings you used to be able to buy to replace the plastic bushings on RD350s) since Kawasaki didn't leave a lot of room for bushing thrust flanges but let me know if you have something that I might be able to assist you with. I won't promise that I'll be able to help, but I often know people who can take care of odd specialist problems.

The porting mods (and squish/timing modifications) might be more important than the long headpipe exhaust. To my frequent chagrin, I'm not a very sensitive rider and many times I can't detect subtle changes so I have to go on theory. But the head/cylinder/timing mods with the stock exhaust seemed an improvement to another rider who rides one line higher than I do and who also has a KT250. I suspect that for novice level riders extra flywheel weight would be useful. I don't see that happening without a new mag cover or a spacer for the stock one, depending on if you do a weight that bolts on to the end face of the flywheel or that is a ring shrunk onto the periphery.

cheers,

Michael

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