[vegasdave]

I just added new cobra slip on's and did a rejet, I really think the shop that did it had no idea what a rejet was. I now get popping during 2nd and 3rd on the down side, it's ok during acceleration and the choke has to be on longer to keep from stalling. The mileage has dropped 50% I used to hit reserve at 200 miles, now 100. The bike is in mint condition only 15k on it and runs great before the rejet.

 

[JPT]

Unless you changed your airbox, you should ask them to put the jets you had back in. You only need to rejet if you alter the fresh air side. And only if you increase/decrease the volume of flow.

So if you have a stock airbox, you should put it back.

To me, a shop shouldn't be doing jet kits unless they have a dyno with a sniffer. Otherwise they are doing the exact same thing you can do at home, just getting it close as possible using trial and error (educated trial and error).

 

[Vinish]

While you do not have to rejet when you put on pipes, you still can. You would not be fixing problems caused by the new pipes. Instead, you would be fixing the problems that the stock carb jetting causes which are very lean running and difficult cold starts. I recommend leaving on the new pipes, at least pulling the snorkel out of the air box to make it slightly more free flowing, and then rejetting yourself using ONLY a Factory Pro jet kit. Do not use a Dynojet jet kit. You can find the instructions for rejetting and tuning the carb here on the Cafe in the thread "Carb - what effects what". JPT and I respectfully disagree on the need for dynotuning. I do not believe it is necessary if you follow the rejetting/tuning instructions. The VTX1300 is not a high performance bike. Dynotuning might squeeze a little bit more performance out of it but it will not make it a high performance bike. The main goal of the rejetting/tuning is not to improve performance but, rather, to get better fuel mileage, make the bike run a little richer, and to eliminate the difficulty in starting and keeping it running in cold weather or when the bike is cold. You will also get a small amount of improved HP/torque but this is a secondary benefit.

 

[vegasdave]

Thanks and I agree with you. I took it to a shop that deals in carbs this morning and they pretty much said the same thing. They found a leak in the switch going from reserve to main on the petcok and are going to change that out, they also said that the K& N filter wasn't necessary even though their great filters, but the one on mine was drawing too much air and changed it back to stock. there doing a once over on the air and fuel mix and the idling.

 

[Vinish]

I believe that going back to a stock air filter is the wrong path. Instead, you should make the air as free flowing as you can while still retaining a filter and without using a Hypercharger (or similar). My suggestion is to leave in the K&N filter, remove the snorkel, consider decapping the airbox, and rejet/tune the carb. Oh yeah, also do the pair valve mod using dimpled blockoff plates. This will help with power a little, remove almost all the decel popping and gurgling, increase fuel mileage, result in a cooler running engine, and make the bike much less "cold-blooded". That is, it will start and run in colder weather and before it is warmed up without having to use the choke.

 

[vegasdave]

I believe that going back to a stock air filter is the wrong path. Instead, you should make the air as free flowing as you can while still retaining a filter and without using a Hypercharger (or similar). My suggestion is to leave in the K&N filter, remove the snorkel, consider decapping the airbox, and rejet/tune the carb. Oh yeah, also do the pair valve mod using dimpled blockoff plates. This will help with power a little, remove almost all the decel popping and gurgling, increase fuel mileage, result in a cooler running engine, and make the bike much less "cold-blooded". That is, it will start and run in colder weather and before it is warmed up without having to use the choke.

Thanks for the advise at least here in Vegas there's no cold weather issues. The main problem seems to be air flow a little too much that's why they advised a return to original filter along with a few adjustments. I don't know much about the carbs that's why I'm a slave to the shops lol I can do minor work on my bike but the intense stuff I leave to all you experts. Most of my work is on the custom side, I seem to have a way of turning metric bikes in great looking harley's lol they call most of my stuff here in Vegas Honda Davidsons lol. They sound and look like a harley but have the operating cost of a honda lol.