Engine thoughts?
Page 1 of 2 1 2 LastLast
Results 1 to 20 of 24
  1. #1
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133

    Engine thoughts?

    Engine diagnosis came back after the overheated and it's bad, piston and cylinder are gone. Most likely bottom end damage. Anyways with this kind of damage I'm thinking I'm going to go with the popular 41mm carb, +1 valves, 540 BBK and 8/06 cam. The place that is working on it is called extreme tech ATV in Mount Gilead, OH. He claims to have the machinery to bore it out. Can I trust this? I've read about the cylinder walls getting too thin and that thumper does something on their 540/570's to prevent cracking. Also would it just be smarter to stay stock and go with a 525? I ride trails and sometimes open fields and the 450 is nice but I could really use more. Any help is appreciated!

  2. #2
    Senior Member KTMATVHQ Addict
    Join Date
    Dec 2008
    Posts
    937
    Sorry to hear about your issues. Thumper uses billet sleeves in their big bores so they are stronger. If you are going to have it bored, just have the same place that is doing the plating bore it too. That way they can bore it to the dimension they need to re-plate the cylinder correctly. A 525 has a nice increase in power over the 450 and a 540 has about the same increase over a 525. The 540 does rev slower, but has a ton of torque. If you have heavy sand or a lot of hills you climb then go with the 540 kit from thumper. Otherwise my vote is to just go to a 525 with 12.5:1 compression or 13:1 if you don't mind mixing a little race gas.
    Mine:
    2009 505 SX
    2008 525 XC-modded for mx (currently 450 cylinder)
    2008 450SX-F two wheeler-complete with thumb throttle
    Dad's:
    2009 450 SX
    2008 540 XC

    2016 Sponsors- Oneal, Smith Optics, Amsoil, Twin Air, and Chuck's Welding and Repair.

  3. #3
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    My vote would be to go the 525 route w/ bored carb, 8/06 and FCI and +1 head, 12 or 12.5/1 compression piston. That should get you in the vicinity 54-56 hp. Which I think would be real safe on the RFS.

  4. Remove Advertisements
    KTMATVHQ.com
    Advertisements
     

  5. #4
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Thanks guys! Alright so I'll probably go 525 cylinder, +1 head, 41mm carb, 8/06 cam and porting. Im assuming that you recommend the high comp piston because the 8/06 will take some bottom away so it would offset it? I don't know how I feel about running anything other than stock pistons, maybe KTM is different but they have caused me hardships in the past. Maybe just stock piston with stock cam? As far as FCI goes in OH summer gets real dry and so dusty that it's almost like smoke sometimes. FCI has a K&N style filter. Will it still be safe?

  6. #5
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    Quote Originally Posted by Youngwildandfree View Post
    Thanks guys! Alright so I'll probably go 525 cylinder, +1 head, 41mm carb, 8/06 cam and porting. Im assuming that you recommend the high comp piston because the 8/06 will take some bottom away so it would offset it? I don't know how I feel about running anything other than stock pistons, maybe KTM is different but they have caused me hardships in the past. Maybe just stock piston with stock cam? As far as FCI goes in OH summer gets real dry and so dusty that it's almost like smoke sometimes. FCI has a K&N style filter. Will it still be safe?
    Yes, you will have noticeable loss in bottom end w/ 8/06 and stock piston. I'm assuming the bored carb is for top end? At least that is the way I remember it from my 250R days. I have not run a bored carb on a 4T. Higher compression will help offset the loss in bottom end. I run the 8/06 w/ stock 525 piston and I did lose bottom but the gain in top end was well worth it.

    I recommended 12-12.5/1 Compression because I think that will give you more bang for your buck and still be able to run on non-ethanol premium Rec pump gas. I would say 93, if you have it in your area. We don't have it available in my part of AZ or SoCal.

    But by all means, for reliability piece of mind stay with the stock piston.

    As far as the FCI goes, I don't think there is much out there worse then sand getting into your motor. I only ride the dunes and I will only run the FCI in my quads. I have never had one issue in the sand w/ a K&N style filter (and the FC is more ply protection). The gain is very noticeable.

  7. #6
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by steveo525 View Post
    Yes, you will have noticeable loss in bottom end w/ 8/06 and stock piston. I'm assuming the bored carb is for top end? At least that is the way I remember it from my 250R days. I have not run a bored carb on a 4T. Higher compression will help offset the loss in bottom end. I run the 8/06 w/ stock 525 piston and I did lose bottom but the gain in top end was well worth it.

    I recommended 12-12.5/1 Compression because I think that will give you more bang for your buck and still be able to run on non-ethanol premium Rec pump gas. I would say 93, if you have it in your area. We don't have it available in my part of AZ or SoCal.

    But by all means, for reliability piece of mind stay with the stock piston.

    As far as the FCI goes, I don't think there is much out there worse then sand getting into your motor. I only ride the dunes and I will only run the FCI in my quads. I have never had one issue in the sand w/ a K&N style filter (and the FC is more ply protection). The gain is very noticeable.
    Thank steveo and quad97! The carb boring is for gains all around as far as I know. I'll try to remember to come back to this thread to let everyone know what I went with and the gains and/or losses I noticed in case someone has a similar question. I'll consider the FCI, I think sand is thicker than dust, from what I've read it lets very fine elements through, regular air impurities it can handle, I could be wrong.
    Last edited by Youngwildandfree; 03-07-2017 at 04:30 AM.

  8. #7
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    So what do you think caused the failure? I would also do the Mino pump if it has not been done so already.

  9. #8
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by steveo525 View Post
    So what do you think caused the failure? I would also do the Mino pump if it has not been done so already.
    Forgot to say I already gave him the mino to install along with a rekluse clutch, I know what caused the failure but the guy hasn't "confirmed". I let someone I know ride it and he ran around punning it and I had no clue. I figured it out when he over heated it and proceeded to still run it until I waved him down. He's one of those people that just like to whiskey throttle and doesn't really ride fast rather than just liking to sit on the limiter which I told him not to. Should have never let him touch it. Anyways drained the oil and out of both screens metal everywhere, The one on the bottom that I believe filters the top end made me cringe. 90% sure It started by the piston scraping cylinder shavings and then the metal carried through the oil and took out other things including what looks like to be crank/transmission issues on top of the top end damage.

  10. #9
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    Wow, sorry to hear that. Well, if he is a stand up guy then hopefully he will pitch in for some of the rebuild costs.

  11. #10
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by steveo525 View Post
    Wow, sorry to hear that. Well, if he is a stand up guy then hopefully he will pitch in for some of the rebuild costs.
    I'll not get riled up about it but let's just say it looks like I'll be funding this completely by myself. At least I will get to make more power out of it I guess.

  12. #11
    Senior Member KTMATVHQ Addict
    Join Date
    Dec 2008
    Posts
    937
    All the info I've seen floating around here over the years has shown very little to no loss on the bottom end up to 41.5mm carb. These engines were under-carbed from the factory. More compression does yield more power, but it will also build more heat. I had good luck with CP 13:1 pistons in my 525.

    How many hours are on your engine? My transmission started to go and wrecked everything. If it was being revved hard the main bearings on the crank may have galled up too.
    Mine:
    2009 505 SX
    2008 525 XC-modded for mx (currently 450 cylinder)
    2008 450SX-F two wheeler-complete with thumb throttle
    Dad's:
    2009 450 SX
    2008 540 XC

    2016 Sponsors- Oneal, Smith Optics, Amsoil, Twin Air, and Chuck's Welding and Repair.

  13. #12
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Understood, well I just got off the phone, I also looked at other engine threads and decided that since you don't have to dig into these much I should just get what I had in mind. He said he uses the billet sleeve so the cylinder walls are at less risk. Im getting trail porting with a 41mm carb, an FCI intake, 8/06 cam, 540 BBK, +1 valves and that leaves me with these questions. I heard I am sacrificing little to no engine life as this is a reliable build, this is true, correct? Also he suggested a 12:2 piston which sounded good to me, does that sound alright? And I read to go with the corillo rod with the pro x bearings, is this my best option for con rods? Last question is is there anything else I should add to this mild build? Thanks.

  14. #13
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    With those build specs, would the 8/33 be a better way to go?

    http://www.ktmatvhq.com/forum/outlaw...ge=2&_k=oens3n
    Last edited by steveo525; 03-08-2017 at 08:06 PM.

  15. #14
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by steveo525 View Post
    With those build specs, would the 8/33 be a better way to go?

    http://www.ktmatvhq.com/forum/outlaw...ge=2&_k=oens3n
    I heard the were discontinued. But it being a stage 2 cam I would think yes. It would make the bottom controllable and add mid/top for when I get in the open. But wouldn't it make it rev faster? Therefore putting more stress on my motor?

  16. #15
    Senior Member KTMATVHQ Addict
    Join Date
    May 2009
    Location
    Yuma, AZ
    Posts
    509
    Quote Originally Posted by Youngwildandfree View Post
    Quote Originally Posted by steveo525 View Post
    With those build specs, would the 8/33 be a better way to go?

    http://www.ktmatvhq.com/forum/outlaw...ge=2&_k=oens3n
    I heard the were discontinued. But it being a stage 2 cam I would think yes. It would make the bottom controllable and add mid/top for when I get in the open. But wouldn't it make it rev faster? Therefore putting more stress on my motor?
    I'm pretty sure that they are not discontinued. I would go with the 8/33. It compliments your BB build better than the 8/06.

    You are punching out your motor. So, yes, you will be putting more stress on your motor no matter what.

  17. #16
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by steveo525 View Post
    I'm pretty sure that they are not discontinued. I would go with the 8/33. It compliments your BB build better than the 8/06.

    You are punching out your motor. So, yes, you will be putting more stress on your motor no matter what.
    Yes I understand it's more stress, i was more taking about the 8/33 making me rev even more to get power on an engine that doesn't like It.

  18. #17
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by quad97 View Post
    How many hours are on your engine? My transmission started to go and wrecked everything. If it was being revved hard the main bearings on the crank may have galled up too.
    Sorry just saw this, but I just bought the quad I have no idea. He said around 25 but I can tell you it has more than that. Obviously hard to guess but I'd say closer to 80.

  19. #18
    Member Rookie
    Join Date
    Sep 2013
    Location
    Redding Ca.
    Posts
    42
    The 8/33 cam is still on the market. I purchased one a while back with no problems and about a week wait.

  20. #19
    Senior Member Member
    Join Date
    Jun 2009
    Posts
    182
    The weak point is going to the crank. Thumper Racing upgrades the cranks and trues them up so you can safely go big and more power. Look into it. Safest way is a billet crank but not cheap.

  21. #20
    Senior Member Member
    Join Date
    Nov 2015
    Posts
    133
    Quote Originally Posted by sheriff525 View Post
    The weak point is going to the crank. Thumper Racing upgrades the cranks and trues them up so you can safely go big and more power. Look into it. Safest way is a billet crank but not cheap.
    I'll take a look, they may do things to the crank that helps but I don't think KTM would release a factory 540 at one time if the crank couldn't handle it. I wont be going high in compression either so I can't see that putting too much extra on the crank. All knew to KTM's so could be wrong. Just my thought process.
    Last edited by Youngwildandfree; 03-09-2017 at 04:05 AM.


 
Page 1 of 2 1 2 LastLast

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •