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Post by oldgeek on Jan 4, 2016 7:49:26 GMT -5
As shown by the chart I posted previously, that is likely your rich stutter problem around 1/4 throttle.
You need a 50 or about a 45 and you will be happy. I do not think they make a 45, but you can get a 40 and carefully file it down to a 45 if necessary.
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Post by Lucass2T on Jan 4, 2016 8:26:06 GMT -5
Lucass2T Thank you very much! What you just explained makes absolutely no sense since I don't understand the basics behind it. I will not touch the timing unless it is really, really necessary and only as last resort. I will try simple things first. Today again I put in a brand new spark plug and again I got this nice caramel color after a couple of WOT runs with the 95 MJ so that stays like this for now. I know from past experience that if I add stiffer clutch springs for example I could get rid of that sputter because it revs up fast and basically skips that part. But I want to get the carb tuning right this time from 0 - WOT all the way. I failed to do that with my stock carb because I couldn't find low number pilot jets for it, but there is plenty for the PHBG. I will now fill my shopping cart at treatland and see that I can pull the trigger on a new order this week. Thus far I have - Main Jets #93 and #94 - Pilot Jet Set 30s (#30, #35, #37) - Needles W7 and W6 - Gasket Set - 36mm Airbox adapter Ooops! Forgot to check the number off the slider. *grabbingtools* And out we go..... Slider is a #30. What does that mean now? Good? Bad?  I'll have to read back the Dellorto tuning manual about the real in dept workings of the slide cutaway. But in general the bigger the cutaway the more air can enter the engine at around 1/4 throttle. So you'll need the slide cutaway nr to tune the engine at part throttle. The bigger the number, the bigger the cutaway, the more of a 'lean' slide you have. I think the dellorto slides vary from .20 to .60 or something. Or at least when you need something beyond those numbers something's way off. |
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Post by spaz12 on Jan 4, 2016 16:56:13 GMT -5
Throttle Slide Cutaway www.mopedarmy.com/wiki/How_To_Tune_PHBG_Carburetors If you haven't placed your order then maybe you should order a #40 slide as it will help lean it out in the lower throttle position. If you had easier access to all this carb stuff I'd just say wait, but if you can't fix your low end stumble with a smaller pilot or needle position, then you would do it with the throttle slide and you'd be stuck waiting again. If your are very careful then you can increase your cutaway yourself. I've never done it, but I've read plenty about it so I know it can be done. Corrosion has done it. The joys of tuning  EDIT: Wow, I did it again. I missed an entire page of new posts. |
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Post by Lucass2T on Jan 4, 2016 17:05:43 GMT -5
EDIT: Wow, I did it again. I missed an entire page of new posts. Happens to me all the time  |
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Post by tsimi on Jan 4, 2016 17:18:28 GMT -5
Thanks guys! #40 slide is in the cart already.  Still the mixture screw issue is what bugs me and that would mean it is a pilot jet issue. But I want to be well prepared just in case it isn't. Therefore anything that has an influence on the lower throttle area will be ordered this time. I would love to keep the mixture screw all the way in for now but according to the chart that oldgeek postet it impacts the whole throttle range. Maybe not as much as at the low end but still it would lean out mid and WOT area. Or am I misinterpreting that chart? |
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Post by spaz12 on Jan 4, 2016 17:23:28 GMT -5
You'll be a tuning Sensei in no time.
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Post by tsimi on Jan 4, 2016 17:25:17 GMT -5
spaz12Edited above post. Please read again... thx
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Post by spaz12 on Jan 4, 2016 17:30:44 GMT -5
Your plug looks great so you know you're not lean. You'll be fine until you get the new parts. It'll just stumble off the line because you are rich, which is alright as far as the cylinder being okay.
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Jog-Mania
Jan 4, 2016 17:43:48 GMT -5
via mobile
Post by tsimi on Jan 4, 2016 17:43:48 GMT -5
Your plug looks great so you know you're not lean. You'll be fine until you get the new parts. It'll just stumble off the line because you are rich, which is alright as far as the cylinder being okay. So you would suggest to keep the mixture screw in it's default position? (2 turns out) At the moment I have it in that default position just to be on the safe side. I could screw it in all the way and adjust the idle a bit since it revs higher when all the way in. I also connected my CHT gauge again to keep an eye on the temps. |
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Post by spaz12 on Jan 4, 2016 17:49:38 GMT -5
If you pulled the plug and it looked like that with the screw all the way in, then you are still fine. Just keep an eye on your temps, especially mid throttle temps.
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Post by tsimi on Jan 4, 2016 17:55:28 GMT -5
I never really drove with the screw all the way in. Was not sure what range it would affect. Now that I have the CHT connected I could give it a try though.
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Post by Lucass2T on Jan 4, 2016 18:22:44 GMT -5
Its a back and forth game with tuning carbs. When you change this it also to some extend affects that. So you'll have to adjust that too...
The more you'll reach the perfect tune the smaller the changes you'll need to make.
When you screw out the mixture screw a few turns to lean out idle and part throttle it doesnt really affect mixture @ WOT. Ofcourse you'll have to make a good testrun to make sure. But my experience is that the mixture screw only really works @ idle speed and beyond that you'll wont feel any difference.
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Post by tsimi on Jan 4, 2016 18:55:11 GMT -5
Lucass2TYeah, the PHBG carb is a lot more complex then the stock Yamaha carb. You can adjust really anything on it, which is cool but also gives you more factors that matter when tuning. If that what you are saying is true then there is not much to worry then. I just arrived at my working place and I drove with the screw at default position. Today it is really cold and highest temps I got was 120F when shroud is spinning. Once I arrived I right away start to tune the idle and mixture screw. So today on my way home I will be able to test it and see what temps I get and how it drives. I'll keep you guys updated...
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Jog-Mania
Jan 4, 2016 23:52:28 GMT -5
via mobile
Post by tsimi on Jan 4, 2016 23:52:28 GMT -5
Anyone knows what kind of diameter the fuel and vacum hose connectors have on a PHBG carb? I wanted to buy new fuel and vacum hoses today because the old ones a worn out and that is why they come off that easy. I just didn't know the inner diameter sizes.
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Post by spaz12 on Jan 5, 2016 0:25:46 GMT -5
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