Cant stop wont stop

[ChrisZx7]

So i bought this 97 Kx250 few weeks ago. From what i was told, it was the year that it won the shootout and had the best porting. I was also told it should rip my arms off and pull a wheelie up to 4th. Well it didn't. So did some searching and reading, and found out my power valves were coverd in carbon and not working properly.

I also saw some scoring on cylinder walls. Well i opted to get the cylinder replated instead of a sleeve put in. Included in the price, is a power valve disassembly clean and reassembly. By who? Ofc Ken. I wouldn't send it anywhere else after the work he did on my blaster.

So while its apart (already sent out). Im going to change a few parts. Not doing a full rebuild since practice starts next month (Area 51 mx track). Next winter will be a complete rebuild.

Here's my list of parts orderd:

Clymer manual
Motion pro throttle cable
Motion pro clutch cable
Moose shifter
No Toil filter
Acerbis chain guide
Kill switch
Clutch / brake lever
New rear pads
New rear rotor
Cylinder replate
Wiseco top end kit
Dunlop rear tire
FMF Fatty / powercore 2

And here's some pics

 

[Awk08]

holy carbon batman, wonder what oil/ratio the P.O. was running in it ???

keep the pics comin !

 

[ChrisZx7]

holy carbon batman, wonder what oil/ratio the P.O. was running in it ???

keep the pics comin !

Idk. But when i drained the tank, im pretty sure it was straight gas.

 

[ChrisZx7]

Stock engine 160main, 45 pilot, middle clip, putting on full exhaust, how many should i bump the main up?

 

[89blaster89]

most dirtbikes run 50:1 thats why it seemed all gas im guessing, he probally just had it jetted extremely rich for racing?

 

[ChrisZx7]

most dirtbikes run 50:1 thats why it seemed all gas im guessing, he probally just had it jetted extremely rich for racing?

Jetting was acctually set up exactly how it comes from factory. Idk about the 50:1. Im running it at 32:1.

Pretty pumped i just won a brand new full FMF exhaust on ebay for 243$.

 

[89blaster89]

Jetting was acctually set up exactly how it comes from factory. Idk about the 50:1. Im running it at 32:1.

Pretty pumped i just won a brand new full FMF exhaust on ebay for 243$.

i would run it at 40:1 32:1 i think is a bit to much oil for a dirtbike motor

 

[ChrisZx7]

i would run it at 40:1 32:1 i think is a bit to much oil for a dirtbike motor

Can you please explain the difference between a 2stroke atv engine, and a 2stroke dirtbike engine?

 

[89blaster89]

Can you please explain the difference between a 2stroke atv engine, and a 2stroke dirtbike engine?

this is a 125 right, these things are pretty much race bikes and, all my friends race and they all ran it at like 50:1 40:1 ect... not to much oil, bad for top end life but you get more performance and cooling, and you said you will be racing this? to get the most cooling and performance out of it i would say 40:1 but if your just trail riding it then yeah 32:1 is fine.

 

[Larry's Shee]

most dirtbikes run 50:1 thats why it seemed all gas im guessing, he probally just had it jetted extremely rich for racing?

this is a 125 right, these things are pretty much race bikes and, all my friends race and they all ran it at like 50:1 40:1 ect... not to much oil, bad for top end life but you get more performance and cooling, and you said you will be racing this? to get the most cooling and performance out of it i would say 40:1 but if your just trail riding it then yeah 32:1 is fine.

Really wouldn't matter what type of riding/racing you do, if anything I would go heavier if racing.

Can you please explain the difference between a 2stroke atv engine, and a 2stroke dirtbike engine?

More oil ratio MYTHS. I suggest you both (and all, really) read this: http://www.blasterforum.com/engine-13/pre-mix-ratios-myth-facts-read-14935/
Straight from Banshee owners manual: 20:1 for initial break in, 24:1 after that. The slight amount of power gained by running a thinner oil mix would hardly be measureable on a dyno, let alone an A$$ DYNO. 8-|

JMHO, your results may, and will vary.

 

[Blaaster]

You loose power if you run a gas rich AFR, many racers run on the wrong side of lean for more power.

Too much oil is not bad for top end life, you can gain more performance with a heavier oil mix,if it is jetted correctly.

Extra oil will not make it run any cooler, but it could run hotter do to the lack of fuel in the mix.

We are talking a 250 here and it will run just fine at 32:1, and if it is run at high revs a heavier oil concentration would help, but would need a jet change to compensate.

If I had to make a guess what has happened, the PO has jetted it way too rich presuming that he could safely run a deficient oil mix to lubricate the motor.

It makes me wonder if they paid any attention to the needle.

What happens here is that the combustion chamber heat is not hot enough at WOT to fully burn the oil and it leaves carbon deposits everywhere.

Carbon deposit in the exhaust port can be dislodged and forced back into the combustion chamber by the pipe backpressure which will give the piston a very hard time.

 

[ChrisZx7]

The carburetor was up set up at 45/160 2nd clip from top. Which is exactly how it came from factory. I do not know why it has so much carbon build up. Im sure the powervalve was not working correctly so the extra oil was not being pushing back in the be burnt.

Anywho, it will be jetted for the new FMF and run @ 32:1.

Ill have more pics up tonight after mailman comes.

 

[ChrisZx7]

New levers came in today, so did goggles for helmet.

Waiting on:

Top end from KOR
Top end kit from Wiseco
FMF exhaust
Chain guide
Rear tire from shop
Kill switch

Still gotta order rear disc and possibly rear wheel bearings.

 

[Larry's Shee]

Might have been cheap oil

 

[ChrisZx7]

Wiseco top end came in. Decided to order my own off ebay because it was about 40-50$ cheaper than what any shop quoted me for.

Just gotta wait for Ken to finish top end, then its time to throw this thing together.

 

[best]

I have to agree with Larry's Shee's advice, both the Pre-mix article and the cheap oil suggestion.

The heads on the right and left have HUGE highway miles on them but used high quality Motul and Ipone synthetic oil. The one in the center is from a motor that showed very exterior wear, but was owned by a guy that no doubt in my mind used the cheapest 2-stroke oil. The piston and Nikasil cylinder were fine but the rings were shot and the powervalve was plugged stuck with carbon. The good quality synthetics don't go to carbon, but go to a goo instead, although the top of the piston will still carbon. With a powervalved 2-stroke you pretty much HAVE to use a good quality synthetic 2 stroke oil.

Steve

 

[Blaaster]

Wiseco top end came in.
Just gotta wait for Ken to finish top end, then its time to throw this thing together.

Will not KOR need the piston for measurements.

The piston will need matching to the bore.

 

[Longview]

most dirtbikes run 50:1 thats why it seemed all gas im guessing, he probally just had it jetted extremely rich for racing?

I have buddy's with cr's rm's kx's blaster's never heard that. They all run 32:1.

 

[ChrisZx7]

Will not KOR need the piston for measurements.

The piston will need matching to the bore.

It's getting replated to stock size 66.40mm. If he needs it ill ship it to him, I still saved 50$ by buying it myself.

 

[ChrisZx7]

I have to agree with Larry's Shee's advice, both the Pre-mix article and the cheap oil suggestion.

The heads on the right and left have HUGE highway miles on them but used high quality Motul and Ipone synthetic oil. The one in the center is from a motor that showed very exterior wear, but was owned by a guy that no doubt in my mind used the cheapest 2-stroke oil. The piston and Nikasil cylinder were fine but the rings were shot and the powervalve was plugged stuck with carbon. The good quality synthetics don't go to carbon, but go to a goo instead, although the top of the piston will still carbon. With a powervalved 2-stroke you pretty much HAVE to use a good quality synthetic 2 stroke oil.

Steve

I use Kendall gt-1