BBK Shopping [Purchased]

[drawkward]

Went to go install the kit. Had it all ready to go, and then started to realize that something wasn't right after putting the cylinder on the piston and putting it to the case. I turned the flywheel and the fucking top of the piston and THE TOP RING came passed the cylinder.

Ben did a test fit for me, but I guess I miss read the info he gave me. I was hoping he would fit the cylinder and head fit. Not just the head...? Hmm. Glad I realize that now. Totally thought he was checking the actual cylinder and head fitment for me, as that was the part that we were not sure about.

Here is a copy of the message I received.

"Hey dude. I swapped top ends today and the verdict is:

It'll fit, but the rods are too long on the stock FM for the QMB head.

This is what the QMB cylinder with the FM head looks like


This is what the QMB cylinder with the QMB head looks like


And this is what I'm going to throw in with your stator order to fix it


I'm extremely unhappy. I have to rebuild to be stock 50cc, which isn't looking too good due to the overheating. & I now have a surplus of parts that I doubt I can return, including the cylinder kit ($135 lost) due to the fact that I chamfered and tried to install it. What a let down this was. Now I know if my engine goes there is nothing I can do.

[90GTVert]

It sucks that it's not a direct bolt on, but you aren't screwed just yet. You can probably use an aluminum cylinder spacer to remedy the issue with the longer crank or stroke.

www.spmotostore.com/product_p/hr5200951.htm

www.scootercraft.com/product_info.php?info=p15575_Stage6-Spacer-Kit-for-85mm-Crankshaft---Minarelli-Horizontal.html

Make sure you get enough gaskets to put one on each side of the aluminum.

[190mech]

I've made a bunch by hand with a saw,drill and file.Its a lot
of elbow grease,but a guy will work hard to get his new parts
on!!Install the piston,set the crank to TDC,slide on the cylinder
and align the top of the piston to the top of the cylinder,then measure how much of a spacer thats needed under the cylinder.
Sounds like you need a fairly thick one....

[drawkward]

it's about 4 millimeters off. The only problem is that I need the scooter to get to work, so I was hoping for the direct bolt on...

[90GTVert]

I know you don't wanna put it back together stock, but if you get all the measurements like 190 mentioned you could stick it back together for work and take your time if you wanted to try to make one rather than buying one. Or just stick it together and order a spacer. If you get it straight, you'll be glad to have the 70cc.

[drawkward]

Just don't want to end up with an unusable kit. I only have a few days to make up my mind before my return window is closed. How would I go about getting the measurements? Measuring the height of the stock cylinder vs the height of the 70 kit? I also do not have the tools to make a spacer on my own at the moment. Even if I did, my confidence level regarding it is not very high.

Wish I would have taken the time to measure the difference while it was off, as I don't think I'll have the time to do it before the return window is closed. I'm dependent on daylight, unfortunately.

[90GTVert]

Try to measure how far the crown of the piston is above the bottom of the ports at bottom dead center and make a spacer that would put the piston's crown even with the floor of the ports or just a little below the ports at BDC. Hopefully that measurement will put the piston's crown below the deck of the cylinder at TDC. You can try measuring from the base of both cylinders to the floors of their ports to see if that number is close to your number. I'd do both anyway, just to be sure.

[drawkward]

Ok I've made up my mind. I'm not giving up on this kit. I've been dying to get the 70cc and god damnit, I'm going to get it.

I'm thinking the spacer you linked me to (top link) will work, Brent. I'm not going to take the scooter apart again because I don't have the time. But I will be ordering plenty of aluminum spacers and extra gaskets. I figure, if I can't get the right height doing that, then there is something wrong with me. My only problem then will be getting the right compression. Hell, this might even work out to my advantage, running higher compression and pushing more power.

So, do you guys know a good place to pick up gaskets and spacers (smaller spacers, along the lines of .5 - 1.0 mm).

Also, I was wondering... If I get the TDC right, wouldn't the BDC correlate?. Hopefully it's just my crank rod that is longer, and the crankshaft is the same size. If so, the BDC should correlate to the TDC... Correct? It just seems easier. But all the same, when I go to install the 70cc I'll make the measurements to be sure, and also be sure I have plenty of spacers and gaskets to get it right.

THIS IS GOING TO HAPPEN - I'M NOT GIVING UP!

[90GTVert]

Check these out. 2strokd pointed them out to me when I was looking for some.
www.provoscooter.com/athena-cylinder-gasket-set-70cc.html

As long as you have the same stroke as the kit is intended for, then once you get the piston setup to be correct at BDC it should be under the deck or even with it at TDC. You want to worry more about what's happening at BDC than TDC for 2 strokes. Of course you don't want your piston too deep in the cylinder or smashing into the head either. The ports are where all the action is though. You really don't want the piston blocking the ports at BDC. That will reduce and disturb intake and exhaust flow and you won;t have a very strong running kit.

[drawkward]

Thank you!

The bottom of my lowest port to the base is about 18-20mm on the 70cc kit. Hard to get it exact.

Ben - Would you be willing to pull your 1E40FM cylinder and measure your lowest port to the base for me?? It would really save me a lot of time. If I have to pull apart my engine to check it, I have to immediately put it back together and get it running; I need it to get to work every day. If not, no worries.

---

EDIT:

I just spoke with Garrett at Provoscooter.com and he measured the total thickness of the gaskets for me. Said it was just under 2 mm. They don't carry the stage 6 spacer yet, but will in about a month (can't wait that long :/ ) He was extremely helpful. I explained my situation to him and confirmed that using the stage6 spacer kit and his gasket set, I should be able to get it in the right zone. Going to wait to hear back from Ben to just see if he can confirm the difference in the cylinders for me. Even if not, I think the spacer and gaskets should do the trick.

[2strokd]

And you had a 40mm bore stock?
Hhhmm, a stock stroker? That would be sweet in the long run.
Keep it up dr. You will get it bud!

[Greg]

I know right now this is a pain, but really, this is a blessing in disguise.
You might want to at least tell Autotech355 about this to see what he has for solutions.

Carlos (autotech355) warned me of this when I asked some questions before ordering my kits.
He told me, if my cylinder was bigger than 64mm, then I had to use a different kit, as bigger then 64mm is a stock 65cc engine.
I don't know if his calculations are correct or just just rough estimates.

If Dr. got Autotech355s "other kit" for the longer stroke, without using a spacer, wouldn't he end up with even more displacement, like 80-something CCs?

[90GTVert]

Assuming the bore is the same, he'll have the same displacement with any kit. As far as displacement is concerned, it doesn't really matter where the piston is in the bore. It's all about bore and stroke. It depends just how the cylinder is setup, but if the cylinder is for a standard 1E40QMB and his engine has a longer stroke the piston will go higher at TDC and lower at BDC. If the connecting rod is simply longer than a standard 1E40QMB the piston should be higher at TDC and higher at BDC. I believe all we know at this point is that the piston is higher at TDC, which could point to either one. It would be great for DrAwkward if it ends up being a longer stroke. I don't think the stroke is gonna be so long that it's a stock 65cc engine. To make a 65cc engine with a 40mm bore it would need a stroke above 51mm.

[Reign]

Holy shit, I just saw this thread. I measured everything twice! How could it be off by that much? I even fit the 40FM piston inside of the 40QMB cylinder and cranked it forward and it was fine. I'll go and measure the port right now. I still have it apart in the garage. I'm really sorry dude.

EDIT: just measured. All of the ports are at the same distance from the base of the cylinder. I'm seeing around 26 to 30mm

[drawkward]

I sent him a message on eBay.

Ben - Could you measure the cylinder height (1E40FM) for me? That way I could get a better idea of how much it needs to come up. Once again, I could do it, but that would just take way too long and be way too much work for one measurement.

Yeah guys, I'm going to get it to work... No worries (anymore). Was freaking out right after it happened but I've calmed down a bit and things are looking good.