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Post by JEGZ on Sept 11, 2023 3:50:57 GMT -5
Hi forum I have been away awhile finishing up some projects for a long time. I am a very slow builder and it has taken me some time to swap this 100cc minarelli style motor into an icebear/Ruckster gy6 clone frame. My dream was to make an affordable powerful 2 stroke bike without having to spend the $$$ of a high end 70cc bike with all the stage 6 parts I did the first 2 stroke bike you guys helped me with. I blew that motor up because the squish was too tight and the piston was hitting the head. I thought well I am not the best motor builder so I will just add cc's and it eventually all came up Millhouse.LOL. The big Icebreaker was firing up the bike hoping I hacked all the electrical right. Well anyway my question. I have her running and have read all this non sense about 100cc mina bikes with phbg's needing 100+ sized jets. And so that is what I tried in my carb but it just would not run. I worked my way down from there because usually it is a rich condition in my experience when it flat out wont excellerate. So i have worked my way down as I was saying all the way down to a 70 jet. 80 boggs/stuggles to get to high rpm but that is with the needle in the richest setting. I have not moved the needle yet. I am missing jet 75 so 70 is what runs the smoothest. My question first of all is I have a choke with a knob will upload pics if ya'll want them is up or down on. I would think up is on but the idle just dies in up position. Idle goes up in down contrary to my feeble research on the interwebs could I be crazy.lol. My next question is obviously why the hell is my bike running so good with a 70 main and could that be related to the choke. Great catching everyone up and hail to Brent you are the man.
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Post by JEGZ on Sept 11, 2023 4:25:28 GMT -5
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Post by JEGZ on Sept 11, 2023 4:26:08 GMT -5
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sinfull
Scoot Enthusiast
Posts: 413
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Post by sinfull on Sept 11, 2023 4:46:51 GMT -5
Don't be too focused on jet size, too many variables to go by, go off what the bike is telling you. Use a temp gauge and tach.
There really isn't a one jet size for every bike, elevation, pipes, timing, intake yadada. Seeing cylinder temperatures reach 300+ shut down and up jet, temperatures barely above 160 ish down jet. Just note what size jet is getting what temps so you know which way to go
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Post by JEGZ on Sept 11, 2023 5:04:53 GMT -5
Ya that is kind of my attitude when dealing with carbs over the years. They just like what they like and if you could use another few sizes up it almost would be too hard to find the sweet spot to notice. It does like 70 but I have notice at high rpm on a longer stretch of road it will have fuel starvation, again though it could be lean or rich at this point. I threw in the red clutch spring before I went into hibernation you know for pulling a 36 hour work day. after sleeping a day and a half I did not get much time with the red spring in but noticed it definitely hitting higher rpm. I will get back out today and mess around with it. I have ordered a jet assortment. I really think it is going lean at high rpm but my gut tells me when it comes to carbs that my first intuition is always wrong. I guess the newer red spring and the higher rpm will tell me more I did not get her on a long stretch of road yet. If it clears that up I will now it was still rich, if you follow me. Anyone know about that choke would be nice for any input really a faceplant when something is working the opposite as it should, Uhrg.
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Post by oldgeek on Sept 11, 2023 5:25:02 GMT -5
Nice work, looks good!
I am not sure what is going on but if you are running the carb without a filter as shown in your picture, a 70 MJ does seem way small. With an airbox id say around 90-100 MJ, with a uni type filter 105+? Choke should only be needed on initial cold startup. Get your airflow consistent and go from there. Tuning without a temp gauge is like driving blind folded.
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Post by JEGZ on Sept 11, 2023 6:15:51 GMT -5
Urhg more bad news another trip to HF to buy a temp gauge, or I could commit to it and buy a Snap On, Lol the later was a joke btw. Thanks for the complement Old Rider! It took me awhile considering I built my 1971 VW Squareback station wagon during and at the same time as the bike. I remember thinking and having no love for the bike the whole time and when I finally got to ride it I took all the hate back. Zipping through all the parking lots at 40 mph and destroying those speed bumps by simply going around, words cannpot express lol.
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Post by JEGZ on Sept 14, 2023 4:34:08 GMT -5
Ok so I am going to be waiting until my jets arrive. It does not want to rev past about 3/4 throttle then it just poops out. Good news is I can hit 50 mph on my chinometer at at 3/4 twist. Also it hates the needle/pin that came with the carb so I ordered a tuning kit for those as well. I get a very choppy throttle response until the main kicks on. I will keep you guys posted on the progress, on this thread. May be awhile though my pins are coming from The great land of Italy. Btw my head temp is about 295 after a thorough ride.
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Post by oldgeek on Sept 15, 2023 5:46:27 GMT -5
Ok so I am going to be waiting until my jets arrive. It does not want to rev past about 3/4 throttle then it just poops out. Good news is I can hit 50 mph on my chinometer at at 3/4 twist. Also it hates the needle/pin that came with the carb so I ordered a tuning kit for those as well. I get a very choppy throttle response until the main kicks on. I will keep you guys posted on the progress, on this thread. May be awhile though my pins are coming from The great land of Italy. Btw my head temp is about 295 after a thorough ride. Sounds like the top end is pretty good, I routinely take mine to 235F 335F with no problems. Get the rest of the range tuned and you are golden. Edit: Fat fingered temp, meant to type 335F |
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Post by JEGZ on Oct 14, 2023 5:28:26 GMT -5
Ok so a quick update. I have the main jet kit and noticed some weird stuff. eventually that stuff led me to looking at the pilot jet. I do not know how they gauge them but if it is like the main jets than it is a 50, which is way to rich probably. I ordered a pilot jet kit from China direct and will let you guys know what happens. I had it jetted at an 80 main but it poops out on a long stretch and backfires so I assume it is too lean and getting too hot. If anyone knows or has a 100cc setup with a dell phbg what size pilot should be around right.
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Post by aeroxbud on Oct 14, 2023 7:27:21 GMT -5
A 50 pilot sounds about right for a 21mm carb. How far do you have the air screw out?
Down should be off for the choke.
Be careful ordering jets from china. You can end up chasing your tail of they are not machined accurately.
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Post by JEGZ on Oct 14, 2023 9:58:22 GMT -5
The carb is a 19mm don’t know how much of a difference that makes. I have very small drill bits handy for checking the jets if i need to. Either way it absolutely hates the 50 pilot jet it has no power until the main kicks on just a dead flat spot. And i can’t get it to run with the right size main either. Thank you my friend your advice is appreciated.
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Post by Zino on Oct 14, 2023 12:25:33 GMT -5
with a 19mm phbg i was running a 38-40 pilot i was in the low 80s for main with that carb with stock air box
i tried ordering cheap knock off jets from china in the past they were all mislabeled for size .
so measure them up from smallest to largest
The easiest way for me to set the pilot
After the scooter is well warmed up is
I turn the air mixture 2 turns out and then work through the pilot jets .
At Idle on the stand
I just blip the throttle a few times and listen or watch rpms if I have a rpm gauge .
3 things will happen
The rpms will drop below regular rpms then clean up and rise back up to idle rpm this is rich try a smaller pilot
The rpms will drop almost immediately to regular idle speed This is ideal for a daily rider
The rpms will increase /stay above regular idle and hang there before coming down this is too lean need bigger jet
If you find close to the right jet than you can use the mixture screw within 1 turn richer or 1 turn leaner to dial in best throttle reponse at 0- 1/4 throttle
You may find you need to go up a couple jets on the main if you drop alot smaller on the pilot
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Post by JEGZ on Oct 14, 2023 12:54:01 GMT -5
I would love to do things in the center stand but this crate engine did not include it lol. I remember seeing the right model stand used many year ago when i started building this bike in hindsight i probably should have bought it lol. Thanks for chiming in great info.
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Post by JEGZ on Nov 14, 2023 4:48:40 GMT -5
Update: I got the idle jet replaced with a 40 and the main to 88 . I still have a bog off acceleration. So I suspect the slide is the problem. It came with a 60 slide so I ordered a 40 and 50 from treats, god bless them.lol. They will be here in a few days I will post an update then. I know people like to see problems actually getting resolved here. On the other hand the backfiring stopped and the top end is too fast to go in a scooter so I am happy.
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