Author Topic: the baking soda plastic repair method (Read 13583 times)

750K2 · « **on:** April 24, 2007, 01:29:39 PM »

hi guys - new member here and i'm thrilled to have found this site. it's very inspiring. now, having chased the plastic side cover repair threads, could one or two of you gurus walk me through the super-glue and baking soda repair method? like so many others, i now have a 1 inch crack on the left side cover from pulling it out of the grommets. (and yes, i will definately pick up replacement grommets). i'd like to get through this repair without repainting if possible, though i do have full spray facilities here at my woodshop. (sunrise metallic orange, so no rattle can possible)
thanks!
frank

c_kyle · « **Reply #1 on:** April 24, 2007, 02:00:36 PM »

I would go to Harbor Freight and buy the plastic welding kit. I'll throw instructions for plastic welding cracks in here just in case you decide to do it.

Using a Dremel tool, grind the crack into a V shape. The sides of the crack: ||, now like this, \/. Do this to both the front and back of the crack.

Clean side cover with Dawn, or other degreaser soap. Then clean with alcohol.

Now, either plastic weld the V-shapped crack, or do the superglue/bakingsoda.

The ideal thing to do is to mix a small amount of baking soda and superglue until you have a thicker mixture; but it doesn't work. The mixture hardens in a matter of seconds and you never get it to the crack. So, do this: Make a funnell out of paper or something, and pour baking soda 1" long into the V-shaped crack. Fill to the top of the crack. Squeeze superglue onto the baking soda. It is going to want to run away from the baking soda, so using a wooden toothpick stir the mixture around until it hardens. Move onto the next inch of the crack.

Sand, prime, and paint.

andy750 · « **Reply #2 on:** April 24, 2007, 02:09:53 PM »

I wouldn't use the baking soda method either. Either use the above method or get a fiberglass kit and cover the back of the cover for added strength.
cheers
Andy

mick750F · « **Reply #3 on:** April 24, 2007, 02:16:54 PM »

I've used the baking soda method on a couple of side covers and the results are excellent. The repair is done from the inside and if there is no damage to the outside of the cover the repair is nearly invisible.

You simply gouge out a shallow trough along the crack which is then filled with baking soda. Then you drip liquid super glue onto the baking soda being sure to saturate it. Let it set up, which it does fairly quickly, and you're done. I taped the covers on the outside to hold them in place.

Mike

upperlake04 · « **Reply #4 on:** April 24, 2007, 02:26:49 PM »

A key point is to fill the crack. The fiberglass cloth and polyester resin reinforcement on the back works well, but I didn't v-groove the crack, just flexed the cover open a bit at the crack and thought the resin would seep into it and glue it together. It didn't, the cracks have reappeared through the new paint on the front, but the back is still solid.

gtyler5 · « **Reply #5 on:** April 24, 2007, 02:41:27 PM »

Super glue's tend to be brittle, and taking the side covers off and on makes it need something with some more flex to it. you would be better off using fiberglass resin or an epoxy I think lock tite makes a "plastic weld" epoxy that you can get at Lowe's or Home depot I have not used it but have used epoxy and fiberglass resin with good results. my two cents.

750K2 · « **Reply #6 on:** April 24, 2007, 04:12:43 PM »

thanks guys! these are all very educational tips and the breadth of experience on this site is terrific. i am truly in the presence of highly intelligent maniacs! i should have added that i'm trying to keep this bike as close to show quality as i can - not sure if that's very realistic but hey, goals are nice... so having said that, and found a very nice link to a shop in england that sells aftermarket reproductions, should i just cough up the dough for one of those plastic covers and paint it? seems like with the plastic welding equipment, or the fiberglass repair, i'm in for a paint job either way. any thoughts?
thanks again!
frank
p.s. ya, i'm one of those guys that bought a low mileage bike from a friend's garage. trust me, i know how lucky i am!

Faol · « **Reply #7 on:** April 24, 2007, 04:23:44 PM »

Before you go that route, do yourself a favor and keep an eye on EBay. If you don't need them immediately, that's a good way to get covers in decent shape for pretty cheap. That's been my experience anyway.

upperlake04 · « **Reply #8 on:** April 24, 2007, 04:25:55 PM »

Quote

highly intelligent maniacs!

wulfshrunting, andy750, mick750F, upperlake04 and gtyler5

mick750F · « **Reply #9 on:** April 24, 2007, 04:31:59 PM »

Quote from: gtyler5 on April 24, 2007, 02:41:27 PM

Super glue's tend to be brittle, and taking the side covers off and on makes it need something with some more flex to it. you would be better off using fiberglass resin or an epoxy I think lock tite makes a "plastic weld" epoxy that you can get at Lowe's or Home depot I have not used it but have used epoxy and fiberglass resin with good results. my two cents.

The reason I used super glue and baking soda is because the original fiberglass and resin repair failed. The second repair has held up much longer.

750K2...If the place in England you mention is David Silver then yes, they have a very good product. I believe it's a bit softer than original so is less apt to crack. If you need paint try here... http://www.vintagehondapaint.com/ Don is a member here and makes up kits for all of the Honda sohc colors.

Mike

mick750F · « **Reply #10 on:** April 24, 2007, 04:33:01 PM »

Quote from: upperlake04 on April 24, 2007, 04:25:55 PM

Quote
highly intelligent maniacs!

wulfshrunting, andy750, mick750F, upperlake04 and gtyler5

Hey!!! I resemble that remark!

Mike

BobbyR · « **Reply #11 on:** April 24, 2007, 07:48:22 PM »

Quote from: 750K2 on April 24, 2007, 01:29:39 PM

hi guys - new member here and i'm thrilled to have found this site. it's very inspiring. now, having chased the plastic side cover repair threads, could one or two of you gurus walk me through the super-glue and baking soda repair method? like so many others, i now have a 1 inch crack on the left side cover from pulling it out of the grommets. (and yes, i will definately pick up replacement grommets). i'd like to get through this repair without repainting if possible, though i do have full spray facilities here at my woodshop. (sunrise metallic orange, so no rattle can possible)
thanks!
frank

I would do what you are doing. I used a two Part JB Weld type product and coated the inside to stiifen the plastic. When you put new grommets on I use a Silicone grease on the grommets so I don't need to pull on the cover that hard to check the oil.

andy750 · « **Reply #12 on:** April 25, 2007, 05:15:54 AM »

David Silver Spares repro covers are very good in my opinion - I have one and they are better than original -easy to paint as well. CB750K2 if you are needing the right side cover (oil tank) I have a spare that is intact and needs to be painted. Let me know and I can drop it off for you.

cheers
Andy'

750K2 · « **Reply #13 on:** April 25, 2007, 08:46:09 AM »

hi andy - thanks for the recommendation on the side cover. the right side is a-ok (so far) but thanks for the offer. you guys are great! so glad i found this site. not quite sure what i'm going to do with this cover yet. if i ever decided to show this bike, how would a replacement cover do? i don't know if there's a show around here but would like to keep the bike as 'original' as i can within my abilities. the fact that the bike was darned near perfect 'til i dropped it just kills me.
frank

pelicanwheel · « **Reply #14 on:** April 25, 2007, 09:07:39 AM »

a lot of nice recommendations here...I agree this is a great board. I too am involved in a near perfect restoration (just need to source some new intake rubbers (inside the airbox) and paint the covers and tank and I'm done!!!!!

You should contact me if you want my take on any part of restoration. I plan to post some of the things I've learned (such as restoring the airbox to look practically brand new buy wet sanding the scrathes out with 600 wet/dry paper, then spraying with paint specifically made for plasitc, then rubbing out with MOther's brand car polish).

But to the point of this thread. I had a collection of broken covers, so I was able to experiment with methods of repair, including all those mentioned here.

And the winner is:

Crazy glue and baking soda!!!

repeat:

Crazy glue and baking soda!!!

it was easy, it was fast, it was also very easy, and lastly, it was also very fast!

On one of the sacrificial pieces I experimented on, I intentionally tried to break the glue/soda repair and the surrounding plastic broke first!!!! What more could you ask for.

I didn't even go out and get fresh super glue...just went to walgreen's and got the stuff off the rack. I drilled a hole on the end of the crack to prevent further expansion of the crack (just like you do with a crack on a windshield of your car)..I used a 1/16 drill bit (1/8) will do too), sprinkled baking soda over the crack...working some of it into the crack (oh yeah, I put masking tape of the outside of the crack to hold the soda and glue in) then saturated the soda with glue. I then removed the tape...sprinkled more soda and repeated with the glue on the outside. I then wet sanded with 400 wet/dry sand paper, and the repair is nearly undetectable from the outside. entire process from beginning to end was less than 10 minutes...and that was 90% sanding time.

again baking soda and superglue.

I think I'll write my congress person and tell then to enact a law preventing any other method!

Pelican

andy750 · « **Reply #15 on:** April 25, 2007, 09:14:14 AM »

Pelican I got my airbox rubbers at David Silver Spares - very cheap :-D....they make a HUGE difference!!!!!

good luck,
Andy

pelicanwheel · « **Reply #16 on:** April 25, 2007, 09:58:13 AM »

Thanks Andy...just checked it out...seems to be cheaper than the ebay auction I'm eyeing!

Pelican

andy750 · « **Reply #17 on:** April 25, 2007, 10:23:06 AM »

and fast shipping as well!

good luck,
Andy

ZirconDrummer · « **Reply #18 on:** March 23, 2018, 01:56:00 PM »

Probably LONG GONE/DONE by now but excellent repros available from LPM (low pressure moldings in Coventry UK) also panel badges all quite reasonable and really good quality. Just got left side panel & badges for my CB750K7. Very happy after three years of searching.
Cheers,
Bill

WhyNot2 · « **Reply #19 on:** March 23, 2018, 02:28:00 PM »

Good stuff here.

https://www.fb-stuff.com/fb-stuff-store.html

rotortiller · « **Reply #20 on:** March 23, 2018, 04:57:03 PM »

Hold the crack closed and carefully wick super glue in from the back side. Wait for it to set. Get some fiberglass cloth and super glue to the inside of the cover, a couple of layers will make it stronger. After that I'd get some LDM replica covers and paint them up.http://lpmreplicaparts.com/

Don R · « **Reply #21 on:** March 25, 2018, 12:36:09 PM »

I owned one that had been fiberglassed, it looked like new on the front and was still good later when I sold the bike.

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Author Topic: the baking soda plastic repair method (Read 13583 times)

upperlake04

upperlake04