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ca_101

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About ca_101

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    TT Bronze Member

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  • Gender
    Male
  • Location
    Michigan
  1. ca_101

    Repack FMF 2.1

    Not experienced with that exhaust, specifically, but a couple of nights ago I repacked my stock KTM exhaust for the first time. I picked up the FMF Premier 2 Stroke Packing at a local shop. Thought for sure it would not be enough, due to the length of the stock silencer. Ended up being perfect. https://www.motosport.com/fmf-premier-muffler-packing-2stroke
  2. ca_101

    Cylinder Fit On Base Studs

    I have another thread regarding tuning in the top end of my 2011 250 XC, but I have a general question I’d like to ask separately. All of the top ends I’ve done before have some method of doweling or locating the cylinder to case. Being new to KTM I’m curious on the fit of the cylinder on the base studs. I can move my cylinder around on the studs (w/o nuts) maybe 1.5-2mm in any direction. Is this normal? Seems like the base studs would have a tighter fit in the absence of locating dowels/bushings. Or is this amount of movement insignificant to the two stroke?
  3. ca_101

    Problems After Rebuild

    Thanks you for that info. Yes the ProX piston is domed. Are the stock vertex pistons flat top? The SX head is stock KTM, but not sure the year. Are some stock heads designed for flat and others domed? I’ll see if my KTM shop has the deck height tool. I do plan on trying to get an accurate deck height measurement tonight. My ktm shop has an oem 0.50mm base gasket in stock, as well as some wiseco circlips (which we believe are the same, but will verify). Yes I’m in MI and will be riding in between 0’-1000’. PO claimed he only rode in TN, where he had a second house and some family. I will be installing a 175 main, leaving the 42 pilot and switching to the N8RH needle clip #4 from top. Oh and mixing up some fresh 93 w/ SuperM, 50:1.
  4. ca_101

    Problems After Rebuild

    I’m in MIchigan. I have a new bottle o Maxima SuperM that I plan on mixing 50:1 w/ some fresh 93. I’m gonna richen up the jetting a bit, also. Also might swap back to my XC head. Or possibly pick up the KTM 0.50mm base gasket, to replace the 0.40mm ProX base gasket that’s installed, and continue to run the SX head. My biggest problem now is that I don’t think I’ll be able to find a replacement ProX circlip by the weekend. Was hoping to test, but I doubt anyone is gonna have some local. Anyone know if Wiseco’s run the same circlips? Might expand my chances of finding some. I can confirm that the Vertex clips are a not compatible.
  5. ca_101

    Problems After Rebuild

    Well I first pulled the exhaust and saw that lite scoring on the piston. So I decided to get a better look. I do have a 170 main I can try out.
  6. ca_101

    Problems After Rebuild

    Don’t have one here at work, but I can get one later. Head looked pretty clean, aside from some existing dings.
  7. ca_101

    Problems After Rebuild

    Thanks for the info on the cylinder Bob. Sorry about the slang[emoji6] I picked up some Maxima SuperM that I’ll be mixing up. I do have a 170 main, I can try that. How about the 42 pilot? I think the manual called for a 35. Do you think its safe to put it back together and run it with some new fuel and mix? 50/50 93/110? Run the xc head? I kinda don’t want to change too much at once, so that I can pin point the issue. Do you think it’d be worth taking in for a leak test? I don’t have the equipment. I do have a compression tester, which I haven’t done yet. The entire bottom end went together smooth, with all new seals and gaskets, but I guess you never know unless it’s tested. Also, any suggestions on testing cooling system? Thanks again for the help.
  8. ca_101

    Problems After Rebuild

    PO said he was running pump premium, Klotz and, if I remember right, 50:1. But obviously I can’t confirm that. When I tore it back down last night, there was lube present on crank halves and wrist pin. Also, fresh lube under the PV covers as well. As far as cooling, not sure how to test for proper cooling, but the impeller spun smoothly when apart and I filled it with fresh Engine Ice.
  9. ca_101

    Problems After Rebuild

    I’m asking for help on getting my new to me 250xc tuned in. My history with the bike is short, I basically tore it down right after bought it, not too long ago. It seemed to run good when I test drove it, but I have no real seat time before tear down. I just got done with a bottom end rebuild last week and took it out to break it in over the weekend. During the 1.5 hrs I rode I was noticing a rattle or knock at about 1/2 to 3/4 throttle, under load. I didn’t catch it at first - been on a thumper for 7-8 years. But it started to strike me as irregular. So I took it home and tore the top end back down to inspect. Parts replaced were main bearings, crank rebuilt w/ ProX rod kit, and ProX B size piston. Worth mentioning that this bike had an SX jug and head installed by PO. Bore measured good for the B size piston by several shops. Here is the piston after 1.5 hrs. Jetting is untouched by me and is: Main: 168 Pilot: 42 Needle: N8RW on 2nd clip from top. Squish: 1.30mm Didn’t do a proper chop, but plug looked good. Now to show a little humility. I hastily decided to run the fuel that came in the bike, which in hindsight, is probably from last fall. I guess I figured it was running good with it when I test rode it and I would burn through it quick. Anyway, now that I have top end off, the crank feels solid and smooth. So I’m erring on the side of pre ignition. Does that sound plausible? Any other suggestion you guys have from the pics? So I’m trying to come up with a plan of action. I do have the XC head. I was thinking about putting the jetting back to stock, putting the XC head on the SX jug and mix some 110 with 93 50/50. My concern is that with this SX jug, I have know way of going back to a baseline, ie stock.
  10. ca_101

    Primary Gear Spacer Sleeve

    Andrew Cooksey just replied to my post over at another forum. He confirmed that the spacer can go in either way. He mentioned that there is a slight chamfer, on the OD of one end, to ease in installation into the crank seal. Thanks again.
  11. ca_101

    Primary Gear Spacer Sleeve

    Thanks for the reply, but there was no lip. One end of the spacer was discolored in a way the other was not. That’s what got me thinking. I installed the discolored side towards the primary gear. Then I though, after it was buttoned up, that the the ‘cleaner’ side probably would have been in the clutch side.
  12. ca_101

    Primary Gear Spacer Sleeve

    Question for the engine builders. I was building my lower end back up, last night, and I am curious about something I may have overlooked. Bike is a 2011 250 xc. The spacer/collar that is behind the primary gear: is it directional? My manual made no mention of a direction, and in my haste I didn’t inspect it’s characteristics well. Now I’m second guessing work. Thanks for any replies.
  13. ca_101

    Piston Read

    Another thing I’m curious about it the base gasket. I now see that KTM offers different thicknesses. I measure mine at 0.50mm. Anyone running a straight 0.50mm base gasket?? Seems like most ppl are stacking them to around 0.70-0.75mm to get the proper squish.
  14. ca_101

    Piston Read

    Plug looked pretty good to me, a nice toasty brown. I’ll snap a pic later.
  15. ca_101

    Piston Read

    So I’ve done some measuring. Cylinder measures 2.614” (66.395mm) everywhere, with a telescoping bore gauge and mic. Spec is 66.400-66.412, so there’s obviously a bit of error in my hand. Having trouble getting a measurement that accurate, though. I even stopped in at a local shop to have it measured with a dial bore gauge. They gave me 2.614” 🤦‍♂️. At least it confirms my method, with the snap gauge. I don’t feel a ridge at the top and the bore looks clean, so I’m pretty confident it’s good to run this season. Crank small end free play was 1.5mm overall. Big end axial play was top of the limit at 0.7mm. Still can’t feel any up and down. Piston was measuring small at 66.281mm. So still trying decide if “it ain’t broke, don’t fix it” on the crankshaft?? Definitely putting a new top end in. Let me know your thoughts. And thanks again for the advice.
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