Other More squish and squash questions

R

RoTAxGreNade

X-
Location
Port St. Loozer
I am putting together a fresh 86mm motor with 33cc domes and when measuring my relief I have .045 and .035" on each hole... Has anyone ever seen that type of variance between domes?

The cyl has been decked a couple times over it's life and recently bored and decked by X scream with Wiseco slugs.
Brand new ADA head /domes along with new SBT crank also.
Using .062" solder doubled over and twisted 1" and it is against the cyl wall every time.

I read in the archives on squish clearances and how to measure and I came across where Chuckie said to run the engine a few moments and then check squish relief and then compression - Could there be that much settling in of components versus an motor on the bench never fired up that will change this measurement???
 
R

RoTAxGreNade

X-
Location
Port St. Loozer
215 maybe ???

Well my dial indicator has been dropped checked over the years but i put the tail end of my verniers in and sure as $hit I am .010" off....
I don't think Wiseco's production tolerances would be that far off so my next call is to SBT - I'm feeling a stretched or compressed rod at this point
 
Freakrider

Freakrider

X247
Location
Tampa Bay area
My advice, buy an oem quality crank from Paul Lehr in Ga. He posted up a new crank offer thread last month for 500.00. It has OE Seiko Koyo bearings,fyi...I would sell the SBT and not gamble.
 
Last edited:
McDog

McDog

Other Administrator
Staff member
Location
South Florida
Jump On It said:
My advise, buy an oem quality crank from Paul Lehr in Ga. He posted up a new crank offer thread last month for 500.00. It has OE Seiko Koyo bearings,fyi...I would sell the SBT and not gamble.
Click to expand...


Selling the SBT just passes the problem on to someone else. Call SBT and make them make it right.
 
R

RoTAxGreNade

X-
Location
Port St. Loozer
Agreed - Many people out here have had no issues with SBT cranks and I know without a doubt they stand behind their stuff..... We still haven't squashed the piston theory even tho it it is not likely.
 
W

waxhead

wannabe backflipper
Location
gold coast
I have no issue with sbt cranks. Since they are a rebuilt stock crank it cant be that unless one conrod was longer.

I suggest changing pistons from one side to the other and see if the issue follows it
 
Freakrider

Freakrider

X247
Location
Tampa Bay area
Let us know what you find out, this is mind boggling...those forged pistons are made with a 2,000 ton press and you would think they are precise...did one piston travel up higher in the cyl with the head removed ?
 
R

RoTAxGreNade

X-
Location
Port St. Loozer
I'd have to remove the studs and use bolts to clamp the cylinder down to get that measurement, may be easier to bolt the head on backwards to rule out the head shell ( I had the .010" difference with 38cc domes and the 33's I just bought)
Think I'm gonna swap pistons like Wax suggested, that should tell the story there
 
2

2XLR8

X-
Im willing to bet that it is the rods if the squish is off on the same hole between front and back. Good enough for people who don't check.
 
E

egbrig

I've read through this post and did I miss the part where the domes themselves were checked? Just because someone made them doesn't mean something slipped through the QA process. Why would pistons be the first thing or the rods? Move the domes around then look elsewhere. If you have .005 on piston and .005 on a dome or .002 on a rod it could be a matter of several small variences. Cranking pressure and squish do not corralate directly. What really matters is not psi but ratio.
 
You must log in or register to reply here.
Top Bottom