How far can the head be shaved before you have to run race gas.Im wanting to add some pep to the new top end.will I have to jet up if I shave it down?
head work
- Thread starter blastblast
- Start date
There is a cart on the site somewhere that gives the list, you'd have to search for it (I don't remember where it is) but it's .030"-.035" before you have to go to race gas, according to that chart. I'm sure there is some factors that would have to be considered but the chart is a good guide.
Ok well I was thinking. 010 or 0.15 nothing too much just to add a little bit.think you for the help
Looks like I'm going to have an. 080 over piston and mill the head. 020 I just wandering if I will need to jet up and how good it will run
Shouldn't have to worry about jetting with just changing to a high compression head. Neither should you have to worry about jetting when going to an over size piston unless its a big block 240 piston.
Are you talking about shaving down the mating surface by youself or having it rechambered?
Because the resquirements for them are vastly different.... If you have a belt sander, a super smooth surface, and A LOT of patience you can shave the head yourself somewhat. This has the advantage of increasing the compression ratio (reducing the head volume) but doesn't take full advantage of a rechamber (changing the shape of the head).
I've gone the sanding route on a stock head before and it worked with good results (didn't try a rechambered head on that engine yet to compare but will be soon!). I shaved mating surface off until the "step" was gone from the head and the squish band was completely flush with the head gasket (on a stock stroke engine!).
As far as jetting is concerned, you MAY not have to change jetting. Shaving the head DOES make the combustion more efficient but the jetting may be adequate for that.... the only way to tell for sure is to pick up 2-3 spare spark plugs and do a few plug chops. On twostroker99's engine (the one I sanded the mating surface away on) the main jet was a 290 before the engine work and a 290 after (with no airbox lid and a FMF SST pipe).
Anybody mill thier head? I work at a machine shop n have access to a manual mill and pretty damn good at running it . Wat r major gains from this?
You could probably do it with a rotary table on a knee mill but it's easier to run it on a lathe to cut the head out.
The trouble is, there's no one "set" size that the head needs to be designed to.... Engine RPM, exhaust port height, fuel to be used, even ignition timing come into play when designing a head shape...
http://www.blasterforum.com/engine-13/squish-mystery-not-47719/
we simply just sent out blaster head with a dt200 head. the dt200s already have a good chambered head compaired to the blaster and we desided to copy it. we also shaved the head .010 and it was an awsome inprovement. were going to try new designs on our new builds copying ktms new still which is more of a donut shape. i personally think that the head is the 2nd best bang for buck with these blasers other then the pipe.
Dakotademon and Surfrjag had their heads done by other builders and I'm not sure how those particular builders held their heads in the lathe but there's what I did....
The "arbor" is a piece of 3/4" steel rod turned with a double shoulder on it and then a NGK BR8ES spark plug with the threads parted off and the two pressed together:
The head I pictured above, mounted in the lathe chuck:
Thank you.
I'm told that the head I cut would have been shiny like yours had I turned it up to about 1,500 rpm and held sand paper on it. I don't think it makes any power difference but perhaps some "coking" would be avoided like that.
SCD, is "coking" a typo for "cooking"? I've been looking into the best finish for the combustion chamber. I've read and been told that a textured finish will help prevent hot spots. The only thing I've seen that gave me an idea of how rough is an old guy I know said "400 grit sand paper". I know you spend a lot of time researching things like this, what have you come up with?
O sh*t si i can make that arbor inna bout ten mins at work . Thanks man now just gotta find a head . How much off ya think before 110 feul is to be used ? .015 to .020?
