SPECS ADDED!!!Can any of you engine builders tell me what to exect from this port job

Dubs chops

livintit dot com
Okay correct me if i'm wrong (because I probabbly am) But if i put the spacer in the bottom and deck the top. wouldn't that raise my exhaust ports? i would be shaving 1.5-2mm off the top making the ports actually closer to the deck?
 

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
removing sleeves to deck the bottom of the cylinder? then running special spacers and gaskets?

I think a cylinder with the correct port configuration for your needs would be simpler AND Cheaper.
 

Dubs chops

livintit dot com
bwahaha i figured something technical out on my own. this is going to turn out way more work than i expected blah! i will take some measurements when i get the motor today and see what you guys think my best measure is.
if you use a spacer do you put a gasket on both sides? and does this make for a less reliable motor?
 

Dubs chops

livintit dot com
yeah but im already over budgete, and i know a guy that has a machine shop and nikad said i could have his spacer plate. so i am just weighing out my options at this point.
 

Dubs chops

livintit dot com
OK to the best of my mesurements here we go
cylinder ports are

39.6 tall measured on the outside of the case (bottom to top of port)
Couldnt measure them on the slleve due to pistons already installed.
36.10mm top of port on the sleeve to deck
48.5 wide on the outside of the cylinder
and to my surprise 81.mm bore to the best i could measure.

so now knowing these facts what is your input?
 

nikad58

1974 YZ 701
okie dokie.. so would a spacer plate on the top and deck the bottom help enough to justify the time ?
1. Remove sleeves
2. cut the bottom of cylinders
3. reinstall sleeves

Would the domes need to be cut ? (I'm thinking no)

He has access to a mechine shop and I'm thinking his time is cheaper than money
 

Dubs chops

livintit dot com
if this is a 81mm bore and i get a new cylinder if this one cant be salvaged for freestyle. can i use my sleev's and pistons? or even just the pistons?
 
Location
hhh
maybe im crazy, but i would ride it before i did all that. i know nothing about those port specs or any for that matter. im just thinking it might RIP!! i dont know how a good 701 wouldn't rip
 
Your xports are too high for decent bottom end.
If you use an aluminum spacer on the bottom of the cylinder you can sandwich it between 2 gaskets or just use the same sealer you use on the crankcase. Spacer on top would require o rings for sealing both sides. Your sleeves are not usuable in another cyl., cause the ports are too high.
 
maybe im crazy, but i would ride it before i did all that. i know nothing about those port specs or any for that matter. im just thinking it might RIP!! i dont know how a good 701 wouldn't rip

yeah ride it for the summer, then tear it apart. plus if it is missing the low end you want, you can always try a different prop, pipe, etc, until you tear it down.
 

Dubs chops

livintit dot com
let me ask this. will it still have more bottom hit than a stocker? i,m going with dual blackjack 44's if it makes a difference to you.
 

Cross

X
Location
WA
let me ask this. will it still have more bottom hit than a stocker? i,m going with dual blackjack 44's if it makes a difference to you.


That all depends on the rest of your set up. You can somewhat make up for tall exhaust ports with ignition timing, compression, prop, etc. Its about the whole package, not just one part.
 

Dubs chops

livintit dot com
well i'm foing to be running an ada girdle head with 35cc domes more than likey. also running dual black jack 44's lighned flywheel and advance my timing around 3deg. on exhaust probabbly b pipe limited when i have the money. but all that aside. say i had all that stuff on stock cases and cylinders, will it run better that the stock cylinders or am i actually going to have less bottom end hit than with stock 61x cylinders.
 
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