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Thread: Yamaha 2.6L Frankenstein build
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05-25-2014, 07:01 PM #1
Yamaha 2.6L Frankenstein build
Hi Folks
I've started a 2.6L Yamaha Engine build and wanted to post it up here so that I could hopefully draw on the combined experience of the forum members.
Back ground: I have a formula 233 that is currently powered by 2 x 150HP V6 Yammies.
My plan is to replace the power heads on both motors, the current motors have over 700hrs on them and are low on compression and becoming hard to start when cold. (plus I have no idea of their condition)
I recently picked up a 225Excel powerhead, I plan to rebuild this as a stock motor with the inclusion of carbon reeds and possibly a exhaust tuner. This is the easy one.
The second engine is where the fun begins (as I have 2 I can afford to tinker with 1). I have a 2.6L block that I will start with its in good condition and just needs a hone. I have a set of 225Excel heads for it (6K7), a set of 1993 D4E 32mm carbs and a set of 200HP reed blocks. I will also be using the later model 200HP oil pump. As per the 225 engine, carbon reeds and an exhaust tuner will be used.
Firstly does anybody see any major issues with this parts combination?
Secondly carb jetting will be interesting, given the carbs are 32mm chokes compared with the 225's 34mm chokes I don't think with the increased air speed the #168 jets are required. I was planning on a combination of #160 and/or #164. I would be happy to here what peoples thoughts are on this? These motors are just for cruising and the reason for the increased HP is just so that I can spin larger pitch props.
Cheers
JasonLast edited by 225XCL; 05-25-2014 at 11:43 PM.
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05-27-2014, 08:21 AM #2
The main difference in porting between the Excel and many of the other 2.6 is the exhaust port is 2mm higher. Measure your motors and you might find with trimming the top of the exhausts you can duplicate your Excel.
Any of your other engines have the horizontal fronts?
There are plenty of 34mm carbs on US ebay.
I am running a set of 34s on my 150 ProV with no jetting changes, Excel jets, not 150. I expected this to run rich but that is not proving to be the case.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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05-27-2014, 09:50 AM #3
No I'm afraid that they are all vertical fronts, I may look around and see if I can find another block/case with horizontal front. I have a spare horizontal manifold.
I will look for carbs, I noticed in another thread that Ray Neudecker said that was also the way to go. He seems to really know his way around these motors.
I had already noticed the difference in size of the exhaust ports between the 2 blocks. They seem easy enough to get to form the outside and considered having ago at them myself. I have never done anything that before but nothing ventured nothing gained,
He also talked about removing the computer and putting the mechanical advance system on. I will have a spare once I am done so may give that ago as well.Last edited by 225XCL; 05-27-2014 at 09:53 AM.
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05-27-2014, 10:34 AM #4
One thing Ray mentioned when I was starting my project is the machining is accurate enough that you can swap front halves of the block. So I did swap my vertical front to a horizontal. Works nice.
Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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05-27-2014, 04:30 PM #5
Thats good to know, I will keep an eye out for a front half.
Thanks for your help.
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05-27-2014, 05:19 PM #65000 RPM
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I have a front half and other items you may need.
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05-27-2014, 05:38 PM #7
Thanks Hyrdo. I will PM you to discuss details. Tried PM but your mailbox is full.
You can flick me an email to car1568@gmail.com if you like.Last edited by 225XCL; 05-27-2014 at 05:45 PM.
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05-27-2014, 07:25 PM #8
If you can get a horizontal front and a set of 34's you'll be well on your way. Port Match your block to the excel and a set of excel/225 heads, tuner and an early 2.6 exhaust plate you'll have...a second excel I guess lol. If they are going on something heavy I wouldn't go any higher on the exhaust ports than the excel.
'08 SRV
Yamaha 3.1 Phase III
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05-27-2014, 11:16 PM #9
Its reasonably heavy comes in around 2000kg/4000lbs.
I don't any more power than the Excel pushes out so the plan was to grind the exhaust ports to match. If the intake ports also need to be done then there too difficult for me and will not get done.
I have a set of 6k7 heads ready to be bolted on. I already purchased a new exhaust plate it looks the same as the Excels. What are the differences?
If I can get it within 25HP of the excel I will be happy.
The combined result will be ~150HP increase, it will be like bolting on a 3rd motor but with out the additional weight and hopefully not the same fuel burn.Last edited by 225XCL; 05-27-2014 at 11:18 PM.
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06-01-2014, 11:57 PM #10
A tech question for the collective.
Will a post 1990 oil pump drive work in a pre 1990 block and pump?
My second block doesn't currently have the shaft just the drive on the crank.
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06-02-2014, 04:08 AM #11
They changed the direction of rotation of the pump, so in simple terms, no.
The upgrade pump used with adapter spins as the early pump did.
In order to used the later pump you would need to get into the bottom of the crankshaft and swap out the drive gear on the crank. Need to check the length of the later drive shaft compared to the upgrade shaft for length when used with the pump adapter.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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06-02-2014, 05:18 AM #12
Thanks for that bit of info Charlie. Looks like i need to find a pre 1990 oil pump shaft.
I better add that to the list of parts I need.
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06-06-2014, 08:00 AM #13
Thanks to DoktorC all the parts are sourced once they arrive here down under I can start putting the 2nd motor together.
The first motor will be ready for reassembly in a few weeks, the new bearings and gaskets are also coming form the US. Carbon reeds arrived today, I better place my order for the exhaust tuner.
I'm not looking forward to the actual swap, the excel powerhead took 2 days to separate from the mid section due to corroded bolts.
Before I attempt doing this I will run the engines up and see if I can free up the bolts. Are there any other tried and tested tricks to prevent the bolts snapping?
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.
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06-06-2014, 08:27 AM #14Are there any other tried and tested tricks to prevent the bolts snapping?Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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06-06-2014, 09:02 AM #15
The remaining piece of the bolts came out easy the long shaft section is where it had welded it self in.
I have 3 head bolts that I need to get out of my first block, I have heated them up drilled them for an easy out and soaked them in WD40 but they haven't moved yet. I will go a larger size drill and tray and break out the remains if the next few attempts don't work. I may just get a tap and use the tap to get the remains out.
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.