1996 cr125 project

[rufus1138]

Hey guys...first post here....I'm on the last leg of working the bugs out of my sadly mistreated cr125 project....lovely bike great Honda twostroke engineering rides like a dream but the catbureated needs rejetting....here's a short run down of the motor story so far...i bought it running but wouldn't idle...after everything got shook out it had been adjusted to cope with an exhaust leak and blown out reeds in a first gen rad valve cage...switched to a vforce 3 setup with a little garage level machining to the rad valve cage and resealed the exhaust....still need new pipe springs at the moment bit its not leaking so the next item on the menu is the catbureated....we have adjusted it back to a good idle and done everything we can manage with the slide needle...still starving for fuel in the top end....its not wrapping out all the way to the top....pulls like a hoss in the mid and low power band but its not smoking enough and just running out of gas about 1/3 of the way up the powerband I just wanted to test the waters here for suggestions on main and pilot jet sizes for this setup if I'm gonna go for hare scrambles at my local track....pensacola Fl basically sea level usually hot and muggy....for a recap I'm working with a high flow intake manifold from the old boyesen rad valve a vforce 3 series reed system an old fmf fatty gold series pipe and the standard khein carb from 96 with unknown jets and needle....any suggestions about where to start or what direction to go from there 

[cnrcpla]

With the modifications on there, depending on if the jets are stock or not, you probably need to go up a size or so. When you order them, the company you order from should know about what size you need.

[rufus1138]

thanx, ill definitely keep that in mind when i get started here in the next week or two, i gotta get time to go visit the bike, its about an hour away from me at the girlfriends house, 140 acres and a barn is a lot better than my city apartment, ill keep an update on here tho, from what my internet digging pulled up it seems that pro circuit and fmf both suggest going smaller from stock, but im gonna make sure i start from factory settings.

[cnrcpla]

Yeah, definatly check what the stock size should be, but going smaller would would make you run leaner, so keep that in mind.

[SachsGS]

What brass are you running in the carb. now? A sparkplug photo would also help.

[rufus1138]

I haven't got the chance to open the carb up....the bike is an hour away at the test track and my last visit was spent modifying the old rad valve cage to mate up to a new v force 3 setup....made a huge difference but I'm not getting the overrev still I gotta get out there this weekend or next and take it apart/ figure out what model number that damn carb even is....I looked on the kiehein website last night and I'm not even sure what one I've got now lol

[Super Trucker]

If I remember right,the 95 and up cr125 had a rich main jet stock-no topend.With a leaner mainjet you get the topend back,a plug check will tell ya where your at. A 125 properly tuned is not supposed to idle,for a mx track,for trails I guess getting your bike to idle would be ok tho. Your powervalve is problembly gooded up,and needs cleaning.Warm engine up,ride wideopen then kill engine,while wideopen,pull plug,if it,s not brown,it,s not jetted right.

[rufus1138]

Yeah that's the wierd part....I haven't been getting white plugs like I would expect with it being lean bit from the visual indicators of the smoke it seems like its only lean at wot...smokes a little down low....I just gotta get the time to go up there and take the carb down and index what I've got....ill be happy when I get that top end back...the 96 frame is so perfect its a shame its not running right

[ford832]

the 96 frame is so perfect its a shame its not running right

A 96 CR frame with a 6spd YZ engine in it would be a rocking machine.There's your next project rufus-now get to it! 

[rufus1138]

the 96 frame is so perfect its a shame its not running right

A 96 CR frame with a 6spd YZ engine in it would be a rocking machine.There's your next project rufus-now get to it! 

im really not a fan of the yz powerplants, i would love to shoe horn a 01 cr250 motor in there eventually, or a ktm 200.....u got me thinking now, massive power upgrade in the future for sure, ill be posting up pics next time i get out there to the bike, ive decided to keep it a sleeper bike for a while tho, im gonna get this 125 working good and start freshening up the hardware and frame, powder coating everything but keeping the ragged out old plastics on it, just to keep most ppl off the scent

[rufus1138]

Been digging arround about my missing rpm's and I've got an interesting question....in a 125 do u usually run a more lean oil mixture...and how much if any will a super rich oil mix effect the top end rpm figures....I've been running the motul 800t factory line oil at 32/1 or 3.5% and just noticed they suggest running this oil at 50/1 or leaner 2% or lower....thoughts/input plz

[MetalMike1982]

I run a 32/1 ratio with synthetic Honda hp2 oil in both my 03 rm125 and my girls 91 cr125 with zero issues . That ratio should be fine for your bike

[rufus1138]

I have a feeling that hp2 and motul are worlds apart as far as the chemistry goes.....I'm just thinking slit since I can't wrench on the bike lol

[rufus1138]

Well got out to the girls place Sunday and spent all day on the bike working out with my best friend who's gonna jockey the bike for me in local races....he just has more experience than me and enjoys the competition more than I do....we got the carb apart and it ended up being just a clogged air passage....and I could definitely stand to replace my air filter....its ok but its robbing just a little bit of top end from us still....but it will now rev out properly and its pulling reliable wheelies in 4th so I'm happy with the improvements....pics when I get home....some minor tweaking and cosmetics soon then me and austen are gonna start hitting the local scene and with luck the goal is to earn some ameture sponsorship

[MetalMike1982]

I have a feeling that hp2 and motul are worlds apart as far as the chemistry goes.....I'm just thinking slit since I can't wrench on the bike lol

Not sure about motul but Hp2 is the cleanest burning 2t oil Ive used .