Big Bore w/o boring?

[bullet28027]

Hello Rebs,
Does anyone know if a 61mm cylinder will fit on a stock 57.4mm cylinder engine with out machining? I read the 170cc post on SD and sin said he recommended using a dremel on the 61mm cylinder to get it to slide in. I found a 61mm cylinder and it says the O.D. is 64.5mm any idea what the stock 150cc crankcase bore is?
Thanks, Bullet

[shiftless]

The only way to really know , is to pull your cyl
What you gotta do is measure your case opening, I lucked out and a 61mm slipd right in my case ( it was marked 1P57QMJ... but the head and cyl measured the same as a regular 157
I emailed my measurements to Carlos (autotech355) and he sent me a kit that fit my measurements
Most QMJ's require a lil opening of the case
If you choose the dremel route........ split your cases to ensure no dremeldust gets lost in case
I recently saw on another forum where some1 said they bought a 63mm kit that requires no case modification, but I doubt that

[kliff]

EXACTLY what Skipp said. You won't know till you pull it. Normally, about 65.5mm, BUT, there are variances between manufacturers.

I pulled two 44mm(65?cc) engines down recently.... and guess what, 52mm/85cc jug slide right in with 1.5mm clearance. Damn I wanted to try that case boring tool I built, but hey, a "freebie" is still a FREEBIE! Just more time to spend on the heads now.

I still ain't got a clue, but I sometimes wonder, who amongst us does, at least on the subject of what ir IS, before we tear it down and find out for sure. I can't even look at a 139qmb anymore and tell anyone ....yeah, "...its a 50cc engine...."
So I just ask how big they want it when I'm done....LMAO! Don't ask me what it is, ask me if it can be made into a _______ ?

Skipp.....63mm/ no bore, I read that too. Can you imagine how thin the cylinder skirt must be? If it's pourous at all, you'd probably read the newspaper through it!

[bullet28027]

Thanks Guys,
I am going to take it apart later this week, when gaskets come in and space rings correctly, because I spaced oil ring gaps 10mm to either side of wavy ring gap, and they could have slipped. I will measure it then. Also do you know where I can buy some guides for my variator, I have some new Dr. Pulley weights on the way but I dont think they come with it, bought from ebay.

[Rebel]

Bullett,

Here is a link to a list of places you can order parts from that we know of, also, if you send a message to Jeremy, aka enviromoto, I'm sure he will get some out to you pretty fast.

scooterrebels.proboards.com/index.cgi?board=otherreadonly&action=display&thread=46

[kliff]

Nov 29, 2009 13:59:11 GMT -5 bullet28027 said:

Thanks Guys,
I am going to take it apart later this week, when gaskets come in and space rings correctly, because I spaced oil ring gaps 10mm to either side of wavy ring gap, and they could have slipped. I will measure it then. Also do you know where I can buy some guides for my variator, I have some new Dr. Pulley weights on the way but I dont think they come with it, bought from ebay.

I guess I'm about as bass ackwards as they come, but I'm a tad more radical with ring end gaps. The OLD 120 degree gap separation came from the days when the oil ring was a one piece cast iron ring, with some holes drilled in it, and some fancy machining on the face.

The Hastings style 3 piece scraper is lighter and more efficiient, but it sure make interepreting that "Mercedes" 120 degree spacing difficult, at least for me. So about 30 years back, when first exposed to the 3 piece oiler, I came up with my own solution. All I can sa is it's been working for me for 30 years, until something else changes, I'm gonna keep on like I am.

If you feel fiesty, and wanna try it, here it is:

Looking at the top of the piston, the wrist pin on te right side is 3 oclock, on the left, 9 oclock. Piston Top at 12 noon.

Install the sping for the oil scraper first, gap at 12 noon,
Bottom scraper rail gap at 8 oclock
Top scraper rail gap at 4 oclock
(close to the 120 degre pattern on ONE ring assembly)

Second compression ring gap at 2 oclock

First (top) compression ring at 10 oclock

Nuttin "by the book" about it, just something I tried, and it works,
Most all horizontal engines benefit from this, by keeping all end gaps above the lower 120 degrees of the piston, where more oil is likely to puddle, and cause a hydraulic lock during long "sit-ups", and doesn't tend to load the cylinders when crankcase pressures get high.... I could go on for hours. In a nutshell, horizontal and "Vee" engines it seems to keep the cylinder cleaner, compression higher, and leak-down lower.

Reference material supporting all this....bull hockey, I never read it like this anywhere else, and until now, I've never shared it. If you require written permission to do this, then don't do it. If you wanna try something a little different, I don't think you'll be displeased. But don't take a piece of this, and a piece of that info, and come back whining to me, if your experiment doesn't work. I went out on a limb 30 years ago, and this one worked. I've lost count of the experiments that didn't, but I never blamed anyone but myself.

[Rebel]

We all have to rebel a little don't we.

[bullet28027]

Thanks Kliff,
I will try that, sounds alot better than what I did by spacing the oil ring gaps only 10mm apart, I believe that will fix me up, and thanks for sharing your secret with me. I will not hold you responsible for any bad results. Thanks Kliff,
Bullet

[bullet28027]

I got her tore apart again, waiting on the gaskets that should be here tomorrow. I have already regapped the rings 12, 8, and 4 on the oil rings and 10 and 2 on the compression rings, and have them in the cylinder ready to go. I can't believe I installed the oil ring gaps at 11:30, 12:00, and 12:30. Tomorrow is suppose to be nasty weather here, so maybe I'll be in my shop all day, BTW pictures coming soon of the Rebel Blue & Silver Bullet, but I want it centerfold ready first.

[Rebel]

Can't wait to see tomorrows pin up shots.