KTM Transmission Rebuild

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4/28/2018 7:48 PM

Hey guys, finally got my parts back and started putting the engine together. I’m stumped at this tranny instal with the shift forks and drum:
-I’ve double checked the correct orientation of the forks
-Checked the tranny shafts are put together correct

The problem I’m having is when it’s all together with the cases it shifts 2-3 times then jams up. I’ve tried so many configurations, but do you think it’s just cause the engine isn’t running?

I’m mostly confused on where the shift fork pins go into the shift drum, I’ve also tried starting with the shift star in neutral Photo
Anyone who’s been in the bottom end have some advice?
It’s all layed our pretty simple just can’t figure out if I’m missing a step?

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4/28/2018 9:21 PM
Edited Date/Time: 4/28/2018 9:22 PM

I just did a ktm 250f, replaced 2nd and 3rd gear, but I had the same thing, it would jam up like after 2 shifts and I had the 2 shift forks in wrong spot. Top had to go on the bottom basically the 2 forks were hitting each other not allowing movement. Even after that it was a bear to shift really had to play with it alot. I did get it to go through all of the gears once then I put it together. If it's jamming up u may have top and bottom fork swapped

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4/28/2018 9:32 PM

Any photo you have of orientation? I took a photo when disassembled, and looks correct via the parts finch.
Photo

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4/29/2018 4:53 AM

No I don't have a pic. Have u tried leaving one case half off and try going through the gears watching it to see if anything is binding? Sometimes lubing the shafts will help

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4/29/2018 5:36 AM

CarlinoJoeVideo wrote:

Any photo you have of orientation? I took a photo when disassembled, and looks correct via the parts finch.
Photo

Look in your service manual. It should tell you what goes where.

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4/29/2018 8:36 AM

The service manual is actually super vague in this section. That’s why I feel like it should be simple.

I’ve put everything in with the half open and get same results. Was there any indication on where direction the shift drum is or doesn’t matter?

I’m just wondering if it’s not shifting because the engine isn’t running and I’m over thinking it.

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4/29/2018 3:01 PM

CarlinoJoeVideo wrote:

The service manual is actually super vague in this section. That’s why I feel like it should be simple.

I’ve put everything in with the half open and get same results. Was there any indication on where direction the shift drum is or doesn’t matter?

I’m just wondering if it’s not shifting because the engine isn’t running and I’m over thinking it.

I don't think it matters where the shift drum is but I think I usually try to start it at neutral also, have u installed the shifter shaft and shifter also when trying it?

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4/29/2018 4:39 PM

appears to be an KTM 85sx, put on the front sprocket and turn it as you shift with the shifter. It may help, been there before- J

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4/29/2018 4:42 PM

also some trannys dont like to shift when both shafts arent held nice and straight, so leave the crank out and put the other case on and you can then see if it works

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4/29/2018 4:47 PM

had this problem with a suzuki and the drum was actually upside down pinch so in some cases i do believe the drum needs to be oriented correctly. other than that my only advice is moly lube the forks and be certain you have the left center and right forks in the correct spots

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4/29/2018 6:01 PM
Edited Date/Time: 4/29/2018 6:02 PM

One thing i do to help with tranny assembly. Is i take different color paint pens and mark each fork tang top and bottom and shift drum in the same spot. So i know exactly which fork was 1st 2nd last and can tell exactly were it was on the shift drum. An as someone already said dry fit without the crank and put the sprocket on for a little better leverage. Had to do that all the time with the original kxf/rmz 250s.

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4/30/2018 8:42 AM

hold one shaft while you rock the other, and try to shift thru the gears.

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4/30/2018 12:26 PM

My guess is you aren't lining up the star correctly, assuming that the tranny is in correctly. And it should shift through all the gears on the bench regardless of how fresh everything is

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4/30/2018 12:28 PM

Thanks for the ideas, I’ll give them a shot again. I’ve been dry fitting with no crank as well.

I have some good photos before I disassembled, I’m really leaning on the side of it not working because the engine isn’t spinning.
Photo
PhotoPhoto

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4/30/2018 3:40 PM

which shaft did you rebuild? Did the shift drum come out?

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4/30/2018 6:30 PM

Never had an engine shift cleanly through the gears on the bench. With some manipulation, spinning the countershaft while trying to shift ,it can be done, but not a smooth operation like it is when installed in the bike, running.

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5/1/2018 4:07 PM

JBoneMotorworks wrote:

which shaft did you rebuild? Did the shift drum come out?

Full rebuild, everything came out and tranny got polished. I’ll double check everything tomorrow, gears in order and facing the right direction. I feel like I’ve already double and triple checked, but why not another ya know.

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5/2/2018 5:12 AM

When I built my son's KTM 85 I had a binding issue. For me, I had the top gear (the biggest one) up side down. It would shift once or twice, then lock.

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5/3/2018 10:31 PM
Edited Date/Time: 5/3/2018 10:35 PM

Looks pretty close to the 65s. The drum is deceiving. Try starting the pins on the shift forks on the opposite side of the drum. If i remember correctly i was putting the pins in how i thought they went and i was only getting a few gears but once it was in correct it was smooth.

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5/3/2018 11:22 PM

dirtmike86 wrote:

Looks pretty close to the 65s. The drum is deceiving. Try starting the pins on the shift forks on the opposite side of the drum. If i remember correctly i was putting the pins in how i thought they went and i was only getting a few gears but once it was in correct it was smooth.

Could you explain more? I’ve read it 5 times but not sure I understand. Thanks man!

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5/4/2018 3:27 PM

dirtmike86 wrote:

Looks pretty close to the 65s. The drum is deceiving. Try starting the pins on the shift forks on the opposite side of the drum. If i remember correctly i was putting the pins in how i thought they went and i was only getting a few gears but once it was in correct it was smooth.

CarlinoJoeVideo wrote:

Could you explain more? I’ve read it 5 times but not sure I understand. Thanks man!

You can only start the shift fork pins from 2 points. Rotate the drum until the shift fork pins will drop into the other side.

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5/5/2018 1:12 PM

Hey guys, so I pulled everything apart. Double checked the transmission was put together in order. Doubled checked the shift forks and all seems good now. I put the engine in vertical orientation and got everything to shift.
Photo
It really will only go together 1 way. I’m gonna button her up and finish the build. Thanks for all the suggestions!
Photo
Photo
I had to just step away and look at it with a clear head.

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5/6/2018 8:21 PM

Bravo amigo! Props for having the patience, they can be tricky sometimes.

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