Tri-z 250 race bike build

[nitrometh king]

Hey guys I'm going to build a tri-z race bike kinda I'm thinkin of bumping up the compression some boyseen power reeds and a 38mm pj carb off a cr500 rejet the carb port and polish done by madman eng and plan on some suspension upgrades not sure what tho cld u guys give me some tips on any mods that work good let me know what u think

[torker]

What type of racing will you be doing? Moto-X, Flattrack, Enduro? What year is your Z? Some of the mods will depend on the type of racing you'll be doing. Will you also trail ride the bike?
X owner
TORKER.

[nitrometh king]

It's a 85 and I ride trails just wanted a tight setup that'll scare me when I hit the throttle:naughty:

[MudBug]

:lol: just ride that 88mph 175! :lol: seriously though, it shouldnt be too hard to find the right set up for your type of riding. I dont think you would need anything on the bottom end

[torker]

This is what I would do personally.
1. Stage one Yamaha wrench report, dont wanna ruin the Z great trail characteristics, it's the best in my opinion. Don't forget to spend as much time as nessesary tunning your bike, this is the most important step.
2. Warrior Elka/Axis/Fox etc. Rear shock, they pop-up once in a while on e-bay for a good price. Set-up as nessesary.
3. ATC 250r front suspension (you'll need the 86 Z tripples) with progressive rate springs (these are fairly inexpensive) and heavier weight susp. oil. If keeping the stock front susp. try playing with 83-84 suspension internal parts (search the forums, not sure if it works for the Z). Make sure all your bushings and bearings are in top condition. All of them.
This should give you more than you're looking for suspension wise. Don't forget the all important tires !!! Withouth good tires the suspension cannot work at its best.
20" in the back and 23" in the front. Hope this helps a bit. Now spend some money and go do it !!

TORKER.

[nitrometh king]

A how did u know bout my 175 and be sounds good for those mods I do keep the bushings clean and I'm thinkin about rebuilding my shock and money is very tight right now so cld it be possible to build the forks to hold a 260lbs person? what about the boost bottle is bigger better or is smaller? and has annyone ever ran the the pj carb?

[torker]

Well, you can re-build the front forks. The Z forks can use motor oil. For 260# rider I would use 30 weight motor oil. Get a service manual It will tell you all you need to know about the suspension, including the amount and type of oil needed for your aplication.
The PJ carb is very good, provided is in good condition. I would not go more than 36mm for trail riding. The boos bottle is not a big help.

TORKER.

[Tri-Z 250]

I'd go coolhead, water pump impeller by Sprock, full DG pipe/silencer, Gforce, or other aftermarket banshee axle +4" A large carb really isn't needed if the Z's-tunned in. You can port the other window into the head; and thats what I'd do if you really going large carb route/open air filter. As mentioned suspension in the rear comes by at a large $price tag(well worth it) but a Custon Axis new is $850(ebay one for $200-350: re spring and recondition will run $225). You can use pvc(1"-3") to stiffen the old fork springs. Rumor has it there is a knock off brand that has a 23" holeshot style front tire for the Z...keep your eyes open for that. Out back traction depends on rim&size and personal feel.

[nitrometh king]

Is it possible to get close to 50hp out of this bike

[audioworks04]

It would be possible, but it probably wouldn't make for a very nice trail bike more of a duner or drag bike. In order to make 50 your looking at high compression, portwork and timing along with a large carb and lots of fuel and possibly big bore. Personally if I was building a tri z trail bike I would do like others have said and up grade suspension first, then possibly light portwork, but nothing extreme as to raise powerband or make less reliable. HP doesnt really mean a whole lot in the trails, its about ride-ability and a machine that can be lugged around without fouling plugs but get right back with it.

[nitrometh king]

Ok I was justwondern if I cld get close to the horsepowr as the 09 yz250

[torker]

H.P. / Speed is money...How fast you wanna go ???
Now, money does NOT necessarily means H.P. / Speed !!!
TORKER.

[nitrometh king]

Well i want a reliable motor I'm going to increase compression on one of my hEads and get the cyclinder ported and polished maybe have it niksil coated and have swain tec coat my piston

[nitrometh king]

What about pipes I have the full stock setup and dg both are dent free where do the pipes range ie low to mid
mid to top wich muffler works best stock with dg or dg with stock
pipe or is it better to keep them together Ps when I say trail
I'm talkin open areas where there's enough room to do 100mph on my cr500 so the 75mph that cooked this thing at is a little behind my dads and brothers 250s and I'm gettin suspion takin care of so it's down to
tire motor and gears I'm goin to run a 22in Itp holeshot with current gears and see how it does

[nitrometh king]

New update Iv got the forks off a 1985 cr500 cld it be possible to shortin them to use on my tri-z

[nitrometh king]

Hey iv got the pj on the way what's a good place to start jetting the bike?

[nitrometh king]

Is there any way to shortin some forks off a 85cr500 to make them fit

[torker]

I think you need an organized work plan and a realistic goal and time frame...And stick to it.
If you improvize a lot, the project will run forever and your budget may run very high.

TORKER.

[nitrometh king]

Well after talking with a freind for an hour yesterday iv finly decide to raise the exhaust port 1.5mm clean up the other ports put a 36mm pwk from a kdx200 and put the pj on the 200 getting stiffer springs and have the bike revaled and also milling the head for a little more compression and boyseen reeds with some 22in itp hole shots and I'm still tryin to figure the front wheel I'll post some pics as I go thanks for all the in put

[tri-Z ripper]

go with a kehien carb 35-39 v-force or just boysen reeds with a fresh top end and you'll be holding on trying to keep the front tire down! don't forget the head pipe and silencer!

[nitrometh king]

Well I already ave a full dg system the port work well provide a better transition as will the reeds I might folow the tri-z wrench report stage 1 for porting a new filter and bigger carb well really let it breath also with the suspion work and tires I should be much faster I well check the top end and see if it's still good

[volfan537240]

there are a few front tires on this list

http://www.denniskirk.com/jsp/tpl/cmn/prodlist.jsp;jsessionid=NE5UTLJYA3JIDLA0WTVSM4VMDK 0NCIV0?store=Main&category=10802&av=126:10144,28:2002,95:5638