Vibration

[Capnspaldin]

Hi. I'm kind of new around here and I've read some great tips and ideas...I just built my first MB and I have a few issues. I was able to fix my idling problem just by reading through past topics. Another issue I'm having is that there seems to be a lot of vibration going on..any comments or ideas?

Bike is BMX style Mongoose 26"

 

[Venice Motor Bikes]

Can you post some pictures of how you have your engine installed (& also the chain & sprocket).

 

[Capnspaldin]

 

[Capnspaldin]

It was a very tight fit. For a moment there I thought I might need a different carb.

 

[Degoragon]

For starters, I see your air cleaner hits against the frame, which will cause issues with the gas frothing in the carb. I had this same problem with my bike. If it is against the frame, it will vibrate it as well.

In my case, I had to use an offset intake, as my carb would not even fit in the frame. However, I also used a 24" bike as opposed to a 26", so that is a factor. A Shorty intake (12.99) should keep it clear of the seat tube, and should allow for a race carb to be applied.

Secondly, I recommend using rubber or pipe wrap foam where the engine mounts to the frame to reduce vibration. I went with the pipe wrap foam, you can buy it for about $4.00 or so (Duck brand, same as the tape), then I cut it with a utility knife as close as I could.

Lastly, Make sure those bolts are tight! I would recommend at least some Loc-tite, or Permatex Thread Locker, the blue stuff, not the red. Of course, you can also buy some lock nuts, which is what I did.
The lock nut may or may not require different studs, depending on how your is set up, and the nuts/bolts you buy.

 

[Capnspaldin]

I did skip putting rubber in between motor mounts and the frame....I didn't have anything to put there at the time. I will fix that. I used blue loctite everywhere. But I can't stand my carb being so crammed where it is thank you for
Telling me about the shorty intake I'll have to look around for one.



my bike. If it is against the frame,
it will vibrate it as well.

In my case, I had to use an offset intake, as my carb would not even fit in the frame. However, I also used a 24" bike as opposed to a 26", so that is a factor. A Shorty intake (12.99) should keep it clear of the seat tube, and should allow for a race carb to be applied.

Secondly, I recommend using rubber or pipe wrap foam where the engine mounts to the frame to reduce vibration. I went with the pipe wrap foam, you can buy it for about $4.00 or so (Duck brand, same as the tape), then I cut it with a utility knife as close as I could.

Lastly, Make sure those bolts are tight! I would recommend at least some Loc-tite, or Permatex Thread Locker, the blue stuff, not the red. Of course, you can also buy some lock nuts, which is what I did.
The lock nut may or may not require different studs, depending on how your is set up, and the nuts/bolts you buy.[/QUOTE]

For starters, I see your air cleaner hits against the frame, which will cause issues with the gas frothing in the carb. I had this same problem with my bike. If it is against the frame, it will vibrate it as well.

In my case, I had to use an offset intake, as my carb would not even fit in the frame. However, I also used a 24" bike as opposed to a 26", so that is a factor. A Shorty intake (12.99) should keep it clear of the seat tube, and should allow for a race carb to be applied.

Secondly, I recommend using rubber or pipe wrap foam where the engine mounts to the frame to reduce vibration. I went with the pipe wrap foam, you can buy it for about $4.00 or so (Duck brand, same as the tape), then I cut it with a utility knife as close as I could.

Lastly, Make sure those bolts are tight! I would recommend at least some Loc-tite, or Permatex Thread Locker, the blue stuff, not the red. Of course, you can also buy some lock nuts, which is what I did.
The lock nut may or may not require different studs, depending on how your is set up, and the nuts/bolts you buy.

For starters, I see your air cleaner hits against the frame, which will cause issues with the gas frothing in the carb. I had this same problem with my bike. If it is against the frame, it will vibrate it as well.

In my case, I had to use an offset intake, as my carb would not even fit in the frame. However, I also used a 24" bike as opposed to a 26", so that is a factor. A Shorty intake (12.99) should keep it clear of the seat tube, and should allow for a race carb to be applied.

Secondly, I recommend using rubber or pipe wrap foam where the engine mounts to the frame to reduce vibration. I went with the pipe wrap foam, you can buy it for about $4.00 or so (Duck brand, same as the tape), then I cut it with a utility knife as close as I could.

Lastly, Make sure those bolts are tight! I would recommend at least some Loc-tite, or Permatex Thread Locker, the blue stuff, not the red. Of course, you can also buy some lock nuts, which is what I did.
The lock nut may or may not require different studs, depending on how your is set up, and the nuts/bolts you buy.

 

[Degoragon]

I did skip putting rubber in between motor mounts and the frame....I didn't have anything to put there at the time. I will fix that. I used blue loctite everywhere. But I can't stand my carb being so crammed where it is thank you for
Telling me about the shorty intake I'll have to look around for one.



my bike. If it is against the frame,
it will vibrate it as well.

In my case, I had to use an offset intake, as my carb would not even fit in the frame. However, I also used a 24" bike as opposed to a 26", so that is a factor. A Shorty intake (12.99) should keep it clear of the seat tube, and should allow for a race carb to be applied.

Secondly, I recommend using rubber or pipe wrap foam where the engine mounts to the frame to reduce vibration. I went with the pipe wrap foam, you can buy it for about $4.00 or so (Duck brand, same as the tape), then I cut it with a utility knife as close as I could.

Lastly, Make sure those bolts are tight! I would recommend at least some Loc-tite, or Permatex Thread Locker, the blue stuff, not the red. Of course, you can also buy some lock nuts, which is what I did.
The lock nut may or may not require different studs, depending on how your is set up, and the nuts/bolts you buy.

[/QUOTE]


You're welcome. Speaking of, I actually switched to a CNC short intake as well since I wrote that post. Since the HP carb hit against the side of the bike when I installed it with the offset, I found the short intake allowed me to place my HP (Runtong) Carb inside the frame, although in my case, I do need to get a smaller air filter. Mine barely fits in there, even with the Short intake. Of course, my frame is smaller than yours.

However, since your carb seems to (barely) fit with the stock, the short intake should give you plenty of room. This will be better if you should decide to go with an HP carb.