50 Yamaha 6H4

[MWhite]

Yeah, hopefully this thread will run a while.
To bad there are still people around who try to kill this thread by insulting other people who are just sharing thier opinion.

I'll just be the bigger man here and ignore it.

Lets stick to the Yamaha 6h4 and 6h5 blocks from 1984 to recent and share our improvement effords

Sounds like to me,,,, you need to listen and take down notes on what there talking about. I promise u these guys know what makes them go and what dont.

[ccaiken]

coffee time again - thanks for the inputs from everyone. I don't feel like anyone is trying to kill the thread, but to avoid flaming, and increase rather than decrease your credibility, just input what you've done. If you haven't done something, don't accuse people who claim they have, that they're lying, or that several of them have all had the same tachometer error. 88workcar's last post was perfect: a lot of general directional info on what he's done, with the caveat to test your *** off, and not a word directed at anyone else's inputs.

Back to the intent of this thread:

* Any input on how much to mill the head for 160's cranking pressure?
* stuffing the crankcase is referring to increasing the crankcase compression ratio by decreasing it's volume usually with epoxy. I believe this started with the kart racers in the 50's and 60's tho may have been the boat racers. You can decrease port volume, and increase volume of crankshaft by machining rings the dia of the crank, putting them around the throws, then filling them with epoxy. The WestBend 820 I had was built by a Nasa Engineer named Jim Akkerman in the early 70s and had both done - the transfer ports had epoxy poured around Tygon tubes pulled up thru the transfer passge thru the port into the cylinder, so what you saw was three perfectly smooth round (ish) passages going from crankcase to cylinder. Beautiful work made ~ 23 horses @ ~ 10k from 125cc on Nitro (yes!) which was the shiznit back then and aint really much at all now. Jason, I believe the trend these days is more to increase crankcase volume esp with engines with well developed exhaust tuning - which we don't have - correct?

[Mark75H]

Thread on lock down pending review. It will be edited or deleted as I see fit.

Arguing about admin actions will lead to you being banned. No second chances, no appeals.