I was in for the gas tank recall. Mechanic told me that the difficult to start issue was caused by the KACR doing too much and causing the compression to be too low. He said that if I come in and complain about it that they'll fix it through Kawi's customer satisfaction program. He says they will remove a little material from the KACR, I think he said grind it. He did say I'd have to leave it for a day.
Is this old news? Makes since. What do you think?

 

I don't know if Kawi changed the ACR timing again to an even easier to kick position, but I've heard no starting complaints from the 120 ACR retimings that I've done. The position I move it (pre 2002) to is very close to where Kawi moved it to in 2002.

Changing from the stock carb to a Mikuni cleared up my starting problems.

Ride on
Brewster

 

I've heard of another fellow on this site that had that "fix" done. Seems like going around your elbow...


When it often seems this "hard to start" problem is easy to fix with a simple starter hole enlargement (0.018?), I'd try that before I let ANY dealership work on the innards of a machine I own. Especially one that jumps right to a big, somewhat complex job, compared to a simple small job.

 

I allready knew from last month , when I was playing with the cams on the bike , that the ACR is at the absolute limit of the necessary compression needed for the bike to start up . I put mine 2 mm ( on the outer edge ) more advanced than what itīs original position was . It does make a big difference on how the bike acts when is warm .
The thing is that the dealers are not allowed to disassemble the ACR from the exhaust shaft ( they will only sell the ACR and exhaust shaft as one part ) , the only thing left for them to do is to grind a little bit of the trailing edge of the little cam the ACR has , this allowing the exhaust valve to close a little earlier leaving a little more compresion for the engine start up .

 

Grinding down the KACR by dealers was a normal fix on the '08 KLR650 for hard starting problems. Didn't have mine done because mine started slow but okay.

Norm

 

" Things that make you go Hmmm ! "

 

If my thinking is correct, modding the KACR in the manner described allows more compression which causes more vacuum which pulls more fuel and air in such a manner that brings about easier starting? Just to keep things simple, is that about it?

As far as cold starting goes, it was lot easier to just drill the starter jet a tiny bit for immediate starting. On the hot start issue, are that many of us with "uncorked" KLX's really having a hot start issue?...unless you've dumped the bike, and that's actually a little different hot start issue. It seems to me to be a bit of work to mod the KACR for cold starting issues when an easier starter jet mod works. Now if some are having some horrible hot start issues that this might address, then that would be logical, but I'd tend to thing something else might be going on in those cases.

In Marclelino's or anyone else's case where they've pulled the cams to do the cam timing mod, it's a convenient thing to do at that time, so why not. Most of the folks on this forum have '06 or later KLX's, so the KACR mod probably isn't as critical as some of the instances described by Brewster on some other models.

 

BTW, on the hot start issue in general, here was an interesting post.

Any ideas for a DIY Hot Start System ? My KLX300 needs one - ADVrider

 

TNC , let me paint the ACR as easy as I can for you .
The ACR opens at the begining of the compression stroke and closes midway in the compresion stroke dumping half of your mixture and compresion to the drain ( into the exhaust ) . If you don't have enough compression you donīt start period . You can add all the gasoline you want , it won't make any difference , only 10 psi more compression will make a small , but all the difference it takes for the mixture to ignite .

 

Appreciate the primer, but I was only trying simplify why we're even talking about the KACR and its effect on starting...hot or cold. If we took a poll, I'd bet there would be some regular posters who don't fully understand all the issues of the KACR, and as usual there are lots of lurkers who don't post who are trying to wrap their heads around the concept. And please understand...it's not like I'm some kind of all-knowing engineer either...LOL!