DRZ 125 piston Q's

[gman255]

I'm Look'n for some piston measurements (DRZ/KLX 125, stock/wiseco) for a custom BBK project. Does any one have a piston lay'n around for some numbers?

Top of piston pin to top of piston (deck)

Top of piston pin to top of dome.

Piston dome solid? (Machinable to modify the dome/cut custom valve reliefs..)

Thanks

G

[smrmx14]

are you using in drz or xr I tried on in my old xr big bore cylinder and piston is way to tall.

[gman255]

You know me to well. lol

I don't mine some machining the piston (sure looks like it could go on a diet any way), fab'n cylinder spacer for the XR jug, playing with the timing chain and all that good stuff!

[smrmx14]

the wiseco I tried had huge dome but I played a little with it but really haven't messed with the xr motors since I got the drz motor running good.

maybe I will revisit it later.

[gman255]

Planing on picking up a Big valve head (Takegawa, Kitaco, Shiftup). These combustion chambers are significantly larger/open style. (12cc for the Take' Superhead/9cc for the stocker)

Interested in the largest bore possible with a resleeve (59mm). The DRZ 125 pistons looks to have plenty of material to machine any compression ratio that I choose. Also retaining the stock XR 14mm wrist pin, leaving the option to build a 11.5mm stroker with aftermarket crank/s (155cc) down the road.

[gman255]

I imported a raster image of a Wiseco 11.5:1 piston into autocad, and scaled it up to 1:1

These measurements should be pretty close, +/- .5mm

Top of piston pin to piston deck = 17mm

Top of piston pin to top of piston dome = 27mm

My only concern is if the dome is forged solid?

Can any of you DRZ motor heads confirm?

[BruceD_500]

which wiseco ? the 143cc piston ? I have the old 190cc piston from wiseco/Vance&Hines it's a low dome and not solid under neath. Not enough to mill a bunch off any how .

Some of the pistons I was looking into when I was trying to find a cheap combo was the newer 200-2010 GSXR600 pistons they are the same pin diameter and have a bigger bore. I never did get hold of one to take measurements. Check the wiseco web site for these but I think they may be a bit too big on the bore for what you after.

[gman255]

The Wiseco 59mm 133 kit.

All the Wiseco piston offerings for the DRZ are 11.5:1 CR

I'm pushing the limit with a 59mm bore. Cylinder stud spacing isn't large enough to go bigger with a sleeve. They're 61/62mm BBK's on the market for the XR100. These use (sleeve less) plated cylinders and skirt less pistons (aka SCUT kits)

I've looked into some other piston opitions. A common BBK back in the day use a machined 58-59mm piston from the old 80's Kawi GPZ/KZ/LTD 550 street bikes. This engine was brought back to life as the ZX 550 Zephyr in the 90's. Kawi has discontinued the pistons part numbers. No after market replacement that I've found. Wiseco only offering is a Big bore 61mm (615cc) for these engines.

I was able to score a new 58mm GPZ 550 piston from ebay. The dome isn't large enough for the CR I'm look'n for with a aftermarket BV head.

Spent some time on the Akunra site as well...Some piston option with a rod swap (13/15mm pin dia.) Or ream 13mm piston out 1mm? I'd Like to retain the 14mm pin, for aftermarket stroker cranks option.

Also looking for some info on KLX140 pistons, as well. There is a 59mm over bore through Kawi. No aftermarket as of yet, just the 61mm BBK offered by BBR and EO.

[chete44]

Hi everyone .Bruce, Gman :What BBK means?

Yep Gman, Stock DR125DualSport Piston : PinTop/Deck=17mm ; PinTop/Dometop= 25mm Skirt/Dometop=61mm(sorry, mine sizes that!).

-Stock GSXR600 : 67mmDia/14mmPin, PinTop/Deck=15mm; PinTop/Dometop= 17mm.

Skirt/Dometop=41mm ; its shape is mainly flat with 4valve pockets=3.5mmIN/3mmEX), the good bit is : it feels similar/even lighter in weigth. There are aftermarket BigBores to 70mm Diameter for a GSXR600 Piston.

-The bad bits are : you cant get a decent CR with a DR/LT head : I´ve grinded mine to the limit(valve seats) with disappointing results. No problem with cylinder, I used one off a LT230(ebay) for 30$(1mm overbore included!) Grinding it 4+4mm=8mm off the Top/bottom (DR cylinder is 69mm tall,while LT is 76mm : 69-76=7mm); next step is a 4valve Head (HYousung) but these are hard to come by.. .Does any1 have one?

-Another Issue : Cam chain gets too loose ; Bruce : do you know wether DR100/LT160 are shorter?

- The Biggest 13mm Pin Piston I know of : is 69mm from a Honda GCV200 utility engine (Lawn,Waterpumps etc.)here you have its figures:

69mmDia/13mmPin, PinTop/Deck=14mm; PinTop/Dometop= its Flat,sligthly hollow

Skirt/Dometop=45mm. It comes Chromecoated? .The bad bit its that its rev.Limit is under 4000revs (cruises at 3600rpm only!). I wouldnt dare to fix it anywhere.

[chete44]

Gman : Sorry I forgot your question ,DR125piston: I measured inner Top/Skirt=55mm,DomeTop/Skirt:60mm; 60-55=5mm Dome thick; pretty heavy, but this makes sense to keep a balanced engine when you go to bigger bores (remember how alike feels a GSXR/67mm piston.

[chete44]

Sorry, I was completely off topic, my apologies.

Gman : Arent chinese engines a copy of XR100s? cant bigbore kits fit them then?

I found these two with14mmPin 63mm,65mm, pretty doomed.

http://www.agbikes.es/tienda/index.php?main_page=advanced_search_result&search_in_description=1&keyword=piston&sort=20a&page=3

[gman255]

Thanks for the info Chete44

Is your piston's Dome solid aluminum? Possible to machine the dome and valve reliefs?

There are Vertical China copy engines stating 100cc, Lifan, Loncar etc. These look to be based around the larger XR200 engine famialy...?

Your link is for the horizontal Lifan, GPX, Jailing, etc. engines. I have seen some 57/58/59mm bore pistons with a 14mm pin, on some of the PitBike sites, That may be an option. I am restricted to a maximum cylinder sleeve O.D. of 62mm, A 59mm piston is pushing it.

BBK= Big Bore Kit

[chete44]

If, as I suppose, we´re still talking about stock DR125(art) the answer is yes, it all depends on how far you want to go , and yes it is SOLID Alu(+-100grs.). As I said the piston is pretty heavy for a 125. I´ve measured comparing figures from the inside to the outside : by least 5mm Dome Thickness(top center), getting thicker the more you get to the outer border. you have too 5mm from Top-topRing/Deck

What is your Head? is it 2valves?.

-I whould choose a overbore cast piston(ART), as its walls are thicker, instead of the thinner forged ones(wiseco),so you´ll have more room to grind out; however I´m not positive as I´ve not one to compare.

[gman255]

The stock XR100 is a 2 valve (23/20mm) head. Looking to up grade to aftermaket Big valve (28/23mm) head.

I'm just gonna have to splurge on a piston, give it a go, and see what happens.

[chete44]

Gman :

I´ve Seen this:

http://www.ooracing.com/store/index.php?act=viewCat&catId=65

[gman255]

A while back, I spoke with OOracing about that piston, via email. I was ready to purchase. However, They weren't very cooperative in informing me of the shipping details and payment information. They never responded with a total, even after a reminder email...?

I may pick up the phone and try again.

I also haven't seen that piston advertised any where else

[bbr 150f]

gman try akunar.com

[gman255]

I've searched the akunar site. Some option with a 13mm pin rod swap. Slim pick'ns with the 14mm pin and At least a 58mm bore with a good size dome.

Have you come across that OOracing piston anywhere else?

[bbr 150f]

they get there pistons from akunar. shoot them an email sometime they have more than whats on the site.