Need help with cylinder head and valves.

[BPT7594]

I'm running a modded SH150 variator

How much did the guy machine off? I have an SH150 variator, might try the same That is one advantage you have with SH150 being made there.

Yeah it costs about 10 bucks here from honda dealership.
I don't know how much, the guy is a pain in the *ss when asked about his tricks, but he basically change the angle of the belt to get more gearing ability or to make it smoother, he also insert a 1mm or 0.5mm washer (in Vietnam we call it rondelle - the french term I think) and use 12g roller weights, next time I clean my transmission, which maybe this weekend or so I can take pictures for you.
Or if you want I can send you an already modded piece. Just for the sake of modding fun.

[dasshreddar]

YOU need the hi lift rocker arms for that cam!(or grind(file)your stock ones... been there done that

Thank you, I will order those rocker arms then. In the mean time, would it make too much damage to the stock rocker arms or the yuminashi camshaft?
By the way, did you happen to measure the maximum lift of the Yuminashi camshaft? I know they advertised it as 8.6 lift, but we must also take into account the rocker arm ratio, and my mechanic said at first sight he thought it was about 5.5 at maximum lift.

I could see where the cam was self grinding the arms after only maybe 2 minutes of use (not a good idea).
measurements? no idea.

[BPT7594]

YOU need the hi lift rocker arms for that cam!(or grind(file)your stock ones... been there done that

Thank you, I will order those rocker arms then. In the mean time, would it make too much damage to the stock rocker arms or the yuminashi camshaft?
By the way, did you happen to measure the maximum lift of the Yuminashi camshaft? I know they advertised it as 8.6 lift, but we must also take into account the rocker arm ratio, and my mechanic said at first sight he thought it was about 5.5 at maximum lift.

I could see where the cam was self grinding the arms after only maybe 2 minutes of use (not a good idea).
measurements? no idea.

To the yuminashi website then...

[waspmike]

Oh those ocean liner engines. I still smell the fumes of pakura while literally shoveling that mud out from the cylinders...

70mm pistons sound a bit too big in a pcx. As far I can remember I've seen 62mm at max - as the cylinder head bolts would be in a way. I might be missing something though. Do you have any links where I could check installations like that. As per my quick back of the envelope calc it would give a displacement close to 222cc.

Also 13 and 14 mm sounds like a piston pin diameter to me. The pin center to crown distances are more in the 18-21mm range as I've seen so far.

Can you recommend any webshops I could order any of the cams you have mentioned? Those seem to be really good bang for the buck. Do you know if they are reground or billet?

Yeah, I don't know the PCD of the cylinder studs so don't know how or if anything larger than 62 would work I simply know they are available. If BTP says a Sonic piston fits then the 70mm reference could simply be a reference to the Sonic piston as the also show a very short skirt piston up to 75mm, but they are listed on the PCX page. Then of course there is the gasket problem, the fuel problem (CBR250? throttle body), Valve sizes ( 250?), etc., etc.
There is a large drag racing culture here both organized and "underground" so if there is now a class for PCX this is what the market is aimed at. There are CVT scooter smaller than PCX here bored out to 300cc! They roar up and down small streets but one doesn't see then out of town touring with their mates.

Below is an off the shelf 175cc (62mm) kit for PCX150 I found which shows there is still a bit of meat left before we break into the cooling water jacket but the cylinder would have to be resleeved.



There might be some webshops here but it would all be in Thai and Thais are not very good at answering emails! Before I bought two cams for my Honda Cub project . One was reground, the other supposedly new. I would have to look at the ones in question to be able to tell you.

I think if I was to build a modified 150 I would go the improved breathing , transmission route before the increase in cc. route.

[BPT7594]

+1 on that e-mail thing. I tried to contact Hispeedpiston to order a clutch set, customer support is unbelievably horrendous. Take more than 1 day to reply, no paypal, no bank account, I've heard good things about their products, but this kind of customer support is ridiculous.
I think that a 62mm is too much. Make it too big and you'll run into all kinds of problem.
A sonic fits, but I do not think it's optimal. Yuminashi told us to use the original 125 esp head with his 164cc kit, while I think that he must have done tests himself, still cannot get my head around the fact that a 27mm intake and 22mm exhaust would be incredibly restrictive for a 60mm piston.
The difference between a 150 esp head and a 125 esp head is the dome area is a little carved out to drop the compression ratio.
the head of the SH 150 piston also reduces compression.
this is a picture I get online

IMG_3546_zps37c6a8c3.jpg (92.71 KiB) Viewed 875 times

I wonder, just wonder, if I can perhaps put in a new Sonic piston with the SH150 head (29mm intake/23mm exhaust) and use the yuminashi camshaft + a new set of rockers and sonic valve springs. The compression would be a little below 12 but above 11, using thin gaskets also. Wonder if the sonic piston which has a high head will touch the valves.
Too many options

[Oyabun]

Oh those ocean liner engines. I still smell the fumes of pakura while literally shoveling that mud out from the cylinders...

70mm pistons sound a bit too big in a pcx. As far I can remember I've seen 62mm at max - as the cylinder head bolts would be in a way. I might be missing something though. Do you have any links where I could check installations like that. As per my quick back of the envelope calc it would give a displacement close to 222cc.

Also 13 and 14 mm sounds like a piston pin diameter to me. The pin center to crown distances are more in the 18-21mm range as I've seen so far.

Can you recommend any webshops I could order any of the cams you have mentioned? Those seem to be really good bang for the buck. Do you know if they are reground or billet?

Yeah, I don't know the PCD of the cylinder studs so don't know how or if anything larger than 62 would work I simply know they are available. If BTP says a Sonic piston fits then the 70mm reference could simply be a reference to the Sonic piston as the also show a very short skirt piston up to 75mm, but they are listed on the PCX page. Then of course there is the gasket problem, the fuel problem (CBR250? throttle body), Valve sizes ( 250?), etc., etc.
There is a large drag racing culture here both organized and "underground" so if there is now a class for PCX this is what the market is aimed at. There are CVT scooter smaller than PCX here bored out to 300cc! They roar up and down small streets but one doesn't see then out of town touring with their mates.

Below is an off the shelf 175cc (62mm) kit for PCX150 I found which shows there is still a bit of meat left before we break into the cooling water jacket but the cylinder would have to be resleeved.

I have a resleeved original 125 cylinder and the issues one can run into is on the crank side not at the head. If you read Maddiedog's how-to on BBK installation you can notice that the water jackets on these larger casts are offset compared to the original (this picture shows it best

Nevertheless. So far I'm ok with the 164 cc BBK as this is my daily ride.

There might be some webshops here but it would all be in Thai and Thais are not very good at answering emails! Before I bought two cams for my Honda Cub project . One was reground, the other supposedly new. I would have to look at the ones in question to be able to tell you.

Can you recommend anything as a start to look for at local webshops?

I think if I was to build a modified 150 I would go the improved breathing , transmission route before the increase in cc. route.[/quote]
S
I just did. Went the brakes, suspension, Malossi multivar variator, longer geared transmission, simota air filter route already. And have the CBR/Sonic throttle body, injector, wideband O2 sensor and fuel controller sitting on my bench and parts to fabricate a custom exhaust (with a high flow catalysator) for the bike when the BBK is installed.

What I'm looking for is either a cam with a 150 head or a 4 valve head to complement the whole package.

[BPT7594]

That picture is terrifying. btw is that a 150 head or a 125?
You can buy yuminashi camshaft. Pick the RR version, reggy said it's compatible with esp 150cc engines. I guess, pop in the entire 150 head with double springs, slide in the yuminashi RR cam and you're good to go. Not sure about the 60mm piston that comes with yuminashi set as he said it's for use with 125 head and the pocket on the piston may need to be machined a little.
Yuminashi set has about 13 or more compression ratio. My mechanic said it's batsh*t insane . Wonderful power and fuel economy though.