sa50p with 72cc bbk needs bigger jets or carb?

coppah37 · Post by **coppah37** » Tue Sep 04, 2012 5:49 pm

Ive got a 99 elite s that i derestricted. It has a 72cc bbk but falls flat on its face at about 25 mph. It takes off from stop up to 25 then i have to go about half throttle or it wants to stall. I can get it up to about 32 mph at half throttle like this. I have the oil pump plug coming in this week so i can premix as well as a high speed variator. Im not sure what to do as far as the jet size or up to a bigger carb. Please help

Downsouthdio · Post by **Downsouthdio** » Wed Sep 05, 2012 9:50 am

Yea thats running lean.. Mixture is off.. See what main jet you have in the carb now.. Dont run it anymore that way, your going to damage it.. A 17.5 or 19mm carb is a good upgrade and better all around for your 72cc.. Might want to consider it but like i said check your jet your running now

coppah37 · Post by **coppah37** » Wed Sep 05, 2012 5:37 pm

Running a 78 jet now. what brand and Where would i get a 19mm carb?

veedubh20 · Post by **veedubh20** » Thu Sep 06, 2012 3:45 am

dellorto phbg carb.

coppah37 · Post by **coppah37** » Thu Sep 06, 2012 6:29 pm

Id like something that could bolt onto the stock intake and keep the stock exhaust if possible.

I also wouldnt mind a carb kit that comes with a corresponding intake manifold to make it easy for adapting.

I found this kit on ebay but 28mm carb seems way to big to me.
http://www.ebay.com/itm/Dio-ZX-SR-DD-Jo ... 57&vxp=mtr

coppah37 · Post by **coppah37** » Thu Sep 06, 2012 6:57 pm

Or would a 28mm carb with an aftermarket exhaust be ok?

coppah37 · Post by **coppah37** » Thu Sep 13, 2012 7:57 pm

So i got a few parts in. I got a high speed variator with 9gram weights, oil injector plug and an 88 main jet for the stock carb. I premixed the gas to 32:1 but now it doesnt want to idle. Ive tried tuning correctly but nothing seems to help. I can rev it on the kick stand gently and get it to hit high rpms. Seems like i now have high revs and no low revs which is opposite of before.

I took it for a ride and had to push off with my feet and give it full throttle to get up to any speed at all then at about 15 mph the thing takes off like normal and pulls realy strong up past 35.

All low end acceleration is gone and im not sure why!!!

SOMEONE HELP PLEASE!!!

Downsouthdio · Post by **Downsouthdio** » Fri Sep 14, 2012 6:12 am

Lighten up your rollers.. 9 grams is to heavy.. Arreche makes a carb that bolts to the stock manifold..$120 here where i live

coppah37 · Post by **coppah37** » Sat Sep 15, 2012 1:34 pm

so i put the stock rollers back in with the high speed variator and it helped tremendously but i still cant seem to get it to idle with out keeping the throttle slightly open. It just wants to stall. At speed theres no problem up to 50ish. I ordered a ct manifold with a 24 oko carb and jet kit. I guess ill see how that does with the premix.

JJ Joseph · Post by **JJ Joseph** » Wed Sep 19, 2012 2:33 am

coppah37 wrote:I premixed the gas to 32:1 but now it doesnt want to idle.

DON'T remove your oil pump! You're just making the problem way more complicated because premix changes the mixture ratio. The oil pump is there for a reason, and it can handle up to 100cc bored/stroked. It meters the right amount of oil and you can concentrate on other problems, like maybe your low-speed jet is plugged. It's difficult to clean properly, but if there's any crud in the low-speed jet, it won't idle. Use a fine E string from a guitar to gently clean the jet if you don't have an ultrasound cleaner.

paulpauly7 · Post by **paulpauly7** » Wed Sep 19, 2012 3:30 am

dont listen to this jj fellow he knows nothing the oil pump can not supply enough oil for anying above the stock size

abreen89 · Post by **abreen89** » Wed Sep 19, 2012 1:57 pm

JJ Joseph wrote:
coppah37 wrote:I premixed the gas to 32:1 but now it doesnt want to idle.
DON'T remove your oil pump! You're just making the problem way more complicated because premix changes the mixture ratio. The oil pump is there for a reason, and it can handle up to 100cc bored/stroked. It meters the right amount of oil and you can concentrate on other problems, like maybe your low-speed jet is plugged. It's difficult to clean properly, but if there's any crud in the low-speed jet, it won't idle. Use a fine E string from a guitar to gently clean the jet if you don't have an ultrasound cleaner.

Wheelman-111 · Post by **Wheelman-111** » Wed Sep 19, 2012 3:20 pm

Greetings:

FROM THE OFFICE OF THE SECRETARY OF MISINFORMATION PREVENTION
Quoth JJ:

DON'T remove your oil pump! You're just making the problem way more complicated because premix changes the mixture ratio.

JJ my Brother what you don't seem to get is that the PUMP Does the VERY SAME THING! (Yes, I'm yelling at you...)
Y'see, as the pump dribbles its little Lick O' Lubricant into the intake stream, the aerosolized fuel vapor roaring by is "Pre-Mixing" it on the way by, dissolving the thicker oil and carrying it off through the reeds and into the crankcase. There is NO difference between that and doing the mixing in the plastic tub beforehand, except that the pump's Oil input can have further variation because of its throttle-controlled lever. At least with PreMix, you know the ratio stays at 32:1 or whatever you mix in.

Honda-san went to a lot of work pre-calculating how much oil per piston stroke a 50cc intake charge was going to need, and Honda was very concerned about excessive smoke and HC emissions. (About which all good 'Smoker enthusiasts could not care less...) So Honda ordained the very LEAST amount of oil upon which a 50 could survive, and not a drop more.

With all due respect, You can NOT adjust the pump to deliver enough oil for 65cc, let alone a 100+cc stroker. Guys here have measured this, (Scroll to the bottom of Page 1) with pumps set to Wide Open and at all speeds. The MOST oil the pump could produce calculated to a 50:1 mix when added to the mixture inhaled by a 49cc engine. That becomes almost 75:1 with the increase to only 72cc, or nowhere near enough oil, particularly with a higher specific output, hotter-running performance build.

You seem to have had pretty good luck doing it your way, or do I recall a seizure you reported? Even if I am mistaken about that, you are part of a Chorus of One. NOBODY else runs a Big-Bore that relies on the pump alone. I tried it myself, and despite a dilute mix of extra premix to supplement the pump I have a couple of scratched-up/holed pistons to show for it.

Follow JJ's advice at your peril, Coppah.

coppah37 · Post by **coppah37** » Thu Sep 27, 2012 6:16 pm

Yeah i know enough about 2 stroke motors to understand JJ is wrong. How does he think a weed wacker works? haha

sleeperscoot · Post by **sleeperscoot** » Fri Sep 28, 2012 2:02 am

Hey Texas and wheelman, the guy just posted a bog after 25mph, its not oil pump nor jetting, its a simple thing that costs $10.00 remember i have 35 yrs of engine building experience

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sa50p with 72cc bbk needs bigger jets or carb?

sa50p with 72cc bbk needs bigger jets or carb?

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Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?

Re: sa50p with 72cc bbk needs bigger jets or carb?