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Discussion Starter #1 (Edited)
This is a mod that I've been going back and forth on for awhile. Still not 100% sure If or When it's going to happen . But everything starts with a plan, so here we go.....

I'm considering a Low budget, simplistic, 686 Big Bore Conversion for my 550cc Grizzly. By simplistic I mean utilizing my stock 558cc head, cam, and throttle body for this build. The emphasis would be on Low and Mid range Rpm torque gains, utilizing all OEM yamaha parts.

So here's the parts lists and prices from Yamahapartspitstop.com

- 686cc Piston
1S3-11631-10
87.1$

- Piston rings
1S3- 11603-10.
28.78$

-Piston pin
5vk-11633
17.74$

-C clips
93450-24154.
1.82$ x2

-686cc Cylinder
3b4-11311-10.
396.71$

-Bottom cyl gasket
1S3-11351-00.
10.82$

-Head gasket
3b4-11181.
25.19$

Other parts that may be required

-Chain guides
3B4-12231-01-00.
13.46$
3B4-12241-00-00.
26.30$

Total for parts 586.02$ US

Definitely going to need a fuel programmer for this build. I'll admit I'm still nieve on this subject and I'll need to educate myself thurther before I would ever buy anything.
 
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CONTACT LOUDTRONICS ON THIS FOREM. HE DID A FEW OF THESE KNOWS ALL THE PROS AND CONS.
HIS NAME IS TRISTAN


SEARH THE POSTS GOING BACK 2 YEARS YOU SHOULD FIND SOME INFO ON ONE OF HIS BUILDS
 

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Discussion Starter #3
CONTACT LOUDTRONICS ON THIS FOREM. HE DID A FEW OF THESE KNOWS ALL THE PROS AND CONS.
HIS NAME IS TRISTAN


SEARH THE POSTS GOING BACK 2 YEARS YOU SHOULD FIND SOME INFO ON ONE OF HIS BUILDS
Appreciate the heads ups. I've read quiet a few big bore threads on this forum including Tristan's. I will certainly be reaching out to him and a few others for tuning tips. Thank you for posting.
 

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@Vincent, pretty cool. I didn't know that was possible. If you do it that will make for a very interesting thread.
 

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If you're going to do it, why not do a 734? You can get a kit with piston, cylinder, gaskets for around $500 (Canadian, that's what I paid).

Sent from my SAMSUNG-SM-G870A using Tapatalk
 

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Discussion Starter #6
If you're going to do it, why not do a 734? You can get a kit with piston, cylinder, gaskets for around $500 (Canadian, that's what I paid).

Sent from my SAMSUNG-SM-G870A using Tapatalk
My concern with that setup would be the effect of the extra weight of 734 piston on the lighter crankshaft and counterbalance of the 558.
 

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The JE piston that came in my 734cc kit was 10 grams lighter than the stock piston, but I have no idea about the crank or counterbalancer in the 550.


Sent from my SAMSUNG-SM-G870A using Tapatalk
 

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Discussion Starter #8
The JE piston that came in my 734cc kit was 10 grams lighter than the stock piston, but I have no idea about the crank or counterbalancer in the 550.


Sent from my SAMSUNG-SM-G870A using Tapatalk
Thanks for posting info / prices on your big bore kit, and these piston comparison pictures. All great information
 

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Thanks for posting info / prices on your big bore kit, and these piston comparison pictures. All great information


That JE piston sure has a petty narrow skirt compared to the stocker
 

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I would highly recommend using a 700 head. The 550 head will not flow enough to see any gains. You may even set your self back.

If it were me, I would get the 700 head and throttle body. Get a bazzaz with auto tune and call it a day. You will be much happier at end of the day.
 

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Discussion Starter #11 (Edited)
I would highly recommend using a 700 head. The 550 head will not flow enough to see any gains. You may even set your self back.

If it were me, I would get the 700 head and throttle body. Get a bazzaz with auto tune and call it a day. You will be much happier at end of the day.
Appreciate the information ,
Is a 550 head on a 686 jug something that was done before and proven to not to yield good results? Has anyone even tried this combo?
Pitty cause I was really itching to give her a try.

That said, I agree with you on the fact that with 23% more displacement ( air flow) the 550 head and throttle body may be over taxed at the higher rpm ranges and ideally the best way to maintain a smooth wide powerboat from idle to max rpms are with the 700 parts.

Not that I'm in any rush to get all the parts at this time, but would you suggest a supplier or a good source for a used 700 head and throttle body?
 

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Discussion Starter #12
I would highly recommend using a 700 head. The 550 head will not flow enough to see any gains. You may even set your self back.

If it were me, I would get the 700 head and throttle body. Get a bazzaz with auto tune and call it a day. You will be much happier at end of the day.
Checking out eBay, doesn't seem to be a shortage of 07 to 13 700 heads.
Are 700 Rhino heads a good choice? I'm assuming they are basically the same as the Grizzlys?
 

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Its all a matter of flow. If you do not provide it with enough air and fuel, smaller explosion or same size explosion in a larger displacement will yield less power.

Lots of heads out there on Ebay as you have found. You will want an 09-13 head as well as TB. the 07-08 heads are slightly different and TB is completely different.
 

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Discussion Starter #14 (Edited)
Its all a matter of flow. If you do not provide it with enough air and fuel, smaller explosion or same size explosion in a larger displacement will yield less power.

Lots of heads out there on Ebay as you have found. You will want an 09-13 head as well as TB. the 07-08 heads are slightly different and TB is completely different.
Thanks for the info. I knew about the 07 & 08 TB being different but not the heads. So I guess 07 & 08 heads are out of the question.

Noticed Rinho heads have a different part number then Grizzlys. Probably best if I avoid them to.
 

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This is a very interesting thread, I recently purchased a cylinder works big bore kit for my 2014 700. I also own a 2010 550 and would be nice to know if I could take the top I replace on the 700 and install it on the 550.
 

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Discussion Starter #16 (Edited)
Downloaded a couple of pics of a 550 and 700 heads. Don't know the actual valve sizes, but the difference is undeniable.
 
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Discussion Starter #17 (Edited)
Thread closed...

I'm closing this thread. I've decided I simply don't have the heart to change such a damn nice, rock solid, just plain wonderful little 558cc engine. The plan at the moment is to eventually find a low mileage / hrs immaculate 14 or 15 Grizzly 700 and upgrade to that. T'ill then my 7500+ mile 550 will get me by just fine......
 
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