Carbon Fiber Bodywork

Hey Adam, check out the last two posts on this thread: kzrider.com/forum/3-carburetor/483649-ae...at-to-do-with-airbox



But you should finish your bike first.

mtbspeedfreak wrote: Hey Adam, check out the last two posts on this thread: kzrider.com/forum/3-carburetor/483649-ae...at-to-do-with-airbox



But you should finish your bike first.

You bastard Mark! Just for that, you should be the one to make the moulds! :silly:

Before you guys get all gung ho into building CF airboxes, do keep this in mind. The original airbox is designed to create a certain resonant frequency that will offset a flat spot in the original engines power curve. Part of what creates this resonant frequency is the volume and shape of the airbox. However, the material selection will influence this resonant frequency to some extent. As you well know, a carbon fiber airbox will be considerably more stiff than the plastic, factory airbox. It may not me much, but the resonant frequency will change. I'm sure it can be tuned for the new airbox, but don't think that just because you replicate the factory airbox from CF that it will be a drop in solution with no jetting changes necessary. In the end it may be a good solution, but it's likely not any easier than tuning for pods.

You need to study Helmholtz Tuning for more information on this subject. TDub linked an excellent SAE paper about this subject a while back.

Thanks for pointing that out Josh. I had dome some Helmholtz reading a little while back. Shapes, dimensions and volume were in the calculations, but I do not recall material selection. While I'm certain material does play a part to some small degree as you pointed out, someone with more education than myself would have to figure out how much influence it would make.

The point is relatively moot; I'm not in the market to take on ANOTHER project I can't finish! Besides, IF (big if here) I ever did, I wouldn't be too concerned if the airbox didn't behave exactly like a stock airbox.

porchev914 wrote:

mtbspeedfreak wrote: Hey Adam, check out the last two posts on this thread: kzrider.com/forum/3-carburetor/483649-ae...at-to-do-with-airbox



But you should finish your bike first.

You bastard Mark! Just for that, you should be the one to make the moulds! :silly:

:laugh: Well, hows about you put it on the back burner till you have a bike to ride around. Then we'll talk.

Actually, that'd be awesome. I got a lead on some 29mm smoothies the other day. It'll give me a chance to save some bucks for them. How'd you like to collaborate on an airbox specifically for smoothies?

Been following this tread as I have been working on the mold for my custom tailpiece. I went about it in much the same fashion as you, except for the graphite. I didn't think that a bit of undercut in a 1 piece mold would be a problem as it appeared to work for you, but now im having trouble getting the plug out of the mold. It was sufficiently waxed (5 coats) and sprayed with PVA (3 coats) is there some undercut on your mold? Its hard to tell in the pictures. I'm not sure how the KZ900 and KZ1000 tail pieces differ, but The KZ1000 tail has some undercut but not much. I'm trying to figure out if its permanently stuck in there or if i just need to muscle it out.

Doctorot, can you post some pics of your plug with the flange installed prior to laminating the mold? Also, some pics of the inside of your new mold with the plug in it, especially the edges of the plug (not the edges of the flange). And one piece mold MUST have some degree of draft. The tail kz piece has plenty, so that's not the issue. I have had some issues with pva releasing properly with polyester resin. What type of resin did you use? If that's not the problem, then its likely a mechanical lock. Where the mould wraps around the edge of the plug enough to prevent removal. There's only a few things it could be, we'll figure it out

Well good news is I managed to get the plug out. I was messing around with these little plastic wedges they sell at the place I buy resin and fiberglass and wasn't having any luck. It got to a point where finally I decided, well, I'm ripping this fucker out, it will either hurt the mold or the plug, hopefully not both. I put it on the ground stepped on the flange and starting pulling and it finally popped out. Plug cracked a bit but the mold is solid! After I removed the plug I think there might have been a bit of a mechanical lock where I could have been more liberal with the plasticine, but it doesn't seem like that would be enough. However I am using a sophthalic polyester resin. I asked the guy at Fiberlay what products to buy so I figured everything would be compatible, I think the next time i do this I'm going to go the graphite route.

I probably could have done a better job on the flange, but it just the flange. Depsite a bit or Orange peel from the PVA the mold looks good, no bubbles or pinholes, the flange needs some attention but looks like im gonna start laying in the first tail piece tomorrow. Have you tried any "core" materials? the guy at Fiberlay talked me into using a 2mm core cloth to laminate in between the chopped matt, he said it would make it stronger and I could get away with less layers. Ill probably try both since it was pretty cheap.

Wow Docto, you REALLY studied this thread, didn't you? Thats not bad for your first mould, better than my first attempt!! If you recall, I had an issue removing the plug from my first mould, the left sidecover. There were three things at work there though. One was the edge: I didn't take nearly enough time with the clay to make a smooth, lip free transition from the plug to the flange. The second issue was a conflict with the plug material and the tooling resin I used. The thinner in polyester resin is styrene, and styrene will melt ABS plastic. The factory plastic body panels are ABS plastic. So, even with multiple coats of PVA, the ABS plug still melted a little in spots, and adhered itself to the new mould. The only way to remove the plug was to destroy it, ripping it out with vice grips. The third issue was surface finish. I didn't have a great finish on the plug. I think I hade it sanded with 800 grit, the polished it with buffing compound. It had a dull shine, and I thought it would be fine. I was wrong. The smoother the better. Aim for a finished autobody quality paint texture. 1500 grit finish sand then poish to a mirrow finish with buffing compound before making the mould. But hey, looks great from here! I did see easier release of the plug from the mould when I switched to graphite infused epoxy resin as the tooling coat.

As for the core material, I have indeed used it. I have some 2mm core mat cut out, and ready for a tail layup. Increasing crossectional thickness will increase rigidity and strength of the panel with very little weight, as it does not absorb much resin. For a tail like that, I'd do an initial layer of 2 oz cloth, followed by 6 oz cloth, then the core mate, then the chopped strand mat (rip in into pieces, about 3"-5", it will help the mat to conform to compound curves much easier) followed by another layer of 6 oz cloth. the 2 oz cloth as your first layer will give you a much nicer, smoother surface to work on, less finish prep Good luck! I can't wait to see how it turns out man :woohoo:

Adam

I better step it up! Guys around here are gonna beat me to the finish line!

did i ever show you this pic adam?




it is on a bulldock bike.

and this sinister sanctuary mk11 w/ carbon fairing and fender.




just for motivational purposes,ya know .

leon

I have been cleaning up the mold and wet sanding the orange peel out, and I noticed in some places where the plasticine was touching the gel coat it seems to not have cured completely. Its slightly soft to the touch, It appears that this only happened where the PVA got a little thin, but its good to know. I just cut it out and put a little gel coat over it.

I'll have to wait a bit on the first tailpiece until I can get some 6 oz cloth. thanks for the advice

-Vic