New build, stud & port questions

GoldenMotor.com

quik225

New Member
Aug 13, 2011
33
0
0
Eustis FL
First MB build.

I took apart my new 66cc from RAW Motors to do the recomended mods for reliability. I expected it to have 8M studs, only has 6M. Since I will be buying new grade 8.8 studs, should I upgrade to 8M?

The other thing I noticed, the exhaust pipe tube is smaller the the exhaust port. Worse still, the pipe flange is smaller than the tube! I'm going to open up the flange to the same size as the pipe and taper the flange a bit to help "funnel" the gasses towards the pipe. Anything wrong with this?

Lastly, why is the intake port smaller than the exhaust? This is the opposite of a 4stoker.
 

Tohri

New Member
Aug 28, 2010
159
0
0
People's Republik of Massachusetts
Oh, trust me, you're going to find a whole lot on these motors doesn't make any sense at all.

Yes, port match like Crazy. In fact, tear the whole motor down, read as much as you can about 2 stroke porting, and in the case of these motors, General cleanup. Just about anything you do (That isn't bloody stupid) will help these motors run better.

Furthermore, order up some M6 allthread in Grade 5 (Metric class 8.8) to replace the cylinder studs, and throw the acorn nuts in the trash. To start with. The 3' of allthread will leave you with enough to replace every piece of god forsaken chineese steel on the whole motor.

After that, well... There's half a million things that should/could/better be done to these motors, from transfer port matching all the way up to converting to Reed inducted and cutting boost ports. They really need attention paid in a bad way.
 

quik225

New Member
Aug 13, 2011
33
0
0
Eustis FL
What about going from a 6M to a 8M head stud? Is it worth the trouble, or will a grade 8.8 6M be enough on a 66cc motor?
 

Tohri

New Member
Aug 28, 2010
159
0
0
People's Republik of Massachusetts
High quality M6 studs should be more than enough. The main reason they bumped them to M8 was to offset for the horrendous quality steels they use.

Furthermore, you'd have to drill and tap your cases, which is a pain. AND if you're going to go through all the trouble of drilling and tapping cases, You'd be better off switching to 5/16-18 threaded studs. They're more readily available here in the states, cheaper, and the 18 TPI is a tougher thread than M8-1.0.

Of course, on top of ALL that is all the other stuff that really needs to be done to these poor beasts before you run them. I should probably make up a technical document or something.

...Just wait till I can get an extra motor on hand, I'll make up a .PPT with all the neat stuff you can do to these poor little motors. (Trust me, a major part of my job is making Visual Assembly PowerPoints.)
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
I'm looking forward to seeing what you have to present on reworking the transfer ports, T !

I can't go reeds, but I'd like to window a piston skirt when I figger out proper timing...

...and the 8mm studs may end up too close to the edge of the casting on a 6mm threaded block... that's another of the probs w/chinagirls ! threaded holes are too near the edge!

Best
rc

...have a look at the permatex thread repair product I posted a link on...
good for 128ft/lbs! WoW !