Surfriding 61X Build

be_lain

be_lain

Currently sending it
Location
Oregon
So I have a 61X/61X motor on the shelf that I am going to rebuild for my new ski. It came out of my superjet and ran great, I just pulled it to rebuild before anything grenaded.

I'm looking for advice on how to build it. It's stock bore currently, but has a billet head with removable domes (not sure what volume). Also has porting according to the previous owner but haven't verified. It's a single carb motor. I'm going to run a b pipe on it. It will be surf ridden primarily.

This is my first motor build so I just wanted to get any helpful hints or advice before I start. Things to look out for, best practice for a rebuild, etc. I want to bore it out a bit but not sure how much. Was looking at group k which said the 61X cylinder can be bored to a 718 without risking reliability.

Anyone have any advice? Also any other mods I should do electrical-wise, etc. Any help is appreciated! Thanks

-B


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long beach local

long beach local

long beach local
Location
Az
The 61x is a great surf motor IMO the snappy power works very well . I have alot of trouble free hours on one of my own. If it were me i would just rebuild it with a rebuilt Jet Maniac SBT crank and bore it to 81.5mm + (save bores) clean rebuild carb , bore and port match exhaust manifold and run the poop out of it. Maybe a modified stock cdi or a msd enhancer will help too.
 
Wake Rider

Wake Rider

Location
Winter Haven, FL
You always want to bore/hone as little as necessary so that you will be able to do it again...(like long beach local said)

1st thing I would do is get rid of the stainless steel reeds. I had one break last season and it took out my crank/pistons.
 
yurkanip

yurkanip

Location
Great Pacific Northwest
be_lain said:
So I have a 61X/61X motor on the shelf that I am going to rebuild for my new ski. It came out of my superjet and ran great, I just pulled it to rebuild before anything grenaded.

I'm looking for advice on how to build it. It's stock bore currently, but has a billet head with removable domes (not sure what volume). Also has porting according to the previous owner but haven't verified. It's a single carb motor. I'm going to run a b pipe on it. It will be surf ridden primarily.

This is my first motor build so I just wanted to get any helpful hints or advice before I start. Things to look out for, best practice for a rebuild, etc. I want to bore it out a bit but not sure how much. Was looking at group k which said the 61X cylinder can be bored to a 718 without risking reliability.

Anyone have any advice? Also any other mods I should do electrical-wise, etc. Any help is appreciated! Thanks

-B


Sent from my iPhone using Tapatalk
Click to expand...
As others have said, the 61x/61x combo is a snappy, and super reliable package. It has been my motor of choice for surf for years now! I have built my 61x from stock bore to to 84mm (760) on the latest. They can be bored safely to 84mm, and in my opinion these little motors don't come to life until 83mm bore and porting (obviously with pipe and enhancer).
There are several options for you, in terms of top ends. Jetmaniac sells a drop in, moderately ported top end for pretty damn good price I think its $650. Or you can send your cylinder to Chuck Nuklear on here (CPT) who does great port work, and I have used him lately for several of my builds.
If you have yours apart, might as well send the top half of the cases to whomever is doing your work and have it ported also. (all of the little things, add up to performance gains). For pump gas, you want to be in the 180psi range in terms of dome size. Replace stock reed petals with Carbontech (made for 61x) and drop on a single 46 mikuni, or Blackjack 44, bore B pipe manifold/headpipe to 50mm and you will have a great motor!.
The above is Perfectly matched with a 144 solas mag (good priced mag pump), and 10/16 hooker, reduction nozzle bored to 85mm.
Attached is my build, sheet that has served me well, for many many builds.
 

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be_lain

be_lain

Currently sending it
Location
Oregon
Ok I have actually made progress. Wasn’t able to do much until school ended and parts came in.

First of all big thanks to @x2mafia @yurkanip @JetManiac for all the advice and help along the way. I never realized what a stooge I am with skis until I started this build lol.

Tore my old motor down (which ended up being a bigger pain than expected) and have been cleaning up the cases and everything for painting and reassembly. I’m just going to use duplicolor engine paint from Napa, thought about powder coating but I don’t want to spend $100 on powder coat for a $50 set of cases.

Decided to take advantage of my campus privileges and do the dirty stuff at the lab haha
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These things were grimy!
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I don’t know who this dude is who last built this motor but he doesn’t use antisieze, it made things really fun for me...
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All cleaned up! Well, good enough anyway...
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Also I took some time to clean up the inside of the hull. There was some splintering in the glass where some turf or whatever was glued and peeled up. Decided to hit it with some epoxy and paint
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When I pulled the pump from the SN I found that the driveshaft was buggered.
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I could have bought a new shaft and had it pressed in, but I said screw it after I found a mag pump on here from @McDog. Pretty stoked on it!
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That’s it for now. Gonna keep plugging away today. Hopefully I’ll have the pump together and installed by the end of the day
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
“I don’t know who this dude is who last built this motor but he doesn’t use antisieze, it made things really fun for me...”
7a46a719e295214ce89b20ece8a67728.jpg


The engraving is from oem yamaha showing the cases numbers, should be same engraved on case bottoms.




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Something is up with the prop spacing? That is crazy far from the stator. Are you using it? That prop will work but much better to get a newer swirl prop like hooker 9/15.
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
be_lain said:
@JetManiac @tomski thanks for the heads up on that, I had no idea. What is the consequence of using this impeller? Will I damage the stator?
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If it is not hitting the stator, then you will not hurt anything, but performance will probably be poor with lots of slippage and wasted power.

If you were building a stock 701 on a budget build, then that would be an ok prop for you. But a ported motor with a mag pump in an a/m hull, you need a Hooker 9/15 or a Skat big hub impeller. This is not the place to save money.
 
McDog

McDog

Other Administrator
Staff member
Location
South Florida
It would be like doing a bunch if engine mods on your race car and then buying some spare tire donuts to run instead of race wheels/tires. Overall performance will suffer despite the engine mods.
 
be_lain

be_lain

Currently sending it
Location
Oregon
JetManiac said:
be_lain said:
b18f1e6f97b6610fbc86dda3113491db.jpg

Finally done. Tomorrow she goes in the ski. Took me a while, but hey it was my first motor build....
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Looks good! But what is going on under all the electrical tape on the stator harness?
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Someone else had cut the stator harness at some point... The connections were all corroded so I redid them and put heat shrink on each one. I just didn’t have any heat shrink large enough to cover all the wires.

Should I be worried about this?
 
yamanube

yamanube

This Is The Way
Staff member
Location
Mandalor
be_lain said:
Someone else had cut the stator harness at some point... The connections were all corroded so I redid them and put heat shrink on each one. I just didn’t have any heat shrink large enough to cover all the wires.

Should I be worried about this?
Click to expand...

If you are going to ride in saltwater...yes. There's probably no reason to pull it apart until you test it, but bring a rope (and a buddy).
 
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