Yamaha 2-Stroker 50Hp HMHO Tuning?

[heffak]

Hi

Getting fast for summer in Sweden!

My to do list:

1.135#Jets
2.Boysen Reeds
3.Exhaust mod?
4.Velocity Stacks
5.Cut rev-limiter
6.Weld Crankshaft?
7.Shaving Cylinderheads?
8.Mill Cylinderhead?
9.Remove Autolube.
10.Unsure of porting?
11 More tips??


I am tuning my Yamaha 2-stroker 50hp for my Thundercat.
I have red about sevrel tuning tips but still have a few questions?
How much can I cut off from the exhaustmanifold ? Is there a risk cutting off too much. As I have learned a 2-stroke engine must have some resistens? Maybe there is enough resistens inside motor ?

Why should I weld my Crankshaft if I cut off rev-limiter?

How much can I remove from the cylinderhead and how much shaving on cylinders?

Porting? only exhaust?

Grateful for all tips.

[spartacus]

Welcome to the forum.

Roflhat is your man when it comes to tweaking the hell out your engine. If you haven't read this, grab a cuppa. http://www.rib.net/forum/f50/my-thundercat-61912.html

[heffak]

Thanks .
Will check this out a.s.p.

Cheers

[Roflhat]

Posted a reply on your other thread 

[heffak]

Thank you for your answer. Really helps alot.

I have now started working with my engine. Wondering if I should use my Reed Stops as in picture nr.2 or leave them out as in picture nr.1?
I have disassebled autolube and will run on premixed 1:50.I will probably make some kind of tray with a gasket for sealing, insted of leaving oilpump on motor.
I have looked at Hydro Techs homepage and was thinking of buying a High Perf Head Kit. But probably I can mill the original one instead? If I do mill the original one 1 mm do you think I also have to shave the cylinderheads?

Is this what I should put on for extra speed?

https://www.ebay.com/itm/Signature-S...JaXSLC&vxp=mtr



Cheers Fredrik