First build... CPI Oliver

[kevin55950]

Devcon F is the best thing you can use IMO. Expensive but it lasts, and once sanded, it's as clean as welding and it's easier to work with. A good clean-up with acetone is generally enough to take the oil out (I asked this to a guy who converted a used AC aluminum cylinder to LC).

[waltinhawaii]

Crank arrived today from Parts For Scooters...(45mm stroke) it looked to be OK, but the threaded part for the left side of the crank (variator side) was too small (shaft size is fine, 16mm, 15 spline); I could live with that, I guess, by just going to a smaller nut to secure the variator; however, this crank uses a 10mm wristpin for the piston. Their website says this crank should be used with the Big Bore Kit (which is advertised with a 12mm wristpin). Wrote to them and asked how did I get one with 10mm wristpin conrod?

[waltinhawaii]

Hmmm. Tried the aluminum weld, boy this area is tight:
[img src="img.photobucket.com/albums/v722/wtani/IMG_7985_zps7130ddc1.jpg" src="" alt=" "]

I had to use a new tiny 90 degree grinder that I actually got to help redo the transfer porting... it's crappy quality. The diamond bit kept jumping out of the collet... and as you can see from the shiny parts, the cleaning was hit or miss.


The welding was pretty crappy, ugly as all hell. But, just need it to hold together and seal properly (I know I know. All crappy welders say the same... but did you see how cramped this was?? I had a helluva time getting the nozzle of the gun into these areas and angles were all off, very poor control and visibility in this area with the webs getting in the way).

I purposely stayed away from the proximal side of the hole, nearer the crank, to try to keep distortion of the bearing boss to a minimum. Not sure how I did, though, until it comes time to put the new crank and bearing in. Even though I have to return the new 45mm crank (wrong wristpin size), I figured the outer diameter of the replacement 45mm crank will be about the same, so will go ahead and mill out the cases today to clear the crank. Wish me luck. Hope the cases fit in my tiny chinese mill.

[waltinhawaii]

Sprayed some solvent into the weld... and there is a tiny bit of seepage into the weld on the inside of the case. The proximal end of the weld is coldlapped and not holding integrity. argh. So it's back to the welding bench (fancy name for the Black & Decker Workmate) for another pass, this time working from the bore side toward the main bearing, to allow the heat to build and get some penetration (could not do this earlier as the break through portion is paper thin). Will post pics in a minute.

[waltinhawaii]

2nd try... still has bad porosity due to inability to get the nozzle over too far, and inability to clean those areas well. If it still leaks, will just use some epoxy in the small porosities, if any. It should be airtight, though.


Big side of case in the little mill... centering on the bearing boss...


First cut. You can see that the casting is not exactly circular, so this is really a truing cut.


OK. So the stock crank web is 2.832" diameter. The stock case is 2.920" diameter, so clearance is about .090"

the new crank web is 3.082" diameter, so I want the cases about 3.170" (assuming I want about the same clearance as stock):


Centering the small side bearing boss:


Cutting to same diameter as the other side... 3.169"....meh. close enough. I'm tired.

[waltinhawaii]

for those of you who do metric, sorry, you'll have to convert my numbers. My boring head (cheap knockoff of a Criterion head, lousy quality) is calibrated in inches so I was figuring each cut in thousandths of an inch for simplicity's sake, to land on 1.370" or thereabouts as my final cut. I got the head from Little Machine Shop, they have very cheap tooling on sale sometimes; but chinese quality, so buyer beware. but unbeatable pricing, in my opinion. I won't use a boring head very often so don't mind the bad quality. In fact, I bought this R8 head specifically for this job.

[190mech]

Its looking real good!!

I like the English measurement when doing machine work too,gives a lot more numbers after the decimal point to calculate while "splitting hairs"..

[waltinhawaii]

Thanks 190mech! wouldn't have been possible without looking at your pictures and following what you've done already. The only problem I'm having so far is finding a comparable crank to use... haven't heard back from Parts for Scooters yet.

[teddy554]

they must of sent you the wrong crank have you tired to call them or you ordered the wrong one buy accident

[2strokd]

Looking real good. Your weld looks fine to me. I dont weld aluminum but no its not easy. Really not easy with the casting of some cases! Epoxy will seal it right up

You might also try Autotech355 (Carlos) on ebay for a crank. His store is closed until tomm. But he usually has stroker cranks of various combo,s in stock for a very decent price.

[waltinhawaii]

Thanks guys. I ordered the correct part, they just sent the wrong one in the box. They contacted me this morning; the 45mm cranks from Hoca are all sold out! Arghhhh.... they do have a replacement, but it is 43.5mm, not 45mm. So, with my 52mm l/c bore, that gives me 92.3cc vs my projected 95.5cc. Hmmm; wait until the replacement Hoca cranks come in (iffy, no ship date) or else take the existing replacement and give up around 3cc of free displacement? Oh hell. I want this thing up and running. Will just tell them that's fine, send the shorter crank and I'll make it work with that. This cylinder kit was designed for a 42mm stroke anyway, so working with a 43.5mm will probably be easier for sissies like me.

Next up: I should begin porting the cases. My existing tiny die grinders (1/8" collets) are not up to that, probably... found that out just now when trying to clean up the aluminum weld area (first time I've used them). Ordered a couple of pneumatics from Home Depot (1/4" collets) with a set of extra long extended carbide burrs from *bay. DAMN. The burr set (4 of them, different shapes) cost more than the 2 pneumatic die grinders. I had to order 2 grinders to get free shipping. That's always how they get ya, huh? They should be here next week. Stay tuned!

[waltinhawaii]

OK, can someone send me a link to find 2 sets of longer studs to fit a 90cc bore?? Parts for Scooters doesn't seem to have them... someone said AJ Parts might have them? But I sent them an email and no response yet. I need 2 sets (8 studs) because I also plan to do another conversion of another engine I have lying around, the other engine is a short case mina, that's why I don't mind having the 'wrong' 10mm wristpin crank as I can use it in that build. My deck height with this liquid cooled bore is about 78mm (without head).

[190mech]

A&j has them;
www.kaseaparts.com/blazer-90cc-atv-cylinder-cylinder-head-c-225_28_29.html

Carlos(Autotech355) has them too..
Dont forget that you'll need the bigger plastic cylinder shroud too!

[waltinhawaii]

Heheh, thanks 190mech. No shroud on liquid cooled cylinders
Just ordered the studs, thanks for the link!

[190mech]

DANG!You got a LC build..COOL!!