Just had to end done and have no power and is backfiring!

[DrewT]

I just had a local Banshee guy rebuild my top end with Athena stock bore cylinders, pistons and rings, adjustable timing plate +4, reforce 4 reads, also got rid of the K&N filters and switched to UNI filter pod filters two stage. The bike also has FMF Gold Series fatty exhaust, cool head, and I went from 19 mm domes to 20 mm domes. The bike starts first kick but when I go to give it throttle anything past 1/8 of a throttle the bike just bogs and acts like it's starving and is backfiring I believe out of the left exhaust. Both pipes are getting pretty much equally hot and smoking the same. What could it be and where do I start?

[locogato11283]

What carbs and what jetting?

[DrewT]

Keihin 33mm carbs and I don't remember what Jets were in it but the same Jets are still in it from before I took it to the shop and the bike ran perfect. It is the left side that is backfiring. And both pipes seem to be getting equally hot.

[DrewT]

12 hours ago, locogato11283 said:

What carbs and what jetting?

Keihin 33mm carbs as for the Jets they are the same jets that were in the carbs when I dropped it off prior to having the top end and other minor parts added.

[DrewT]

9 minutes ago, DrewT said:

 

 

Edited November 28, 2022 by DrewT
Wrong area for reply

[Tedder]

Check the pilot circuit/jets. If one or both are plugged it'll act that way. 

[DrewT]

2 hours ago, Tedder said:

Check the pilot circuit/jets. If one or both are plugged it'll act that way. 

Is it possible after adding the adjustable timing plate and advancing the timing and bumping up to v-force 4S and triple exhaust ported cylinders I would need to add bigger pilot Jets? Also I have not had the exhaust off on this bike but where my expansion chamber meets the rest of the exhaust where that coupler connection is on the left side is clearly leaking as if I let it idle I see smoke coming out of the coupler. Does that need a gasket or o-ring?

[Tedder]

Assuming the jetting was good before I doubt those upgrades would make such a huge difference on your current running issue.  If lean pilot circuit is the problem - *There are always exceptions* such as carbs that sat around a long time with fuel in them and dried out/gummed up but most often if the pilot circuit is lean it's from a piece of foreign material stuck in the jet itself. You should be able to see daylight through the jet when held up to the light. 

[locogato11283]

We can't help you if you don't tell us what jets are in it now.

[DrewT]

On 11/28/2022 at 2:30 PM, locogato11283 said:

 

 

Edited December 17, 2022 by DrewT

[DrewT]

My jets  are 150 main 50 pilot

Edited December 17, 2022 by DrewT

[locogato11283]

Reeds good?

[DrewT]

 Brand new V-Force 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[SKEETER]

Probably just the decrease in power, from going to athena cyls .

[DrewT]

Wow really?  I was told these are better than what I had.