Blaster BPipe Tuning

[kranch07]

I need some help/advice Tuning a 61x single carb with Factory Bpipe Mod and ADA 37cc head.

Initial carb settings that I started with are 150 main jet-high speed @ 1-1/2 turns out. 120 pilot jet- low speed @ 2 turns out and 95g spring. (Jetmaniac recommendations)

BPipe settings are, bottom Tuning screw 1 turn out, middle and top Tuning screw fully closed. (According to BPipe directions)

For about the first 30-45 minutes of riding she was great, crisp snappy throttle response, at about 40% throttle it would hit the power band and you could feel it, ran WOT great. After that she started sputtering on acceleration and at about 75% throttle it was all it had. No change in rpm or speed from 75% to 100% throttle.

Played with the carb settings both directions and couldn't get it to clear up. Messed with the FCV a little 2 complete turns each way at the most. I haven't messed with the Tuning screws at all.

If anyone has an any advice please let me know, if you have a similar or same setup let me know what your running everything at.

 

[tor*p*do]

Replace your own rings

 

[kranch07]

O rings on what?

 

[tor*p*do]

Cylinder head. If it ran great and then didn't, something changed. May have blown an o ring

 

[kranch07]

Ok, I'll take a look at it. They were brand new orings and just installed 2 days ago. Followed directions to the "T" and torqued the correct pattern.

 

[JetManiac]

Ok, I'll take a look at it. They were brand new orings and just installed 2 days ago. Followed directions to the "T" and torqued the correct pattern.

Just do a compression test instead if you thinking orings.

Try running it again with cold motor and see if it runs good again or the same.

 

[kranch07]

I'll do a compression test, correct me if I'm wrong but my thoughts are if the orings are leaking I'll see a reduction in water out of the pissers bc of the introduction of air into the cooling water. That was what someone else recommended, I wasn't sure if they were just shooting from the hip or if that's an actual common problem

 

[Roseand]

Did you use ada torque specs? Because they're too loose.

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[kranch07]

I did a compression check, on a cold engine. I had 170 lbs on fwd cylinder, 160 lbs on rear cylinder. Pulled head and didnt see any damage to the orings. When I reinstall head I'll swap the domes and see what compression is again.

I did follow ADA torque specs, could you tell me what torque specs would be better suited?

 

[Roseand]

Doesn't seem too abnormal, especially with 37cc domes.
@JetManiac knows.
I think 23 on head, 34ish on girdle studs? Not positive

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[kranch07]

I'll take a look at the specs that came with the head, sounds to me like that's very close to what they sent me. ADA says to run BR8ES or BR9ES. I went with the 8's bc I figured a hotter plug would be fine. What are most people running with the ADA heads? Could the Tuning screws have any affect on the sputtering issues I'm having on acceleration?

 

[Nimmer705]

Have you checked the 1 way valve on your gas tank? Is thier pressure in the tank after riding for 10mins? Do you have your temp sensor plug in? Might wanna disconect it and try again

 

[kranch07]

Yea. Gas tank one way valve is holding pressure on the Tank. The temp sensor has been eliminated. About to take it out again this morning and see how it acts. Everything is adjusted to manufacturers recommendation. (Factory Bpipe bottom screw out 1 turn, carb settings on Jetmaniac recommendations)

 

[kranch07]

Alright, another unsuccessful day or Tuning. Ski ran great for about the first 30 minutes, then I shut it off on the sandbar for about 10 mins, after that ran like crap. Almost felt like it was running on 1 cylinder and engine makes a popping and gargling noise. After about a minute or two it will clear up but as soon as you drop below 50% throttle or so it will act up again.

I messed with carb settings, BPipe Tuning screws and even the Flow Control Valve and didn't get any change. I also moved the FCV from the straight leg of the "T" fitting to the "90°" fitting and didn't notice any change. I took a few temp readings and can't seem to get the engine quite to 160° (did take me a few seconds to stop, pop seat and hood up and hit it with temp gun). I also can't seem to get the BPipe to the recommended temperature they specify in the installation instructions.

Compression is still 170 and 160. O-rings were not damaged on the head, swapped the domes from fwd cylinder and rear cylinder. Put a new set of plugs in (BR8ES) this is the third set in 2 rides and get no difference. Could someone point me in the next direction, I'm stumped and don't know where to go other than trying a set of colder plugs and tearing the carb back down for another rebuild. Thanks

 

[Nimmer705]

Almost sounds like your stator is breaking down. Either that or the cdi is, i would be seeing how strong your spark plugs spark cold compared to when thier hot,

 

[kranch07]

Thanks, I'll take a look at those and see what I can find. The part that baffles me is after it sits when you go to accelerate next time is when its most prominent after you run it mid throttle or so for about a minute it clears out and will be fine. Its always during acceleration when its the worst. I guess you could say when the engine is loaded up

 

[Nimmer705]

Have you checked your needle an seat to make sure thier not leaking? Airbox off at an idle an see if gas is coming out of the bomb sight in the carb,

 

[kranch07]

No, I haven't looked at that yet. I'll look at that this weekend. I also saw a thread somewhere talking about the BPipe Tuning screws and how 1 turn could just be dumping water into the pipe. So I went ahead and pulled the headpipe off and connected the water hose to it. Turns out 1 turn out on the Tuning screw was dumping water, I played with the setting while connected to the hose and ended up with about 1/8th of a turn out on the bottom screw and I'll use the mid and top screw to adjust and get the pipe temperature correct. I was hoping that maybe this had something to do with the poor performance since it was dumping so much water into the exhaust.

 

[kranch07]

I am still having the same issues as mentioned at the beginning of this thread. Can anyone give me specs of what they are running with the same or similar setup? Jets in the Stock 44 and settings for High and Low speed? Also the pop off spring? I understand how the pop off spring works and what it's controlling just not sure what symptoms you would see if your pop off spring was incorrect.

Today the ski wouldn't run anywhere above about 50% throttle, also had a few times that seemed like something was limiting the engine to 25% throttle. If I held it at WOT it would take about 30 seconds to clear out.

If anyone has ideas let me know, I'm getting thoroughly frestruated with it

 

[Quinc]

Next time it happens either pull the plugs or use a spark tester and see if it is sparking. It sounds electrical related.