Slotted cam gears, opening overlap; Any experiences? Worth it?

[andyb]

From the FactoryPro website:

Thanks for the feedback!
Marc


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Feb 03,1999

Hello,
I have a 1991 Yamaha FJ1200, and saw a tech article in Rider magazine about a problem that these bikes exhibit. At low speed, the throttle is nearly "light switch" touchy on my bike, and the article said that this was normal for FJ's but there was a solution. The article went on the explain that the FJ1200 has a very sharp ignition advance curve, about 33 degrees difference from 1000 to
2500 rpm. I checked the shop manual and saw that this was correct.

Rider magazine referred to your company as one offering a fix for this tendency. I checked your website and noticed that the FJ1200 was not listed (or I didn't see it) and was wondering if you offer an ignition advancer for this bike and at what cost. Also, do you know why the factory would put such a sharp curve in the advance of the ignition? Normally this is not a problem, but at parking lot speeds it can be quite a handful, as you can imagine.

Any help you could give me would be greatly appreciated.
Thanks!
Chris D.

Well, well, there's an FJ1200 page now!

Actually, the problem is twofold - the low-end carburetion is too lean and the ignition timing curve is pretty aggressive at low rpm.
Try adding the advance and see if that's enough. Adding the Carb Recal Kit and the advance will cure the FJ's "twitchy throttle" when properly tuned.

BTW - The FJ1100 needs the carb kit before the advance - as the advance alone will cause a light pinging at cruising speed when going up slight hills on the freeway.

Thanks for the question,
Marc

I interpret this as saying you'll need to rejet before advancing it, not necessarily putting on their jetkit.

I did a quick online search and didn't turn up much, so the easy way to advance your timing may be slotting the rotor.  You could pull the cover and compare what you see with ebay item 250452219541, but that looks like a late model rotor to me.  Maybe you could talk Randy into trading you for one already slotted, for a fee?

[Pat Conlon]

Thanks for the info Andy.
I'm aware of the need for a stage 1 kit for my '84 if I run the advance plate. Makes perfect sense. The added fuel will also help the '84 run a tad cooler.  Looking at the plugs I see that the factory settings are quite lean.
I contacted Factory Pro 2 years ago and they no longer had the advance plate for FJ's, hence my question.

Great idea about sending my oem plate out for slotting. If I had my choice I would opt for a set plate so I wouldn't have to worry about the plate slipping (similar to slotted cam sprockets Randy mentioned above)

Cheers!

Pat
<edit> I see that the eBay item is for the 84/85 FJ1100, Thanks Andy!  I'm on it.

[racerrad8]

I have not heard any on mine. My wife on the other hand, while she is still learning, tends to lug the engine. I can hear on the low speed lug that she is putting on it. That tells me I need to richen the pilot & needle circuits in her carbs. I am running 117.5 jets in my carbs with the stock needle raised .020. I am at about 70 above sea level here, but we ride up into the sierra's ever week beyond 5000 feet without issue.

Randy - RPM

[racerrad8]

The one Andy has noted is the early model with the dual pickup coils. The later model single pickup system uses this rotor; 150369874295 which is currently on eBay.

There is not chance of the P/U plate moving once it is mounted. The is nothing that is putting tension on it like the cam gear is trying to turn the cam.

Randy - RPM

[andyb]

I believe they're only referring to the 1100's when they said that, not the 1200.  

When reading the plugs on the FJ, make sure that you're reading them right.

http://www.strappe.com/plugs.html

[SlowOldGuy]

<edit> I see that the eBay item is for the 84/85 FJ1100, Thanks Andy!  I'm on it.

Pat,
Call me!  972-sixonetwo-zero9three6

DavidR.

[RichBaker]

All the big-bore bikes of this era were way too lean on the idle and off-idle circuits. The factories did it for emissions.... the big-bore bikes don't use the other carb circuits during the EPA testing, so they left the mains and lower sections of the needles at a properly rich setting.
I have put #40 pilots in my '90, as well as the DJ air correctors and needles/main jets(114, IIRC). My mixture screws are all around (the ideal) 1 turn out and she runs GREAT! 

[simi_ed]

Rich, what are you running for pipes?  Still stock, or 4>1?

TIA,

[RichBaker]

D&D.... 4-2-1, and a UNI airbox insert. Stock airbox with a lot of holes in the cover.