1998 Yamaha Wolverine Runs Lean

[merky161]

:no:Hi new member here with a question. I have a 1998 Wolverine with the following modifications.

1. bored .030 over

2. new valves

3. hot cams stage 1

4. wiseco piston

5. white bros air filter

6. modified air box lid

7. dyno jet kit stage 1

8. warn 424

9. full DG exhaust

When I got this quad the only thing not installed was the dyno jet kit, the previous owner told me I would have to rejet. Before I rejetted it the bike was running lean, the exhaust head pipe would glow orange within 5 minutes of idling, it would backfire through the carb and sputter off idle, 1/2 throttle and above it was fine. I bought the jet kit and followed the instructions, for my location I was to use a 160 main jet, stock jet was 140. After the install the quad fired right up and idled good. Throttle response was a noticible difference and I did not have any sputtering, however, the pipe still gets extremely hot! I pulled the plug and it was white indicating a lean condition still, also it pops through the carb only when I let off the throttle. I contacted DynoJet and explained everything above, they wrote back and suggested that I start with the modified air box lid since the jet kit I purchased was for a stock air box. I haven't removed the small round air filters that were put on the air box cover yet, but was wondering if this doensn't solve my lean condition what else is there to check, I checked for air leaks around the carb boot, and base gaskets and they were fine.

[Ajmboy]

:no:Hi new member here with a question. I have a 1998 Wolverine with the following modifications.

1. bored .030 over

2. new valves

3. hot cams stage 1

4. wiseco piston

5. white bros air filter

6. modified air box lid

7. dyno jet kit stage 1

8. warn 424

9. full DG exhaust

When I got this quad the only thing not installed was the dyno jet kit, the previous owner told me I would have to rejet. Before I rejetted it the bike was running lean, the exhaust head pipe would glow orange within 5 minutes of idling, it would backfire through the carb and sputter off idle, 1/2 throttle and above it was fine. I bought the jet kit and followed the instructions, for my location I was to use a 160 main jet, stock jet was 140. After the install the quad fired right up and idled good. Throttle response was a noticible difference and I did not have any sputtering, however, the pipe still gets extremely hot! I pulled the plug and it was white indicating a lean condition still, also it pops through the carb only when I let off the throttle. I contacted DynoJet and explained everything above, they wrote back and suggested that I start with the modified air box lid since the jet kit I purchased was for a stock air box. I haven't removed the small round air filters that were put on the air box cover yet, but was wondering if this doensn't solve my lean condition what else is there to check, I checked for air leaks around the carb boot, and base gaskets and they were fine.

Welcome to QUADCRAZY!

It sounds right, you're letting too much air in causing the lean condition. The engine is demanding more because of the modifications. Maybe you should go a little higher in jet size or go with a more restrictive air box assembly, but you may loose some power.

* Adjusted your thread title for better searches

[DirtDemon]

You need to adust the pilot circuit as well, the main jet is only responsible for metering fuel at the upper throttle range. I would increase your pilot jet size, adjust the fuel screw and lastly drop the clip one notch on the needle. One thing at a time though, test it after each adjustment.

[merky161]

ok, the needle clip on on the #4 position which is the lowest it can go, the air/idle screw is out 2.5 turns, I didn't want to go any more because I heard that you shouldn't go past 3 turns. The quad runs fine, I have no issues with it running other than the popping through the carb when I let go of the throttle. By changing the pilot jet will this make it run richer?

[Stoopidbot1]

Yes, you need to get more gas in there. If the jet kit was set for a stock lid and you're running a modified lid. You're letting a lot more air in than the kit is designed for.

[merky161]

Thanks all for the quick responses, I posted on other forums and did not get nearly as much response back in such little time. I am glad I found this forum

I will try to get the lid back to stock hopefully this weekend and will let you know what happens...

[Stoopidbot1]

Please keep us updated...we're glad you found us to!

[merky161]

Ok, removed the little filters from the lid, took quad out and it ran fine. It didn't pop through the carb but when I shut the engine off I get a bloop sound coming from the end of the exhaust, kinda of sounds like when you throw a match on some gasoline. Plug color is good now so the jetting must be correct. Any ideas?

[DirtDemon]

Could be excessive carbon buildup in the combustion chamber, it sounds like some thing is lighting off fuel after you shut the engine off. Try using a product called Seafoam to clean the motor out, it can be found at some auto part stores. Also check your ignition and cam timing, idle settings and check for air leaks.