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  1. #1
    1200Jet's Avatar
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    Long live the 2-stroke big bore build

    The time has come for a freshen up and what better way than to just go all out with one of Lowell's finest stroker creations. I'll get in the engine later first up is the hull, it's taken some hits over the years so I have given it the royal treatment. I flipped the ski over, filled all the scratches, sanded and repeated until every line was clean and defined not to sharp. After putting down an epoxy primer and once again sanded to perfection I'v chosen an epoxy rock hard gloss black top coat by indestructible paints. This paint sets rock hard and really needs to be sanded after 24hrs as keeps getting harder until it's fully cures over 7 days by then sanding isn't an option. It's amazing how the surface tension changes from a gloss finish to a sanded finish, so I used this technique to determine how much sanding was required for a fast hull. I used 320 grit wet and dry with a heap of water the finished product is matt black. I have taken a pic (cos I know everyone loves pics) to show the difference between sanded and gloss finish. Okay so I can't find the comparison pic but this one shows the hull and how there is absolutely no beading of water I will get more pics up as I go.

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  2. #2
    1200Jet's Avatar
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    Okay so I had to put this project to the side while I moved house but it's up and running again.

    I'v spent a couple of days cleaning the crank cases and bolts of all the old sealant and loctite and anything else that wasn't meant to be there. I used acetone and scotch brite for all the mating surfaces and a tap and die for all bolts and threads then finished of with contact cleaner and an air gun. I also used acetone on a rag (damp not wet) to remove any excess preservation fluid from the crank as well as a little special attention to the bearing races just to ensure everything is clean and dry for the installation. I then followed OsideBill's crank install sticky for the assembly. I put together my own workshop manual using the gp1200r manual, print outs from the 'how to' sticky's and all the tips and tricks Lowell provided with the engine. Having this info on hand saves you missing a step, there's nothing worse than needing to pull it all apart to start over which means cleaning those parts all over again.

    I'm hoping to have the assembly competed tomorrow.
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  3. #3
    Did you use a hot rods crank? That's what I put in my bb lowell build I'm about to fire up. Mixed reviews.

  4. #4
    CJ's gpr's Avatar
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    Looking forward to watching this build. Keep us posted!

  5. #5
    007GPR08's Avatar
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    Interested. Keep the updates coming.

  6. #6
    1200Jet's Avatar
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    I'm a bit disappointed I hit a snag today, I was hoping to finish the top end but I soon realised I was short 2x piston circlips I'm also going to try and source some different cylinder mount bolts. I spent all day chasing the clips and had no luck as every store here only stocks them on request so I need to order them in from the eastern states which will push this job out until next week. I'm also looking for a better style of bolt to use, Lowell warned me that he wasn't 100% confident on the ones he supplied or the idea of using the stock ones. The head of the bolt is 17mm which means I can't fit a socket because of the clearance between the cylinder unless I want to use a crow foot spanner. So I'm going to try and find something similar to the girdle kit style or an internal hex either way they have to be approx 5mm longer that the stock ones due to the stroker spacer.

    I did manage to lap the flywheel today, I didn't blue it or anything I just did it by feel with some fine paste. Since the sealant had cured I also lubed the engine with 2 stroke oil to all bearing galleries.

    A few pics of the assembled case you can see the stroker spacers in place.
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  7. #7
    1200Jet's Avatar
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    The majority of the parts are Yamaha the crank was sent to crankworks for most of the work but it is Lowells creation, I believe this is forests old engine.

  8. #8
    1200Jet's Avatar
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    Finally the bolts arrived, I'm very happy with the quality of these, as you can see in the pic the quality of finish is 10/10 and the shape of the head will allow clearance. The cur-clips are on back order so the engine will be put to the side for now. I'm going to finish off the electrical connector replacement in the meantime, I'm using deutsch connectors as they are top notch, my old ones were corroding from all the salt water use.
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  9. #9
    1200Jet's Avatar
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    Woah can't believe it's been over 2 years since I last updated this. The engine is yet to be fired. Turns out those nice shiny bolts were only 1/4 of the strength of the grade 8 stock bolts, luckily I checked. They have since been replaced with arp bolts. I wanted to note that I torqued them to the arp recommended spec and not the Yamaha manual. The torque is around double the Yamaha spec, I just hope the case threads don't pull through.

    I'll load pics tomorrow

  10. #10
    1200Jet's Avatar
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    Progress
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