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Old 10-23-2007, 11:20 AM   #1
whitezw OP
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Cry 1997 KTM 620 LC4 High Flow Head Conversion and other motor mods

Well I'm stumped and need some help from the hive mind...

I've been restoring/modding a 1997 KTM Adventure 620 for about a year. So far I have grafted a 2003 model rear onto the 1997 frame. I have now started to rebuild the engine and have hit a snag. Thus far I have done the following:
  • Sent the cylinder to Langcourt, LTD to be bored/replated (factory bore 101mm)
  • Ordered the following parts:
  • 5843602020023 CYL. HEAD CPL. LC4/SXC SAS 04
  • 58536031000 EXHAUST VALVE D=32 MM 2001
  • 58036030000 INTAKE VALVE D=36 MM
  • 58630035200 CYL. BASE GASKET 0,5MM M.SICKE
  • 58330036000 CYLINDER HEAD GASKET 101,3 MM
  • 58430007100 I PISTON I CPL. D=101 ELKO 03
  • 58536029044 VALVE SPRING KIT RALLYE 2001
  • 58536010044 CAMSHAFT RALLYE CPL. 2001
After assembling the cylinder, cylinder head, and valve cover, (adjusting the valves to spec) I rotated the engine by hand. I then noticed that there is an interference problem between the exhaust valves and the piston. I thought that this was from the rallye camshaft. So, I installed the original 249 factory camshaft. No go for that on either. So I then backed out the adjuster to see how much I would need to get it to clear. It was quite a bit (not sure how much yet, but I'm planning on measuring it tonight).

So, my question is, has anyone here retrofitted a 1997 LC4 Cylinder/Engine to a 2003 Forged piston and 2004 High Flow head?
Right now it looks like I'll need to increase the valve reliefs on the piston for the exhaust valves or try to use the 0.7mm Black base gasket or stack two 0.5mm metal base gaskets.

I have cross-checked part#s with other models to see if there is anything different in the valvetrain, connecting rod, crankshaft. All that I have found is the following:

1997 LC4 620
101mm x 76mm (bore x stroke)
2003 LC4 640
101mm x 78mm (bore x stroke)

Valve cleareance is 0.15mm for 1997-2003 LC4
Connecting rod is 141.5mm for 1997-2003 LC4
Base gasket (0.5mm) is the same part# 1997-2003 LC4
Rocker arm assemblies are different part#s
Cylinder is a different part# for 2003 LC4

Any ideas

-Zeb

Links to pics
http://eng.auburn.edu/users/whitezw/ktm640/ktm.jpg
- High Flow head (bottom)
http://eng.auburn.edu/users/whitezw/ktm640/ktm (1).jpg
- High Flow head (top)
http://eng.auburn.edu/users/whitezw/ktm640/ktm (2).jpg
- Rallye Camshaft
http://eng.auburn.edu/users/whitezw/ktm640/ktm (3).jpg
- Final frame and exhaust mock-up
http://eng.auburn.edu/users/whitezw/ktm640/ktm (4).jpg
- Cylinder after plating and painting
http://eng.auburn.edu/users/whitezw/ktm640/ktm (5).jpg
- Shiney bore after plating and honing
http://eng.auburn.edu/users/whitezw/ktm640/ktm (6).jpg
- Valve train components
http://eng.auburn.edu/users/whitezw/ktm640/ktm (7).jpg
- Valve train components 2
http://eng.auburn.edu/users/whitezw/ktm640/ktm (8).jpg
- Forged piston
http://eng.auburn.edu/users/whitezw/ktm640/ktm (9).jpg
- Original bike as purchased

whitezw screwed with this post 10-24-2007 at 06:49 AM Reason: Added picture discriptions
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Old 10-24-2007, 05:59 AM   #2
NICO
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Throwing you a Wednesday morning bump, as I am interested in why this is not working out.

I do recall others have successfully swapped in the High-Flow onto a 620 mill, but don't think they swapped the piston.

I won't pretend to know squat about the internals of these motors but, maybe the new piston is an issue given the different stroke length? (Although, I would think the 620's shorter stroke would create more clearance.)

Is the relation of the wrist pin to the top of the piston the same from the 620 to the 640 piston?

Is the piston "reversible"? In other words, any chance it went in backwards and the intake/exhaust valve clearance pockets are 180deg from design?

Any chance you didn't time the motor correctly when re-assembling it? This seems like it would be the most likely cause of the issue.

You may want to PM a couple of the Guru's who've written extensive how-to guides in the Index pinned at the top of this forum. "Laramie LC4", in particular, has gone through his 640 numerous times. His experience is with straight re-builds though, not upgrading the 620 with 640 parts, but the assembly of the beast is what he should be able to help with.
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Old 10-24-2007, 06:57 AM   #3
whitezw OP
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Bluhduh So, I feel like an idiot...

Well, I guess that I had one to many PBR's last night, but I discovered the error of my ways.
A picture is worth a thousand words...
http://eng.auburn.edu/users/whitezw/ktm640/ktm (11).jpg

-Closeup shot of the Cam sproket and Rallye Cam

I must have been one or two teeth off on the outter alignment dot last night. As of right now everything works like a champ!!!!!

So, if any one is interested I will be posting the entire project build w/photos soon.

Here are some more pics -->
http://eng.auburn.edu/users/whitezw/ktm640/ktm (10).jpg
http://eng.auburn.edu/users/whitezw/ktm640/ktm (12).jpg

Thanks,
-Zeb
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Old 10-24-2007, 07:03 AM   #4
whitezw OP
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To answer your question about the piston. Yes, the piston has a mark that point to the direction of travel (points toward the exhaust port) and the valve reliefs are cut to 36mm on intake and 32 on exhaust.

See previous post for my other reply about my stupidity...

Thanks,
Zeb

Quote:
Originally Posted by NICO
Throwing you a Wednesday morning bump, as I am interested in why this is not working out.

I do recall others have successfully swapped in the High-Flow onto a 620 mill, but don't think they swapped the piston.

I won't pretend to know squat about the internals of these motors but, maybe the new piston is an issue given the different stroke length? (Although, I would think the 620's shorter stroke would create more clearance.)

Is the relation of the wrist pin to the top of the piston the same from the 620 to the 640 piston?

Is the piston "reversible"? In other words, any chance it went in backwards and the intake/exhaust valve clearance pockets are 180deg from design?

Any chance you didn't time the motor correctly when re-assembling it? This seems like it would be the most likely cause of the issue.

You may want to PM a couple of the Guru's who've written extensive how-to guides in the Index pinned at the top of this forum. "Laramie LC4", in particular, has gone through his 640 numerous times. His experience is with straight re-builds though, not upgrading the 620 with 640 parts, but the assembly of the beast is what he should be able to help with.
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Old 10-24-2007, 10:49 AM   #5
NICO
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Quote:
Originally Posted by whitezw
Well, I guess that I had one to many PBR's last night,
So the root of the problem was cheap American "beer" while working on expensive Austrian machinery? Makes total sense.

EDIT: After looking at your pics I think you should dump the Mikuni (even though they are fine carbs) and spring for the FCR. Hell, you've dumped enough into the thing to this point that an extra 5 bills won't kill ya.
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Old 10-24-2007, 01:30 PM   #6
whitezw OP
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Laugh

Well, PBR was my only choice after the money I've spent on this project.

Yeah, I've got my eye on a FCR41 for the final touches on this project... I was very tempted to stroke the motor while I had it apart, but I wanted to be able to a few more upgrades later...

I'm kind of worried about the jetting on first startup... I have changed pretty much everything except the carb as far as the engine is concerned.

Quote:
Originally Posted by NICO
So the root of the problem was cheap American "beer" while working on expensive Austrian machinery? Makes total sense.

EDIT: After looking at your pics I think you should dump the Mikuni (even though they are fine carbs) and spring for the FCR. Hell, you've dumped enough into the thing to this point that an extra 5 bills won't kill ya.
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Old 10-24-2007, 03:01 PM   #7
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Hey whitezw. It's about time ya posted. I am looking forward to your write-up, as I have a 97 with a bad crank bearing. I will probably just do a rebuild and not an upgrade. Looks like a sweet bike.
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Old 10-24-2007, 05:12 PM   #8
NSFW
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Quote:
Originally Posted by whitezw
Well, I guess that I had one to many PBR's last night, but I discovered the error of my ways.
A picture is worth a thousand words...
http://eng.auburn.edu/users/whitezw/ktm640/ktm (11).jpg

-Closeup shot of the Cam sproket and Rallye Cam

I must have been one or two teeth off on the outter alignment dot last night. As of right now everything works like a champ!!!!!

So, if any one is interested I will be posting the entire project build w/photos soon.

Here are some more pics -->
http://eng.auburn.edu/users/whitezw/ktm640/ktm (10).jpg
http://eng.auburn.edu/users/whitezw/ktm640/ktm (12).jpg

Thanks,
-Zeb
Oh please, post the entire rebuilt. Make your pictures in a lesser resolution, it's way toooo big, and taking forever to load.

Thanks.

h8c
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Old 10-25-2007, 05:25 AM   #9
NICO
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Quote:
Originally Posted by whitezw
I'm kind of worried about the jetting on first startup... I have changed pretty much everything except the carb as far as the engine is concerned.
IIRC, the stock jetting on the BST I poached from an '03 SXC (high-flow head, non-ralley cam) was 152.5 main, 45 pilot, 1.2 air. Not sure what is in yours. You may want to give a good read to the carb set-up guide in the Index. Should be enough there to get you close.

Start here: http://www.advrider.com/forums/showthread.php?t=79898

Good luck and keep us posted. I agree with h8chains, a full write up with lots of pics would be greatly appreciated.
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Old 10-25-2007, 06:31 AM   #10
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You've got the clutch off, are you going to do the main-shaft bearing upgrade?? Perfect time for it and I'd hate for it to fail after all the other upgrades.
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Old 10-25-2007, 07:02 AM   #11
whitezw OP
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Talking

I resized the images linked in my original post. I will try to put everything together and also include all my many, many mistakes, recomendations, and part cross references I have found along the way. I have about 600mb of pictures since I started this project a year ago.

Quote:
Originally Posted by h8chains
Oh please, post the entire rebuilt. Make your pictures in a lesser resolution, it's way toooo big, and taking forever to load.

Thanks.

h8c
Yep that is the next thing in line to be replaced. I also plan on doing the starter clutch fix.

Quote:
Originally Posted by Beez
You've got the clutch off, are you going to do the main-shaft bearing upgrade?? Perfect time for it and I'd hate for it to fail after all the other upgrades.
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Old 10-25-2007, 11:34 AM   #12
NICO
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Quote:
Originally Posted by Beez
You've got the clutch off, are you going to do the main-shaft bearing upgrade?? Perfect time for it and I'd hate for it to fail after all the other upgrades.
Jezz Beez, good catch. Didn't even look that way in his pic. And here I was mentioning the FCR. Fekkin' priorities.
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