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i nudged the idea of it being the carb around. then i got to thinking.. i did 4 or 5 runs that day of up to 5 laps each (which was all i could take with it running so crappy) and the results were all the same. upon cold start and out the gate, i could only get 2 laps with the bike running very well before it would start to sputter.

conditions: high 70's low 80's. sea level. 100oct mixed to 44:1 Motul 800 fresh from that morning.

i can probably rule the carb being free of any problems based on a previous day where i didn't have any problem with the motor running. sadly it wasn't a long riding day so i wasn't able to get much tuning out of it.

plug is a bit odd. shiny and wet, but its clean. no sut.. not oily. theres only a little bit of dark oil around the threads
Shiney and wet are two characteristics of a cylinder or coil doing downhill....My YZ490 had the wet and shiney plug out of nowhere and with-in no time it just finally lost feesable compression....

One of our members N!pples was experiencing similar results as I recall it ended up being his coil crapping out of left field....same result as you,,,running killer the weekend race before then things went downhill almost at the flick of a switch.....

Heres the thread...... http://www.pocketbikeplanet.com/172...s/79639-coil-problems-testing-ohms-volts.html

The Polini and Blata guys had us chasing our tails saying their coils just quit they dont fail in a downward spiral......N!pples debunked their theory as it as an original genuine coil...Polini told us the same thing

He has a thread and video of it running,,,,sounds quite similar to what you have going on........


Do a compression test.........post the #...........If compression is good change the sparkplug,,,run it again and see if the plug gets wet and shiney again,,,,,,if so and have another coil to try try it out................

Good Luck
 

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Discussion Starter · #43 ·
Have you tried 93 or 91oct? There is something slightly wrong with your fuel. As the air warms up it thins out, throwing off your mixture.

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ill give 91oct a shot. I'm not opposed to running lower grade fuel. if it runs better then thats what ill be fueling up with.
 

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Discussion Starter · #44 ·
did a little bike day today at the local kart track.

my bike ran pretty good today. changed my gas from 100oct to 91 oct and pulled the BR10EG and popped the B10EGV. on startup, the throttle response was very snappy. went out for a couple laps and would still get a weird high end bog. came back in and jetted down to a 115 main and that did the trick! could finally wind the motor out all the way. no heating problems. still have some dislikes about how the motor was running, but at least i can improve upon an actual running bike instead of spinning in circles trying to figure this one out.

ENJOY!
 

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Nice man! What carb are you running on it right now? Great video! Real clear it looks like you're flying around that track haha. I'm so jealous... I haven't been riding in months. Too much rain here.

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It looks like you're finely getting it. I'm excited for you. Man I wish I had a genuine polini. And your vid really makes me itch to ride again.

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It definately sounds alot better but not in the realm of 12-16hp like its supposed to be,,,,,,,,,,,,,Nice job getting it to run better in any event...

An engine like that should be between 15 and 17:1 which is a very high finger ripping compression ratio,,,,,so high it makes you grab the welding glove to pullstart the engine...

If you went down that low in the octane range that kinda says to me that either the high octane fuel youre using is tainted or the compression is now somewhere in the 9-11:1 range ........................

Have fun............
 

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Discussion Starter · #51 ·
its rebuilt and fresh but i tried a conservative squish of .05. i was advised that this head likes to be at .03. i once had the squish at .03 and i broke a few expensive starters.
 

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On my C1, 50cc Blata clone W/C bike, I have a Clone 19mm Dell PHGB piston carb, w/ a 1.01mm main jet, you might need bigger than that. It came with a .85mm stock, bike would bog if you opened the throttle, way to lean. It came with a clone SHA 14/14mm Dell. A 21mm is really to big for a 50cc engine w/ a 40mm bore & 39mm stroke. Not enough suction thru the crab bore to draw gas thru the main jet & up the main tube & into the carb bore, with a .85mm. So, you have too over jet it to get the right mixture, which leaves you with a rich idle and low end. You can go smaller on the idle jet, and raise the clip on the carb piston needle to lower the needle, to make it leaner. The you have 100 different sizes of the main jet Atomizer tubes with bigger and smaller holes. I have a 19mm Walbro HDA223B purge pumper carb w/accell pump and old C1 intake manifold sealed & attached to a Cag 16mm alum manifold bored out to 19mm w/ carbon fiber reeds., which the Walbro bolts up and a pulse line runs to the cases. So, easy to adj., you have high and low mixture screws, and an idle speed screw.
 

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On my C1, 50cc Blata clone W/C bike, I have a Clone 19mm Dell PHGB piston carb, w/ a 1.01mm main jet, you might need bigger than that. It came with a .85mm stock, bike would bog if you opened the throttle, way to lean. It came with a clone SHA 14/14mm Dell. A 21mm is really to big for a 50cc engine w/ a 40mm bore & 39mm stroke. Not enough suction thru the crab bore to draw gas thru the main jet & up the main tube & into the carb bore, with a .85mm. So, you have too over jet it to get the right mixture, which leaves you with a rich idle and low end. You can go smaller on the idle jet, and raise the clip on the carb piston needle to lower the needle, to make it leaner. The you have 100 different sizes of the main jet Atomizer tubes with bigger and smaller holes. I have a 19mm Walbro HDA223B purge pumper carb w/accell pump and old C1 intake manifold sealed & attached to a Cag 16mm alum manifold bored out to 19mm w/ carbon fiber reeds., which the Walbro bolts up and a pulse line runs to the cases. So, easy to adj., you have high and low mixture screws, and an idle speed screw.

Welcome to the forum...….Ive learned the benefits of pumper carbs from way back in my kart racing days when I was a kid...…

That pumper carb mod is one of the best and easiest mods to do to them...

Just think had racers adapted the pumper carb theyd have the best of the best every heat quite easily.....

Have you ever thought of a way to get finetune adjustment on the fly....?

Its very possible too with a couple of micro servos with a couple arms n ends...two buttons on the handlebars adjusts the low and high or just the highspeed alone up to 1/2 turn in each direction of correction to keep that edge.....LOL

 

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On my C1, 50cc Blata clone W/C bike, I have a Clone 19mm Dell PHGB piston carb, w/ a 1.01mm main jet, you might need bigger than that. It came with a .85mm stock, bike would bog if you opened the throttle, way to lean. It came with a clone SHA 14/14mm Dell. A 21mm is really to big for a 50cc engine w/ a 40mm bore & 39mm stroke. Not enough suction thru the crab bore to draw gas thru the main jet & up the main tube & into the carb bore, with a .85mm. So, you have too over jet it to get the right mixture, which leaves you with a rich idle and low end. You can go smaller on the idle jet, and raise the clip on the carb piston needle to lower the needle, to make it leaner. The you have 100 different sizes of the main jet Atomizer tubes with bigger and smaller holes. I have a 19mm Walbro HDA223B purge pumper carb w/accell pump and old C1 intake manifold sealed & attached to a Cag 16mm alum manifold bored out to 19mm w/ carbon fiber reeds., which the Walbro bolts up and a pulse line runs to the cases. So, easy to adj., you have high and low mixture screws, and an idle speed screw.
You can run phbg 21 on a 50cc engine also the cs carb with 23mm runs perfect on the 50th.

The problem is the Blata clone haven't 50cc and not enough power for such a big carb.
 
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