157 vs 1P57

[Rebel]

OK, as most all you know, the need for pollution controlled motors made a change that gave us the 1P57 motor. I thought, the two were enough different that they could not use some of the same parts, like a big bore kit, or just a head swap. I thought I had read on that other forum that the studs were spaced differently and the newer version had a wider spread. I also am under the impression that the CDI is not interchangeable, I'm not the least not sure about that though. My assumption was that the charging system might have been altered and not compatible with each other making the CDI a specific unit for the subclass specific motor.

So now we have a member that was able to use a standard GY6 big bore kit on his 1P motor with a very small deck height issue that is easily overcome.

So what's going on here, does anybody really know? Can you use a stock GY6 CDI on a 1P motor? Is there no real difference?

[shiftless]

The studs are the same, as far as spacing, the P studs are longer to accomidate the taller head that comes on a P (allegedly)
I have 2, 1P57 QMJ's and 1, 157QMJ
One of the P engines the engine measures exactly the same as a typical QMJ
The other has a taller head ??
As far as wiring.............. I'm still trying to figure that one out, cdi's are not compatable between the two, I think it is more in the harnesses and regulators
I put a 61mm kit on a case stamped 1P57 that was for a non P engine
If I bought the P kit it wouldn't have worked
I did have to use 3 base gaskets to allow the piston to clear
I think it's a crapshoot unless you use calipers before ordering parts

Good question though
Pretty sure the chinese kids who put them 2gether are the only ones with the real answer

[kliff]

Like Doug said...

Aug 1, 2009 16:59:04 GMT -5 Rebel said:

So Kliff, are to saying that motor is really a 157, not a P?

I'm gonna start another thread on the differences between the two, so as to not take this one too far off topic.

Just bringing this forward.

Yup Doug, your case is actually marked XX1P57QMJ, so I sorta figurred it would be a crap shoot. I orderred a !P head, in with my last 3 overbore/big valve 157 heads, so there is no problem there. And as the 157 heads are about 20.00 cheaper, it works out even better on your end. I'll just keep the 1P on the shelf till an honest to goodness P engine shows up, or I get back on the "turbo" kick, as the P has a better air passage above the combustion chamber, and more meat around the valves, will probably be a better head for a boosted engine, but for a N/A, looks like a wast of time, and WAY more porting than on a decent 157 head.

No worries, just doing the prelims, and final parts matching, will be getting real serious in about 2 week or so!

[xs650]

Kliff,

Would you take some pictures of a P157 and a standard 157 head (and a big valve and port if you have one) together to show the differences in porting and also give us your rundown on what the port differences are and what the differences mean.

We hear about the differences but I have never seen the heads evaluated by someone like you who knows what they are talking about.

[kliff]

Close ups, are not my fore XS, but I'll do the best I can, The overall height in a side by side will be most obvious. Ports, etc....like I said....BIC...

[wcurtin1962]

Here’s some info that may help in getting good pictures of small parts and details, also it’s a excellent site for camera info:


digital-photography-school.com/how-to-make-a-inexpensive-light-tent

[Rebel]

Aug 6, 2009 11:31:00 GMT -5 wcurtin1962 said:

Here’s some info that may help in getting good pictures of small parts and details, also it’s a excellent site for camera info:


digital-photography-school.com/how-to-make-a-inexpensive-light-tent

That is a nice project, something I might do some time. I usually just use ambient light though and a macro focus zoom and all comes out pretty well.

[stradarx150te]

There is the 1P57 and the 1P157QMJ As fare as i know the 1p157QMJ is the same as the 157QMJ I have gotton two motors now with this stamped on it 1p157QMJ and the QMJ parts work

[br]

Aug 2, 2009 9:37:41 GMT -5 kliff said:

Like Doug said...

Aug 1, 2009 16:59:04 GMT -5 Rebel said:

So Kliff, are to saying that motor is really a 157, not a P?

I'm gonna start another thread on the differences between the two, so as to not take this one too far off topic.

Just bringing this forward.

Yup Doug, your case is actually marked XX1P57QMJ, so I sorta figurred it would be a crap shoot. I orderred a !P head, in with my last 3 overbore/big valve 157 heads, so there is no problem there. And as the 157 heads are about 20.00 cheaper, it works out even better on your end. I'll just keep the 1P on the shelf till an honest to goodness P engine shows up, or I get back on the "turbo" kick, as the P has a better air passage above the combustion chamber, and more meat around the valves, will probably be a better head for a boosted engine, but for a N/A, looks like a wast of time, and WAY more porting than on a decent 157 head.

No worries, just doing the prelims, and final parts matching, will be getting real serious in about 2 week or so!