1981 KTM 250 MC

wpark89
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wpark89
Edited Date/Time 11/26/2021 3:30pm
This build has taken me the longest and has been the most challenging. Still a few pieces to tie together…but wanted to share.

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quiknic
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quiknic 10/30/2021 3:02pm
10/30/2021 3:02pm
Nice work on a tough bike to get parts for. Will this be one of your riders or a something killer to look at? A few extra CC’s over your white lightning KTM beauties.
wpark89
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wpark89 10/30/2021 3:20pm
10/30/2021 3:20pm
quiknic wrote:
Nice work on a tough bike to get parts for. Will this be one of your riders or a something killer to look at? A few...
Nice work on a tough bike to get parts for. Will this be one of your riders or a something killer to look at? A few extra CC’s over your white lightning KTM beauties.
Plan to race it. You know how addicting this gets. I have a good stable of later 80s and 90s bikes…I’ve wanted to add a air cooled twin shock bike to the garage for some time. At this point I’m kind of committed to keeping everything rare, Euro, and difficult!

It seems that depending on the race weekend a lot of my Cagivas and 90s KTMs can get grouped together…it will be cool to have a twin shocker, as it seems in the NW anyway that those classes normally have the biggest gates.

If anyone can help…I can’t seem to find any machinist that can do internal splines to remake the lower kickstart piece. It was a poor design, the splines wipe out, and obviously not much demand to reproduce 81-83 KTM 250 kick levers.

wpark89
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wpark89 10/30/2021 3:25pm
10/30/2021 3:25pm
I fabricated and welded peg mounts to use modern KTM pegs
4

The Shop

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wpark89
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wpark89 10/30/2021 3:32pm
10/30/2021 3:32pm Edited Date/Time 10/30/2021 3:43pm
Man Bear Pig….Throwback MX Guy…David Allen, whatever you call him (just cool dude) and a big help with some vapor blasting






wpark89
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wpark89 10/30/2021 3:45pm
10/30/2021 3:45pm
Cerakoted hubs, swingarm, and engine cases.
Things that are no fun…lacing 40 hole drum brake rims!
4
MaicoJC1
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MaicoJC1 10/30/2021 3:58pm
10/30/2021 3:58pm Edited Date/Time 10/30/2021 3:59pm
Have had a couple of early 80's KTM over the past decade or so...for the KS spline/lever you might want to reach out to Andre at https://www.enduroklassiker.at/en/ and/or Helmut "Speedy" Clasen. You can find Speedy on Facebook - he used to be a KTM dealer and I think he still has quite a bit of NOS OEM parts for 80s-90s KTM. As a matter of fact he helped me out with my KS issue on my 81 KTM.

BTW, I had the 81 KTM 250GS (same fox Shox as well) -- great mid-range and top end (ran great with a Bing to 36Mikuni conversion too). Didn't turn as well as any of my Maicos, but it was close - and the motor made up for any handling deficiencies it may have had.

Wish you the best.
quiknic
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quiknic 10/30/2021 4:56pm
10/30/2021 4:56pm
Sweet, Dave is one of the cool kids for sure and does stellar work.

Never owned or even ridden a dual shock bike but that may be something that I will need to do at some point but for now we have way too many projects.

Here is a sweet 79 YZ125 that my boy Jeremy picked up and has been working on. We picked this up shortly after the Washougal NWCVMX event that we finally met you at. More cool stuff coming and I am still working on getting an 89 Cagiva 125 from someone that has one, been trying for years and he may be coming around to selling it soon.

Again, nice work bud!



5
MaicoJC1
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MaicoJC1 10/30/2021 5:51pm
10/30/2021 5:51pm Edited Date/Time 10/30/2021 6:29pm
Here's the GS (Reed Valve) version. Bought this bike from Rik Smits (former NBA Pacers Bball player). He has an amazing vintage collection of bikes and is big vintage bike enthusiast. Wish I would've never sold it.

Post-race 2013, AHRMA Vintage XC race, took 2nd place that day at Wicomico in MD

AND finally, my 77 Penton 250 GS6. Holding on to this one. Love this bike.


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wpark89
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wpark89 10/30/2021 7:04pm
10/30/2021 7:04pm
Maico…Helmut and Andre and all the normal sources don’t have anything. The problem is the lower piece pinches on the shaft, but it’s only cut through on the inside part of the piece…so it doesn’t pinch well and wipes out the splines. Some guys are claiming to use PW 50 kick levers, another is using an extra shift lever to start his bike as they are both 14mm shafts.

This bike actually started as a GS. I got a MC motor, found out the only difference is they took 1st gear out of the 6 speed GS to make the MC 5 speed. A few small parts needed to be switched to make the MC…like the rear brake hubs and stay arms are different between the two.
MaicoJC1
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MaicoJC1 10/30/2021 7:40pm
10/30/2021 7:40pm Edited Date/Time 10/30/2021 7:40pm
WP89,
Since it's a 14mm shaft you could use a KS completely assembly from 72-78 KTM 125-175 (which are most robust, IMHO, than the stock 81 KS). Saw this on Al Buehner's site and thought it might be of some for use for you:

Reproduction KTM Kick Start Levers for 1972 thru 1978 bikes
A - #52-33-036-244 - Sold out
125 & 175 lever assy. Fits 14mm shaft NOTE: will also fit 1981 250 engines
http://www.pentonpartsusa.com/images/3-%20ktm%20photos/KTM%20kick%20sta…

I've bought new ones for my big bore KTM 400s and the newer steel or whatever material that they use these simply couldn't handle the compression - so I ended up buying used KS levers for my 78 & 79 400's.

I've even seen older style KS used on 81 & 82 250 models - see Al's page on the Penton owners group: http://www.pentonpartsusa.com/images/3-%20ktm%20photos/72%20kick%20star…

Unless they're OEM NOS I won't buy Repros for the big bore KTMs. I'd do it for the 250 for though, but still, I prefer to buy used oem KS levers (at least for KTMs and Pentons) on ebay -- seems they were made of better material way back then.

Looks like Al is sold out, but I think you could find a 14mm KS on ebay. And yeah, if all else fails I'd definitely give that PW KS lever a try.


wpark89
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wpark89 10/31/2021 6:35am
10/31/2021 6:35am
Thanks Reese.

Maico…I had a question. You mentioned swapping the Bing for a Mikuni? I have seen lots of different posts saying to get rid of the Bing or that the Bing is the best for this piston port engine.

I looked at using a different carb. But the problem is that the Bing is much smaller on the back side than anything else.

Originally I wanted to try this new 37mm Dellorto that I had off a 88 Cagiva WMX 250.

MaicoJC1
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MaicoJC1 10/31/2021 9:01am
10/31/2021 9:01am Edited Date/Time 10/31/2021 9:19am
I didn’t have a problem using a Mikuni on mine. If you look closely at my picture you can see clearly that it’s a Mikuni carb that I’ve installed (36mm). I don’t recall even having to use a heat gun for the install, but I might have purchased a new air box boot.

I was also taught by some old timers that you can use a accordion style cv boot (trimmed of course) in lieu of an oem airbox/aft carb boot. Also have successfully used rubber couplers from Lowes for the airbox/aft carb connection as well (trim to fit).

With my DKW, Pentons and late 78 & 79 KTMs I stuck with Bings - the Mikunis were too hard to fit and required fabrication and modification that I just didn’t feel like dealing with.

Due to the cylinder and engine redesign, Mikuni carb installs for the early 80 KTMs were def an easier fit.

Btw, 3 out my 4 Maicos have 36mm Mikunis installed. Have quite a few Bings - which I do believe are probably better overall performance - but I like Mikuni for their ease of maintenance, reliability, and improvement and ease of starting these old pieces of iron.

Not racing anymore, so I prefer the path of least resistance - at this point.

MaicoJC1
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MaicoJC1 10/31/2021 9:49am
10/31/2021 9:49am Edited Date/Time 10/31/2021 9:52am
Another tip for anyone with late 70's and early 80 KTMs (Can-ams too!):

Keep an eye on those Marzocchi (magnesium) lower fork tubes around the axles and pinch bolts - they have a tendency to develop fine hairline cracks. Talk about trying to replace those - it's def a needle in a haystack experience. They can be repaired as well - you just have to find someone who is good with welding magnesium.
MaicoJC1
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MaicoJC1 10/31/2021 10:05am
10/31/2021 10:05am Edited Date/Time 10/31/2021 10:41am
WP89,

Just in case you wanted to know I'm pretty sure my 36mm Mikuni set for the KTM was 35-40 pilot jet, and 310-340 main, and needle jet clip was in the middle - adjusted for temp, elevation accordingly.

Edit: My GS was actually an 82 - and it had a reed valve cylinder. My Penton & Late 70's KTMs (all piston port) run just fine with the Bing (all rebuilt). All of my Mikuni carbed Maicos are piston port - and they run and idle nicely. Even the 1 Bing mounted Maico runs well. I just prefer the ease of a Mikuni and parts availability & durability -- and of course price.

Pit Row

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wpark89
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wpark89 10/31/2021 10:51am
10/31/2021 10:51am
Thanks for the tips.

The problem I ran into on my forks was the typical 80s Magnesium rot. When I pulled the stock fork rubber caps off water had rotted the forks severely around the seal retaining clip.

I found a nice set of lower tubes off a Can Am in California.


1
MaicoJC1
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MaicoJC1 10/31/2021 10:57am
10/31/2021 10:57am
Good deal. Nice find on those forks, WP.
RDnutz
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RDnutz 11/2/2021 7:33am
11/2/2021 7:33am
quiknic wrote:
Sweet, Dave is one of the cool kids for sure and does stellar work. Never owned or even ridden a dual shock bike but that may...
Sweet, Dave is one of the cool kids for sure and does stellar work.

Never owned or even ridden a dual shock bike but that may be something that I will need to do at some point but for now we have way too many projects.

Here is a sweet 79 YZ125 that my boy Jeremy picked up and has been working on. We picked this up shortly after the Washougal NWCVMX event that we finally met you at. More cool stuff coming and I am still working on getting an 89 Cagiva 125 from someone that has one, been trying for years and he may be coming around to selling it soon.

Again, nice work bud!



I have a bunch of 1970's Yamaha Monoshocks and love them. Most are stalled projects due to some life events but a couple are riders/racers. I love the 79 125 and have a couple to work on next spring. I found out about these when racing Vintage 100cc stuff years and these easily accept a 100cc top end or even complete bolt in motor swap with 1978 YZ100. Just got to modify your pipe a little. Sold my hybrid 100/125 after it sitting 4+ years Sad Hope to be racing mine again 1 day Cool


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Frog #1
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Frog #1 11/13/2021 4:37pm
11/13/2021 4:37pm
Awesome job! Love your Cagivas too!
darren7878 11/22/2021 5:32am
11/22/2021 5:32am
Top job but good luck keeping it on the track!! Most friends with that era of KTM leave it in the garage!
wpark89
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wpark89 11/22/2021 8:47pm
11/22/2021 8:47pm
darren7878 wrote:
Top job but good luck keeping it on the track!! Most friends with that era of KTM leave it in the garage!
Thanks? I couldn’t ever build a bike to just look at. I talked to Andy Stacy who was AMA rookie of the year in 81 and raced a stock KTM 250. He said he had no problems and the bike was super reliable through the Florida Winter series , Nationals, and then Trans AM in the fall.
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wpark89
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wpark89 11/25/2021 10:54pm
11/25/2021 10:54pm
I can concur that these Penton/KTMs use a 3 piece bearing (to allow for correctly shimming the crankshaft) and the race does stay in the case. They are tricky to get out, but I managed to with so with some heat.

wpark89
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wpark89 11/26/2021 2:33pm
11/26/2021 2:33pm
You’re right Reese, that would make sense. I wasn’t paying close enough attention. Too much turkey
38special
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38special 11/26/2021 3:30pm
11/26/2021 3:30pm
wpark89 wrote:
Thanks? I couldn’t ever build a bike to just look at. I talked to Andy Stacy who was AMA rookie of the year in 81 and...
Thanks? I couldn’t ever build a bike to just look at. I talked to Andy Stacy who was AMA rookie of the year in 81 and raced a stock KTM 250. He said he had no problems and the bike was super reliable through the Florida Winter series , Nationals, and then Trans AM in the fall.
I like your style. Why build a bike if you're not going to ride it? I'm guessing more than half of the blinky-bling builds on this board never see dirt, or even get finished.
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