KTM 85cc Motard build

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grnman

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I thought id start a build thread of a KTM 85cc motard project im doing. i have been doing alot of research on it so i thought that this maybe helpful to those also who are thinking about doing it.

Firstly, i chose the KTM over all the other 2-strokes as it has a powervalve, direct link suspension, hydro clutch, Excel rims (to re-sell) and all the other nice KTM parts.
This is it.
 

grnman

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i dont want to spend to much time typing so ill get everything out i can and you can ask about more detail if you like. Firstly the wheels need to be converted to 12 inch motard to compete in the state and national rounds. The big problem with this is the KTM rear axle is 17 or 20mm so the off the shelf motard wheels of 15mm will not work. to get around this you can turn out the off the shelf motard rims and put the KTM bearings in them and then make up some spacer to the wright lengths. alternatively you can lace a motard width rim to the original hubs. this is the option i have choosen as everything will line up easier. i have order my 12 inch spoke kit especially for a KTM85 from here;
RAD Spokes and Nipple Sets
you can also get full wheels and rims as well for all 85's and CRF150's.

next is the brakes. i have done some research and it looks like they make a kit for the KTM 85. it is a 260mm floating disc with Brembo caliper.


and this is what a 260mm setup looks like on a 12 inch rim. it fits...........



and this is what it should do once installed.

 

grnman

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This is the KTM id want to base it off, but im going more for speed rather than spending money on bling bits. here it is boasting the brakes i was talking about.

 

grnman

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And there is the all important suspension. after alot of research, i am please to find out that there are different springs that fit the 85. i am awaiting to here back from these guys.

RACE TECH PRODUCT SEARCH

and the rear spring calculator and product list. try typing your weight in.

Spring Rate Calculation

i can start talking about engine stuff yet as you could spend a day on it. but suspension and things come first anyway. i hope some of these resources can be of use to other that are thinking about this kind of conversion.

-Dave
 

rumble

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Ahh man....

Hate these inspiring threads :(
 

grnman

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Ahh man....

Hate these inspiring threads :(
hey, by all means stay with your current setup rumble. just expect me to come flying past you in the open class next Aus titles when i work out how to get the 2-stroke off the line quickly enough.
 

FMX_22

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Niceeeeeee . I have 2 questions . 1 y did you choose the ltm over the yz or cr? .2 how meany hp should you be able to get out of it ?
 

grnman

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the KTM has a power valve and therefore has more torque down low for a heavy person. it also has nicer suspension and other parts.

people have gotten 33hp out of these things (not rear wheel) and with what i will eventually do, it will be big man. but thats last.
 

grnman

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i have ordered both front and rear suspension springs and spoke kit. have 2.15 and 3.0 inch rims to lace them to. hopefully will have this bike on the tar in under a month.

springs cost $240 and spokes $140 plus postage. rims cost $140 and CST tyres $120.

for all you motarders considering it, my bike cost $1,900 for a 2007, plus the mentioned mod's to make it competitive and fast. totaling $2,540. id rather that than a $3,000 pitster pro to race.
 

ringo

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Too right Greeny,

There seems to be a misconception that using a jap 2 stroke is too expensive. :confused-smiley-014
Even if you bought one new it would cost less than some of the bikes on display at Phillip island!!!

I've currently got my eye on an sx 85 '07 advertised for $2500 over here in Perth with 0 hours since top and bottom end rebuild.
 

grnman

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dam that sounds killer. just dont make yours better than mine. hope some of my info has been helpful. a full rebuild kit cost $585 just for your reference plus labor.

yes that is why i created this thread to show its possible and its not too expensive. it might be another story doing a CRF150R though.
 

ringo

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dam that sounds killer. just dont make yours better than mine. hope some of my info has been helpful. a full rebuild kit cost $585 just for your reference plus labor.

yes that is why i created this thread to show its possible and its not too expensive. it might be another story doing a CRF150R though.
Well the labour will cost me nothing!!!

Seeing as I can never "leave well alone" it is inevitable that mine will eventually go well. I recently ported a 50cc BZM engine for a mate over here and compared it on a rolling road with a parilla engine, parilla 18,990 rpm BZM 18,980 rpm no way of telling power but we use the rolling road to check max revs with different headers. Not bad considering the BZM is supposed to be the inferior engine.... well stock anyway!! The parilla was far from stock aswell!!!
 

grnman

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thats it then, the engine modding comp is on. you've peer pressured me. ive got my mill setup to re-work the head and got some inside data on the squish band, angle and head volume coming. im not going to do any of this until i have enough funds for a bottom end rebuild as well as this thing is going to smash out some serious power. hand tig welded pipe would be nice as well.
 

ringo

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It's OK, I've still got my hacksaw and gimpy!!!!

Should of seen the look on my mate's face when I laid into the reed area of his $5-600 crackcases with a hacksaw.... 8D...... Priceless!!! He was very happy with the result though.

Yeah I'm gonna have to research all the squish settings, have a look at some crankcases and transfer port quality of these engines, I've spent the last 6-7 years mucking around with smaller stuff and it's time to step up!!!

At the end of the day it's still mass produced and cast, there is always room for improvement with a steady hand!!
 

sean01

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most ktm 2t gasket kits these days come with a couple of different thickness base gaskets so you can tune the port timing to suit the application, well that and to overcome some height issues that come about from the barrel being machined to much during reco stages..
tho obviously if you find the thicker gasket works best then machining the head down a bit will make it even better..

and yeah, a decent clutch basket, plates and springs is a must..
 

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