Carb Problems

[streido]

Stiffer contra spring AND lighter rollers ?  You'll probably run the poor machine right into the revlimiter all the time  

5.5g rollers with 1500rpm torque keeps my revs around 6500-7000. 5.1g rollers with 1500rpm torque kept me around 6800-7200rpm. Think the rpm sweetspot is around 6800-7000rpm. Been running like this now for well over a year with no problems. I cant get up hills as fast on anything heavier than 5.5g, no matter what rollers to torque spring set up i tried, and i tried a lot 

But like Mono says, do one thing and ride it before doing another. Otherwise you have no idea what the problem is if you just throw a load of new gear in their all at once.

[fabio]

5.5g rollers with 1500rpm torque keeps my revs around 6500-7000. 5.1g rollers with 1500rpm torque kept me around 6800-7200rpm. Think the rpm sweetspot is around 6800-7000rpm. Been running like this now for well over a year with no problems. I cant get up hills as fast on anything heavier than 5.5g, no matter what rollers to torque spring set up i tried, and i tried a lot 

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I'm glad you've clarified that for me... my thoughts were that 5.5g was the recommended roller weights that I had read about when coupled with a 1500 torque spring...I'm a touch heavier than the 8st lads that run most scooters (with being a bit older, hehe !!) so slightly lower at 5.3g would do the trick, or am I going a bit too mad with this???

Thanks in advance

Fabio

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[streido]

Sounds right to me, but no 2 scoots are ever the same as im sure you know. 2008 models seem to work well on 5.5's but 2010/2011 models aparently rev way too high on 5.5's? Or so we have been led to believe on here?

Like i said i ran Malossi 5.1's for a while, also on the 1500 torque and it was fine too, higher revving but it suited me for hills around my way and better acceleration too from stopped. Only reason i went back to 5.5 was i lost 4-5 mph top end on the 5.1's (unless downhill).

[wordslinger]

..coold have compensated for that top loss with slightly shorter boss, or maybe slightly longer belt??

[mono]

The loss of top end might also be caused by running too far into the revlimiter, that costs a lot of power...

[streido]

..coold have compensated for that top loss with slightly shorter boss, or maybe slightly longer belt??

Already on a 36.8mm boss 

The loss of top end might also be caused by running too far into the revlimiter, that costs a lot of power...

Nah, dont think so for mine. Revs didnt go past 8000rpm even on long flats, usually sits around 7800rpm once its up and running on a straight. Goes up to near 9000 downhill tho. Just simply doesnt have the power to get the higher revs and speed on the flats since its only a little 50cc im sure. Im not too bothered, cant expect miracles, it get me around with reasonable performance for what it is and itsceap to run.

I did used to run a 736 belt on the stock boss, which gave similair results to using a stock belt and short boss,  was going to maybe try that again but on the short boss. Far too cold to work outside now tho and i got the other scoot in my garage to lower it right now. Will get round to it eventually. 

[mono]

Even without a revlimiter the power will drop above 7500rpm (with stock camshaft that is)...

[streido]

Even without a revlimiter the power will drop above 7500rpm (with stock camshaft that is)...

I reckon im fine cos it only gets up to 7800+ after im up to speed anyway, all the way from 0-45mph it stays around 6800-7800 usually depending on the gradient of the road. I could prob go to 5.6 or even 5.7g and maybe shave a touch off the revs but it works fine for me how it is. I ride the same route every day so its set up perfect for that, if i go anywhere else i take my bigger scoot or the car.

[streido]

I do fancy trying a better torque drive later so i may have to retune again after that. The only other mod im considering is a BBK but my sons getting to use it next Sept once hes 16 so i need it as a 50cc for him.

[fabio]

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Ok

The stuff has all arrived.... and its fitted....

- 82 MJ
- 5.3g Naraku rollers
- 1500rpm clutch springs
- stiffer torque spring

and I'm very pleased indeed!!!

- I sounds brighter (it sounded a bit flat before) so I guess that's the main jet (I'll have to do some plug shops at the weekend)
- It holds its take off slightly higher (not as high as I expected mind you - I went with the 1500rpm clutch springs so I'll see how I go on once they've bedded in a touch - if not then I'll fit the 2000rpm ones)
- Acceleration is a bit more responsive and i can actually hear the revs rising now as it speeds up - before it just chugged along disappointingly.
- It goes up hills at around 30ish now as opposed to around 20ish !!!

Impressed.....the only thing left to sort is this.....when its idling on its stand, when I take it off the stand (with no revs being altered) it stalls? What's that all about?? 

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[wordslinger]

...thatsa pretty good setup fabio!!


when its idling on its stand, when I take it off the stand (with no revs being altered) it stalls?


...my 08 did that if i dropped it off the stand pretty quick...


...so i started just easing it down...no problem....


..never did worry about it after that....

..my experience with "2000" flys, created too high revs at takeoff....

[fabio]

Q - when its idling on its stand, when I take it off the stand (with no revs being altered) it stalls?

...my 08 did that if i dropped it off the stand pretty quick.....so i started just easing it down...no problem....

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Yes that was going to be my plan too...but I'm fascinated now..... why does it do it??

Fabio

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[streido]

Sounds like youre almost there 

I cant say i felt any great improvement on mine with the clutch springs, i use 1500 ones. I found the 2000 springs just too stiff so didnt use them.

Plug chops should be fine on the 82 jet but it may be worth doing just for peace of mind.
Just double check you got the air in and mixture out tubes tight on the carb. Mine had an airleak before and idled like yours now, fine on the stand but lower it and it used to die. Was due to the carb manifold leaking for me.

[fabio]

Mine had an airleak before and idled like yours now, fine on the stand but lower it and it used to die. Was due to the carb manifold leaking for me.

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I did have an air leak hiss on the manifold last night when I first put the carb back on after replacing the 85MJ with the 82.

I removed the manifold and had a good look but couldn't see any cracking, crazing or similar that could cause a leak - I used a bit of tape under the clamp to pad it out and it seemed to stop the hiss....perhaps I need to take a look at this again?




Another question.... the manifold vacuum connection that draws fuel from the petcock goes to a tee-piece...what is the box on the left that is also connected to the tee-piece?

Fabio

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[fabio]

Just a bit more info.....

I decided that the carb still wasn't right...... after i couldn't understand why it cut out when I took it off the stand.

Also the idle wasn't perfect...and I couldn't accept that in my mind as being correct either.

So, I removed the carb again to investigate....thinking that the idle jet was perhaps blocked slightly..... here's what I found....


I removed the carb from the scoot and turned it upside down and removed the carb fuel bowl, removed the idle jet and took a look through it up to the light in my garage....it looked slightly blocked.....I'd previously bought one of these.....  http://www.ebay.co.uk/itm/Carb-Jet-Cleaner-Tool-Kit-Car-Boat-Motorbike-Scooter-ATV-Carburetor-Cleaning-/160943325772?pt=UK_Motorcycle_Parts&hash=item2578f8424c .....but hadn't used it on this particular carb.....so i gave it a quick go and the jet cleaned out nice and easily.

On refitting the carb fuel bowl I noticed that the gasket was a bit dis-formed so I trimmed it a touch to ensure a better seal.

I also refitted the manifold (including a spot of copper grease on the joints between the inner face of the manifold and the outer of the carb) and ensured that the clamps were nice and tight.

On starting the scooter up I noticed that it seemed to sound better (the idle rpm was higher - perhaps because the idle jet was cleaned out properly now)

Also, the adjustments I started to make to the air/fuel mix screw were now also translating into the more expected results that I previously couldn't achieve.

So.....it looks like I'm almost there......I've left it to cool for a couple of hours or so and will start it again later this evening to see how it reacts from cold

Fabio

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