I absolutely don't know that, that's why I was hesitant to suggest it even. But it does seem to be a recurring theme in these threads. Could just be coincidence.

Proper jetting plays a very big role, so maybe that's part of it, too. It took me a long time to get the FCR dialed in to what I thought was the best I could. But once it was dialed, it was pretty awesome. No bog or surge anywhere. When you get everything right, you can crank on the throttle at idle and as fast as you can turn it, it will go from idle to full rev almost instantly, no bog or hesitation. I loved that. But it's not necessarily easy to achieve, I had to work at it for a while, but I'm no expert, just a weekend hack.

 

I know you didn't say that, and I also don't know for sure that the FCR is better than the Mikuni.
I just suspect it is.

Spot on in regards to jetting and set up.
Took me a few goes to get it right and in the end a Dyno run to confirm things.
Patience grasshopper

I guess the point I'm making is that it is well worth the money and effort if it's the bikes "lazy" power delivery you want to change, and, that there is more than just off stop "snap" to be gained.
Mine pulls hard everywhere compared to when I had the CV.
And bear in mind that I spent a fair bit of time trying to get the most out of the CV before I bit the bullet and went pumper.

And Brian, you are far more than a weekend hack.
You not only know what your talking about, you also articulate things very well.
Let me put it this way, I wish my so called dealer "expert" knew half what you know about the KLX.
Don't put yourself down. (that's our job)

 

Nobrakes,

I did alot of searches and read thru alot of posts with your details on the keihin carb. Your trial & rework on the fcr 35 sure made my decision alot easier. Thanks for your efforts.

 

In the first pic you can see how I've ground the rivets out of the mounting bracket and used bolts instead, so that I could locate the bracket in the second set of holes. This then clears the frame, as you can see in the second pic. You can see where the bracket used to be positioned by the marking on the mid bracket.

Also note in the first pic that I modified the cable slightly. I removed one of the lock nuts and shortend the threaded part by cutting half off. This allows the cable to sit 'closer to the stay', giving it a kinder bend up and over the cam cover. I've had it routed like this for 6-700 enduro kilometers without issue.

Also, Neil, nice bikes I have a VTR1000F as my roadie.

 

[QUOTE=tremor38;367791]My point was that I didn't think the pumper was worth the money because I have the pumper and my buddy doesn't. My bike has no power advantage over his. It's the rider that makes the difference not the $300 carb. We're of equal skill level so if that carb was so important he'd never lead on any type of trail.

 

Cheers, the VTR is a ripper.
V twin charm with reliability.
Something you don't get with a Duke.


Recently added this to the stable.
Going to do a complete restoration over the winter.


And me on the GS I had back in 82.

 

Looks like there are a few Pumper "experts" following the thread here. So here goes..

Just got my KLX, its got an FCR35. The previous owner bought the FCR from someone who had it on a KLX300, and he didn't change the jetting. It runs pretty well, but backfires alot, and there is some soot on the rear fender and plate. I'm assuming its running rich (soot) and the backfiring can be cured by doing the so called "Taffy Mod"?

So, besides "seat of my pants", or a dyno with an exhaust sniffer, how can I tell if the thing is running in a good way? Is there a baseline tuning procedure? I just don't want to melt the piston or anything drastic..

I have the jetting numbers written down which Ill post later today, maybe you guys could post some suggested starting points for settings and something to address the backfiring..?

thanks!!

~Steve

 

The soot would generally indicate you are running rich, so you're probably Ok in not having to worry about running too lean.

The backfire may be due to a leaky head-pipe to engine. If I recall there's a copper washer that goes in there, you might want to take that out, heat it up hot, then drop it into a pail of water to soften it back up and reinstall. Also, some high temperature sealant could help if so, something like Permatex RTV Ultra Copper:



If you do the sealant, be sure and let it cure for at least 24 hours without starting your bike, preferably 48 hours.

Alternatively, the popping might be due to being too lean, but the soot on the tail pipe makes me thing a leak instead. But if you have a small pilot jet in there, then that might make the idle circuit very lean and may contribute to popping under decel with the throttle off.

Is your airbox lid on or off?

Sometimes when you are close on the jetting, it's actually hard to tell if it's too rich or too lean. One way to get an idea if you are running too rich or too lean is to install and remove the airbox lid and note what happens. If the lid was installed and you remove it and it runs better, then you added more air to the mixture which means you leaned it out and you must have been running rich before. And vice versa. That's just a check to see which direction to go on the jets/needle.

It's a process. It can take many trials to get it all sorted. Don't give up. Good luck!

 

Thanks for the pics kbekus. Time to make a few mods to the cable bracket....

 

Great ideas Nobrakes... I really haven't been able to ride it much but look forward to getting it all dialed in.

thanks again
~Steve