Engine backfire as i was riding to work at about 4500rpm 5th gear 75mph it backfired twice and got kinda sluggish , Ive also noticed the tach. bouncin around through out all gears around 3500rpm?????

If it is backfiring, it is likely that the timing belt slipped a notch and needs to be replaced. Backfiring can cause MAJOR DAMAGE to that old engine so please don't drive it if it's backfiring!

Backfiring is a symptom of being too lean, not too rich. Clean your jets, synch the carbs and adjust the PMS.

Year, Make, Model, and Engine Size? Is the check engine light on? Have you checked for codes?

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Sounds like you need to have the carb jets cleaned. You can try seafoam that you add to fuel tank and ride it to see if that will clear it up, but I have had the same problem with my VF750C Honda Magna with only 8000miles and mine turns out to be fine tuning the injectors. This is only after the carbs have been reworked and cleaned.

the best thing to do is to clean or replace carb filter.. check spark plug for fouling clean or replace also if gas has been sitting in unit and stored outside I would drain gas because of water contamination..

For this types of problem,there are few help inks to troubleshoot the problem.Click the link below to go through the troubleshooting procedure to resolve the issues :----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Car still runs Rough after tune up? http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
------------Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed? http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
------------Engine Backfires? http://technoanswers.blogspot.in/2012/02/jeep-backfires.html----------- Nissan stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

-----------
Nissan Pathfinder Backfires? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm? http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.

The engine should be an OHV type. You could try adjusting the valves under the OHV cover. Kinda like the valve lash on cars. When the valves are at rest you can set each one to about .004 with a feeler guage. You can look on youtube for a video one adjusting lawnmower engine valves. Seeing it is easier to understand then reading it.

I hope that this helps you get it fixed.

Try changing sparks and wires

if your engine is backfiring you probably jumped time reset your engine to top dead center valves closed on #1 cylinder check your timing: belt / chain / gears for wear

and has happened when engine braking. The strange part is when the other day I was in 5th gear going 60mph it did it again. It has 2600 miles on it from when I bought it new and and have followed the manufacturers instructions for break in & maintenence to the letter. I have been back to the dealer twice for the same problem and they can't duplicate the problem.Its normal.  Only things I have found that help to cure the problem the easiest way, is to re-route the breather and open up the airbox.,,,