SX engine - 6 basic mods

[kiwi-craig]

This is my thoughts on a handful of simple mods to enhance the SX engines reliability and longevity

1/ FIT AN HOUR METER & CHANGE THE OIL REGULARLY

Self explanatory really...... fit an hour meter and keep tabs on the oil change interval. These engines need fresh high quality oil, change it often !

Oils cheap, rebuilding one of these engines is most certainly not.......

Recreational riders, you will be surprised at the ratio of engine run time vs actual elapsed time (less run time than you think).

those on a budget go with Rotella, and dump it out every 4 - 6 hours.

Racers: change it out after each race weekend, you need to be keeping tabs for any "gunk" in the oil (metallic and clutch gunk).


2/ CLUTCH PACK

Replace the stock KTM clutch pack (9 frictions / 8 steels) with a Honda pack (8 frictions / 7 steels)

450CRF 2002-2008

22321-kz3-690 (x7)

22201-meb-670 (x8)

You cannot use the Honda frictions with the KTM steels, the stack height is to "low".

The stock KTM frictions generate allot of ultra fine black wear particles, these are fine enough to go straight through the oil filter, basically it's ultra fine clutch friction material........ this is also what degrades the oil (makes it appear black). This in part is why KTM recommend such short run time - oil change frequency, you gotta get that clutch gunk out of the engine..........


3/ CLUTCH SPRINGS

add a replacement set of HD clutch springs (for the KTM 450 - 505 SX-F dirtbikes)

Pro-X part number SPRING KIT 17.CS64042

can't find the Pro_X, check with EBC or Barnett they do uprated spring kits also

EBC part no 15-17136

the stock springs are on the whimpy side, I've experienced clutch slip / delay until the clutch bites in, in the higher gears in hi traction situations. With the stock frictions this peels off strands of ultra fine clutch fibre that then builds up around the oil pump intake screen, looks like sodden cotton wool !! all the more reason to ditch the KTM frictions as per 2 above whilst your in there.

4/ CAM CHAIN TENSIONER & OIL PUMP SHIM KIT

Replace the stock cam chain tensioner with Dave Hopkins manual unit, and block off the oil supply port to the tensioner (threaded plug is include in Dave's kit). It's a real nice piece and hands down better than the one I bought in europe (and didn't even fit right...)

[attachment=4153:djh1300_or.jpg]

http://www.djhcyclesport.com/

see Daves videos

http://www.djhcyclesport.com/Installation

Once installed then add two factory shims to the oil pump relief spring (do not do this with the stock tensioner)

shim part number is 0988060121... 1 mm shim cost around $.44.

Go to page 20 of the SX engine spare parts manual. The shim goes on the end of the relief spring (part number 26) in the end plug (part number 28). Check your spring free length is at least 38mm.

you have now increased oil pressure throughout the whole engine by around 8 psi and increased the flow to the critical cam shaft finger follower area in the head.

For you XC guys, Dave also does a unit for these (refer the RFS tensioner)

5/ WATER PUMP UPGRADE

these engines have a tendency to run hot, higher the air temperature the lower the margin to over heating becomes, this is more critical in a race engine than under recreational use.

Mino (Holland - Europe) and now KTM Hardparts both offer an upgraded wider impeller kit to increase flow around the cooling system.

See my review of the Mino unit here: [attachment=4154:Mino.pdf]

Mino Website

KTM HARDPARTS: KTM Part Number(s): 77335955044 (ignore the tag regarding the Akrapovic exhaust, that only relates to the two wheelers).

6/ CARB VENT LINE FILTERS

the FCR carbs have a number of vent lines, there are two from the carb slide area. The slide area can get dust in through the vent lines, this then forms a gunk - paste that then prevents the slide face from sealing in the carb body, the engine then runs really rough and has all the symptoms of an intermittent ignition fault with major misfire occurring, this is due to the engine now pulling air up through the vent lines and around the slide bypassing the the needle jet......... the increased vacuum through the vent lines then sucks in major dust and the whole process get worse quick to the point it will barely run.........

the SX seems very prone to this compared to other FCR equipped engines.

A cheap fix is to squirt foam filter oil up the tubes (don't over do it), the better fix is to install a vent line foam filter, there are a number on the market.

One of the better units is the 7602 filter setup

http://www.7602racing.com/prod_t6cf.php

[attachment=4155:4_wheel_..._filters.jpg]

Dave (the tensioner man) has these in stock, get one to go with that new tensioner !


Cheers


kiwi

[amquadracing]

Once again kiwi, great post, some killer info there!!!

[kiwi-craig]

I added one more, the carb vent line filters so now 6 simple life enhancing mods !

[hamilton]

Thats is so cool, you took the time to make that post! Thanks!

[Oloof]

Is it strange that I after 40 hours runtime haven't noticed any off these things as a problem?

[kiwi-craig]

Count yourself damn lucky then......... Clearly you don't work your clutch hard.

None of these things are a show stopper, but each will enhance the life of your engine especially as the hours build on it...... it took 30 hrs before we started to hit "niggles" shall we call them........

My post is based on actual issues I've faced in the 09 national events over the course of the years racing, and the "fix" implemented.

I'm hard on engines....... the aim is to win, not pussy foot around........ and yes I run a fully built engine cranking around the 60HP mark........

The carb vent lines problem damn here cost me a TT championship, we had the whole damn electrical system out between races, changed CDI's, plugs etc looking for the intermittent electrical misfire........ one of the guys spotted the vents lines where really dirty, soon as we cleaned the gunk out of the carb slide area (and man there was a truck load in there) - FIXED......

[Oloof]

Yeah I problably am! But I can't say that I'm nice to my engine when the gate drops!

But I'll check that vent lines and the cam tensioner. Seems like a good thing to do.

[SIDCON]

Awesome Kiwi, A one stop thread for all the updates. I just ordered the vent line filter, I never even heard of them till your post. Trying to order the Pro X springs but cant find them anywhere here in the states.

[kiwi-craig]

Clutch Springs: try EBC or Barnett

[997GT3]

Once again kiwi, great post, some killer info there!!!

+1

[oakley_xc]

How do I tell if I have the tensioner (djcycles) set right. I followed his instructions, but it's not real clear on where to set it????? Is this
something I can measure or does this not have to be perfect???? And thanks Kiwi for the tips...

[sticko2]

How do I tell if I have the tensioner (djcycles) set right. I followed his instructions, but it's not real clear on where to set it????? Is this
something I can measure or does this not have to be perfect???? And thanks Kiwi for the tips...

i did mine (not the dave hopkins one but similar) hand tight then felt the chain around the top gear and went from there. I feel that the cam chain doesnt have to be tight and there should be a small amount of play.

please anyone correct me if im wrong.

[997GT3]

Yes you don't want to tighten it to the point where you put stress on the cams.

Also should not be too loose where it can skip a gear.

What I like to do is..Tighten it by hand to where I can feel the tension start point.Tighten it another 1/2 turn and lock it in.

Start the engine and get it up to operating temp.Shut it off and redo the tightening process all over again with a warm engine.With the engine warmed up I get a better feel of the chain tension and dial it in nicely.

Hope this helps..

[jtempleton]

Wiseco carries the Pro-X Clutch Springs. I had a little bit of difficulty finding them as well. They are roughly $25.00. I posted the link below.

Enjoy!!

http://www.wiseco.com/ProductDetail.aspx?I...amp;AppID=37099

[ktmbill]

The KTM basket is a gernade with the pin pulled . wiseco basket is a must have . The 2010 and newer are better. We blown 2 with in 2 months time.

[flooringit]

does the xc have same problems with the vent lines? Alot of the vent lines are dirty on this carb.

[kiwi-craig]

XC- yes but not as acute

[harry_ss]

Is necessary add a replacement set of HD clutch springs if I buy the honda clutch pack?
If i go with honda clutch...the springs should be purchased for KTM or honda?

Thank for your help!

[kiwi-craig]

not necessary to change the springs. If you do, it is for aftermaket KTM 450 SX-F dirt bike clutch springs

[harry_ss]

Ok, thanks Kiwi!