NR Racing Great video Neil, and thank you for showcasing our Rattlesnake! 😎 Regarding your comment you made toward the end, here are our thoughts: Overall, we suspect it could be an issue with your carburetor/jetting more so than the cam itself. The pilot jet's circuit is about 0 to 1/4 throttle, and then the main kicks in thereafter. So if you're idling at ~2000rpm (about 1/8 throttle), and the weird noise starts happening around 2600rpm, it sounds like the problem lies in that transition from your pilot to your main. You may need to change the pilot jet, or an adjustable idle mixture screw could help. We recommend the 615 RUIING carb as it's an economy part that comes with that adjustable screw. As an additional note, it's always important to lap and seal your valves, or there may be pressure leakage that could cause erratic carb functioning. This could be contributing to the issue as well if that wasn't done!
First. If you start out wanting to limit RPM to right at 5K it can be done with the governor and stock linkage. The governor spring just needs repositioned to the hole at the end of the governor arm. Then adjust the throttle screw for 5K RPM. I ran one of my 196's for years that way. In my opinion the stock rod should be fine running to 5800 RPM for a few seconds. Especially when the engine is always ran with clean oil. None of my OHV engines have ever ran with black oil. All three of my minibike engines have an ARC rod. When I build my theme is going for better than stock without going for stupid power. The 252 Rattlesnake cam fits that theme well. I used it in my 224 build. Seems like a good economy cam. Are you making changes as you go along to see the gains? I would recommend getting rid of the stock carb for a slide carb. If you are on a budget the VM22 clone kits are $30 on amazon. You will see a difference on the drag strip. Those carbs even work well on a stock engine with a header pipe.
NR Racing
Great video Neil, and thank you for showcasing our Rattlesnake! 😎 Regarding your comment you made toward the end, here are our thoughts: Overall, we suspect it could be an issue with your carburetor/jetting more so than the cam itself. The pilot jet's circuit is about 0 to 1/4 throttle, and then the main kicks in thereafter. So if you're idling at ~2000rpm (about 1/8 throttle), and the weird noise starts happening around 2600rpm, it sounds like the problem lies in that transition from your pilot to your main. You may need to change the pilot jet, or an adjustable idle mixture screw could help. We recommend the 615 RUIING carb as it's an economy part that comes with that adjustable screw. As an additional note, it's always important to lap and seal your valves, or there may be pressure leakage that could cause erratic carb functioning. This could be contributing to the issue as well if that wasn't done!
Thank John for the camera work and your motor sound good when you raise it up thank you for the video
Looks like fun
First. If you start out wanting to limit RPM to right at 5K it can be done with the governor and stock linkage. The governor spring just needs repositioned to the hole at the end of the governor arm. Then adjust the throttle screw for 5K RPM. I ran one of my 196's for years that way.
In my opinion the stock rod should be fine running to 5800 RPM for a few seconds. Especially when the engine is always ran with clean oil. None of my OHV engines have ever ran with black oil. All three of my minibike engines have an ARC rod.
When I build my theme is going for better than stock without going for stupid power. The 252 Rattlesnake cam fits that theme well. I used it in my 224 build. Seems like a good economy cam.
Are you making changes as you go along to see the gains? I would recommend getting rid of the stock carb for a slide carb. If you are on a budget the VM22 clone kits are $30 on amazon. You will see a difference on the drag strip. Those carbs even work well on a stock engine with a header pipe.