Blaster pump gas 91?
- Thread starter catpower
- Start date
- Location
- Cruising Around
Quality of 91 varies by region has been my experience. Same thing happened to me when I moved from Texas to Fort Mohave AZ. I was told about poor fuel quality an engine failure to late lol
Freakrider
X247
- Location
- Tampa Bay area
Make sure you're not running too lean and you don't have a carb or fuel filter issue for next time. Post clear pics of top of both pistons.
Midlake Crisis
Site Supporter
- Location
- Bakersfield, CA
What are the symptoms of detonation before failure?
- Location
- Cruising Around
^^^^^^If you are referring to me then you are correct. I did not have my static timing advanced though. Good point that I see you're making here though. The B1's commonly get longer WOT runs so this should be considered when bumping compression.
Sorry, I was referring to the OP. 180 on pump gas is generally safe on freeride/freestyle skis that see short bursts of WOT. 180psi+advanced timing+questionable pump gas+a seat is probably going to add up to busted parts.
BruceSki
Formerly Motoman25
- Location
- Long Island
Don't forget the larger wet hull surface area plus weight on those long wot runs.
- Location
- Cruising Around
Yeah Yamanube it was a good point to make. There usually is a difference in the length of wot runs between B1's and standups and definitely should be considered. Might not help the op now, but maybe later, or help someone else reading this thread.
In Midwest Iowa we only have 91. I use the B1 more for freestyle so reading and building the motor I follow a lot of 701 standup threads. Over past few years I don't recall reading 35 cc domes and MSD or advanced timing to be an issue. I'm sure it's out there I just did not c it. Motor has dual cooling with a mag pump and 10/16 hooker not that I need it for fresh water but I have noticed more of a loose feel when sliding around. I've been told this pump set up will load motor more. I did post photos of my pistons almost exactly a year ago and asked about piston wash. Jetting was crazy fat with if I recall 150 mains and 75 pilots. Everyone seem to think it was lean but then someone posted it could be the type of oil. I use Super M. I asked an oil rep one time and he agreed some oils may leave a residue on top that makes piston wash more difficult to see. He said to look for a difference in shine on piston although the top may appear to be all black. If WOT means LESS than 1 min and I know it doesn't, I'm guilty. Lake is only 3 miles at longest point and maybe 2/10th mile wide. 50 MPH covers that lake pretty fast. Due to wakes and boat traffic I never pin it for more than 30-40 seconds. Non the less WOT is not where problem occurs with MSD. I've been informed that low to midrange constant cruising is where MSD advances. I'm not saying WOT is safe but FYI to those with similar set ups.
Blue
Judging your cheapness
- Location
- St Cloud Florida
30 to 40 seconds is a lot of WOT. If you have too little or to much squish will allow detination to occur as well.
- Location
- Cruising Around
Agreed. Something else to factor in. I used to run my blasters way more than 30-40 seconds wot. Last rebuild I went to 37cc domes on ported motors at about 700 feet above sea level.
Blue
Judging your cheapness
- Location
- St Cloud Florida
Just a thought but You mentioned last week or so u had custom domes you cut. If the dome angles are not cut correctly the squish band cannot do its job to cool the edge of the pistons properly. Detination was definately the cause but its difficult to tell by the pistons if it was lean or just run hot which will discolor the pistons making the exact cause harder to determine.
Pistons are from different times. Each has approx 50-60 hours of use. One is with stock dome milled and second is from 35cc domes I cut. Used my lathe and used a dial indicator to follow squish angle. I cut to within .001" from original taper. I would question the quality of gas. It does make sense that an MSD would advance in low to midrange and being a sit down ski over time cruising could lead to this. So why was I so foolish to have it happen twice. First time compression over 180 but no MSD. I was mixing 110/91 to give about 96 octane. Thought ok not enough chamfer on exhaust port first go around so I then added MSD made sure chamfer was cut and this year bump compression to 180. Thinking I was safe with 91. Now I'm told combination of gas and advance was too much.