Compression & Dome Size on Ported Cylinder

[Matt_E]

So you want me to call you at home when you measure your junk?

Is that about right?


If you weren't from Arkansaw, I might be offended.

 

[Mouthfulloflake]

I wont get home until about 10pm central tonight, what time is that out there in BFE where you are?

So you want me to call you at home when you measure your junk?

Is that about right?


If you weren't from Arkansaw, I might be offended.

 

[Matt_E]

Got my topend back from Art @ Jetworks.
Beautiful work for extremely reasonable prices.

Art had to bore it up to 85mm (!!!!). I assembled most of the motor yesterday. Ring gap looks MUCH better, and the pistons are a much tighter fit.
I'll come back with cranking compression numbers and ride impressions when I have that info.
Oh, I am switching the 35cc domes to 38cc domes.

 

[Matt_E]

Problem solved.
It's blowing 170-175psi in both holes, fresh bore & hone, new rings, and 38cc domes.
I suspect it might go to 180 after break-in.
Perfect.

To reiterate, this topend was sold to me as bored & honed, ready to go packaged with an 84mm Wiseco Kit.
Art informed me that the bore was slightly too large for even 84.5mm pistons, so I got it at 85mm now.
772cc, yay.

Might get a tank through it tomorrow to test it out.
Setup:
61X bigbore, 85mm w/Wiseco Pro-Lites, 772cc freestyle port
62T ported cases
Dual stage reeds, R&D manifold, dual 48 Full Spectrums.
ADA Head, 38cc domes
B-Pipe, Mod chamber
Modified stock CDI, RAD Flywheel

 

[Matt_E]

Took it out today....

The only gasket I tried to reuse was the exhaust manifold gasket, and that bit me in the ass.
It leaked like crazy, ran like crap.
So I replaced it (thanks Phill & Bobby! :biggthumpup, and took it out again.
Runs great now. Best engine I've ever had.
I ran half a tank through it.

 

[#ZERO]

It's amazing what the right piston clearance and ring end gap will do for an engine. :biggrin:

How does this qualify for your best engine if you've only used a half tank of gas?

It's not even broken in yet.

 

[Matt_E]

I've broken in all my previous engines as well and I remember what they performed like after half a tank.
How wouldn't I be able to qualify it? :dunno:

 

[#ZERO]

If it last six months, it was a good one.

 

[Matt_E]

:haha:

For once, I used mostly new parts, all new gaskets, and had a pro do the topend work.
I've got my fingers crossed.

 

[crammit442]

Took it out today....

The only gasket I tried to reuse was the exhaust manifold gasket, and that bit me in the ass.
It leaked like crazy, ran like crap.
So I replaced it (thanks Phill & Bobby! :biggthumpup, and took it out again.
Runs great now. Best engine I've ever had.
I ran half a tank through it.

And that's with Art only boring it. Imagine what it would be like if he actually ported it.......:wink: J/K...Glad you got it working.

 

[Crab]

:haha:

For once, I used mostly new parts, all new gaskets, and had a pro do the topend work.
I've got my fingers crossed.

Your on the right track now. I have my 61x cyl at Watcon's, not the cheapest but at least I know its done right. Decided not to port, but just get it together and fresh. The Wetjet motor is coming back from the dead soon.

 

[Cross]

Your on the right track now. I have my 61x cyl at Watcon's, not the cheapest but at least I know its done right. Decided not to port, but just get it together and fresh. The Wetjet motor is coming back from the dead soon.

I thought you werent going to cheap out and get it ported. Oh well, I guess you will be kicking yourself when you were wishing you had it done. I am heading over tomorrow for a "fun day"!!!!

 

[Crab]

I thought you werent going to cheap out and get it ported. Oh well, I guess you will be kicking yourself when you were wishing you had it done. I am heading over tomorrow for a "fun day"!!!!

Yea, but as you reminded me its no big deal later. I'm not 100 percent sure what I'm doing with that motor as well yet.

 

[Cross]

Yea, but as you reminded me its no big deal later. I'm not 100 percent sure what I'm doing with that motor as well yet.

You know that I am just messing with you Crab. Maybe if you decide to port it, I will be able to find someone to do it for you

 

[Matt_E]

A little update to this: I've had some deto going on. I've broken two BR8ES solid top spark plugs. One came loose, both broke the center porcelaine electrode loose from the metal casing.
It occured to me that the RAD flywheel might distort the timing a bit, so I changed timing to completely stock - it was at about 3 degrees advanced over stock before that.
So far, that seems to have cured the problem.