Venus 50 (Now 96cc!)

[90GTVert]

It's crappy, but you wanted it, so here's a quick vid...



I started out with 6g sliders from the 70cc setup. Never left the garage, as I described earlier, because it revved and barely moved. Then went to a combo of 8g and 9.5g sliders (8.75g) tonight and tried it out as you see here. Still revs too much. As you can see, it starts to wheelie then just revs too far and kinda feels like it's slipping. It's showing promise though, considering I haven't done anything but adjusted the idle and swapped sliders 1 time so far.

The bad news... It's got a tap/knock when I let off the throttle or it's not under load. It kinda sounds like exhaust in the vid, but in person it's definitely a knock or tap. Check out about 1:10 in the vid. I was trying to get the sound in there the best I could.

[2strokd]

:riding: :thumb:
Cant beat that for a very close to stock 90cc mina!
Nice to see you pop that front end up. Now with some practice you will be wheelying all over on that lil sucker :scoot2: .
I heard the clunk type knock. Whats the squish at? I would do a leak test first i guess? Before pulling it apart anyway.
Runs strong! Any topend runs?

[190mech]

Looks strong!I agree with Robert,do a leak test first,sounds like a head gasket leak,might wanna recheck the head torque..
Maybe some lighter clutch springs too??

[90GTVert]

Good point. Especially since I did file the head and there's no gakset to make up for any imperfections. It passed it's leak tests prior to running, but who knows now. I always re-tq the cylinder nuts on my big scoots... but I don't have to remove the engine to do that on them. I guess I'll pull the engine back out and test it. I like the little scoot, but this is why I don't think I'll build many more little scoots. That annoys me on the SunL too. Can't set the valves or anything with the engine in.

Oh, the squish should be pretty loose. I never even checket it because I had 1.4-1.5mm below deck @ TDC on the high part of the piston's edge. Even more where it's been filed. Only made 140 psi.

[190mech]

I think stacking base gaskets makes them settle and loose head torque.My 103 did this,a bit alarming to hear a knock on a fresh engine build.Retorquing the head fixed my noise,hope thats all yours is!

[90GTVert]

Yeah, lots of stuff to compress with those soft base gaskets. Would be nice not to need it to come apart since I have no extra base gaskets or anything now. I wish someone would start carrying 54mm stuff in the US at good prices. It gets old paying $20 for a set of head and base gaskets or paying $1 per gasket but waiting 2 weeks to get anything done. I think my next order from Autotech will have to include a bunch of gaskets if I have any money to spare.

Also, I forgot to answer one of Robert's questions. No top speed runs. I did basically what you saw. I got it up to about 30 in the yard, but it gets sketchy on wet grass and I run out of distance lol. I was all greasy and sweaty and didn't wanna put my helmet on to try it out on the road (not that I shouldn't wear it in the yard... but you know how that goes).

[90GTVert]

I pulled the engine out. With all the copper spray around it was hard to tell much about leaks with the head on. I don't really like using 6psi to test a seal that sees much greater pressures, so I just popped the head off. This pic shows what looks like a leak on the right side. the weird mark you may notice is from checking squish clearance before I pulled the head. The squish was 1.49mm.



If you look at the pic above and this one, it looks like the tune is pretty darn good considering I just left it the same from the 70cc.



I suspect that my "milling" job may be a little off, on top of probably needing a re-torque, so I'm gonna try and make the head more true. I guess I'll try the glass sanding trick. If it doesn't work after that, I might just take the head and cylinder to a machine shop. Knock a little off the deck while I'm at it if I have to go that route. Hoping to be able to seal it cheap though.

[90GTVert]

I used a pretty cool trick that John suggested and then researched a little and got the cylinder head a little more true. It's a really easy technique that seems to work well and requires very little money, so I had to make a little how-to...

49ccscoot.proboards.com/index.cgi?board=hints&action=display&thread=941

I got the cylinder head re-installed afterwards, but that's about it.

[2strokd]

It should hold well. I have had luck in the past milling heads on glass.
Looking forward to the report.

[190mech]

Thanks for the How To!!!

[90GTVert]

Thank you for the advice. I know I didn't follow it to the word, but I read about the marker as a guide for sharpening tools and really wanted to try that. I wasn't sure that wetting all of the surfaces as you suggested would make that work right.

[90GTVert]

I got the engine back in and swapped to 1.5K contra and clutch springs. First, the bad news... I think I was right. It's an engine noise. It's still doing it and it really sounds like metal on metal to me. It's gonna have to come apart so I can see what's up. Now the good news. Holy crap. With just a small change it's nutty form a dead stop. The initial hit and pull would throw me off when it hits just right if I didn't let off. It still just free revs way too much, but when it does wanna catch it pulls harder than anything else I've felt on a scooter. It's showing some real potential and I have a feeling I won't need to fear any 100lb kids when it's right. I'm just wondering if I'll have to fly by them with both wheels down or one up?

[190mech]

Ya think its a rod bearing?Replacement cranks are pretty cheap;
cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=350384610488&ssPageName=STRK:MEWAX:IT
Maybe the pickup on the flywheel?
Hate to hear its gonna be torn apart,glad its a wheelie machine!!!

[90GTVert]

I'm wondering if it's that or maybe the piston hitting something. I dunno really. It's so hard to tell anything in these little engines. At times it's like a r r r r r r r rapppp kinda noise. lol Really sounds like something the piston might be doing to me. I dunno. If I had good sense (yeah right) I woulda checked it farther when it was out. I had no spare gaskets though, so I just left the cylinder on.

"Dammit scoot, don't make me put in a stroker crank. Then we will flip over." lol

[190mech]

Hey!Ya wanted a wheelie machine didnt ya?? ;D