Fixing the Carb Jetting Once and For All. :)

[X-Ray]

Sorry if this is going to be a bit long, but theres a bit of detail to cover. With my '94 1200, I bought it a couple of years back with a custom 4-1 exhaust and K&N filter in the stock airbox. It ran terribly, but  a full carb teardown and thorough clean got things back to fairly good. Fast forward and I knew things weren't running right, put on a set of RPM Unifilters, ran it for a while, took them off and put the stock airbox back on. I had a good idea the jetting was not correct for the exhaust/filter combination, so raised the needles one notch ( 2nd from bottom), but the exhaust still sounded off, popping too much on the overrun etc.

Rather than order in different jets to try I decided to spend the money and get a proper dyno tune done, and then I would know exactly where the problem is. The young fellas ( compared to me ) at Garage 37 were given the FJ for the week, and I said I would like to ride out of here with it tuned properley to run with the std box or preferably the Unifilters. They let me know straight away that the standard 110 mains and 42.5 pilots were not going to stay in the carbs ( which I suspected), and over the next 3 days did dyno runs and fiddled with the carbs to get things close to perfect.

I picked up the FJ Friday afternoon and rode her home, noticed the difference straight away, and on our 200km ride today, it was a different bike. Acceleration, cruising, rolling on/off the throttle was all butter smooth and 100% better than it has ever been. So what did they do? ---

Changed the 110 main jets to 115s
Drilled out the 42.5 pilots to 45 spec
LOWERED the needles, 1st notch was too lean, 2nd notch (from the top) was too rich, so shimmed to 1.5, perfect.
Mixture screws 3 turns out.

I have supplied my dyno print out as it has some interesting points of reference which may settle (or start ) some debate over pods vs airbox, etc. The red power and torque lines are the final runs with the Unfilters, and the blue line is the final run with the airbox with K&N filter. Pretty much dead on power wise, interestingly past 9000rpm the pods maintain steady output where the airbox drops off 500rpm lower. The torque graph shows a dip around 2200rpm for the pods, and then its fairly even across the whole torque range, apart from again past 9000rpm. ( Which I would say is the first time any of my FJs have ever seen 9000RPM ). 

So I am super happy with the results Jamie and Andrew at Garage 37 http://garage37.com.au/  have achieved, the '94 is just beautiful to ride now. I am going to take the '93 to them when my funds recover a bit, as it is currently spitting back through the Unifilters at 1/8 throttle etc, it needs the dyno tune treatment as well. For approx $120.00, a proper dyno run by people who know what they are doing is well worth it in my book. It costs a bit more once you throw in a few hours labour for carb fiddling etc if needed,  or you can rejet yourself and save some money. 
   

[Pat Conlon]

Thanks Ray, did they give you a print of the fuel/air readings?

[Mike m]

If the dyno is calibrated correctly those are great numbers ray.I had 42.5 pilots and 122 mains in my carbs last year.theyve been changed since.that kinda post is full disclosure as you can get.cool stuff

[X-Ray]

Hello Pat and Mike, you know thats one thing I forgot to get from them was the air-fuel print out, they did tell me it was a bit off from ideal with the jetting I had standard, no suprises there. Will have to go back and get it.

[Mike m]

At the bottom of the graph you provided it does make reference to afr dynoware 2xs which indicates air fuel ratio was being monitored
.very cool

[X-Ray]

ahhhh right, missed that bit. Hopefully they have the readings that can be printed out for me, 

[ribbert]

If the dyno is calibrated correctly .......

Dyno numbers vary from machine to machine, sometimes by a lot but as it doesn't effect their main purpose, no one worries about it. HP and torque figures are interesting but are incidental to the machine's primary function, comparison.

Noel