FRANKENHONDA II the 1982 DOHC CB 750F2 Build

Ant36 said:

There is also stuff called quick fair that is used in marine applications for finishing. It's Like the west systems stuff but easier to use.


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Nice because the smoother I can get it now the easier it is to finish later


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Ok back from our extended stay in hospital, mum and Jnr both home safe and sound..

So while they sleep I thought I’d creep back into the garage to have another go at this seat pan



There were a heap of daggy bits hanging off it so I cleaned them up with the angle grinder



To ensure the fibreglassing wrapped around the contour of the frame this time I sprayed little contact adhesive to the seat pan first







Once that was on I laid my fibreglass cloth





Next I gave it a good coat of resin




This is how she stands while I’m waiting for the resin to cure,

I’ll give it a bit then see if it needs another coating, the seat itself is fine. It’s just the tail section I can see requiring a little more love... I wish I had of though of this before ... the old trial and error is quiet costly when your dealing with resin I think between this and my first attempt it’s cost around $400 but I was set on doing it myself... that’s what experience costs you

I’ll still have to cut out a nook for the tail light led strip but that will be last



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Fibreglassing the saga continues


So it was time to man up and start sanding this bad boy back





Progress was slow



I think my use of contact adhesive was a poor decision I’ve found spots that did not bond and I believe that is the reason why. I’ll chalk that one down to experience

You can see it laminated, it could be a culmination of my poor fibreglassing compounded by the fact I used contact adhesive.



I sanded it back and got it as close to spot on as I could. Some of the edges weren’t sharp so I decided to do another layer of fibreglassing


As I was working in the garage the postman came past



Said Japan had me thinking Honda,



It was the rubber seals for the engine cover bolts.

Probably be another hour or so before the resin cures the weather has taken a turn and it’s become a little cold which will extend the curing time

I tip my hat to guys that make custom fairings... it’s definitely an art, and I ain’t no artist


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So I’m toying with the idea of putting a ridge on the seat pan to tie in with the ridge on the tank




I’ve used cardboard as a template I was going to cut slots into it so the fibreglass resin goes through it and bonds to the surface below

A little unsure


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if you can make it flow, might work out good with the tank. But do not glass the cardboard. Just build it up with glass. Cardboard doesn't do wellbwith fiberglass resin


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innovativems said:

if you can make it flow, might work out good with the tank. But do not glass the cardboard. Just build it up with glass. Cardboard doesn't do wellbwith fiberglass resin


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why is that does the card board collapse with the resin ? I’m just not sure how I can get sharp lines



I peeled the layers of a little at a time to get the rib fading out towards the back of the tail


I cut some grooves in the cardboard so the resin will go through it




I think I’m going to have to put a thin layer of bog over it to smooth it out



I used a marker just to show me the lines. There not exactly where I want them yet, a little uneven I think on the left top

Oh well back to the shed I go


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Fiberglass resin cures through a chemical reaction with the catalyst and creates heat during that process. Cardboard may work but also stands the chance to collapse/be inconsistent with how the resin saturates it. And if you plan to paint it at some point; any issues could rear their head down the road if there is an air pocket somewhere. To build that up, you could use a long straind fiberglass filler and tape off where you want the hardines. Honestly I think it looks good without the center being raised.


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Well I took a punt on the cardboard



I cut slot and drilled holes through it that I later injected the resin through



There was a small void underneath the cardboard that I filled with fibreglass cloth



This is what I came into this morning

I had laid fibreglass cloth over the top of the cardboard also, I had excess resin also so I painted over the fairing to smooth it out the poured the rest where the seat will eventually end up and it smoothed it out a treat

I’ll go walk the dogs then when I return I’ll give it another layer of fibreglass and resin and square up the front of the ridge with the angle the back out the seat pan has.... then I’ll hit it with the sander again see what magic I can conjure up


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Ok so while I wait for the next lot of resin to dry I thought I would update



So I sanded it back a little to see how poorly my makeshift mould held up



I then bogged it to fill in any holes



Once it was sanded back again I decided to put another layer of fibreglass cloth over it

Now wait again for it to dry, I think due to my lack of skill this is a two steps forward 1 step back kind of process, hopefully it’s worth the rigmarole.


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The ridge looks really promising. Will give the tail a pretty unique look and tie in well with the tank, which is a real focal point with the Fs.

And oh yeah, congrats on the addition to the family!


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LightsOut said:

The ridge looks really promising. Will give the tail a pretty unique look and tie in well with the tank, which is a real focal point with the Fs.

And oh yeah, congrats on the addition to the family!


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Cheers weeman is doing alright.. yea I’m hoping the ridge ties in well.



I gave it a bit more of a touch up, I also went out and bought a round, flat and triangle file so I can get the edges of the ridge sharp




Just to get an idea of how my lines were I went over the edge with a marker again


So if you can imagine the preexisting decal of the blue lines from the tank following down either side of the ridge on the tail section this is where I’m heading


Just have to build it up a little to smooth of some more imperfections


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I had allowed the garage to slip into a state of disarray, it was ruining my chi



It probably doesn’t really look like it but it’s a bit cleaner now.

I’ve removed the seat pan and will touch it up on the bench before putting it back on the bike


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So while I was waiting for some fibreglassing to dry, I went off to the paint shop and got the tank colour matched, looks like it will be a white, pearl coat, stickers then clear coat. But there are a fair few hours left on this seat pan :/


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So when I removed the seat from the frame it had moulded to the frames shape a little better than I would have liked and as a result it got damaged around the sides when I was removing it ....

And then I swore .... and swore some more

Once I composed myself I assessed the damage and worked out it was because the fibreglassing followed around the underside of the tubular frame (facepalm moment)

So after hitting it with the deremel and angle grinder then the sander again I got it to fit on and off without too much

Then what I did was put thin cardboard up and in between the frame and the inside of the seat pan, in effect making a straight edge



What I’ve done is cut my fibreglass cloth in strips and put it around all the bottom side of the seat pan

Once it’s dry I can remove the seat and fill in the sides and edges so it goes straight down from the fall of the sides and tail instead of coming around the frame and mak ng it impossible to remove...

I swear by the time I’m finished it would have probably been cheaper to get someone to make one up custom for me. But where would the fun be in that right !


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The worst thing about fibreglassing is the drying time :/



My most unorthodox and unprofessional salvage effort, I’m too far in to turn back now...

This is one side and half the tail done, I should get the other side done in an hour ..


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It's a bit late now, but flashing plus aluminum duct tape work wonders for that sort of thing. Flashing typically comes on a roll and is thin aluminum. It can be easily bent in one dimension but harder to curve in 3d. Tape is excellent for that. I needed a a bump in a fairing belly pan once to clear a pipe bend and used a hard boiled egg in its shell to progressively push/stretch the aluminum duct tape until I had a perfect pipe clearing bump.

In terms of style, the tank ridge slopes at the sides and the seat would probably look better with a similar look. That very rear edge which is very round - like a sausage wrapped around the back and might better match the tank sharp lines if it were more edgy. Styling is very personal and what looks right to me may look totally wrong to someone else.

Just some thoughts for the next time around.

Setting times are a function of % catalyst and temperature, but you are right that there's a lot of time wasted waiting for it to harden.

http://pinkpossum.com/GT750/phattrakka2/p8seat.htm I used flashing and card and tape to create a "mold" to extend that seat and then used card and aluminum tape to create a one time use mold for the inner container. I make a carbon fiber wrap of that one to use for my next project.

That’s a mean adaptation, it would have been nice to have started with some sort of base rather than from scratch... it’s turning into an epic mission now lol


This side built up a little quicker because I used the fibreglass matting first. This side is all but done but the tail on the other side still needs to built up

I fly out to work on the 6th Nov and it’s highly unlikely this will even be in undercoat :/, no point rushing these things

Summer is upon us soon and I would love to ride this summer


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I hear you. Did you catch the MotoGP races at the island last weekend. They were all epic battles. I haven't been back there since we ran the first Southern Classic there. or maybe the first GP in 89 was the last time ? Too long ago and too many polyester resin fumes.......

Good luck with the seat. The thing about it is that you made it and you can change it any time you want to.

teazer said:

I hear you. Did you catch the MotoGP races at the island last weekend. They were all epic battles. I haven't been back there since we ran the first Southern Classic there. or maybe the first GP in 89 was the last time ? Too long ago and too many polyester resin fumes.......

Good luck with the seat. The thing about it is that you made it and you can change it any time you want to.

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This much is true,

I had my hands full with our new addition to the family unfortunately I didn’t even catch it on tv- was baby wife and bike

Speaking of which my guests are due to leave shortly which means I will be returning to the garage


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cb250nproject said:

This much is true,

I had my hands full with our new addition to the family unfortunately I didn’t even catch it on tv- was baby wife and bike

Speaking of which my guests are due to leave shortly which means I will be returning to the garage


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Hah! My bike time has been cut severely since my daughter showed up in the picture. I have a project more or less mechanically done, probably about 120 to 150 hours left todisassemble, refinish everything, and reassemble, and it's been sitting that way for about 3 months now. Not too long ago ì'd have been riding it already!