525 Engine Build

[TYLER329]

Getting ready to tear down my 2007 525 IRS engine. Anybody have any good suggestions on a good XC package? I don't need alot of power, mostly just reliability. I am thinking of upgrading the valve train, piston, and cam. What is a good combo for reliability and horsepower? Need to be able to race 2 hour long harescrambles with the stock radiator and no heating problems. I have got 3 seasons out of the stock motor with only 1 valve spring retainer failure. Any help or previous experience would be greatly appreciated.

[bmerriman12]

id worry about suspension before i touched anything with that motor. i think the 525 is a little too much for xc racing IMO.

[grantmi]

I think Tyler has done almost as much with the IRS suspension as is possible!

[TYLER329]

You are correct. Suspension money is the best money spent but I got that covered. It is just time to freshen the engine.

[somewon]

I have the 540 kit in mine with no mods to the head or valve train and it runs like a champ. I haven't had any over heating problems with the kit. I'm running stock radiator and stock hose set-up. the only change I made to the cooling system was to use a different fan. The only time I ever saw the temp light on was at little sahara on a hot day diggin throught the trails at slow speeds. I've got some time on it since the install and no problems yet.

[TYLER329]

Where did you get your 540 kit and how much was it?

[OutlawBill]

kTM kit around $800 thumper Racing $540
http://www.thumperracing.net/mybikeproduct.php?tpn=KTM540BBK&model=OUTLAW450_525

[somewon]

I had duncan racing do mine, and I wouldn't compare my cost to what you could do it for.

My quad took an unexpected bath at WOT without me on it. There were many many things destroyed when that happened, so I decided it was a good time to upgrade.

[cmpearce]

will the crank bearings handle the bigger piston? i have read of the big bore ktm engines being destroyed after a big bore was installed.

[somewon]

I've had no problems.

[TYLER329]

Top end is off and everything looks very good according to my friend\mechanic\trailer provider. Slight scoring on the piston and the cylinder just needs to be honed. Very good considering the punishment this motor has had to deal with (alot of overheating in the mud races before I finally bi passed the thermostat.) He said he will have the bottom end apart today so hopefully I will just need a forged piston, gasket kit, and new clutch plates!

[fasterblaster02]

how many hours are on your motor? I have about 45 on mine and wondered how long yours lasted. Also do you have any pics or can you explain better about the bolt that comes loose on the "ferris wheel type setup" that causes problems with staying in ger? I thought you said it was on the flywheel side?

[al capone]

Hey faster I remember u said u lost ur chain a few times. I put a new one on and my shifting issues were less I think my chain put irregular tension on the sprocket because it was bent and caused my quad to not want to shift properly. (about ur staying in ger issues)

[TYLER329]

The motor has about 100 or so race hours on it. I am not the guy to ask on the taking apart or reassembly of internal combustion engines.

[TYLER329]

whoops, i hit submit to fast. anyways it is actually behind the clutch basket.

[fasterblaster02]

Hey thanks guys.
al capone-it is funny, I was looking at it the day before you posted that about the chain, and noticed it is doing that exact thing. Anyway, a new chain is on the way.

Tyler-thanks for that, I just couldn't see what you could have been talking about if it was behind the ignition cover. I do hope I can get this motor to run for another year and may tear it apart then and at least put new rings in it.