Engine 781 Big bore 62T/61X $OLD

Location
Texas
• 62T Bottom, DASA ported and filled
• 5mm stroker plate
• 61X Top, Blowsion pre ported big bore sleeves with 5mm shaved off the top.
• Motor is in the break in stage and has some weird wear on the cylinders.
•ADA Head 38cc domes
•Compression read 150 in each hole but my gauge is a piece of poop
•Jetmaniac SBT Crank
•PFM Lightened 61X flywheel
•Brand new Stator from jetmaniac
•Surf armor bilge setup
•Surf Armor battery and starter cables
•Billet ADA Coupler

I can include a black engine cradle the current ones are modified for a X2
If you want any pictures of the flywheel let me know!
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Asking $2000 + 100 ship
Open to offers!
located in Houston Texas

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McDog

Other Administrator
Staff member
Location
South Florida
So non stroker crank in cases setup for 5 mil stroker and sleeves are shaved 5mm? That is confusing. Was the cylinder and domes setup for 5mil before and you converted it back to standard stroke?
 
Location
Texas
So non stroker crank in cases setup for 5 mil stroker and sleeves are shaved 5mm? That is confusing. Was the cylinder and domes setup for 5mil before and you converted it back to standard stroke?

It’s a stock stroke motor, I picked up the motor blown and it had a Stroker plate on it and I was confused for awhile but it’s a rare thing to see, all it does is move all the ports up 5mm.
Edit: it also gives the ski a really nice idle sound. Sounds nothing like a Yamaha at idle


Sent from my iPhone using Tapatalk
 
Location
Texas
Was the 5mm removed from the top deck when it had the stroker crank? Or was the cylinder decked when you put the ss crank in it?

It never had a stroker crank, it’s just a way to move the ports up 5mm.
5mm off the top of the cylinders, then a 5mm stroker plate to move the cylinders up 5mm


Sent from my iPhone using Tapatalk
 
moving the ports 5mm reduces exhaust timing to 82 degrees and intake to 110 on a stock 61x sleeve.
65u pistons implies an 84mm bore
"Blowsion big bore" sleeves are 89mm
can someone explain what the heck is going on here?
 
moving the ports 5mm reduces exhaust timing to 82 degrees and intake to 110 on a stock 61x sleeve.
65u pistons implies an 84mm bore
"Blowsion big bore" sleeves are 89mm
can someone explain what the heck is going on here?

Blowsion Cylinder Sleeve - Yamaha 785​

Yamaha 785 SuperJet 84-86.5mm Big Bore Sleeves. Performance Pre-Ported. To be used with stock stroke through 6 mil stroker motors. Blowsion custom designed include a wider exhaust port, wider boost port, deeper transfers and a narrowed skirt. Sold Each.
 

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maxboost

Super tuned
Location
Ia
moving the ports 5mm reduces exhaust timing to 82 degrees and intake to 110 on a stock 61x sleeve.
65u pistons implies an 84mm bore
"Blowsion big bore" sleeves are 89mm
can someone explain what the heck is going on here?

i think he moved the ports up which increases durations hence the spacer plate moving the cylinder upwards. I bet it rips pretty hard upstairs
 
Anyone know what the original port heights is on those? If it’s designed for a 6mm stroker decking 5mm for stock stroke is still 2mm extra.
 
Location
Texas
Anyone know what the original port heights is on those? If it’s designed for a 6mm stroker decking 5mm for stock stroke is still 2mm extra.

It’s my fault you guys think it has to do with stroke, it’s a motor with ports raised 5mm. Nothing to do with stroke.
 
I understand that bit and maxboost sent me a message with some maths(but for a stock 61x) So I’m piqued to know what the timing actually is.
 
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