Modern Vespa

i got a question...

i took out the 4 long bolts that holds together the cylinder and cylinder head, and i just found out that the new bolts that i just bought have a diffrent size on both ends..one end is a smaller diameter and the other end is a slightly bigger diameter.. so my question is which end goes to the engine case and which end goes to the cylinder head??..

If you are talking about the studs, the side with fewer threads goes into the engine.

The studs should not have different diameters. If they do, they are the wrong studs.

+1

make sure they're the correct studs for your P200 cases. Should be M8 studs, where as most 150's were fitted with M7's, unless they were tapped up to M8s at some point.

Be sure to use some red locktite on those threads that go into the case. And never take them back out.

While I'm a newb to Vespas I do have experience with Harley types and in that case the studs get red loctite and after torqued in place I prefer to let them sit overnight before torquing the heads. Reason is that the studs get only about 10lbs while the heads take 33...think it through and you'll understand why I want the loctite to thoroughly dry!

Same may or may not apply to Vespas, but the above is something to squirrel away in your memory banks.

alrighty.. ill check on that guys..thanks for the advice!

cheers!

Hello

Just bear in mind if you want split the cases it is posible to do this by removing the head and the two outer studs only. The red loctite is heavy duty.

Regards

Grumpy

WOAH! No thread locker is needed on these studs and it's actually a good thing.

You want to be able to remove the studs easilly in order to make it possible to split the cases or pull the jug while the motor is still mounted in the bike. If you use red locktite, you will need to pull the motor every time you need to do a cross job.

Again, NO!

You sound just like that chick at the bar the other night

For anyone "fighting" removing a red loctited bolt just apply some heat, this'll melt the loctite and allow removal without breaking the bolt or stripping the thread holes.

See? I'm not nearly as stupid as you smell.

be nice man. you may need his advice one day....

also.... you can split the cases, without removing the cylinder studs, and without removing the motor from the frame.


remove the carb and air box..... remove the rear shock bolt..... the back of the motor is now dropped down, and the jug and head will slide right off, leaving your studs in place. and how does one SMELL stupid? look.... yes, sound.... yes, but I think touch and smell aren't valid identifiers for stupidity.

Hello

I agree no red on the threads you may be able to use blue or green, why is thought to be needed.
My experience is that it sets like a rock.
Genuine question here.

Grumpy

locktite is bad for those they work fine without it. and 33 pounds may be good for a harley but it will snap those right off. 17-19 is usually what i set mine too. and as for locktite,

blue=low strength for things that you want to remove

red=for internal engine parts

green=for things you never want to remove high strength

so dont use green they will never come out again. also letting it sit over night does nothing because locktite is pressure activated. but really you don't need locktite.

I meant that with love! See above. Such a ludicrous statement surely was in jest. And please don't call me Shirley. Aye, I wasn't recommending red for Vespa, just pointing out it's Harley application and that some (of whatever color) may be suitable in this instance. I respectfully disagree. Loctite is anaerobic, that's to say it dries in the absence of oxygen and has nothing to do with pressure to activate it. The time spent in an oxygen deprived environment is directly related to when it's thoroughly cured (set). Quoting from the Loctite website "The product cures when confined in the absence of air between close fitting metal surfaces"

You're correct otherwise...although there is a even lower strength Purple flavor for very small fasteners.

hey, use all the locktite you want but don't ask me to help you bust your motor apart.

You're totally missing my point, which is: You don't need any locktite on the cylinder studs, none at all. Yes you can release it with heat but you will have a really tough time getting the heat to the studs on the frame side of the motor. Yes you can pull the carb box and assorted other parts and swing the motor down, but this isn't universal on all models and you will have to swing it much further than you think. Again, you are making more work than you may want.

Something that makes sense on a Harley, Honda or Chevy may be totally absurd on a Vespa. Why add more work?

I'll challenge you guys to a cross job any day, I'll be out riding when you guys are still futzing with your MAPP gas torches and chasing down air leaks

Didn't say I was going to use or was suggesting that others SHOULD use loctite on Vespas, just that they MIGHT want to. Obviously I was wrong. Can you ever forgive me

[quote="crazycalabrese"] I meant that with love! See above. Such a ludicrous statement surely was in jest. And please don't call me Shirley. Aye, I wasn't recommending red for Vespa, just pointing out it's Harley application and that some (of whatever color) may be suitable in this instance. I respectfully disagree. Loctite is anaerobic, that's to say it dries in the absence of oxygen and has nothing to do with pressure to activate it. The time spent in an oxygen deprived environment is directly related to when it's thoroughly cured (set). Quoting from the Loctite website "The product cures when confined in the absence of air between close fitting metal surfaces"

Yeah im not a chemist i just know it isn't needed for vespa cyclinder studs

Yup, that appears to be the consensus (said he with dripping egg on his face)

THANKS Guys!

at least i learnt something from this argument or should i say disscussions