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KLX 300 Rebuild

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Completed the rebuild of my 1999 KLX 300 about a week ago. Had the ACR retimed, added Bill Blue 331 kit, and had the head redone. Spent yesterday putting the complimentary break-in miles on it. Everything seems to be working as planned except possibly one thing. When you get up to around 40 mph a distinctive rattle resonates from the engine. I believe it is engine knock caused by the fact I now have 12:1 compression ratio and only have the ability to buy 91 octane fuel. Anyone else had this problem ? Any recommendations on a fuel additive in order for me to test this theory ?

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I have a stroker kit in mine and it will run on 87 with no issues...Good luck, hope you figure out what is going on...

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Kawboy, if you can't get some 91 octane, just to eliminate the detonation assessment, go get some octane booster like "104" or such. I'm not a big believer in over-the-counter boosters, but if you're marginal it might at least help in eliminating what the problem is. That said, I tend to agree with Shakermach that you probably shouldn't get detonation with the kit. Bill's 351 kit isn't known for detonation on 87 octane either. That's what he normally runs in his own.

I have another suggestion. This model bike has a pattern occasionally with cam chain rattle because of a tensioner issue. It doesn't happen all the time at all, but when it does, it sounds a bit like a light engine knock or detonation. In your assembly, you have to disturb the position of the tensioner. Even though it's an autotensioner, sometimes they don't take up chain slack like they should. To test, try removing the back cap of the tensioner...the one on top, not that spring plunger below it...and pull the tensioner spring out. Get an allen wrench or other tool that will reach into the bore of the autotensioner where the spring was. Push in firmly on the tool to see if you hear a click or discern a noticeable movement. Restart the bike and ride it to see if the sound was affected. If it goes away, you've found the problem.

If the noise is unaffected, pull the tensioner and reset it according to the manual...just like you do when you have to pull the cams for a valve check.

If the tensioner is not doing its job, there is a very resonably priced alternative manual tensioner developed by Krieger Tensioners for the 250/300 series. I have one in my KLX, and they work.

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Make sure it's not your skid plate or some other metal rattling. I recently read a post where a member thought he had an engine related rattle for sometime actually ended up being a loose skid plate

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Thanks to all of you for the replies. Bill Blue and I talked at length about octanes before I chose the 331 kit. He did tell me he runs his a little rich to help avoid the rattle. I do not think it is the skid plate but will definitely check it because you are right in the fact that little things can sneak up on you. I have the forks off and in the shop for an oil change and a tuneup. Once they are reinstalled I will readjust the valves and do my best to inspect the tensioner while I am in there. The sounds I heard could very definitely be chain rattle.

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I do not have my forks back but got a little bored so I went ahead and did the valve adjustment. The tensioner is all the way out which is the same position I remember seeing it in the last time I adjusted the valves. However I do not remember hearing the rattle the way I hear it now. I do not see a klx300 manual tensioner listed by Krieger so I will call them to see if they have one. If in fact it is chain rattle will some sort of engine failure be down the road ?

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I do not have my forks back but got a little bored so I went ahead and did the valve adjustment. The tensioner is all the way out which is the same position I remember seeing it in the last time I adjusted the valves. However I do not remember hearing the rattle the way I hear it now. I do not see a klx300 manual tensioner listed by Krieger so I will call them to see if they have one. If in fact it is chain rattle will some sort of engine failure be down the road ?

I worked with Mark to make the prototype for my '06 KLX. Quite a few guys over on the Kawasaki Forum have purchased them at this point. I haven't looked at his site, but I know he has them. An e-mail would answer that. On catastrophic failure...probably not...but the noise would finally become horrendous. I doubt you could stand the noise before it got loose enough to self-destruct. My cam chain was worn out before 10,000 miles...checked the pin number spec in the manual. I installed a bigger bore kit and replaced the chain at 10,000 miles with a Krieger tensioner. Been quiet ever since.

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How hard is the cam chain to replace ? I remember getting the nut loose on the idler gear was a real bear. The gear covering the the chain on the crankshaft is torqued even higher. Do you have to remove the whole engine side cover or can you access it thru the clutch cover plate ?

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You have to remove the whole cover, because you have remove the clutch basket and the oil pump gear. In reading the manual, this sounded like at least a couple of special tools. I was able to get creative by using the cluch hub nut and flywheel nut working in a criss-cross loosening and tightening sequence to get the primary gear nut off and on. I used an impact to get things off and then used the clutch and flywheel nuts to hold the motor while torquing the stated nuts with a torque wrench. Due to the torque value of the primary gear and flywheel nut being equal, you won't overtighten anything. When I figured this out, it was very easy, not hard at all. Are you sure you'd need to replace yours? There's a spec measurement in the manual that is easy to do by just removing the valve cover.

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I did check it when I did the overhaul. It is not easy to hold it in place an measure with a precision instrument but I did my best and I believe it is ok. Talked with Mark Krieger and he does have them. Will be ordering one tomorrow. He kept referring to some guy in Texas who helped him develope a manual tensioner for a 300. I would guess that would be you. He did throw out a very interesting theory. When I pulled my engine apart the auto tensioner was fully in the extended position but I did not detect any sound like I am hearing now. When the head and cylinder was redone both were "decked" for proper mating surfaces. I do not know how much material was removed but possibly enough was to add some slack in the chain. Anyway it makes sense to me. For a little less than $40 it seems like a no brainer to get one installed and if nothing else remove the problem now or sometime in the future. If after install I still have a lot of noise I will go back after the gas issue.

Thanks for the advice.

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