Blaster oil injection block-off

[250rAL]

I put a block-off on my son's Blaster recently and promptly seized it on our first ride. Aparently, I didn't go high enough on the main(so much for following directions!). I did have a 230 in it. The only other info I could find was a guy that had the kit and a 260 main. He had a pipe; I don't yet. I would like some more people to chime in with what they're running if they have a block-off installed in their Blaster.

[OldSchoolin86]

Not to insult you but did you mix the fuel after blocking the injection off? What did you mix it at?

[250rAL]

Now that would be a real boner. Yeah, I used the same mix that I use in my 250R- 50:1 MC-1. The jetting was definately the problem. It went about 5 miles at a steady pace before it stopped.

[HemiChallenger71]

HMMM, I'm guessing the mix. I know Blaster's run a really rich rich mix, like 18-1, 20-1. Maybe after it warmed up a little, the oil thinned out enough while it was in the motor to size it? I realy don't know. That was my guess. I didn't know you had to change the jetting with a block off kit, but if you followed the directions exactly as they say, and jet as they recomend, and run the mix they recommend, you may be able to save some money. Call the company and tell them what hapened see if they will pay for it. If not, maybe you should consider taking them to court.

[Tri-Z_Jim]

i didnt have to change jets when i put on my block off kit,,,that was 2 yrs ago and the blaster is still running . I use klotz super techniplate @ 40 to 1
50 to 1 sounds a bit to lean to me

[freaksfix]

i premixed mine 50 to 1 and left the oil injection owned it for a long pounding year and never fould a plug???for some reason yamy's get more nut with to much oil

[TimSr]

You may have to change jetting when you go to premix unless you stick with the same oil at the same gas:oil ratio as it was being injected (usually 20:1). but if I had to guess, I would say you were ALWAYS running too lean. Running a higher oil:gas ratio will mask a lean condition (not correct it). Running MC1 at 50:1 is perfectly fine in any two stroke motor Ive tried it in, provided you are tuned to it. The most important lesson here is that ANY engine changes should be immediately followed by frequent plug checks so you will know how the carburetion is.

[250rAL]

Thanks for everyone's input. I got the cylinder bored yesterday but I don't have it back together yet. I really want to run the 50:1 mix but I don't want the same thing to happen again right away. I'm not positive that the ratio had nothing to do with it, but I think it was solely the jetting. I'm going to go up one on the main(to 240) and one richer on the needle (3rd notch). I can't use MC-1 to break it in anyway(because it's synthetic) so I'm going to use Yamalube at 32:1. That'll give me a little more time to think about it and maybe hear more opinions on the matter.

[TimSr]

Synthetic premix is perfectly fine for breaking in a two stroke top end. The idea will get heavy debate if youre talking 4 strokes, but thats not relavent here. If youre going to run Yamalube, Id mix it 20:1 like it was being injected until its broke in (about a half hour of mild run time) then use your 50:1 mix and adjust your carburetion, and do jet changes as necessary based on your plug readings.

[YTZ250N]

I'm not a hundred percent sure but I thought in my service manual it says that the blaster's injected mix is like 32:1 another culprit may be an air leak. If your motor pulls air into the cases it will run lean. if it runs at all.