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Post by jetsteve2011 on Dec 15, 2018 17:14:35 GMT -5
I purchased several upgrades for my 2k Zuma “prebug”. I was told to do one thing at a time and out of lack of patience to go fast. I’m going nowhere now. I installed the Athena sport bbk, stage6 big valve intake, Yasuni z (restrictor removed), and Malossi ork. The issue is it’s running like crap. It won’t even run fast enough to engage the clutch/spin the back tire. It sounds ok at idle speed and it will rev some but not a lot. It sorta pops/backfires through the exhaust. Also, if you hold your hand in front of the carb. there’s a lot of gas misting out. It’s smoking like a train too.
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Post by oldgeek on Dec 15, 2018 19:20:02 GMT -5
I do not have experience with the yamaha vertical motor. But for starters I would install an air box to stabilize your airflow. IMO, trying to tune without an airbox, especially as a beginner puts you on the road to insanity.
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Post by harleyracer59 on Dec 15, 2018 19:40:31 GMT -5
start with the basics, are there any vacuum leaks? did you install the piston the correct way? is the cylinder installed correctly? IE cylinder spacing, piston at bdc should be real close to the bottom exhaust port preferably equal to it, does it have proper compression? make sure there are no exhaust leaks or crank seals leaking. what size jets do you have and position of clip. recheck plug gap and retorque all cylinder intake and exhaust bolts im sure im forgetting something important..... but this is a good start. let us know the answers. good luck
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Post by benji on Dec 15, 2018 21:05:57 GMT -5
First, put a damn air filter on. With that new huge carb, you can totally suck something down the intake tract and destroy shit. Trust me, I did it on my first bbk install.
Second, list what jets you have, what size carb, what variator roller weight, and what clutch springs you got. Too much info is better than not enough.
I'm guessing you have a 24mm or 21mm pwk or polini could carb. Your pilot jet should be like a 40 (or so) and your main jet should be like a 110 (or so) to start out, WITH AN AIR FILTER. Even a foam unifilter smoothes out the air a little for the carb to work better.
Third, I can almost promise you have an air leak somewhere, just cuz it's your first. But also cuz it's running like crap, and that's a common cause. So go through your intake install and make sure it's all sealed well. Carb cleaner sprayed on the intake while it's running will help find a leak by changing its idle.
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Post by SMALL CC TEK on Dec 16, 2018 1:33:54 GMT -5
Take the first tip PUT a air Cleaner on ! See if it will run with the air cleaner on or even rev at all , Pull and check your plug did you foul it attempting to start for the first time ? Man you opened a can of worms by doing everything at once with no experience make sure that needle clip is in the center for starters .. You premixing or injected ? premixing i hope , You must be careful mixing head and cylinder parts . Did you take pics of the head and cylinder .. Did you put the piston in right ? I am not being a jerk just thinking about all that could go wrong that's all !
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Post by jetsteve2011 on Dec 16, 2018 6:28:42 GMT -5
I just ran it briefly w/o air filter. After running it for about 10 minutes at 1/3 throttle. I have an air filter with a 45deg elbow, there was quite a puddle of gas in the elbow. So imo it’s dumping way more gas than it can consume. Probably what’s causing the backfires. PCP 21mm, comes with an 100 main jet and I’ve got a set of 80-98 ordered. The needle is set in the middle position.
I tested the engine before I rebuilt it, I had right at 120psi.. What kind of compression should I be seeing before it’s broke in good?
The piston is installed with the triangle thingy on the side with muffler bearing. Jk >exh
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Post by jetsteve2011 on Dec 16, 2018 6:49:44 GMT -5
I forgot to mention I was sorta rapidly jerking throttle and a handful of times it would sorta hook up and it would jump up rpm. All be it briefly, was enough to even engage the clutch and the back tire would spin. I was starting to think I screwed up something installing the ork.
I’ve worked on many Kaw. 650cc stand-up jet skis. They are a heck of a lot easier. Throw on bigger everything and tune by checking plugs. There’s also plenty of room to work with.
Just getting the plug out of the v.min. is a chore.
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Post by Lucass2T on Dec 16, 2018 9:31:50 GMT -5
Make a video with clearly audible what you are trying to explain. Will make things more clear for us.
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Dec 16, 2018 10:26:37 GMT -5
120 compression seems low after doing top end. I just did one and was 180 - maybe a bit high. That was either pre-break-in or mid-break-in. I did another one and measured after two months at 165.
Your throttle cable looks a bit strained but may be no big deal at all. Did you check it, that it rolls on and off properly without sticking?
Other that the possibly low compression, I'd forget about all those changes you made at once (BBK, CVT, and Exhaust) and focus on carb, airbox, and intake/reeds. Check that your gasket is good by the reed cage and those bolts are tight. But - don't overtighten them!
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Post by benji on Dec 16, 2018 10:40:35 GMT -5
It's "fairly" normal for it to spit gas out of the carb a little, but not a lot. You could be way rich.
120 psi sounds like more of a problem tho. You should be higher, 150-180 psi. I would maybe take off the head and check it out. Make sure it's sealed up with some copper spray and wait overnight to fire it up after you get it together. Gotta let the glue dry.
I would get a few more jets, just cuz. Maybe some pilot jets too. I've never tuned a cp Carb, but it looks real close to a pwk D-slide or Mikuni round slide, and I would put your main jet possibly over 100.
What air filter? Uni? Or is it that polini one with the cover? Some guys say that one is restrictive.
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Post by benji on Dec 16, 2018 10:41:35 GMT -5
And what's a malossi "Ork"? Do you mean overrange kit? If so, bravo, but man that's biting off alot haha. Did you do upgears?
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Post by jetsteve2011 on Dec 16, 2018 13:42:13 GMT -5
No the original motor had 120 but I was using a gauge with a long hose too.
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Post by jetsteve2011 on Dec 16, 2018 13:47:14 GMT -5
What’s the best way to link a video?
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Post by jetsteve2011 on Dec 16, 2018 13:56:27 GMT -5
And yes, I got the Malossi la Furia Rossa OR kit. Only thing is I kinda blew my budget on that and the fact I bought 2 exhaust S6 r1400& Yasuni z. I’ve got a generic air filter for now. I will try to address the concerns y’all have mentioned and get a video of how it sounds. I have a large hose connected to the exhaust to vent exhaust outside. It doesn’t seem to affect performance on or off. Just keeps me smelling less like exhaust.
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Post by benji on Dec 16, 2018 18:28:28 GMT -5
The s6 r1400 is an extreme race pipe but it's gonna be rare someday probably so it's a good buy. Did you carve out the cvt cavity to clear the rear pulley and belt like the instructions say?
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