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Discussion Starter · #1 ·
Im running into an issue with my 1995 Yamaha Wolverine i just picked up. It's my first wolverine and i bout it knowing it had a little issue that i thought was just a dirty carb. They put a brand new carburetor on it but I'm not sure what brand it is since they gave me a box for a polaris carburetor. So heres what I've done with it. New Zoom Zoom carb so i at least knew what i had. New intake boot, new yamaha air filter properly oiled. timing checked (maybe off just a tad) checked valve clearance and adjusted. However it starts right up and idles just fine but still tends to pop a bit when not create much power and will not go over 15mph. Today i removed the spark arrestor and it started to actually gain a little speed but started popping real bad and didn't want to stay running well.


Anyone have any ideas?
 

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Discussion Starter · #4 ·
The Intake boot has been replaced and still the same issue. I did start noticing the pop/slapping noise after i adjusted the valves. I followed the proper steps of TDC on a compression stroke then .06-.10 on the intake valve and .16-.20 on the exhaust valve.
 

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by the same do you mean you are still getting back fires and visible fire between the head and carb? or that it still runs bad? i would double check the valves. where they out of spec when you checked? if they were and they are now you might need to replace the studs and jamb nuts, it is possible they are worn and wont stay adjusted. if you have not done a compression test now would be a good time. if you have ruled that stuff out completely it is time to start jetting. after it runs for a while what color is your plug. what color is the exhaust, does it smell funny. my guess at this point is your pilot is ok for now and you are very lean in the main. set your main needle in the middle, pull you main jet and inspect it if it appears to be undamaged and the main jet passage is clear and damage free go up 2 sizes and see how it runs. you will want to pick up a few jets above and below or get a jd or dynajet kit. did it run like this with the other carb? i think i mentioned in your other thread a possible reverse rev limiter, i dont know if you have one but if you do it could cause similar issues if it was failing or out of adjustment. i know that motor pretty well but have never even seen a wolverine so i am just throwing general stuff your way hoping we hit on something, wish i had better answers for you. there is nothing more frustrating trying to fix an issue that happened before you got the machine and had an attempted fix
 

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Discussion Starter · #6 ·
Correct, it still seems to be back firing through the carb. I have not had a chance to see if it has gained any speed with the new intake boot because I am nervous with the backfiring and don't want to cause any deeper issues. One thing that I also noticed is that i do seem to get a little smoke near the valves when its running. Initially i thought it was the little oil that leaks out of the exhaust valve when you take the cover off but thats all gone now. I re-checked the valves yesterday and they are still at the correct spec. However I started to notice the backfire once I adjusted the valves not before. So I am thinking that it has to be something with a sticky valve maybe? I'm just reaching for things that it could be at this point, because that the only thing I adjusted beside change out the intake boot and carburetor. The back fire was happening with the old carb on the bike as well I believe but now questioning that and i think its worth a try to going ahead and put the old carb again and see what happens. I even almost did the unthinkable and brought it to a shop to have them look at it because I'm ready to get out riding... But I have since talked myself out of that for now.

From what i hear Warrior/Wolverine valves are fairly tough and not many cases of bent or broken valves.


no worries cory52000 on not having the answer I know it is very tough to diagnose an issue through text and a short video. I appreciate all the input I can get!
 

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back firing is one thing but if you can still see fire between the carb and the head you need to get to the bottom of that even the slightest air leak in that area will cause symptoms as you describe. with the machine running and the air box in place spray a small amount of starting fluid in the area between the carb and head. if the rpms increase you have a vacuum leak that needs addressed. i am becoming suspicious of a burned or sticking valve. the backfiring and smoke from the valve covers could indicate that. after the starting fluid test and before you start messing with the jetting you need to do a compression test and a leak down test. if you dont know how to do a leak down youtube it there are lots of good videos on it. the compression test is pretty easy and self explanatory. for the leak down on a four stroke you basically put the engine at tdc of the compression stroke and pressurize the motor if you get significant air out of the exhaust you have a bad exhaust valve. if you get significant air out of the carb it is a bad intake. significant air out of the breather bad rings. everything you are describing and the fact that nothing you have done has helped is making me suspect something deeper in the engine. at the top of my list is a burned or sticking intake valve and or bad rings. the result of the the compression and leak down test will determine the next step.
 

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Discussion Starter · #8 ·
I originally did a compression test before I adjusted the valves and i had 125psi. I tested it tonight and its down to 100psi and I haven't driven it more than 70 yards since adjusting the valves to the proper spec. I do not have a leak down tester currently but It's looking more like I might have a valve issue. can they go bad just like that?

I think if it is a valve might be time to replace both valves and since I'm in there might as well take the jog off and do the piston as well. If i do tear it down any good recommendations for a service manual?
 

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if clymer makes one for the wolverine get it, they are by far the easiest to read and follow. i am a fair mechanic and have trouble with the factory service manuals and the haines. all of the critical information is in them but they assume a lot of basic knowledge. the clymers are step by step. my guess is it was not "just like that " but the significant symptoms appeared quickly. if it actually happens quickly i would suspect a hung valve more that a burned valve but it is hard to say for sure. you could try a little marvel mystery oil in the valve guides and see if it helps but if your compression is that low something is wrong. pulling the head and jug is not a real big deal and worst case yoiu get it apart and find it is all perfect you are out 20 bucks worth of gaskets and you have positively ruled out rings and valves. i dont think you will be that lucky from you description but who knows. as far as a leak down tester it is not very scientific and it is a little hillbilly but you can put the machine at tdc on the compression stroke, wrap a rag around you blower and put it in the spark plug hole but you have to be really careful too much pressure in the case and you will blow all of your oil seals, they say 7 to 9 psi. basically just put a little air in there and see if any leaks out. DONT DO IT IF YOU ARE NOT COMFORTABLE i dont want you yelling at m because you machine is now dumping oil as well. i have never tried but you might be able to see the valves with a bore scope as well.
 

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Discussion Starter · #10 ·
I think I'm just going to take the top end apart and just replace everything when I'm in there.

I tend to always use Clymber but they don't appear to make one for the Wolverine 350. The do make one for the MOTO-4 350 or one for the Warrior 350, any recommendation on what one I should buy?
 

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before you yard the motor out and apart follow the trouble shooting in chapter 8 and 9 to absolutely rule everything else out it was pretty easy to follow and had all the numbers you need. the section on the top end was not bad either. pretty good for a yamaha manual.
 

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Discussion Starter · #14 ·
just wanted to post a little update. Took the head and just off and cleaned them up good. I also cleaned up the valves which appear to be fine maybe just a little carbon build up. I still need to lapp them. I also cleaned up the piston and it appears to be just fine.

So a new gasket kit and oil seals for the valves and we'll see what happens.
 

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Discussion Starter · #15 ·
After dissembling and cleaning the complete valve system there was no change. So i replaced the cylinder and piston and still no change. The bike runs and drives on one carburetor that came with the bike that is a niche (thats what the seller told me) however it is not fast it can get up to 30 mph but i takes about 1/4 mile. After looking at it it seem that the accelerator pump is not working correctly so I replaced it with a zoom zoom carb. However with the zoom zoom it idles great but whenever i hit the throttle it cuts out and even kills the bike. Im stuck and have changed many things with no change. Besides the carburetor i can see change. with the niche the bike idles, runs and moves but slow. with the Zoom Zoom it idols just fine but cuts out and kills no matter where I change the fuel screw. I"m stuck and looking to see if i can find a shop to trouble shoot the issue but many won't look at older bikes.

Any help or ideas will be greatly appreciated.

Thanks in advance
 

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if the needle has no effect the main jetting is incorrect or the main circuit is plugged. zoom zoom parts are crap. sometimes they work but for the most part not so good. i would first take the carb apart and make sure it is assembled correctly and air moves freely through the main circuit and that the needle is working correctly. check the float level. if that is all good it could be lean or rich you will just have to mess with it up and down on the main jetting to get it dialed
 

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See my thread on warrior CDI issue. I had the same problem with a ZOOM carb where the throttle linkage inside the carb is connected, not on side but on top. You have to remove carb and take off top. Mine had the lil pin that connects the linkage fall out causing only 3/4 throttle...bike started and ran fine but wouldn't get up to full RPM.
Maybe the ZOOM carbs all have this weak link. I can take a pic if necessary.
Ron
 

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Discussion Starter · #19 ·
Thanks Axiom for the heads up!

Mine appears to be connected correctly. However I took the needle out and adjusted the height and no change.

Would anyone recommend switching my carb over to the 1996+ version? Are they any better? I'm stuck and think buying a used OEM or upgrading to the 1996 + OEM

Thoughts?
 
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