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OK I figured out the wiring short and when I got it running the bike died. Checked the carbs and they were very dirty. I need to seal the tank, so looks like I will be doing paint and body work if I have to drain the tank and seal it. My question is on the carbs. I cleaned them and bike runs without airbox. Just testing bike and it wouldn't run past 1/2-3/4 throttle. If i reached down and manualy activated the butterfly for the choke it would pick up. I didn't realize there was that much restriction from the airbox. Anyways I am rambling has anyone tried these rebuild kits or know of a better one to purchase.

http://www.randakks.com/DOHC Four Page.htm#1

I just don't have much experience with these bikes but if i am going to have the bike down I would like to go ahead and rebuild the carbs just so I know they are good. Any info would be appreciated.


GrayHood
 

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Well the reason your bike won't run above 1/2-3/4 is for 2 reason, the main reason is you NEED THE FREAKING AIR BOX WHEN USING STOCK CARBS!!!!!!!!!!!!!!!!!!!!!!!!! Pods don't help and neither do stacks, these carbs need a constant resriction to lift the slides, the stock air box does this. You want to get rid of the air box you need new carbs. You could put restricter plates in them, someone on another board did this with success. Or you can buy a set of cheap GSXR carbs, heres someone who did it with GREAT success. Second reason could be your strator is shot and your not producing enough charge to keep the engine lit over 1/2 throttle

http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=41909&highlight=

Heres more on his bike for all thats interested
http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=40436&highlight=
 

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Stock carbs can be tuned to run super without the stock airbox. They can be tuned to run well with velocity stacks or pod filters. That being said, they will run well with the stock airbox without much tuning. Tuning the stock carbs can involve changing all the jets, shimming the needles or thinning the retainer, drilling larger air holes in the slides and replacing slide springs. Placing a restricter into the system is not tuning. It is not easy to get these carbs tuned without a thorough understanding of CV carbs and some experience experimenting with them.

Ken
 

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Ken,

I hate to disagree with you but with the DOHC cb750F carbs they really are a piss poor design CV carbs. The only people I have ever seen tune these carbs to run "super" without the stock airbox were the Honda HRC techs when racing in the Bol D'OR, and they did it with specially made velocity stacks.

How bad is the design? cb900F owners (who have larger versions of the same carbs) used to switch to cb750F carbs to get better throttle response without seeing a decrease in perf. The slides in these bikes are heavy, the passages can get all sorts of gunk in them, and you really need to clean them throughly. I have pulled carbs apart where the slides stick because old cristalized fuel managed to get into the air passage and gum up the works. I cleand eone set that had more than a pinch of sand in each of the domes.

AS for Randakk's stuff, normally I am a fan of OEM honda parts but randakk has a lot of quality stuff and I would have no problem buying a kit from him if I needed one (and I just might).

There is a good possibility that your reg/rect has taken a fat shit. I had this happen on a 1982 F that belonged to a friend of mine, the bike would idle fine, run fine at slow speeds, but the moment you got on it she would break up sputter and die. Because the reg was still allowing partial charging it had me chasing the problem all over the bike. I rebuilt those carbs 4 times until one day we discovered it wasn't charging. With the new reg/rect she ran fantastic.
 

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Discussion Starter #5
yes I will be getting some new parts for the chargings system and while pulling off the tank to seal it I thought I would just rebuild the carbs to know they are fine. I realise that not running the airbox was a bad idea. live and learn. And I guess if geeto says the are ok I will just go ahead and order them. The Honda parts guy at the store near me just makes me worry to order anything from them, would you go through honda direct geeto? Just trying to make an informed decision before dropping the money
thanks guys
 

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Geeto,
Nice try, but you are not really disagreeing with me. I will agree that these carbs are not Honda's finest design. I also noted that they are not easy to tune and that is when they re in like new condition. I did not and would not suggest that somebody that doesn't know what they are doing try and make them work. Somebody that does have the experience and parts to get them to work, probably wouldn't waste the time. My main point was that just saying some carbs can't be made to work without the stock airbox just isn't true. I would like to see how they run with the stock rubber velocity stacks out of the airbox on them with pods on those.

Ken
 

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I use hondaparts-direct.com for most of what I need directly from honda. The only thing i would go to the dealer for is if I needed a "kit" like a complete tool kit or a carb kit, since hpd only has individual pieces but the dealers have the parts numbers for the kit.

randakk's kit I am pretty sure uses honda hard parts, and if you were to buy each piece from honda it would cost more. Plus he gives you a manual on how to do it. It is a high price but to me it is totally worth it, do it once, do it right.
 

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Another thing i always hated about these carbs is the fact you cant change the needle seats..theyre made into the car and dont unscrew...you can get a new float needle but the seat stays the same,if it gets corroded you will be leaking till the end of time and its very frustrating to chase shit like that.When i worked in the bike shop we had more than one with that problem..ordering another used set of carbs usually ended up wit hthe same problem..
just my 2 cents worth.
 

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quote:Originally posted by joesmotos

Another thing i always hated about these carbs is the fact you cant change the needle seats..theyre made into the car and dont unscrew...you can get a new float needle but the seat stays the same,if it gets corroded you will be leaking till the end of time and its very frustrating to chase shit like that.When i worked in the bike shop we had more than one with that problem..ordering another used set of carbs usually ended up wit hthe same problem..
just my 2 cents worth.
I used to use valve lapping compund and "lap" the new float needles into the seats. It usually requires another dip in carb cleaner and a good long soak after to get all the compound out but if the seat wasn't "that bad" it usually did the trick. Be careful though, this stuff is brass and any kind of overzealousness will ruin it.
 
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