Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
|
Post by Petro on Jun 16, 2020 2:12:17 GMT -5
I've been running my past three scooters on a simple injection EFI that worked great. I gave my last bike away though and I am now running the stock 18mm carburator. It smell's too much Petrol for my liking, especially when I turn it off and wonder if that's common? I can't remember that it did or didn't.
I am running a 50mm cylinder on stock 18mm carb with a stock low jet (no markings, 35?) and 100 main jet, sea level. The bike runs well and the spark colour confirms it, at full throttle it might be a bit too rich but I am never at wide open, 80% max... Needle is on second from top, first and third doesn't work well at all.
For comparison, what size BBK are You guys using and what jets?
Thank You!
|
|
|
Post by FrankenMech on Jun 16, 2020 10:35:13 GMT -5
There are 6 sticky threads at the top of this 4 stroke performance forum at least one of them should answer your question. The information is from present members and past members which is a rich resource
|
|
Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
|
Post by Petro on Jun 16, 2020 13:27:38 GMT -5
There are 6 sticky threads at the top of this 4 stroke performance forum at least one of them should answer your question. The information is from present members and past members which is a rich resource ...and I searched like a maniac this morning... Too early I guess!!! Thank You!
|
|
Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
|
Post by Petro on Jun 16, 2020 14:24:44 GMT -5
No luck in the 50mm BBK thread unfortunately, found only two posts mentioning the jet, a 24mm carb with 105 and another one with a 107...
|
|
|
Post by FrankenMech on Jun 16, 2020 22:05:24 GMT -5
Jets vary all over depending upon the carb, air filter, etc. Experimentation is required to determine the proper jet for your particular application. What other people use can sometimes help you to get into the right area. There are also threads on tuning a carb. Personally I think tuning a carb with jets and the airflow resistance or pressure drop across the air filter is ludicrous. I vent my float bowl into the carb intake and forget about it.
|
|
Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
|
Post by Petro on Jun 17, 2020 1:34:37 GMT -5
Jets vary all over depending upon the carb, air filter, etc. Experimentation is required to determine the proper jet for your particular application. What other people use can sometimes help you to get into the right area. There are also threads on tuning a carb. Personally I think tuning a carb with jets and the airflow resistance or pressure drop across the air filter is ludicrous. I vent my float bowl into the carb intake and forget about it. I need an indication on where I am standing with my 100 jet. I know how to tune a carb but I am not keen to play that game... As said, it works and it works good but the petrol smell I don't fancy at all... Thank you!
|
|
|
Post by mikehailwood on Jun 17, 2020 6:43:28 GMT -5
" I vent my float bowl into the carb intake and forget about it." FrankenMech, Please explain. Thanks
|
|
|
Post by FrankenMech on Jun 17, 2020 7:55:40 GMT -5
mikehailwood , On larger carbs venting the float bowl to the intake side of the carb is common practice to eliminate the effects of a dirty air filter, airflow flow rate, etc. on carb metering. I have no idea why the idiots that design scoots don't do it that way, unless it is some lame attempt to contain the fuel smell. Some carbs use a temporary bowl vent to atmosphere as an enrichment device. I just buy 'performance' carbs jetted for an open pod filter or no filter at all and vent the bowl to the intake side of the carb and run it with a pod filter. Petro , it just looks like you will have to get used to the smell of petrol. These 4T single cylinder engines spit a lot of fuel back out the intake due to interrupted mixture flow. It is the nature of single cylinder engines.
|
|
|
Post by Mech Warrior on Jul 10, 2020 9:46:58 GMT -5
Most 70cc kits for I.E. Malossi sport will require you to go up 10%-15% in the main jet. Performing a plug chop will let you know where you stand.
|
|
Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
|
Post by Petro on Jul 10, 2020 14:18:43 GMT -5
I now running a 52.4mm kit with the stock 18mm carb and .92 jet, seems to run best so far, will try out a .88 when I find the lust, I find this very boring indeed... No cheap EFI kits available either anymore...
|
|