39mm to 52mm =high RPM'S. Final gear or stroker next? By ockid (Read 822 times)

[ockid]

Hey I'm new here but not to these 139qmb 50cc scooters. About 4 yrs ago I purchased a 52mm aluminum milled piston and block and never upgraded to the proper cylinder head and wasn't very knowledgeable back then and because got frustrated and discouraged. I hope ypu all could help answer a few questions.
I had purchased a new used scooter 2 weeks ago (2011 VIP TAO TAO 4stroke) and since then has upgraded its exhaust, air filter(removed factory air box),installed oil catch, changed 39mm to 52mm bore, new 20 & 23mm cylinder head with rocker arms,A9 cam,.87 main jet, and #45 idle jet, and added aprox. 2grams from the factory rollers because I was taping 10k before it would top out and has way way too much acceleration. Seriously the throttle is extremely sensitive and have trouble staying between 5-15mph but I'm fine with that, it's exciting power! My distance daily would be 10miles 2x a day and most times I'll have to stay below 45mph. My QUESTIONS are I want to stop the RPM's from redlining. I was reading that I may only get 1-2k miles before the original stroker arm will break and want to know if I will be fine or am I stressing the stroker that bad that I will soon face other issues? Also my top end max speed is @ 45mph now. And very racy almost to the point of spinning wheels. I also want to see what it's potential top end could be with A.) New 49-17T final gear, and/or B.) 44mm stroker and are they necessary for long life and would kill two birds with one stone by giving an extra +5mph to top end and would fix my 9-10k rpm issues?
Next question is that I am waiting on a new 24mm intake manifold to be able to install a new 24mm carb. I still have the new exhaust baffled with the threaded nut and am curious what your thoughts are on going this large? Also the larger carb doesn't have an accelerator pump or nozzle like the 18mm OEM has.Another reason why I only installed a .87 main rather then .91,.95 or .1 jet. I figured you can only have a certain about of air that can still go through a 18mm intake or carb so why try flooding it with more fuel...

I appreciate any tips, tricks, or suggestions and guidance on this set up. What am I doing wrong and what can I do better.

[Alleyoop]

Make sure the 24mm intake Manifold is the same size as your Intake, if bigger then it will disrupt the fuel and air flow into the motor. If your really getting that much power from the 18 I do not see the need for the 24mm because you will have to drastically down jet the main?

You can get a 24mm with an accelerator pump just like the 18s They are called 24mm Performance Carbs.
A stroker will lower you rpms but not by a whole lot, not enough to get you down to 8K which is the redline for these motors. Also if you want the motor to last you should get the motor to run in the mid-7K range.
Slapping in taller gears for every tooth up and down expect about 2-3 more top end. But remember this you must have the low end torque to pull the taller gears also it will lower your rpms some.

What gram weights are you currently running with? The easiest means to lower your rpms is slap in heavier weights.
Rollers for every gram up or down the rpms will change by 500-600.
Sliders for every gram up or down the rpms will change by 200-350.

You mention it has a hard time running 5-15mph, what rpms does it idle at??
Alleyoop

[ockid]

I appreciate you responding and please bare with me because I can be all over the place at times. My rollers I pulled out were 4.6g(5g)which I first thought was 7g and I installed 9g. This had help bring the rpms around 1k. The jet in the original 18mm carb is a .87 now from .79 stock, not sure if that's about as big as these should take or recommended..? We have laws around where I live for scooters "49cc &under". That's why I'm tinkering with this one instead of just going up to 150cc and not having to make all these mods. The head cylinder still is one marked with a 49cc stamp. Not sure how stiff these laws are enforced. Anyways this is the dimensions of the new carb I was going to install.
Inner Diameter (intake side): 25mm
Outer Diameter (intake side): 32mm
Inner Diameter (air filter side): 38mm
Outer Diameter(air filter side): 42m

And the Intake Manifold

Bolt hole spacing 45mm
Inner Diameter (carb side):33mm
Inner Diameter (engine side):27mm

Ordered intake spacers I will bore to adapt if it's necessary.

Air Filter
Inside Diameter 42m

So the carb is actually 25mm not 24mm.... Will this carb be too too much over kill? Should I had just went with 20mm or 23mm I guess?
Also I noticed a huge possible past issue when I did it's oil change today. 2 chips were in the oil cap Below the oil screen and spring. Once I noticed that after I drained the remaining I noticed a few more that came out. I know I'm thinking oh crap! Well after inspection of the old cylinder head, valves, rocker arms, piston and it's block and cam I didn't see ANYTHING that it could have came from. This definitely happened prior to the last oil change whenever that was and had to be either from the stroker it's self or from a previous part that's been replaced already. It's aluminum and I'll try to post a few pictures here. This could be problematic if more residential pieces or shavinngs are still in there. I tried kicking the crank to see if any more oil will come out but had nothing. I'll drain the new oil again to check in a few days. I figured if somethings wrong or chipped it wouldn't run as good as it has since I replaced everything. Also my intake and exhaust valves were adjusted to .005". I read you recommend .003 & .004? Is the stroker milled aluminum or a iron casting? My rpms at idle is around 1,700 warm 1,900 cold. Still reaching 9000-9500rpms around 35-45mph. Also another question is that I still have the original style CDI which I thought sets or limits #RPM's?

[Alleyoop]

The restricted CDI's are few and far in between I have yet to have anyone verify that their CDI is rev limited. Back in the older scoots they used to be restricted but you would be hard to fine one in the later scoots. Very noticeable if you have a rev restricted CDI but most are not knowledgable to tell one way or another (LOL) they just think it's restricted cause their scoots are slugs (LOL). But any stock 50cc will only do 30 maybe a little more if your lucky. Takes quite a bit to get them to get up to near 40mph.

IMO the biggest you should put on a 50 is a 20mm but if you can get it to run descent with a bigger carb by all means. Just remember to much fuel will slow things up. I am surprised to hear you have a #45 Pilot jet WOW! Your the first I have heard with a built 50 with such a big arse pilot jet.

Even MILLSC which is a Heck of a builder of 50s only went with a #38 with a full blown 50s build he tried a #40 and it was to much. Even with your 150s some slap in a 32mm carb which not even the 250s come with and they have a heck of a time getting them to run HALF WAY descent. What I do is ask them to video a wide open take off from a complete stop from idle. That will tell right off the bat if the carby is to much.

My Trike I have a #38 pilot a 40 was to much and a 122.5 Main, I have a 62bbk with a 60mm stroker bringing up from 149.6 to 182cc(30) more ccs, plus all the goodies to go with it, 1 1/4 pipe Free Flow Supertrapp adjustable muffler Free flow K&N Filter Taller tranny gears and on and on

Can you VIDEO it idling and giving the throttle a couple quick blips to see how it takes throttle from a standstill.
Alleyoop

[ockid]

[ockid]

[ockid]

I cannot actually confirm its a #45 I just know it's a step up from stock idle jet which I thought was an #38?? I need to pull it and check once I receive the new intake manifold. I thought I could get 50mph on a 50cc with my mods. Maybe I should stop while it's running nicely. Other then the rpms that is. I will try to post a video via YouTube tomorrow after work if it's nice. Hey thanks again and for your quick response.

[Alleyoop]

Normally the 50s stock come with a 30-32 pilot jet, the 150s come with 24mm carb with #35 Pilot and main anywhere from 103-107. Getting 45mph out of a 50 is excellent not to many can get them to 40mph maybe 38mph and they complain cause they thought it would get them 40+. Got to remember they only did 30 maybe 32mph and to get them to go 8 mph faster takes quite a bit let alone 45 (HEHE). So you have a screaming 50 BRO.

Those piecec of metal where they in the mesh filter or did they come out from the crank case? I am trying to picture the pieces to try and identify where they came from. If they where in the Filter then the pieces are maybe from around the oil pump. The pieces do not look like pieces of the rings or the chain if from the crank maybe from the bearing seal Which would not be good.
Alleyoop

[ockid]

The speedometer always seems off on these scooters so I used a GPS. The pieces were in the gully of the oil cap that was past or Below the oil screen/filter. That made it pretty obvious it has been there somehow before the last oil change or else how could it get past the filter since it's intact and sealed with a rubber grommet that's around the screen. There was also pieces that came out with this old oil when drained. The aluminum chips seem to have markings on them that almost looks like threads but is not, more like vertical or horizontal scratches. Very strange. I'll post a zoom in image.

[ockid]

[Alleyoop]

If in the cap then it came from the OIL PUMP SIDE not the crankcase side. The oil flow from the side up through the opening of the mesh filter so any metal pieces would be INSIDE the mesh filter so NOT FROM THE CRANKCASE.

[ockid]

So now I'm more satisfied after reading all this and will be leaving the carb and jet as it is but still wish the rpms would be in a much safer range. So I'll just get heavier rollers or sliders? I bought and used sliders 4yrs ago in my old Tao Tao 50cc VIP but wasn't as impressive as the talk I heard of them. Now I'm not going to settle unless I figure out what and where these chips have came from and to make sure this isn't a current issue with any of the new or previous parts that still remains. If it's not the cylinder, rocker arms, valves, block, piston, cam, or a flange of some sort, what else could it be? A part of the crank? Crank bearings? Idk like I said I bought this used and it's a 2011 scooter with 2 owners and had 2300kms or 1,750miles aprox. Maybe it had something go wrong awhile back and these pieces are just residual from a busted piston or cylinder head. Not sure but I don't like it. I almost want to take everything back apart or at least get to the well that holds the majority of our engine oil.

[ockid]

You know I tried lookin up in the plug hole and noticed a channel coming from the side. Is that what your talking about? It makes sense but this channel was pretty small and these chip fairly large. What's next?

[Alleyoop]

Nothing to do but just clean it out and hope the next oil change you do not get anymore.

[ockid]

My engine would seize quick if the oil pump wasn't working correctly right? Never took this side apart before. What moving parts could break this aluminum apart on that side? If the oil pumps sprocket or gear is plastic then that scares me more.



These are not shots of my engine but this is of my style correct? Also curious about oil Temps should range from? I have a oil catch hooked to my dipstick port and could pull readings from it to check. I've seen oil coolers or coils/radiators that some instances people install. I just want as less stress on the motor as possible since this 39-52mm upgrade you know.. Thanks again for your time. Your answers and helped with guidance is very much appreciated.