Author Topic: '81 KTM 250GS rebuild  (Read 17791 times)

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Offline 09.0

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Re: '81 KTM 250GS rebuild
« Reply #15 on: November 18, 2012, 09:39:16 pm »

and got really grunk


Grunk? That cant be good :D
[/quote] they don't make iPhones for full fingered men like myself...

Offline ozktm

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Re: '81 KTM 250GS rebuild
« Reply #16 on: November 19, 2012, 02:12:16 pm »
Quote
When they ask you " If you went to a party and got really grunk and woke up the next morning from behind a couch with your pants down and a sore arse , you would tell anyone?". Don't answer yes as you will get heaps of invites to Ktm parties!

Brad, you must have been so 'grunk' you mistook us for 'Husky Central'... ;) ::)

Rods are no problem, i have the correct ones.

Regards,
Adrian Goold #101

'72 KTM 175 |'74.5 KTM 250 |'74.5 KTM 400 |Hagon/KTM 250 proj|'76 MC5 250 Project |'76 MC5 400|'78 KTM 250 Project |'81 KTM 250 MC | '81 KTM 495 MC

Olddog

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Re: '81 KTM 250GS rebuild
« Reply #17 on: November 19, 2012, 07:59:42 pm »
Hmmm dunno.....I've been pretty grunk before, but rum will do that to a man.

Anyway, Thanks for all the responses and advice! Adrian I'll give you a call and bend your ear a bit, whens a good time?

I have one important question though, just how solid are these engines? As I think I mentioned, I'm planning on taking this beast on a charity ride to the back of Bourke next year, so I guess that'll be maybe 1400kms round trip, mostly dirt roads. Reckon this engine will stand up to hours of reasonably high rev's or should I put together something a bit sturdier for that job and just restore this bike?

Barrels wise I was fortunate enough to pick up another one with a standard 71mm bore, however when I compare it to the original there are a lot of differences. The original barrel is an Elko 71/6, the replacement is an Elko 71/5R. The bore, and barrel overall height are the same, the head bolt pattern is the same. Differences are that the /5R has 8 fins, compared to the /6 with 7 fins, the /5R has much bigger square fins as well. The /5R also has a different design to the ports in the skirt.
So I'm assuming these barrels will intercharge, should I expect to make any allowances for this?







Bottom pic shows original on the left and replacement on the right, and the skirt length under the barrel is identical on both.

Cheers

Bill
« Last Edit: November 19, 2012, 08:07:39 pm by Olddog »

Offline oz555ktm

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Re: '81 KTM 250GS rebuild
« Reply #18 on: November 19, 2012, 11:41:14 pm »

    no wrong Cylinders

       the cylinder you got is off a 250 yes BUT BUT
        its the 1978 250 engine family 540  yours engine for bike is the 541 engine family

         Look at your engine number it will be something like  1 541 XXXXX

       the 1 = the year eg 1981

       the 541 is the engine family
   
       the xxxx is the engine number 
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Offline Slakewell

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Re: '81 KTM 250GS rebuild
« Reply #19 on: November 20, 2012, 07:37:48 am »
I Think you can put huge front sprockets on these models so take a few on your trip and change them to suit. Help keep the revs down on transport sections. If time permits get the cranked balanced.
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project. Dont need a pickle just need to ride my motorcickle

Offline ozktm

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Re: '81 KTM 250GS rebuild
« Reply #20 on: November 20, 2012, 10:57:26 am »
They are different barrels, but it will still bolt up to the 81 bottom end if required. Porting is different, boost ports different. Runs the same piston, same crank, same rod! The transfers may/or may not line up exactly to the bottom end, but could be match ported if required.

The issue would be if the pipe would clear it.
Would probably look funny, with wide barrel and small 81 head, but functional. Depends on what you want.

Adrian

Regards,
Adrian Goold #101

'72 KTM 175 |'74.5 KTM 250 |'74.5 KTM 400 |Hagon/KTM 250 proj|'76 MC5 250 Project |'76 MC5 400|'78 KTM 250 Project |'81 KTM 250 MC | '81 KTM 495 MC

Offline TooFastTim

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Re: '81 KTM 250GS rebuild
« Reply #21 on: November 20, 2012, 12:55:05 pm »
Nicasil bore I assume?

If that's the case then you may need to sacrifice the new barrel for donor fins.

Offline oz555ktm

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Re: '81 KTM 250GS rebuild
« Reply #22 on: November 21, 2012, 12:09:32 am »

  No   Good old Cast iron
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And I have very Bad Gramer ...too I been told ......

Offline TooFastTim

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Re: '81 KTM 250GS rebuild
« Reply #23 on: November 21, 2012, 10:05:40 am »

  No   Good old Cast iron

Can you swap the liners?

Olddog

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Re: '81 KTM 250GS rebuild
« Reply #24 on: November 21, 2012, 01:34:43 pm »
To be honest the ports look identical in each barrel to me. I'll get some measurments done over the weekend and get some clearer shots of the ports etc and post them up. It looks to me like everything should, it'll just look strange with the oversize barrel fins as Adrian points out.

Cheers

Bill

Offline TooFastTim

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Re: '81 KTM 250GS rebuild
« Reply #25 on: November 21, 2012, 07:05:21 pm »
I forgot that the mounting studs are different on the donor barrel.

Offline ozktm

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Re: '81 KTM 250GS rebuild
« Reply #26 on: November 23, 2012, 10:01:54 am »
Olddog

Check your messages, i have a barrel with out liner.

Adrian
Regards,
Adrian Goold #101

'72 KTM 175 |'74.5 KTM 250 |'74.5 KTM 400 |Hagon/KTM 250 proj|'76 MC5 250 Project |'76 MC5 400|'78 KTM 250 Project |'81 KTM 250 MC | '81 KTM 495 MC

Olddog

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Re: '81 KTM 250GS rebuild
« Reply #27 on: November 25, 2012, 06:25:26 pm »
Adrian, thanks for the offer I'll take you up on that I reckon! As per the pics below the wrong barrel appears to fit right up although I admit it does look a bit odd, If anyone asks me I'll just pass it off as a "Baja" variant or something :)

At this point I just want the beast to run so I can take it on the Scraphead ride http://www.advrider.com/forums/showthread.php?t=833326 the bikes too good to leave as a scrapper though so I'll do a restoration on it next year and use that proper barrel.

I'm taking a holiday down the south coast in mid December so wouldn't mind dropping by for a yack at some point Adrian? Maybe we can fit up a rod kit? What I do need to know is what parts I can buy off you and what bits I need to source. I assume I'm okay to use SKF bearings?

The other issue i have is the electrics, it looks like someone has chopped out all the electrics bar the wires to the headlight and tail light. Fotr the scrapheap ride i'm going to run a 12v total loss system on the blonkers and horn etc hopefully leave the headlight and tailight alone....hell it only has to pass vintage road rego anyway :)
Looks like the speedo drive munched up too so the speedo is going to be there for cosmetic purposes only.

Oh and one last thing, where can i get a hold of seals for the back shocks? Their the usual Ohlins piggyback style. It's either that or I send em to Paul Rooney but he's a busy busy man.

Now for the pics



Rare "Baja Big Fin" motor :D






Well it fits...

Olddog

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Re: '81 KTM 250GS rebuild
« Reply #28 on: November 27, 2012, 09:36:04 pm »
Bit of an update, I've finished rebuilding the forks. They were seized solid so had to do a bit of gentle tapping to get the sliders off. There was no oil left in them, just some muck in the bottom. So cleaned em out with kero, inspected them for cracks (none thank goodness) fitted new seals and filled them up with 10 weight oil. Also got the chance to clean and regrease the steering head bearings and unseize the throttle and choke lever as well. Tomorrow afternoon i'll clean out the carb and fit a new front tyre. After that I have to fit a new back tyre and unlock the back brake which like everything else is seized up! Then back to the engine.

Olddog

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Re: '81 KTM 250GS rebuild
« Reply #29 on: December 02, 2012, 04:11:29 pm »
Well I have the carb rebuilt, and the back brake unsiezed, hopefully during the week I'll get a new tyre and tube and get that fitted. I placed an order with KTMKlassicker during the week for new cables, engine seals and gaskets and the flywheel puller, so I should have that underway soon.

Coupla questions, I see they have new pistons but they are for the earlier 54 series engine, will they still work in the 541 series?
Ozktm151 I see you mentioned using Honda clutch plates? Can you tell me off which Honda, as the original plates I have are under spec so they'll need replacing with something.
Finally, Main bearings, what part number SKF bearing should i use?

Thanks

Bill