87-yz250 ??

[ron89]

hi i have a 1987 yz250 i bought it acouple weeks ago it needed a piston and rings .. so honed out the cylinder, got a new wiseco piston and rings, and replaced the top end gaskets and all that but didnt do the power valve 1s yet .. umm i got her running good today.. but i think its runing lean i did let it idle for the break in and so on .. and i took it for a ride and just got on it a little bit and when i stoped the idle seemed to be a bit hight and it seemed to be a bit hot.. i have a little vid ..

i was thinking of upping the main jet .. but i dont no what the stock main is for the 87 250. this way so i can order some bigger 1s. i have worked on 2strokes befor i have 2 blasters that i work on ..

umm does any 1 have any pics of how the power valve gets hooked up?. so i can make sure i hoked mine up properly ..

thanks Ron ..

 

[CarnageZ28]

Main jet wont do anything. That handles your throttle from say like 3/4 to WOT. If it is mid throttle from like 1/8-3/4 7/8ish, try moving the clip on the needle jet a hair richer. And if its from idle to 1/8 throttle, thats all on the pilot circuit where you would need to step it up a notch with the pilot jet.

And I may be trading a guy a blown up 125 for a Blaster so I might pick your brain on a few things in the near future lol. It has no rear brakes. It is missing the caliper and everything but I am hoping there is a cheap alternative?

 

[ron89]

Main jet wont do anything. That handles your throttle from say like 3/4 to WOT. If it is mid throttle from like 1/8-3/4 7/8ish, try moving the clip on the needle jet a hair richer. And if its from idle to 1/8 throttle, thats all on the pilot circuit where you would need to step it up a notch with the pilot jet.

And I may be trading a guy a blown up 125 for a Blaster so I might pick your brain on a few things in the near future lol. It has no rear brakes. It is missing the caliper and everything but I am hoping there is a cheap alternative?

ok thansk for the reply man .. i seen the pilot jet in the carb but never touched it .. what do i just take as mall flat head and turn it ?.. it wouldnt let me post up the vid idk why.. like it ran great but when i would like cruse in first gear it would like jult or some thing i am guessing thats from being lean?..


thats fine with me .. mm i just hooked up some hydro breaks didnt cost that much i would say like 30bucks to make lol .. u can pm me when u can it or check out .. blasterforum..

 

[ron89]

the needle is allthe way down .. should i up the pilot jet and the main??...

 

[CarnageZ28]

To take the pilot jet out, you just use a small flat head and turn it counter clockwise. Maybe consider cleaning the whole carb out though? Take that out, the main jet, take the floats off/adjust, and clean everything. Blow the passages all out with compressed air, etc.

If it is lean, it will ping/detonate a little bit under loads, run hot, and sometimes idle a little high.

Before you get to far into it though, make sure the boot from the carb to the reem cage is not dryrotted, and the gasket around the reed cage, cylinder base too. Spray them with starting fluid with the engine running and the RPM's will change if there is a leak.

You might not have to play with the carb as much as you think. Clean it out good first... Also you said about changing the main jet, that primarily deals with the air fuel metering from 3/4 to wide open throttle. To test this, you need to wind the bike out in a higher gear 4th/5th with a fresh spark plug. As you near redline, Kill Switch & Clutch. Coast to a stop. Remove the spark plug. Take a look at the porcelin below the electrode. If its black/sooty looking you are too rich. White/white specks, signs of detonation, indicates a lean mixture. Should have a mild brown coloration to it.

Good luck with it.

 

[CarnageZ28]

Tried to Private Message you. Could you send me an email about your rear disc brake set up? I ended up trading the 125 for the blaster. My email is [email protected]

 

[ron89]

To take the pilot jet out, you just use a small flat head and turn it counter clockwise. Maybe consider cleaning the whole carb out though? Take that out, the main jet, take the floats off/adjust, and clean everything. Blow the passages all out with compressed air, etc.

If it is lean, it will ping/detonate a little bit under loads, run hot, and sometimes idle a little high.

Before you get to far into it though, make sure the boot from the carb to the reem cage is not dryrotted, and the gasket around the reed cage, cylinder base too. Spray them with starting fluid with the engine running and the RPM's will change if there is a leak.

You might not have to play with the carb as much as you think. Clean it out good first... Also you said about changing the main jet, that primarily deals with the air fuel metering from 3/4 to wide open throttle. To test this, you need to wind the bike out in a higher gear 4th/5th with a fresh spark plug. As you near redline, Kill Switch & Clutch. Coast to a stop. Remove the spark plug. Take a look at the porcelin below the electrode. If its black/sooty looking you are too rich. White/white specks, signs of detonation, indicates a lean mixture. Should have a mild brown coloration to it.

Good luck with it.

ok .. i replaced all the gaskets so the reed gaskets are fine and the reeds look great .. umm yeaa when i rode it it felt like it was detonateing weird i guess cause its lean on the low end .. i cleaned the carb very well .. i may just trade the bike for a 02 blaster roller and fmf pipe and bored out jug and other misc parts i could use as a parts bike for my other 2 blstys lol .. ill email ya some pics its a little ghetto cause i tryed making it all bolt on this way if it didnt work out i could swap the cable set up back on with no probs .. thanks for your help man ..

 

[CarnageZ28]

Hahah well, I can handle looking ghetto. It really does look like it was pretty traightforward with how you had to make the bracket and such.

Whats the caliper from?

 

[ron89]

Hahah well, I can handle looking ghetto. It really does look like it was pretty traightforward with how you had to make the bracket and such.

Whats the caliper from?

yea pretty simple .. the cailper is from a raptor 660 .. they are pretty cheap on ebay i got mine for 10+ship buy it now ..