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cb650joe

2000 wr400, is it possible to jump timing?

12 posts in this topic

I was riding yesterday, and the bike was running fine in the morning, but later in the day it seemed fto really dog. It also seemed to kinda buzz at higher speeds like something rattling. It still starts and idles fine, you only notice power loss and strange noises when you accelerate or climb hills. Nothing strange seemed to have caused this to happen. Any suggestions?

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Yes, it is possible that it jumped timing. I'd take a look inside the valve cover to see before something bad happens!!!

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Very possible, mine just did it, and some bad things happened, but could have been MUCH worse...

Timing chains seems to be the weakest link in the valve train, and should be checked at least every season, and replaced sooner, rather then later.

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Just curious, but what bad things happened?

Seriously?

You can destroy the complete engine with jumped timing. And I mean complete. As in engine cases and all.

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I plan on pulling the valve cover today and lining up the timing marks to see where I am at. I am fearing that the buzzing sound that I heard was valves being slapped by the piston ( I sure hope that's not the case). I will try to get some photos while I have it apart. I am now wondering why/how it could have jumped time. It's not. Like. The engine backfired or did anything strange prior to it just running weak. Then again, my brothers were also riding the bike that day. I am wondering if my brother messed it up trying to start it. He doesn't understand the whole decompression lever routine. I've seen him try to start it holding the decomp lever in. No matter how many times I show him, he still thinks he is starting his old DR250 that released the decomp when you kick it.

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OK, I'm an idiot. I spent most of today tearing down my motor, expecting to find a bent valve or screwed up piston or something obviously wrong. The timing marks were where they are supposed to be, so i dig into taking the head off. The piston and valves look great, like new. So I throw it back together. I start it, and I think to myself, this thing seems a lot quieter than I recall it sounding. Anyway, I get on it and take it around the block, and it is still dogging, and buzzing and just not right. So I pull back into the garage, and I am listening to it idle, and it just seems too quiet. So I put my hand by the tail pipe, and it is not putting out much air/exhaust. So I pull the end piece out, and low and behold, the outlet is plugged with fiberglass packing. A large chunk of it had come loose and jammed itself into the outlet. I pulled the packing out, and back in business. Lesson learned, don't jump to conclusions without checking all the systems first.

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Yeah it sucked tearing it down, but I learned a lot. It was also time to change fluids, so not a complete waste of time. Next project is to replace fork seals. Looks like that can be interesting. I've done fork seals on my 81 CB650, but those were simple forks. These WR forks look pretty sophisticated.

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Yeah it sucked tearing it down, but I learned a lot. It was also time to change fluids, so not a complete waste of time. Next project is to replace fork seals. Looks like that can be interesting. I've done fork seals on my 81 CB650, but those were simple forks. These WR forks look pretty sophisticated.

Fork seals are not that hard to do, but can be a bit intimidating the first time. At least it was for me. After doing it once, it is easy and thank myself for learning to do it instead of taking it to dealers and spending an unnecessary amount of $$$

Read this:

http://www.thumperfaq.com/fork_seals.htm

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