HELP w assembly

[jrowley85]

that is going to be one sick setup when you get done with it.. one place you should check out if you want to get a big bore kit or motor mods done to your bike is Eric Gorr of forward motion.. he did my buddies bike and took his motor from being a big rust bucket when he bought the 500 to being the fastest thing ive ever ridden.. just a thought.

[81cr450]

The first bike I did was a 525 with an eric gorr jug. Umm... I wasnt really that impressed with his work. The cylinder had little pock marks & I paid for porting & he wouldnt touch it. When it came back it took a couple hours porting for me to call it useable. Slag around the rim of all the ports was bad, & the powervalve areas needed serious help. He did get it back quick though, & refunded the cost of the porting. This will eat it's lunch though.
 I still cant figure how to get decent work done I pay in advance & try not to pressure but, crap work is just that. I'll have the bike I've been trying to get for the last 2 years soon though.    

[jrowley85]

d**n.. sounds like you have have had a F****d up time with motors..when Gorr did my buddies it was clean and porting was done to make her scream.. i also had him do my top end and it was great.... but maybe you just know more about what its supposed to look like then me.. lol.. well if you find someone that does a quality job let me know.. thats one of the many things i wanna do to my 5hunny in the future... hope you get your bike to where you want it

[Motorrad]

I feel your pain

[don46]

  When I ordered the piston I actually ordered a 91 & they said no cant go bigger than 90 without a sleeve, so I realize its gotta be borderline just wondering where the reliability becomes an issue I guess.

 

You could go 91mm if you use the 88 or older cylinder, thats what I did. Haven't got the head right yet but when I get it I think it will be a pretty sweet combination

[81cr450]

Darnit , wish I knew about the 88 jug being able to go to the 91mm before. I like the idea of eliminating that center flapper, as it doesnt seem like you could be gaining much with it & 1 less moving part to wear out , would be great.
I do have a couple more pics but I need to figure out how to do the image hosting thing again.
 

[81cr450]

What is a safe powervalve center flapper to piston clearance? I'm thinking .025 , but I'd rather be safe than sorry.

Found it on wiseco's site

Exhaust Power Valves  (2-cycle engines)
When boring cylinders with exhaust power valves, the exhaust power valve must be inspected
to ensure it does not extend into the cylinder. The exhaust power valve must have
approximately .015? clearance from the cylinder bore. Without proper clearance, the
exhaust power valve could contact the piston and engine damage could occur. If
machining the exhaust power valve is necessary, remove metal only in the area that extends
into the cylinder bore.  (See illustration A)

[81cr450]

How much static compression PSI is pump gas safe ? I have 170 with pretty well stock port timing. & how much will raising the jug .010 help? I have .039 squish clearance if that makes any difference. 5000 ft in elevation & up

[Motorrad]

Short answer.....perfect run it..

Long answer..
Stock they dont like pump fuel...

recut on squish ban is a must

what CC is your Head?

static compression ratio?

[81cr450]

47cc is what I ended up with, for 550cc's of motor.
4-5 degree squish angle. .039 squish
170 psi static , but I'm thinking you want corrected? Which I havent figured. Port heights are stock, just cleaned up. Thanks for the response, I just dont want to detonate the guts out of the thing.



Just a note I had to fix the squish angle after a couple rides, it hit HARD & tacked up quick but hit a wall up top. The constant 4 degree squish was over accellerating the combustibles. You need the 4-5* angle just for the first 4mm from the outside then the angle changes to 14-15* into the dome pocket.

[Motorrad]

47cc is what I ended up with, for 550cc's of motor.
4-5 degree squish angle. .039 squish
170 psi static , but I'm thinking you want corrected? Which I havent figured. Port heights are stock, just cleaned up. Thanks for the response, I just dont want to detonate the guts out of the thing.

I ment 4t ratio..  When all of us around here state our comp numbers it's uncorrected.    So we can have a base comparison...


Only one squish cut?   Most run 4deg. Into 15deg

[Motorrad]

here is my favorate one..

easy to swap back and forth between metric and standard...    stupid metric system

http://www.csgnetwork.com/compcalc.html

[81cr450]

yep just straight cut .125 radius into the bowl. Nice calculator, eagle rod has one but sae only. That is going into the favorites. I'll have to call Pinsinault tomorrow to get the dome cc. 

[GREENKAW24]

47cc is what I ended up with, for 550cc's of motor.
4-5 degree squish angle. .039 squish
170 psi static , but I'm thinking you want corrected? Which I havent figured. Port heights are stock, just cleaned up. Thanks for the response, I just dont want to detonate the guts out of the thing.

90mm bore, 47cc, at stock port heights will be about 7.4 to 1 corrected. 12.6 to 1 uncorrected. That's fine for 93-100 octane.

[Motorrad]

yep just straight cut .125 radius into the bowl. Nice calculator, eagle rod has one but sae only. That is going into the favorites. I'll have to call Pinsinault tomorrow to get the dome cc. 

What's your deck hight?