Rear cowl cracking - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 15 (permalink) Old 10-24-2010, 10:07 PM Thread Starter
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Rear cowl cracking

I have small cracks around the mounting studs near the back of the seat. I am looking for a method of preventing the stress from causeing this problem. I am thinking there is not enough support points for the tail cowl and each bump in the road causes stess at that point... eventualy to it's breaking point. Im sure this is a common problem. Is there a cure ?
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post #2 of 15 (permalink) Old 10-24-2010, 11:20 PM
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Actually no, I've not experienced this problem after thousands of miles.

Are your cracks at the upper mount point near the cowl panel?
Do you have an aftermarket undertail installed, and if so, how is the undertail supported, especially at the rear?

Also, what sort of fasteners are used to mount the rear cowl?
Some photos of the problem may help as well.
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post #3 of 15 (permalink) Old 10-25-2010, 07:19 AM
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I have experienced this on my first RC. It was due to the bolts being over tightened at some point. The cracking accelerated when I lost one of the bolts with the spacer and used a regular bolt with stacked washers.

I have also had issues with the front two mounting bolts for the rear cowl too.

Now I keep a spare set of each bolt in the tool box. Bolts are way cheaper than a new cowl.



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post #4 of 15 (permalink) Old 10-25-2010, 01:06 PM
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I also use a set of the front shoulder bolts also for the upper rear cowl mount bolts.
Works great and gets rid of the frankenstein bolts.
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post #5 of 15 (permalink) Old 10-25-2010, 04:34 PM Thread Starter
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Yes my undertial is after market. Seems like it is only held on by two tiny screws from underneath. Is the stock mount more substantial? I will Check into that because the tail section extends so far past the " frankenstien" bolts that it has quite a bit of leverage at the point where it is cracked. Thanks for your thoughts.
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post #6 of 15 (permalink) Old 10-25-2010, 04:47 PM Thread Starter
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Yes I could see how over torque of the front bolts could damage the plastic as well, fortunatly I don't have problems there. I saw the potential for damage and used medium locktight on the threds so they would stay put even though the bolts are lightly torqued. My plan may be to replace my tail cowl with one of those fantastic carbon fiber units... I want to get the issue resolved prior to the replacement. Your input is helpful, thanks.
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post #7 of 15 (permalink) Old 10-25-2010, 06:16 PM
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Does your undertail have the OEM fender completely chopped off past the battery box?
If so, that leaves the undertail not supported very well.
On mine, I only removed the inner portion leaving the sides of the fender to support the undertail as well as leaving mounts for the relays.
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post #8 of 15 (permalink) Old 10-25-2010, 07:21 PM Thread Starter
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Hey subsailer

Are you in the navy ? Submarines? Now then, ill post some pics... not sure how much I can post but I'll give it a go anyway. I pulled out the bolts and observed how far the cowl wanted to sag on it's own... too much ! I noticed there is a metal brace under the cowl sort of between the frankenstien bolts with a gap of about a quarter inch to the underside of the cowl. looks like it was put there for upward support. Is there a pad or bumper missing ? Yours have a pad there ? Well I had some rubber that thickness and gave it a trial fit. The holes lined up much better... perhaps a fuzz high without me on it so I put the bolts back in and the tail is much more solid. think I'm gonna leave the rubber in there. if that bracket was not made for tail support ... it should have been. Like I said here are a couple of pictures.
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post #9 of 15 (permalink) Old 10-25-2010, 08:00 PM
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The cracking I had was never that bad! I had cracks and bits fall off directly around the bolt hole but never that far out...



The very first schoolbook that was written had God all over it. --Dave Mustaine
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post #10 of 15 (permalink) Old 10-25-2010, 08:18 PM
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Yep, I was in the Navy and on submarines some years ago.

You have got something putting a lot of stress on that rear cowl.
Here's my rear cowl upper cowl mount hole (inside and outside view) with over 2 years on it. Not a single crack.
The elongation of the hole is as it comes

Also there's no pad on top of the bracket that holds the rear cowl.
Only the four bolts and two lower clips hold the rear cowl in place.
That bracket you show is used for the rear cowl panel or seat to latch in place.

Are your mufflers impacting the cowl per chance?



Last edited by SubSailor; 10-25-2010 at 08:23 PM.
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