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That's what Engineers do..:rolleyes: Call me paranoid but I've toasted 2 pistons in 9 months - it's getting way expensive & way a bummer......:crutches: :scared: :crazy: :ugh: :raincloud:

I found this at GropK: "While testing props and nozzles one morning, we were making repeated, long, smooth-water passes turning consistently 7250 rpm. About 2 hours into that testing, the test rider encountered a few ripples at peak speed that set the nose bouncing a bit…. But he still...

Last night I filled in the OEM intake manifold crossover w/JB.:cool2: It came out well but there are a few low spots I want to go back & fill in. Question is, after roughing the existing JB Weld surface w/80 grit do I clean w/Acetone? I'm concerned it might soak into the JB Weld or soften it.

Any hull needs to be able to hold a 5 gallon tank for long rides up & down the beach.:sneaky:

Dome size was 33cc. My headpipe to manifold diameter was 42.7 - 43.7. Not even round. Yamasaki has the right idea w/inscribing diameters, since these parts will float around for years to come....

Kevin, what's different about this hull vs. a Wammer? Is the bottom identical to an OEM? Would it stand up to 3/4 rolls & upside down BFs in the surf?

It was only 190....:cool2:

Bummer Wax. I hear ya on the tight $$$. Why couldn't Yamaha have offered a reliable 100+ HP SJ model....:banghead:

Been running it 9 months, hammering it hard. I am gonna leak test tonight. The bottomof the piston is covered w/black goop from the hole in the side. Doesn't look like it got too hot, but hard to tell.

Well it appears the culprit is my B-pipe - I have one with the 43mm diameter manifold, which is bad for ported/bigger than 701cc engines.:banghead: :banghead: :banghead: This makes the front cylinder run hotter/maybe leaner. An easy fix.:smile: Still gonna do a leakdown test tonight...:sneaky:

Forgot to say - Thanks Crockett!:arms:

BINGO! That's exactly what I was looking for.:arms: :arms: :arms: :arms: :arms: Thanks to Chuck for pointing me in the right direction. :hail: :hail: :hail: I have one of the smaller manifolds & this is no doubt a contributor to my meltdowns.

What's the correct manifold ID for a 701? I did a quick search but didn't find it.....:frown:

Yeah, I only had like 5 minutes of waves before she blew.:banghead: At least we weren't out past the buoy.:hail:

Pipe plumbing is standard - dual cooling to dual inputs on the manifold, front head outlet to a water bypass fitting, rear thru a strainer (gotta keep the pipe adjusters flowing) to bottom of headpipe, top of headpipe to another water bypass fitting. I run a 13/64" restrictor on both head...

I'm running a wet pipe, a Limited "B" from factory pipe, so that shouldn't be a factor. I do have my waterbox fairly dry though. I do wonder if I got some bad gas.....:lightning:

Here's a melted Wiseco. It seems plenty strong.

How much weight does the "standard" WCF hull/hood save over a reinforced OEM hull/hood? :sneaky: How does it compare to a Wamiltons hull as far as handling/durabilty?

So others have had a hole melted in the SIDE of the piston? I haven't been able to find any info on that, the pictures I've found always show the top being melted. I'm running 33cc domes, but the exhaust port is raised a tad over 1mm so comp. is less than w/stock porting. I always run fresh...

Comp. 190 on a cheapo gauge. It's been running this comp. for 9 months though, including hammering it many times at extended (for a standup) WOT. BTW, the cylinder was originally a RIVA pump gas ported cylinder - Paul touched up the porting (he couldn't put metal back into the exhaust port)...