OK, now this is interesting. While the manual clearly says 64psi is within acceptable range, the fact that my stock 250 engine yielded 125psi shows a very wide alleged lattitude of compression for starting. While Kawasaki says this is an acceptable minimum, I agree that it sounds awfully low for good, crisp starting. Brewster has worked with the KACR more than anyone I know around here, so I hope he would chime in.

Before I tore my 250 down for the 300 cylinder swap, this is why I wanted to check what compression looked like with KACR operational. I've had 4 KLR600/650's with KACR and was always curious what cranking psi actually was with KACR. If mine was 125 and yours is 70, that's a huge difference. You gotta think that while it might indeed start at 70psi, it's going to be somewhat weak. I can't with any authority that this is your culprit, but it gets you to thinking.

 

Bearing in mind of course that I am at 1000m or 3300ft, and that I ran the compression test cold. *I'd like to try it again warm but it seems lower than it ought to...

Typographical errors by*iPhone

 

I'll throw another variable out to you all. Many of the ACRs that I've retimed had worn ACR return springs on them. The side of the spring next to the ACR rubs on the weights and wears down. That would result in lower spring tension and allow the centrifugal weights to swing out at a lower rpm. And darned if I know if this would come into play during kicking speed.

Ride on
Brewster

 

Interesting. Thanks Brewster - I should have looked closer at the spring when it was apart.

Will be interested in knowing what you get with the engine warm.

 

It's taken me a while to get back to this matter, mostly because I experienced no difficult cold starts over the summer. Now that winter is back however, so are the cold starting woes.

Picking up where we left off 10 months ago, I have since re-confirmed the valve clearances are still within spec (only just), the KACR appears to operate correctly as per the shop manual, and I have a cylinder compression of 85psi when tested warm (not as strong as I'd like but still within spec).

In spite of all this, the little KLX is still a b!tch to start in winter ambient temperatures (anything below 0C or 30F). *I have recently been relying on a small space heater aimed at the head & carb for 10 min to get it fired up.

All this has got me thinking that either:
- the KLX is simply just not a cold *weather starter, or
- the carb is somehow still suspect as Ranger Ron had been speculating.

As I mentioned earlier, the bike fires up cold fine in summer and I have had the carb off for rejetting & cleaning numerous times so I am reasonably confident the carb's OK.

I have read numerous testimonials on this forum before regarding the performance-enhancing virtues of the pumper carb; do any of you think it could also be the ultimate solution to sub-zero starting problems? If so, will it work well with the stock 250? Or should it be paired with a *351 big bore?

Input from those who run a pumper is appreciated

 

The fact that your bike starts fine in the summer but not in winter, sure seems to indicate not enough fuel on the choke circuit. This is addressed by drilling out the starter jet. I can't recall if you had performed that or not.

On the pumper carb, one thing any pumper carb has going for it is that you can twist the throttle a couple of times in addition to using the choke. I don't think there's any way your KLX won't get enough fuel to start in cold conditions. The stock CV carb is plenty capable of performing cold starts with the starter jet drilled as long as everything else is in proper tune and condition. The real reason to go to the pumper is all the other benefits it provides to the KLX, but it would remove any starting issues for sure. The choke circuit on my TM36-68 is obviously rich enough to insure rapid cold starts.

 

"drill out the starter jet. I can't recall if you had performed that or not."

Yup, I am at .019". It was one of the first mods I performed on the bike almost 2 years ago thanks to advice on this forum!

It works exactly as advertised down to temperatures where water freezes. Below that, starting gets exponentially more difficult.

 

So we have similar temps to deal with...my carb is stock...and my bike will start with choke down to 0ºF...below that (as I discovered on Wednesday, it was -10ºF) the oil just gets too thick. I tried starting it for 10 minutes, no go, almost but that don't count. Rolled it out onto the road and bump started it with the help of the starter.
All this got me to thinking about changing oil for Winter. Maybe we just need a lighter oil for the cold, something that won't turn into a pudding like substance?
Do you leave the fuel on when not running?
I ask because I've found frozen condensation on the outside of the tank and carb showing the fuel level in each. This must happen inside as well, so I try and keep the tank full in really cold weather and always leave the fuel on. Don't know if it helps, but it can't hurt (as long as there are no leaks). Just wonder if your jets get condensation frozen on them?
I've also been considering the pumper, but will probably wait for the 351 to do it.
I've also acquired my race transport vehicle so I will drive when it's below 10ºF and while the KLX gets ripped apart.
Keep us posted because I am quickly shortening the life of my battery trying to start this little pig!

 

Since the discussion has turned to the KACR, why do we need it?

 

It lowers compression by opening an exhaust valve at low rpm, right?
I follow a KLX650 thread on ADV...a guy removed his and said that he could no longer kick it over and the starter had a much harder time turning the engine over.