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ARP head stud kits for ktm rfs

16K views 30 replies 11 participants last post by  LOUISSE66 
#1 ·
Just got together with ARP and came up with some studs and nuts that work to replace the factory head bolts. Allowing a little more clamping pressure and less wear and tear on the case threads. Retail is about $50 for the 4 studs with nuts and washers. Here are the ARP part number:
Stud AM6.770-1b
nut AMN12-1
washer AMW750n
 
#2 ·
sweet, so just order those # up from ARP direct ?
 
#3 ·
Yup those are the arp direct part numbers. If they wont ship international Send me a pm and Ill get you fixed up
 
#5 ·
I can't remember the value but we been torquing to 60. I think I'm gonna go back down to 40. Once I get the new billet cylinder
 
#6 ·
I torque these to 45 ft lbs. Any more and you risk warping the head or cylinder sealing surfaces. The studs have finer threads that create more clamping force for a given torque spec.
 
#7 ·
The early 2000 KTM rfs's came with studs. I have a set here with the nuts if you want them. Clamping force will be identical. Lots of threads in the block. Cannot imagine damaging them myself or exceeding the 38 pounds torque but...... Make sure you anti seize or oil any threaded fastener. And tap the case holes and blow them clean. And wire wheel the threads on any fastener. I use anti seize on both sides of the washer under the normal head bolt.Btw the 2007 and up head bolts suck. Too thin in the middle. Pulls torque funny. Removed most of them and use the 2001 to 2006 bolts which "feel" right when torquing them.I have them also if you want. Cannot think of any real advantage for studs myself regardless of threading. O ring the head and cylinder top and use a copper o ring if 14 to 1 is the drag racers way. My liner guys add a .001 lip on the inner edge of the cylinder. You can feel it with your finger. Not flat on the top on purpose. No issues
 
#8 ·
Man free parts. Are you kidding don't you want to mark your stuff up70% ?
 
#10 ·
here you go bob. Also reduces wear and tear on the case threads.Head Bolts vs. Head Studs
How often do you plan to take this down? We studded engines 45 years ago. You must remove the stud to pull the top end. I have worked on a buch of factory race motors. Non are studded. Go ahead. Same thing as the bolt. A normal rule of thumb in aluminum is you need 2 1/2 either turns of the bolt are the same in depth versus the diameter of the bolt. Bolts go way deep in the cases. Harder to drop the cylinder over the cam chain guides so I put them in last. Head on. Also with the studs in and the chain guides in how do you insert the piston pin clips? I have learned to install the piston in the cylinder then slide the pin out to the cam chain side and tilt it forward so I can access the pin to put the clip in. Would be really hard in a vertical position with the studs and chain guides installed. And I use a bux tool c-clipper. Harder to install the studs later as there is not enough threads showing to double nut the exposed stud or use a stud installation tool.Try to install the cylinder over the studs and cam chain guides with a loose piston. Ring compressor is under the cylinder. No gap unlike the ceramic KTM factory ring tool shown in the parts and special tools for your engine. If you are installing a aftermarket piston with its three piece NPR oil ring setup you will break a few before you figure out you need four experienced hands to do the install.So an oil less Pre installation of the piston into the cylinder using total seals quick seat instead of oil which allows the piston to slip out of the cylinder too easily during installation makes it hard to break the thin oil and compression rings during assembly. I could do it my way using studs but you will become frustrated quickly. And remember my post. You would need the bux tool c clipper piston pin clip installation tool to put the clip in with studs in the way. KTM removed the studs after a 1,000 engines as they were a pain.IF you wore the holes out you could Timesert the hole in steel. Last forever. Sorry I do these everyday. I tried the studs for years. That's why I have them here to give away. I remove them from any early 2000 KTM I see.The fiche does not even show them any more. Bolt only. The stud will not hold the thing together any tighter as far as I know. I tried and the bolts will take much more torque than the spec but you may bend the head casting itself. I have seen case tops not flat from over torquing the head bolts. A "dip" between the bolt holes in the case. Put a straight edge across the cases. I have seen some where a .009 feeler gauge can be inserted under the straight edge between the holes. You can pull the cases "up". Was not designed fir more than a percentage over the spec torque. O ring the head and cylinder instead.
 
#11 ·
Well when you don't hold a head gasket you change everytime you ride lol. I also put piston in cylinder first. Then slide onto rod. But I leave my studs in. There's enough room on a ATv to remove head and cylinder. To have to do it in a sequence. I also don't have the c clip tool I wish I did. But it's a doable. My experience with the stock bolts are they stretch some and everytime I've put on a 570 kit with mls I have to add a few lbs to get it not to leak. I don't think there made for alot of torque.
 
#12 ·
Would you like a set of the thicker older head bolts? Swap for the thinners when you get them out again. Do not use the mls gaskets myself. Have cometic make up a few fibre 102's and use 518 on the gasket. Unless you need copper o rings. 13.5 and up normally needed o ringed parts.
 
#13 ·
Been plenty of quys blowing gaskets in quads of all types when running big bores strokers etc. 660 / 700 raptors. YFZs and others

ARP studs fix the problem everytime

SX are also prone to pulling threads in the cases. Inserts are the fix there.......

Inserts and studs seem to be the needed setup on the 102 / 104 engines to get them to work / last

Can you still buy the earlier bolts new from ktm ?

want to find an engines weak points give it to quad racers for a season.....Stuff that works in two wheelers can often fail under quad use pretty quick..?

I'd sooner work around studs than have to pull this engine again cause off failed shit...... Seen enough failed junk to last me a life time......
 
#14 ·
Bob installation and removal of the top end with the studs installed is no problem in the quad chassis. Also there is no denying that the studs hold torque better and are far superior in quality to the factory bolts. Also no need to worry about installation or removal of the studs, ARP broaches a hex in the end so an allen wrench is all it takes to remove them.
 
#16 · (Edited)
My head has timeserts in it so I can use 8mm arp bolts instead of the 6mm stocks ones I can crank them things down
 
#19 ·
Where you bolt up from cylinder to head. The 3small bolts
 
#20 ·
guys are you using moly grease on the head stud nuts or just engine oil ? Slotting mine in today…… just checking………. Think I will stay with 40 ft lbs
 
#22 ·
40lbs head bolt torque at the compression you are running is fine. Anything over 13:1 and you need to increase it. We blew several head gaskets at 14 and 16:1 until we increased the head bolt torque past 50 ftlbs. The clamping force needs to be higher with the increases in cylinder pressure that comes from increases compression. The heads are sturdy enough that the extra torque will not warp the heads. a little moly on the threads is a good idea.
 
#21 ·
Not using a tithing on mine. I'm back down to 40lbs also. But my new head has Oring in it now
 
#23 ·
i use molly lube. blow out the holes and go easy on the case threads. for the top threads i put moly on both sides of the washer and threads.
 
#24 ·
I do the same and only install the studs finger tight. There is no reason to tighten the studs beyond that.

Just and FYI; The newer style stock bolts are torque limiting bolts. That's why they are turned down in the middle they are designed to "break" when you reach 40ftlbs. And why they feel springy if you try and torque them past 40lbs. The problem with this type of bolt is they stretch through the middle. If they do stretch or are over torqued they loose a small amount of there holding power.
 
#25 ·
cool thanks guys, all in and snugged down. Need to get this engine up and running reliably thats for sure………..
 
#27 ·
Travis may be able to get you some. When I originally got these part numbers I measured the stock bolts and head and bought them based off the bolt specs. If travis cant help you out I may be able to get you some.
 
#28 ·
are these direct bolt in or is thier machining to the cases needed?
 
#31 · (Edited)
Helo everyone,

I'd like to share my experience regarding an issue I encountered with my KTM 450cc competition special cylinder head. I managed to address the issue of accumulated dirt by using a descaler recommendd by a specialist, significantly improving the situation for me. Additionally, I found a solution for studs and nuts by discussing with ARP, where I discovered effctive alternatives to replace the original bolts. These new components, while slightly pricier, offer better clamping pressure and reduce casing thread wear. For those facing similar issues with their KTM, I recomend exploring these options. Furthermore, it's worth notng that the store selling these products offers a 5% discount on all items with the promo code: GIFT5.

Best regards,

Louise
 
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