Blaster HELP - Blaster Build

[BlasterDave]

I'd like to build a Blaster specific for surf. Don't care about top end speed, all low end pop!

I have a stock 701, Riva Red Pipe, Single Carb, and hooker prop in currently. Had someone mess with carbs and they are messed up. Suggestions for setting carbs would be welcome.

I also have a 760 (from old WaveRaider), Factory Blaster Pipe, Dual Carbs

Any ideas on: 1) Making the 701 or 760 really scream? or 2) Buying an engine on a serious budget that I can drop in?

About me?? I am beginner as far as turning the wrench. I have installed an SBT motor and all connections one time - and it actually ran great!!

LAST THING - What ever mods are made need to be very reliable. Set it and go for a long, long time. Don't want to spend more time and $$ constantly fixing issues.

Thanks to everyone in advance!! :brap:

 

[GReenANt]

i know everyone will talk up a 61x/62t setup but i have a 760 (64x minimal porting) factory limited with the dual 44s and am very pleased. what i also considered was the 781 ported 61x/62t motors pretty commonly advertised here. a large chunk of the costs could be offset by selling the motors you have or using the parts as the cores.

 

[BlasterDave]

Ok guys - please don't make fun of me here... What is the difference with the 61x/62t/64x etc...???
Also, what is the difference between porting and something that is bored??

I always thought if you bored out the cylinders you would need larger pistons which would gain you hp. Is that right at all??

Please, keep all explanations simple... I'm not even close to a motor head.......

and please keep coming the advice on the cheap way to get performance on the 2 engines I have above.
Thanks everyone!!

 

[nextlevelinnovations]

Ok guys - please don't make fun of me here... What is the difference with the 61x/62t/64x etc...???
Also, what is the difference between porting and something that is bored??

I always thought if you bored out the cylinders you would need larger pistons which would gain you hp. Is that right at all??

Please, keep all explanations simple... I'm not even close to a motor head.......

and please keep coming the advice on the cheap way to get performance on the 2 engines I have above.
Thanks everyone!!

Don't be afraid to use the search button and don't be afraid to ask. I have have been working on 2 stroke motors for 20 years and just got into jet skis within the past 3 years. I have learned alot from the guys on here and pwctoday since I joined last year. Alot on these guys have a ton of knowledge. Good luck buddy.

 

[eeerieski]

in what I call the the "6m6" class of yamaha engines there is:
6m6 650cc slug
61x 701cc low rpm power
62t 701cc high rpm power couch engine (larger bore in jugs for larger sleeves)
64x/64u 760cc high rpm power couch engine (basically a factory bigbore 62t)

For low rpm grunt you want the 61x 701 engine with either the 61x or 62t crankcase and either a single 44/46mm or dual 38mm carbs, the smaller carbs are slightly more restrictive but give better signal to the fuel metering system for a better F/A mix.

lots of carb tuning info here: http://www.groupk.com/docstech.htm

 

[GReenANt]

61x cylinder -(generally single carb oem 701cyl) general knowledge is that they have lower port timing = better bottom end
61x case - single carb restrictive, not preferred
62t cylinder - (generally dual carb oem 701 cyl) higher port timing more hp but less bottom end
62t case - dual carb better airflow, preferred
64x cylinder - (OEM 760) larger bore(bigger pistons) higher port timing more hp.

760 oem case should be a 62t or 64(?) and are identical. the 760 motors come with dual 44mm carbs where 701 dual carbs are 38mm.

all the cylinders and cases have the numbers cast into them for identification.

Porting is opening up the ports to modify the airflow through the engine. best and safest if done by a pro. more extreme porting will add noticeable power but at the cost of engine life.

yes boring requires going up a piston size. only necessary if compression is bad or cylinder walls damaged.

with your knowledge the simplest thing would be contacting an engine builder on this site and trying to find something in your budget, or dropping in the 760
the only motors i have had in my blaster are a 61x/61x with factory pipe and a 760 and the 760 is better

 

[ajmps1]

swap the cylinders, put the 61x cyl on the 62t/twin carb case. put the 760 cyl on the 61x, sell this setup and keep the dual carb setup, 61x cyl now with dual 44's. you can also sell both power plants as is, assuming they have good compression, and buy a built motor, jetmaniac sells a solid 718 power plant for like 1600 or so thats easier if you are not the most mechanically inclined. just plug and play

 

[BlasterDave]

Good news is I have 61x stamped on the head, the crankcase, and cylinders. It also has an ID badge that reads 62E, this badge is located under the carbs on the manifold that goes into crankcase. Is that the carb manifold? What does the 62E mean??

Ajmps - when you say put cyl on case, is that the crankcase you are talking about or the manifold under the carbs leading into the crankcase?

I know, no stupid question - just stupid people.... At least I know it.... :newbie:

 

[eeerieski]

he meant the cylinders on the case.
You can't put a 62t or 64 series cylinder on a 61x case though as ajmps1 told you to do, the 64 cylinder has larger sleeves. You could enlarge the 61x cases. Many people have had great success with a 61x/61x engine.

Engine Terminology lesson here:
61x/61x means 61x cylinders over a 61x case
61x/62t means 61x cylinders over a 62t case