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Discussion Starter #1
Hello guys,

About two weeks ago, my 1987 was running fine at about 72-75mph on the highway when it suddenly lost power. I couldn't get it restarted and had to tow it home.

I went over everything with a fine tooth comb and couldn't figure out what the problem was. After it sat for a few days, it fired up, but ran very strangely - weird, very low idle, and absolutely no response to the throttle. The motor wouldn't rev, bog, die - it was as if the throttle wasn't even connected. However, playing with the choke would cause it to run worse, and then die. Once it died, nothing would get it started again. I let it sit for a week, and it repeated the same behavior - initial start was great, first or second kick, but no revving at all, and locked into a weird sounding, very low idle.

I triple-checked every electrical connection and I replaced the coil and wire. I swapped batteries, everything I can think of. I'm assuming this is a CDI issue of some kind.

Has anyone experienced this? Any idea what might be going on?
 

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Have you checked your compression?
 

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Discussion Starter #4
I haven't done a compression check yet, but I'll definitely hit that next.

I've got a second bike with a well-tuned carb. I guess I will toss that on there next and see if it changes anything.

For some reason this has just been screaming electrical to me, but maybe I'm missing the forest for the trees.

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. I'm assuming this is a CDI issue of some kind.

Has anyone experienced this? Any idea what might be going on?
Unfortunately I don't have an 87 and can't help a lot, but from many past threads, I think your on the right track with your CDI assumption. With all the other possible problems eliminated (fuel flow, other electrical components, compression, valves) sounds like a CDI. Suppose there is no one else nearby with an 87 you could borrow there cdi from. Otherwise you might have to purchase a new one. Sorry I can't be of more help.:(
 

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72 to 75! Holy smokes! But, when an engine shuts down all at once, I suspect electrical. I would be tempted to swap carbs but I do not think that's it.

Make sure to check the spark plug. They can break or fowl instantaneously. Go ahead, ask me how I know.
 

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Discussion Starter #7
72 to 75! Holy smokes! But, when an engine shuts down all at once, I suspect electrical. I would be tempted to swap carbs but I do not think that's it.

Make sure to check the spark plug. They can break or fowl instantaneously. Go ahead, ask me how I know.
Exactly my thoughts on the situation.

Anyway, I just replaced the plug and I'm gonna give it a shot, after that it's a carb swap, and then it's a new CDI.

Thanks guys!
 

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I have a 87 too and I thought that a CDI was or could be more intermittent..?? Usually I would think carb or plug also, but for some reason, compression came to mind, considering how fast you were going and how you described it. I would still be interested in what your compression is.

Keep us posted on what you find out please.
 

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Discussion Starter #9
Yeah, I just dropped $300 on a new CDI. I'll be doing the compression check in the next day or so, but the way this whole thing played out it just makes me think electrical all the way. We'll find out for sure soon enough, either way!
 

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Since they are hard to find, do you mind sharing with us where you obtained it?
I might need one someday for my 87.
Thank you.
 

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Discussion Starter #11
I ordered it from BikeBandit. In the meantime I'm working on putting together the parts for an 88+ electrical upgrade, because I'm never paying that much for a part for an 87 again.
 

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Thank you, I appreciate that.
 

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I want to know how your getting 75mph out of a stock TW? My valves start floating at 60mph. you didn't burn or bend a valve did you?
 

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^ With stock gearing, I've seen an indicated 70 and 65 isn't unusual.
 

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Discussion Starter #15
I honestly don't know why everyone thinks the stock gearing won't hit 70+mph.

My 87 and my 90 will both get up to 75 on the speedo. Now I've never used a GPS to verify the speed, but I don't think the stock speedo is off by 15mph.

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Discussion Starter #16
Okay the verdict is in:

Don't be an idiot, check all the basics before throwing money at the problem.

It was fuel, not electrical. The screws that hold the needle to the throttle had come loose, hence the lack of throttle response.

So, it looks like I'll have an '87 CDI on eBay soon!

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Glad to hear your 87 is running properly again
I have an 87 too
Will you share the parts list for the electrical upgrade
I would like to do that upgrade
 

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I honestly don't know why everyone thinks the stock gearing won't hit 70+mph.
Cause I'm fat:p


Glad you got this sorted out. If you don't end up keeping the CDI for a rainy day, I'm sure there's a TW owner in need of that CDI somewhere. Should get your money back that way.
 

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Discussion Starter #19
I would like to do that upgrade
My understanding is that you need the rotor, stator, left side engine cover, wiring harness, CDI, and resistor from an 88+ to perform the swap.
 
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