now ive done it....airbox question

[greg78gs750]

well, i took off my airbox today, the beginning of a winter cleanup of the bike....and i was cleaning out the slot in the top that (i guess infamously) gets clogged with rust and crud, and in doing so poded a hole through it into the airbox itself.....oops....so, my question is, is the fix just some pc-7 or jbweld or something, or is there something more elegant that i can do? apart from sourcing a new airbox, of course. thanks in advance for your help, i have spent the last year obsessively ingesting all this site has to offer and cant wait to break my perfectly good motorcycle this winter so you folks can help me fix it....ha. 8-[

[greg78gs750]

that's poked. not poded.

[80GS1000]

How big is the hole?

[bwringer]

http://www.gorillatape.com/

[greg78gs750]

that was my first thought too: duct tape. or duck tape. whichever school you ascribe to. the hole is about the size of my pinky...the metal in that slot is so decroded that i could enlarge it if i wanted.....now, of course, i am paranoid about getting every speck of crud out of there, as it is on the "clean" side of the filter...and sucking 30 year old rust into my carbs seems like it might affect performance....

[knotzilla]

My airbox was plugged up in the same area (slot) What I done was to get rid of the original black vent hose and substitute it with 3/8 ID black hose (dishwasher hose, about 6 bucks and cut to about 6 inches longer than the original hose) I drilled a hole through the top of the airbox a bit smaller diameter then the "dishwasher hose" This smaller hole will help seal around the hose. In the compartment above the air filter I inserted a tee in the 3/8 hose and stuck hoses about 2 inches long also on the tee. The tee actually rests on the surface right behind the top of the filter. If this explanation isn't clear enough I can take a photo when I get home, Ted

[greg78gs750]

seems reasonable, ted. bypass that slot all together. after following some of the "airbox vs pods" discussions, i wondered if there was any special magic in the flow that the slot might create....some mystical vortex or something....pods are, for me, out of the question, as the jetting woes seem like more than i could deal with, especially when the bike runs fine now. i have been debating a 4-1 exhaust, since my original is developing holes where the pipe goes into the megaphone, but i will probably just braze it shut like i did with the other side more than a year ago and live with it, thus avoiding and flow changes....blah blah blah. anyway, thanks for the tip....(now that i think of it, i could, if i used some hose, just seal the slot with epoxy and bury the crud forever....hmm...out of sight, out of mind....and orifices...)

greg

[greg78gs750]

next question

well, the hole is HUGE now, after cleaning out the crud. i think i am going to epoxy the whole mess closed then drill it out and use the tubing per the earlier suggestion. i am about to take off the carbs, so wish me luck with that. my question is this.....if i do take off the carbs to clean them, will i have to re-synch them to get them running again? i think i will, huh. this is all new territory for me, so sorry if my questions are tedious....i am just really hesitant to tear into a pretty good running bike, even if it is due. more questions to follow, thanks in advance for everyone's help

greg

[gremlin]

you could do plastic welding. this is a post from a gold fourm that i go to. its a how to weld plastic. there is some good info that will work on bike parts. http://www.49ermike.com/dc/dcboard.p...ng_type=search

http://inventors.about.com/od/mstartinventions/a/Marlex.htm

HDPE is widely used for plastic bags, outdoor toys, milk jugs etc. It is a oil byproduct and therefore be consumed completely by fire. Anything left will be additives like UV stabilizers and pigment. It takes almost 2kg of oil (including energy) to make 1kg of HDPE.

Welding plastic is just like welding metal you need heat and a filler material. You must use compatible filler to make a good weld and the heat will vary depending on what you are wleding. Buried in this link is some info on identifying types of plastic, Look in the library:

http://www.abbeon.com/

Here is a good primer for plastic welding:

http://www.plasticsmag.com/ta.asp?aid=3750

Just like metal welding you must have clean surfaces, heat control and the proper filler. After that you need practice. Grab some scrap and spend some time, you will get it.

[greg78gs750]

thanks, but my airbox is metal. and awfully thin and rusted out to weld.

[SqDancerLynn1]

You can get pretty close sync doing it mechanically. 78 VM carbs - back the idle screw out & make sure the #3 slide closes completely!!! IF not adjust it. Then turn the idle screw in until you can just slide a 1/16" dril bit under the # 3 carb slide. Kind of like adjusting valves, then do it to the other three

[salty_monk]

You won't necessarily have to re-synch, it depends what you do to them.

With CV's you can do pretty much anything apart from split them apart, with VM's I think you have to synch after messing with needles, jets etc.... not so sure about those.

Dan

[Steve]

i have been debating a 4-1 exhaust, since my original is developing holes where the pipe goes into the megaphone, but i will probably just braze it shut like i did with the other side more than a year ago and live with it, thus avoiding and flow changes....

Keep in mind that when the pipes came from the factory, there might have already been a hole there. Not all systems have it, but many times there was a drain hole to drain any condensation that might have formed. The hole was less than 1/8", probably about 2mm. The need for the hole is minimized if you always get the bike up to full operating temperature whenever the engine is started.


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