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Who Has A Kt250 And What Have You Done To It?


michaelmoore
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I'm working on getting mine back together after having it in pieces for several years. I did a search and it looks like there are a few other KT250 owners (at least one with a Gollner frame) here, but some of those posts were pretty old.

http://www.eurospares.com/kt250.htm

is a page on my website with information on my bike.

I've put Fox Trials Shox on, retoothed the dished rear sprocket, modified the head squish clearances, done a little porting, built a pipe, aluminum tank (terminal rust on the stocker) and front fender stays and not much else. The piston is a second series Honda CR/MT250 Wiseco ((1975-77). Details of some of the changes are on my website.

I'm getting close to either cutting off the bent (again) under engine frame rails and putting on an aluminum bash plate or just building a new frame that is the way I want it to be. The frame, swing arm, footpegs, electrics and brake lever are 32.5 lbf on my digital scale. That seems close to 10 lbf more than necessary. The KT250 engine with kick lever and carb is 64 lbf. That's 10 lbf more than the DOHC Yamaha

250 dirt bike motor (also used in the Scorpa trials bike).

I'm also thinking about adding mass to the flywheel. The KT250 just doesn't run like I recall my 1974 325 Bultaco doing (which is hardly Kawasaki's fault). I'm not sure if the extra flywheel mass will be too much on a 250, but then it is hard to add as much as the Bultaco could since the latter had (IIRC) an extra flywheel on the primary drive sprocket.

I'm having to order new rims as both OEM rims (mine is a 1975 model) have cracks and several years of sections in streams left the stock spokes and nipples pretty badly corroded. A friend who has a wheel shop has told me that the DID rims of that time seem to have been hardened a bit more in order to keep them from denting, leading to cracks instead of dents. My tendency to go as fast as possible between sections may not have helped to prevent cracks.

It seems like the footpegs could go down a little, and maybe slightly back. The bike seems a bit nose heavy, but then that is compared to the Bultaco which had no trouble lofting the front end with a bit of throttle without the need for any heaving on the bars.

I've seen one road test that mentioned that sometimes during a dead-slow full lock turn the steering will "crab" a bit and have the bike want to fall in to the turn. I think I've noticed that, has anyone else? Has anyone tried different forks/clamps with a significantly different axle offset (a TY250 has the same rake of 26.5 degrees but 90mm of trail to the KT's 79mm, and sounds like it doesn't have that issue).

What modifications, if any, has anyone else done, or considered doing?

cheers,

Michael

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Can I ask a really stupid question?

Were the Kawasakis every really competitive when they were new? Even with, presumably, full factory tweaking?

If the case, I assume you are attempting to make the proverbial silk purse just to say you did it.

Not that isn't reason enough... next thing you know you'll be sticking a Hodaka engine in a Sherco fram... wait a second... nevermind.... :)

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I stopped my trials riding about the time the KT250 came out, as I graduated from Uni in 12/75 and moved away from home (after selling all the bikes but my 350 Ducati cafe racer) in late summer 1976. I remember some of the other people in the NMTA having TL250s, Ty250s and RL250s but I can't recall any KT250s. My impression is that the KT250 was never as successful as the TY, but whether that was due to it not being as good or just that "big K" didn't put the money into developing it, I don't know. Jay Leal has mentioned riding a supported KT that sounds like it was pretty heavily modified. I suspect that Don Smith probably managed to beat a number of good riders, but how "stock" his KT250/300/330's were is questionable.

I think I bought my KT250 in 1999. It came available locally and I had money available to buy it on the spur of the moment. If it had been a TY250 or Cota or MAR for a similar price I would have had that instead. I'm not a big "marque" snob. I'm easy, I'll ride most anything. :)

Good riders can ride the 3 line in AHRMA on a stock TL125 and clean sections I don't (though I've placed reasonably well at some AHRMA regionals in the Novice class I'm not very consistent and I'll have those "why did I clean this twice and five it the third time?" moments). Having had a TL125 for a bit I think I can safely say that the KT250 is significantly more "trials ready" than the TL, so I don't think the KT is holding me back.

I've got a period article from an Australian magazine that compares the TL, RL, TY and KT and they picked the KT as the overall winner, though they did say the TY handled better "in section". But they liked the KT engine over the TY's powerplant.

Maybe a TY250 is better. It wouldn't surprise me. I know a 325 Bultaco is better. But I don't want to spend the money to buy another Bultaco when I'm not outriding the KT250. And on the 3 line (and probably the 2 and 1 lines for vintage) the rider is the significant factor that determines the score. That's a nice thing about trials, the bike isn't a huge factor. That doesn't mean we don't want to tweak things, but I suspect that most of us could hand our bikes over to a better rider and say "I didn't know that section could be cleaned on my bike."

I think that any shortcomings of a KT250 wouldn't show up until someone was riding the 2 or 1 line in AHRMA. And anyone who is that good of a rider could probably ride around those shortcomings.

My silk purse project is the TTY400. If I can get that built I suspect my scores will get significantly worse. But oh, what an excuse for that I'll have. :)

Dave, are you at Nike? I think there's a number of Nike guys from Portland vintage roadracing Honda CB160s. If you know them, they know of me as many of the F-160 guys have bought the tuning guide I wrote.

cheers,

Michael

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Guest majestyman340
I'm working on getting mine back together after having it in pieces for several years. I did a search and it looks like there are a few other KT250 owners (at least one with a Gollner frame) here, but some of those posts were pretty old.

http://www.eurospares.com/kt250.htm

is a page on my website with information on my bike.

I've put Fox Trials Shox on, retoothed the dished rear sprocket, modified the head squish clearances, done a little porting, built a pipe, aluminum tank (terminal rust on the stocker) and front fender stays and not much else. The piston is a second series Honda CR/MT250 Wiseco ((1975-77). Details of some of the changes are on my website.

I'm getting close to either cutting off the bent (again) under engine frame rails and putting on an aluminum bash plate or just building a new frame that is the way I want it to be. The frame, swing arm, footpegs, electrics and brake lever are 32.5 lbf on my digital scale. That seems close to 10 lbf more than necessary. The KT250 engine with kick lever and carb is 64 lbf. That's 10 lbf more than the DOHC Yamaha

250 dirt bike motor (also used in the Scorpa trials bike).

I'm also thinking about adding mass to the flywheel. The KT250 just doesn't run like I recall my 1974 325 Bultaco doing (which is hardly Kawasaki's fault). I'm not sure if the extra flywheel mass will be too much on a 250, but then it is hard to add as much as the Bultaco could since the latter had (IIRC) an extra flywheel on the primary drive sprocket.

I'm having to order new rims as both OEM rims (mine is a 1975 model) have cracks and several years of sections in streams left the stock spokes and nipples pretty badly corroded. A friend who has a wheel shop has told me that the DID rims of that time seem to have been hardened a bit more in order to keep them from denting, leading to cracks instead of dents. My tendency to go as fast as possible between sections may not have helped to prevent cracks.

It seems like the footpegs could go down a little, and maybe slightly back. The bike seems a bit nose heavy, but then that is compared to the Bultaco which had no trouble lofting the front end with a bit of throttle without the need for any heaving on the bars.

I've seen one road test that mentioned that sometimes during a dead-slow full lock turn the steering will "crab" a bit and have the bike want to fall in to the turn. I think I've noticed that, has anyone else? Has anyone tried different forks/clamps with a significantly different axle offset (a TY250 has the same rake of 26.5 degrees but 90mm of trail to the KT's 79mm, and sounds like it doesn't have that issue).

What modifications, if any, has anyone else done, or considered doing?

cheers,

Michael

I have heard of a guy here in the UK who built a very trick KT250, with 300cc conversion, different exhaust, modified steering geometry, special Ohlins shocks, and Gas Gas forks. Probably a bit of an expert on these bikes and someone on here might know who this is, and be able to provide more details or pics of the bike?

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Michael I've had mine for about 5 years and have done lots of minor tweaking to try and make it as easy to ride as a TY250 and reckon what I've done has taken it to about 90% of being as good for trials competition.

The big weakness for the KT compared with the TY250 is in tight turns. It will turn tight but you have to manage your body position, the clutch and rear brake very closely to do a tight turn that you wouldn't even have to think about on a TY250.

I see the strengths of the KT as:

Ergonomics - there is plenty of room to move around and the kickstart is a dream to use compared with most trials bikes.

Ground clearance is better than the TY250.

Clutch is more positive in engagement than most of the Spanish bikes (is similar to TY250)

Great ergos for sitting down riding.

Setup:

Wiseco CR/MT250 piston

Standard porting, carby, exhaust, airbox, timing, cylinder head shape

TY250D fork springs, 20WT oil 125mm from top, non-vented fork caps (from TY250)

360mm Falcon shocks with 50lb/in springs

Standard rubber swingarm bush arrangement

Standard frame (and no tube damage under the motor yet)

Standard footpeg position but with grippy pegs

Increased leverage for clutch. New plates and springs (standard). Modern low friction cable.

Standard flywheel weight

Front drum machined and high friction oversize shoes machined to fit the drum perfectly. Modern low friction cable.

Standard rims (and no cracks yet)

Very low gearing. 12T or 13T front and standard size rear (flat with spacer). 428 chain.

Replica KT250 handlebars (much higher and a bit wider than 6" Renthals)

Standard fuel tank.

Michelin tyres.

David Lahey

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Can I ask a really stupid question?

Were the Kawasakis every really competitive when they were new? Even with, presumably, full factory tweaking?

I was given one of the early ones to "test" for a month when they first arrived in the UK by the then importer Alec Wright. I rode it in a couple of minor events and I can't say that I really liked it compared to the Yam and the Ossa. Of course Don Smith and Richie Sunter rode them pretty well but they never seemed to feature prominently in any of the majors. Probably a good bike with some of the alterations you suggest.

Good luck with the project.

Tony

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Dave, are you at Nike? I think there's a number of Nike guys from Portland vintage roadracing Honda CB160s. If you know them, they know of me as many of the F-160 guys have bought the tuning guide I wrote.

cheers,

Michael

I haven't run into the 160 guys at work. I've seen all the 160s at the track before. Quite the crew.

One of the guys on our team (Hi, Keith!) started last season on a TL125 and pretty much cleaned up on the 3 line. He moved to the Kawasaki and did just as well. He'll be moving to the 2 line this year and he should do just as well.

P1000617.jpg

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I rode TLs, RLs, TYs, Montesas and a KT in the 1970s and it was my least favorite. It just seemed like the least specialized of the bunch (lower frame rails and all). Or maybe it was the fork vent hissing at me all the time...

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I had one and frankly it was rubbish. Nowhere near enough flywheel weight, though we are used to that now so it might not seem so bad if I rode one today, and too easily stalled. The carburetion was poor especially on the road, which mattered in those days, and the "cure" according to the importer was to remove the outer electrode of the plug - didn't work of course. I got rid of it before it got too badly marked so that there was still some value in it.

Given that they started with a clean sheet, unlike Suzuki who cobbled a trail bike motor in to a trials one (and I still think my RL was about the best bike I had, certainly results wise), it was a poor do. If only they had sold the 450s that Messrs Smith, Sunter, Kemp (and Galloway?) rode in the SSDT.

The importer had Napier College develop the motor and I went out with the late Bill Stuart for a comparison test. I rode it "blind" not knowing what had been done and didn't notice a lot of difference. Given that it had an Amal and was out to 300cc or so I think I should have. I believe that bike still exists.

They looked nice though.

Edited by 2/4
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This thread needs more pictures.

This a clean KT that was at Donner last year. I think the only thing amiss is a little paint missing from the side covers.

IMGP0118.jpg

And since someone mentioned it... this Suzi was for sale. US$750. I don't think it sold.

IMGP0115.jpg

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building mine right now, built the motor 1st to make sure it would run and shift through all of the gears,not really sure how it will be in the sections but I figure something to with different ignition timing with a dial indicator might help. the head has to be removed to use the factory dial indicator set up. by no means is it par with a bul,yam or montesa(old skool 70's trials marques) but I think it can be dialed in eventually. I think you can flog any bike if your skills have progressed over the years. the montesa 348 had ignition timing set quite differently than what the shop manual stated,but the different timing settings were night and day. my kt is going to be GREEN! I'm waiting patiently for shocks to come in from ups and should start posting pics and my data sheet. engine on one bench frame on another.

p.s. is there cure for this vintage madness? I can't even take my wallet to work anymore for fear I will buy more goodies for it!

cheers,dgraf

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If you want pictures, here's one taken at a trial (before I built the new exhaust). The tank I built isn't as nice looking as the stocker, but it is lighter and rust-free:

fourkt250s3a.jpg

Four KTs at a regional trial seemed like an event worth recording. :) They owner of the bike right behind mine rides the two line and seems reasonably happy with his bike, though when I let him ride mine after I built the pipe and did the other engine mods he did prefer the power of my bike.

I have two friends here in the area that have KT250s that are nice and original and have all the lighting kit (one of those is for sale as it looks like the person is going to stick with roadracing and not do any trials after all), and I've heard from a fellow in Norway who has one with all the lights.

I didn't try retarding the timing until after I did the porting and cylinder head modifications, but it is quite a bit retarded from the stock position now.

I've been looking through some old magazines today, and generally the KT250 seems to have gotten the nod as being best overall (not necessarily by much) Japanese trialer. Pretty cool seeing all those full page inside cover ads for Sherpa Ts too!

Since the mid 70s Bultacos were 27 degrees and 76mm ground trail, and the KT250 is 26.5 degrees and 75mm ground trail (though with a just slighly shorter wheelbase) I'm not sure why the KT doesn't handle pretty much just like a Bul.

I'm going to put together a chart of all the dimensions/weights from those 70s roadtests and add that to the KT page on my website in the near future.

Today I got a few sample spokes pulled out of the wheels and then chopped the rest so I'm hoping to get the hubs sent off tomorrow to Buchanan's to have rims and spokes made. They say they don't have specs so I'd rather send them the hubs instead of a drawing so that they have no excuses if they make a mistake.

I did some measuring on the forks and I'm going to have to pull those apart as I think one of them may be very slightly bent. I couldn't get the assembly to be dead square on the surface plate. It wouldn't hurt them to get all cleaned up with fresh fluid anyway.

I'm not sure what tire diameter they calculated trail with (it should be 702mm), but using an unmounted new Michelin front (693mm) my measurements of the fork offsetss are giving me 77mm of ground trail at full droop, where 79mm is what the manual claims. With the non-parallel clamps (1.5 degrees) at full bump (if the rake stays unchanged) trail will increase by about 5mm. The axle offset in the sliders is 24mm so the clamps are too flat to make me want to try them with center axle forks (that would be about 104mm of ground trail - a TY250 is 90mm). I'll have to see if I've got anything in the 75mm offset range as I've got some center axle Betors I could try. I do have a set of Sherpa T Betors that I'll need to look at to see how they divided up the offset between the clamps and slider. I might be able to mix and match to get some different total offsets, though there is a 1mm difference in fork tube OD I'd have to deal with.

Power characteristics are the main difference I can recall between my 1974 325 Bultaco and the KT250. I'll have to try and do some swaps with people at the next trial I go to so I can get some idea of how different the various bikes feel.

cheers,

Michael

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David, since you sound like you've got the stock steel spokes and nipples pay attention to them after that water section. I was able to get some of the nipples off the KT wheels today so I could send sample spokes with the hubs, but things were really ugly inside the rim. I'll be going with stainless steel spokes and aluminum nipples for the new rims.

I looked and my bike does run the stock sprocket sizes (15/52 IIRC). I'm not sure I've felt much need for lower gearing in the kinds of novice sections we have, though I think there would be less need if it had more flywheel mass. It runs slow enough, it just is easy for it to stall if it hits a rock or branch or something that slows it down any when at the lowest possible RPM.

Is the reason you changed the clutch leverage because you ride using the clutch a lot? The clutch seems like a typical Japanese dirt bike -- reasonably light.

cheers,

Michael

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