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1998 Yamaha Big Bear - Slow Throttle Response After Snorkel Install


MadMan
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I own a 1998 Yamaha Big Bear 350 4x2. I recently purchased a Submarine Snorkel brand snorkel kit for it which didn't fit properly, so I decided to build one homemade. I ran 1.5" PVC from the stock air box up to the front of the quad. It passes thru the front right fender and pipes into a 2" PVC mounted to a crash plate on the front rack. I connected the crank case breather line into the 1.5" PVC as well. I made a 2nd Snorkel on left side of quad which is a faux snorkel since it's purpose is to conceal the breather lines I have extended from the rr drum brake, rr dif., and carb. I took care to loop the breather lines a couple of times to prevent water from getting in, in the event I ever sink the quad. I also siliconed the air-box lid and used Dielectric grease on all electrical connections. I don't go swimming with my Big Bear but I do ride thru fairly deep water occasionally and I just wanted the snorkel installed as a precautionary measure for those unexpected dips u take when traveling across what u thought was a shallow puddle on the trail. LOL. Any way, since installing this snorkel my quad has an odd throttle response. When riding at normal speeds it's unnoticeable, but when hammering the throttle or fluttering the throttle the response seems to lag. I also notice if I'm in a gear too high for the slower speed I'm going the quad sounds like it's about to stall. I know normally u downshift the slower u drive, but it used to drive in a higher gear at low speeds and not bog down like it does now. I'm told I should re-Jet my carb. I'm pondering installing Dial a Jet. Any suggestions from you experienced riders? Removing the carb is a PITA and reinstalling it is equally fun. I've already rebuilt the carb prior to snork install. I like the concept of a dial a jet being able to adjust on the fly, but wasn't sure if it's the way to go. Please help. Any advice is greatly appreciated guys!

quadcrazy 01 snork.jpg

quadcrazy 02 snork.jpg

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57d773458ed46_quadcrazy02snork.jpg.900e68bf2670511cb7b712b45aa73a17.jpg

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  • 8 months later...

Hey MadMan did you ever figure out how to fix your problem. I recently made a snorkel for my 95 Big Bear 350 and am experiencing the same issues. It idles fine and runs good in high gear, but when you give the throttle quick revs it sounds like its being sufficated and wants to die. I tried to adjust idle screw and fuel mix screw and no luck. Thanks.

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Soco499; Yes, I did fix mine. I adjusted the carb needle to remedy my problem with throttle. I opened up the carb, pulled the needle out, and moved the needle clip one notch down which raised my needle slightly. By raising the needle position it makes bike run a little RICH. My snorkel mod increased my airflow, so I needed more fuel to compensate. The bike previously was running like crap. It'd bog down when i would punch throttle from a stand still. Now throttle response feels right. My stock exhaust is rusted to Hell, so I am ordering a new DG RCM ll slip one exhaust from Amazon. I'm sure I'll have to rejet my carb afterwords. I'll keep u posted how the bike runs after the install. BTW I have discovered no one sells an after market slip on exhaust or these old Big Bear bikes. A stock Yamaha ugly steel can one cost more than a new DG pipe. I hope it's not a POS. Good luck with your Big Bear! These old Yamahas are bullet proof IMO.

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  • 5 months later...
Hey MadMan did you ever figure out how to fix your problem. I recently made a snorkel for my 95 Big Bear 350 and am experiencing the same issues. It idles fine and runs good in high gear, but when you give the throttle quick revs it sounds like its being sufficated and wants to die. I tried to adjust idle screw and fuel mix screw and no luck. Thanks.

Its been a while since my last post. To recap, I have a snorkel and after market DG RCM slip on exhaust installed on my 98 yamaha 350 4x2 big bear. The raised the carb NEEDLE up a bump and changed my Main stock jet from #120 to a #145. Bike was running great afterwords. It was peppy and sounded killer. I recently had it in storage for maybe 4 months and now its running crappy. It doesnt want to idle for very long, keeps stalling. It drives fine with light or medium throttle but if I punch the throttle the revs stop. Its like a let off the gas when in reality Im holding it down. If I drive up steep incline the motor stops. It will then start back up once bike is on flat ground again. Could this be due to a sticky float in carb? This bike had a float that would stick about a yr ago and I chgd the needle valve set. Maybe it needs to be done again or a simple cleaning? I forgot to check the carb drain to see if it was pissing fuel last ride. Thats usually my clue the float is stuck. The needle valve set looks like its made out of aluminum and the tip appears to be dipped in rubber. Last time I changed it the alum looked pitted which caused it to get stuck in place and not move freely with the float. I hope its a simple fix. For an old bike this thing is solid! Yamaha built it like a tank and it drives like one too. LOL!

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