Can anybody help me with a problem I'm having with a 1999 VTR that has a bad intermittent miss on the rear cylinder. The bike will run fine then start missing then clear up and run for a while and start missing again. Some times it will back fire, I have drained the carburetor and have good fuel in the tank. I'm thinking it might be an electrical issue but I don't know what to look for. The spark plugs have a nice blue spark color when the motor is turned over. I am stumped. Any ideas would be greatly appreciated.

 

you might have to sync the carbs and set your air mixture screws.
has any mods been done to the carbs.
do you have stock or after market exhaust.
you will have to do some digging,but all the answers are here in the forum.
some quick mods and you should be good to go.
well not quick,but not hard or a long process.

 

Synced carbs already they are spot on. Pilot air screws appear to have a plug over them so as to be factory set. the bike was running fine and just started acting up. It has D&D slippons and a jet kit. I am not original owner.

 

A jet kit and the plug still capping the fuel screws?.. that makes no sense..
Still whatever it was..was working and suddenly it's not now....
No parts changed, adjusted?

 

The previous owner said it had a stage 1 jet kit. The only thing that was done to the bike before it started missing was the carb sync.

 

well,caps over the air screws isnt right,can tell you that,its suppose to have a little screw in there that is D shaped.makes it a pain to adjust while on the bike.
and a jet kit does not work on these bikes.there is only a few pieces you would use out of the kit at most and the rest is at home fixes to get it close to or spot on.

try these reads out,may get you where you need to be.

https://www.superhawkforum.com/forum...-manual-11365/
https://www.superhawkforum.com/forum...changes-13841/
https://www.superhawkforum.com/forum...n-sensor-9876/
https://www.superhawkforum.com/forum...-removal-9875/

 

At some point you should confirm if it has a jet kit (pop the top off a carb, if you find a adjustable needle, it has a kit)
All Jet kits, and well jet kit opr not.. All fine tuning of a bike jetting will require adjusting the fuel screws.... again... no matter as it was running right...

So carb sync.. have you checked the vac line to the affected cylinder?
Have you checked the sync again to confirm it was not somehow off when you thought it was good?

 

than here is the 2 most mods done first on the bike.
https://www.superhawkforum.com/forum...why-how-25117/
https://www.superhawkforum.com/forum...pe-ccts-11275/

 

have you checked the petcock and made sure the vacuum is in the correct spot,which should be the back cap of the petcock and not the one that sticks out to bottom or side.
make sure the vacuum is hooked up to the rear cylinder.
https://www.superhawkforum.com/forum...ix-pics-19843/

 

Saige your last post was right on the money. The vacuum hose was on the bottom port. I switched it to the back and all is right in the universe. Thank you and E. Maruquz for the help.

 

lol pvlir strikes again
glad i could help.

 

Saige, you are just lurking in the wings waiting to swoop in and save some hapless newbie out of this very dilema.

 

lmao,no,was just doing some reading on stuff since hopefully i will be soon servicing the complete bike.figured,its easier just to throw it out there than see 5 pages of questions

 

Make sure that the rubber seals that connect your carbs to the heads are tight. I maybe new to this site but not when it comes taking those carbs off. You may think they are seated correctly. I would double check...