914-6 backfiring while driving?

P-DUB · 10-29-2007, 05:37 AM

I have a stock 914-6, it has a rebuilt motor and carbs and has been running great up until yesterday. The wife and I wend for a drive yesterday, car started fine, warmed up, and then we took off. As we were driving, the car ran worse and worse at low RPMs. Between 1500 - 3500 RMPs the car would backfire under a load, and then quit above that. When at a stop, it would idle fine, but lower than normal like around 500 RPM. Would this be in my ignition, timing area? Any help would be appreciated.

jtf914 · jtf914's Garage

Pull the idle jets and clean them, 10-15 minute job (no need to drain the gas or anything). The gas transitions from the idle jets to the main jets as the RPM's rise thats why it runs better once you get the RPM's up.

-Justin

P-DUB · 10-29-2007, 06:21 AM

Thanks for the quick responce! Which ones are they and how do I go about cleaning them. I am no mechanic, but i do work on my own Harley, and this is like having three giant Mikuni's on each side!

jtf914 · jtf914's Garage

Do you have webers?

If so:
http://www.pelicanparts.com/914/Parts/914-6/914-6_weber3_big.htm

number 23, unscrew them. there are three pieces:
1) A jet carrier, this is the big part with the threads
2) Rubber O-ring
3) Idle Jet

Pull the jet out of the carrier clean the jet and the carrier blow some air through them and reinstall.

jtf914 · jtf914's Garage

In this diagram you will see the three parts as 24, 25, and 26:

http://www.pelicanparts.com/914/Parts/914-6/914-6_weber4_big.htm

P-DUB · 10-29-2007, 06:27 AM

Thanks a pile, this sounds like a good Saturday (non hang over) morning project!

jtf914 · jtf914's Garage

No problem.

P-DUB · 10-29-2007, 06:31 AM

Just to make sure I am on the same page, there should be three of these on each carb correct?

jtf914 · jtf914's Garage

Quote:

Originally Posted by P-DUB

Just to make sure I am on the same page, there should be three of these on each carb correct?

Yes, one for each barrel. They are located near the top of the carb, just below the seam for the webers top piece.

P-DUB · 10-29-2007, 07:32 AM

Thanks. I may even take a swip at it after work one of these night, but it looks like rain for the next two. I want to be able to take it for a drive afterwards to see if it clears up. Thanks again!