Ok, SO I spoke to Dave at LA Sleeve who indicated he could turn the sleeve around in 6 weeks for approximately $500. So I package it up and ship it off. Couple days later he and I are on the phone for over an hour discussing every detail of the sleeve. LA Sleeve has moved into the computer age and all of their sleeves are digitally designed and computer made. They ended up creating a file for my sleeve and what took a little time to work out, will be easier when I have the next one made. Fast forward about 11 weeks and Dave calls to say the set up is finished and my bill is .....oh lets just say around $1000. Gulp, but I think I'm in it this far lets keep going. Stepping back I'll break it down like this. I charge around $500 to machine the cylinder for an internal coolant passage and around $300 for a FL350 specific port job. The porting on this cylinder is way more then gets done on the 350 so I'm gonna say the bill would be higher. So if I made a cylinder from scratch, plus the Rands head and the machining for the head, I'm at $2225 (or more) for this big bore cylinder and head assembly. The new sleeve is 1/8" thick and will handle over bores up to 89mm.

I love the engraving on this one LOL so badass! I'm ready for the video of this monster!!! Still drooling over here....

Ok, so I have the cylinder back from LA Sleeve and it looks great as the pictures show, but I run into another thought provoking moment. The bottom part of the sleeve doesn't fit in the machined cases. No worries, I can fix it, but the more I look at the cases, the less I like the work that was performed. It appears as though when the cases were bored, they were bored off center. Additionally there is some welding work that looks like they bored in a complete circle and then built the case halves up with weld. I wasn't liking it, So, I put a nice case I had in my jig and off to work I went. I'm very happy with the new set up.

Alright, I had a set of cases machined and the cylinder prepped, now onto other components. I made a call to Nuke em to pick his brain. I gotta say, this guy is not only pretty crazy in the cool way, but full of oddy information. We discussed big bores at length. Two items I picked his brain on at this time were: Engine balance and piston prep.

In some of Nuke Em's past posts he had mentioned race engines with and without balance shaft set ups. I wanted to know more about this and he delivered. I further looked over several of Speed Chaser's posts regarding pistons and cranks and then formulated a plan. One of the first things I did was determine the balance factor of a factory FL350 Engine I had. I cam up with a factor of approximately 55% from a 78mm bore Art piston set up. I moved forward with modifying a 87mm 1982-83 YZ490 piston and used that to check where the current factor checked in at. I came up with approximately 45%, as the YZ piston and Prox rod are over 100 grams heavier then factory stuff.

I did some calculations and wanted to shoot for a factor of 60% for this Engine. I went a litttle higher then factory because at some point I want to remove the balance shaft and see what happens. I have some ideas, but want to experiment. I ended up drilling the crank I prepped and stuffing the holes with some delrine I machined. I think the crank came out fairly nice. I did a ton of other piston prep, but will need to find a few pics..

Also, in the past there were discussions about weather the cases needed to be clearanced when using a Prox CR250 Rod. Well I can tell you without a doubt, yes they do. I ended up not only porting the lower cases in the crank cavity, but doing more work so the rod didn't hit around its rotation and the top portion of the cases where they are already notched for the factory rod.

This is a cool read.
When I first saw the pic of that rod I went OH NO !!
I didn't see any grind marks on the back of the rod indicating you clearanced it.
Apparently you did it the hard (correct) way and not the way I did mine. I ground off the back of the rod so it clears everything LOL. It works. The FL350 Engine I did is in the death machine and is running.
I guess if you run no counter balancer then you don't have to do the vent mod either, right ??
Just wonder how bad the vibs are gona be.

Why did you weld that pin ?? I didn't weld mine.

TURBO ????

welding the pin is pretty common, it just prevent any movement of the crank and throwing it off balance, my 360 is also welded, welds can always be ground out if needed and rewelded

So, I welded the pin, as Fully explained, to keep things in check. The crank is spinning more weight then factory, the RPMs will be higher and I don't want to worry about the crank halfs coming out of alignment. Removing the weld would be pretty easy and not really affect the crank halves. The welding just has to be done right so the halves are not pulled out of alignment.

So before final assembly of the short block, I had to take measurements for a cylinder spacer. When the cylinder is on the YZ490 piston is in, with no space the piston at TDC (Top Dead Center) is above the cylinder a fair amount. I ended up starting with a 2mm aluminum spacer.

Then it was on to assembly, everything went together nicely. I'm gonna run the Engine with the balance shaft to start off with I can say since the Engine is already running, that it is as smooth as butter.

I must say the pictures are deceiving. The bore is absolutely HUGE.

very nice..would love to see a video of this beast running

I don't even understand half of what you've done but HELL YEH!

...THIS is what America is all about.

(and you're a fellow Pennsylvanian - right on! Im over near Chambersburg)

Hey meth:
Just curious about the picture above of the two pistons.
I noticed they are two different pistons.
The skirts and cut outs are different. One piston has corner ribs (which I like for strength) and more rounded cut outs. The other piston has a more square cornered cut out and no ribs.
It also appears that the piston on the left has a shorter skirt.
Did you re-work the pistons ??

CO, the 2 pistons are both for a YZ490. They are slightly different, from the factory. Do you know how you used to be able to buy the "old" style wiesco piston for a FL350, well I'm guessing this is a similar situation. Other then that, One has been cut down and modified, the other is not modified. The skirt is cut off the one so it doesn't bottom out on the crankcase.

The next Item I machined up was a new 3rd bearing side cover. I really like these and they are hard to come by. I have an original superlite cover, but wanted to make some changes. I think it came out nice.

Man that's a beautiful cover. Ribbed for strength and a lot deeper than stock to hold what looks like a double roller bearing. Does it really need that ??
Wish I had the ability to run a cnc.

love that cover, I have seen these on a few engines and was wondering if you were going put one on..build one even better

So I put this on FB and youtube, thought I'd put it here too. The big bore kicks butt, so much so it likes to eat 102c clutches. HAHA.

I might have missed it, but what brand/size of CNC machine do you have?

What did the HP end up at on the Engine?

Wasn't someone selling a new Powerbloc clutch on here? That'll handle the HP. I thought those 102's were known for being wimpy.

hum.. honestly never heard of a 102c being wimpy. but then again I live under a rock...LOL.

Yeah, I'm no clutch expert, actually I'm not an expert at anything, But every time I've seen those 350 stadium lite race cars they have Powerbloc's on them, including all the Briggs Built cars.

How much HP? The Phazer engines are rated at 80 and I go from brake to full throttle on mine and the PB hasn't blinked.

If your HP is much higher, not sure.

A lot less parts to break on the PB.

It's that feeling you get when you call in a favor, and the box with the only brand new Power Bloc made for an FL350 in who knows how many years, shows up at your door :)

Manufacturer pulled this out of the archives and made it happen...

Sweet hookup,video?

Ok, so I'm working on the Power Bloc tuning, finding springs is interesting....and EXPENSIVE! Anyway, the original spring was stalling around 3400 to 3700 hard to pin down exactly the way this thing revs. So I installed a spring that stalls around 4500 to 4700, seems very nice for the type of riding this thing sees. I'm still working on the weights but it's moving along. I have a second combustion chamber design I'll be trying and I'm also working with Neil's Power Pipes in Canada to build a new custom pipe.

I was planning on making a slightly longer video then the one here, however, before I started filming, I rode a wheelie up my driveway (all the way) and flipped over backwards. Pretty cool...but not cool. So here's a short clip where I was a little gun shy and also.....That Poll...

Hey buddy, that is just---------------------AWESOME!!!!!!!

Glad you are OK on the flip over.

Nice!

Keep an eye on that clutch bolt.

Forget the clutch bolt. Meth needs to look out for that pole!!!!