Bolt size on the carb?

[M-Oorb]

So I think everyone is pretty much in agreement that the bolts on the carbs to get to the needles pretty much suck. I've just about stripped mine...maybe have one more go left in them...so I'm looking to replace them with better hex bolts.

Does anyone happen to know the specs on these bolts? I'd love to get them before I tear down the bike. TIA

[kkim]

I seem to recall the allen bolts they give you in the Factory Pro jet kits for the float bowls can be used for the carb tops. let me check my jet kit and see if they have the specs for those bolts listed when I get home. Perhaps someone else with a jet kit can do the same before I do.

[kkim]

just checked my FP install sheet. The allen bolts for the float bowl are listed as 4x16mm. 16 is the length... 4mm must be the thread bolt size.

[CANTFUNCTION]

Kelly you are right about the bolts from the Factory Pro jet kits being for the float bowls. And I am almost certain that they will work on the top part of the carb also. The size for the bottom bolts are 4mm diameter and .70mm pitch which is a coarse thread. (So 4m). I would get some 3mm, 4mm and 5mm coarse thread bolts just to be on the safe side.

Matt please let us know which size works as this seem to be a recurring problem.

[M-Oorb]

Alright...hitting up the Depot tomorrow so I will let you guys know what works...hopefully they have what I need as these stock bolts really do suck

[kkim]

Matt,

Before you thread the new bolts in to the carb and possibly strip the threads, if the bolts you got are not correct for some reason, take the old bolt out, find a nut that will thread onto the original bolt, then thread that same nut onto the new bolt. That way you'll be able to see if what you bought is correct before installing it and possibly damaging the carb body.

[Ramen]

I'm sure a lot of the board will appreciate your effort and sharing of knowledge, Matt. Definitely buy various sizes - you can always take what you don't need back instead of making several trips.

[M-Oorb]

So just came back from the Depot. Picked up 3 different sizes of allen head screws. I got 1 set of 3mm, 1 set of 4mm, and 1 set of 5 mm. Haven't taken the gas tank off to examine but from what I remember and just eyeballing these screws...it seems that the 4mm take it. Goin on a little weekend vacation starting tomorrow(ok a long weekend) over to the west coast of Fl, so I'm tackling lots of maintenance on Monday so I'll let ya all know which fits.

[CANTFUNCTION]

Matt, also take the old screw and place on the top of the new screw. Then look at the threads and see if they match up. Or you can get a metric screw checker, they're only a few bucks. These thing are great to have. It has a bunch of holes in it that tell you the screw diameter. Then there are more holes that are threaded that tell you the pitch or(thread size).

What Kelly said will work also. Just check them before you put them in.

[M-Oorb]

Ok so finally have the time today to do some work on the bike. Managed to get the old screws out and found a nut that they will screw into perfectly. Went on to test the new ones that I purchased...I have a fit!! A perfect fit!! Got these at Home Depot and they are 4mm by 16mm. No information about the threads, but these were the only ones there. After inspecting the threads on the old and the new they look exact and again, both fit perfectly into my test nut (no jokes here kiddies) The new ones are called "Cap Screw socket" and they are used in conjunction with an Allen wrench. The metal feels much better quality and shouldn't strip as easily. Hope this helps others in the future!

[M-Oorb]

Just noticed a problem though, so hopefully someone can help me out. While removing the stock bolts from the top of the carb I noticed all 8 of them had lock washers and 5 of them had an additional regular washer. Wanted to take these pieces off to put onto my new bolts...but they dont seem to come off. Sprayed them with some WD-40 and nothin. Anyone have an idea on how to remove these?

[kkim]

Thanks, Matt. I'm sure it will. Mahalo for posting the information.

[kkim]

Originally Posted by M-Oorb

Just noticed a problem though, so hopefully someone can help me out. While removing the stock bolts from the top of the carb I noticed all 8 of them had lock washers and 5 of them had an additional regular washer. Wanted to take these pieces off to put onto my new bolts...but they dont seem to come off. Sprayed them with some WD-40 and nothin. Anyone have an idea on how to remove these?

if you don't have some lock washers that size, just use some blue loctite (just a little) on the new screw's threads when reassembling.

[M-Oorb]

I was thinking about using some loctite and I know blue isnt permanent but do you think it'd be a wiser choice to go to a hardware store and just pick up some of the lock washers. I feel like taking the bolts off (which will inevitiably have to be done at some point) would be easier with the lock washers than the loctite and I don't mind spending a couple cents. Am I correct or is the blue stuff not that big of a deal if only using a small amount?

[kkim]

the best solution would be to use the same flat and lock washer arrangement that the stock bolts have. You only have some of the bolts with flats because they go back onto the places that don't have metal backing on, like the plastic carb tops. The ones w/o the flats go where the metal cable brackets are.

blue loctite would be fine to use, the only caution was to use just a little cause sometimes it will react with plastic and you don't want to cause the plastic carb cover to crack by getting some on there, if in fact they react with that type off plastic.

[M-Oorb]

Very good, that is what I thought as well...try to stick with the way they did it at the factory. This evening I will go to the hardware store and hopefully they have the things I need in such a small size.

[CANTFUNCTION]

Originally Posted by M-Oorb

I have a fit!! A perfect fit!! Got these at Home Depot and they are 4mm by 16mm. No information about the threads, but these were the only ones there.

Matt do you still have the stock screws? Because I would like to check the threads size. If you send me one screw. I will check it then send you back the a stamp and the screw.


If not I am almost certain the size is 4mm diameter and .70mm pitch same as float bowls screws.

[NJD022588]

I went to the hardware store and the screws labeled M4 had the same pitch and diameter as the carb screws - M is for metric, 4 is for 4mm.

I cant remember the length of the top screws, but I bought screws for the fuel bowls and they were M4 x 14.

[M-Oorb]

If Nick's post doesn't help I do in fact still have my old screws. PM me if you want them shipped Chris

Another note. the lock washer and the flat washer on our screws CAN NOT be removed. So if your going to be installing new screws make sure you stop at your local hardware store and pick up 5 lock washers and 8 flat ones

[seis gunnar]

I've got some 4mm metric course (i.e. .7 pitch) allen head bolts, but they are partial thread; does anybody know if the carb cover is threaded, and/or what the diameter and depth of the hole in it is? The shank on my bolts is just about 10 mm, so with the washer and lock washer I would guess around 7 or 8mm is the clearance I would need. The SAE, Standard, or what ever you want to call it equivalent is around 5/16.

I would go and check myself, but work has me out of town for the next two weeks.

[NJD022588]

Originally Posted by seis gunnar

does anybody know if the carb cover is threaded, and/or what the diameter and depth of the hole in it is?

The plastic carb cover is not threaded, only the carb is. Since a 4mm screw fits, the diameter is 4mm, right? I'm not sure what the depth is, but most likely around 16mm.

[M-Oorb]

Nicks correct...diameter is 4mm and the stock screws are 16mm long. I personally wouldnt use those Jon and I'd go out to the local hardware store and spend (literally) a couple cents and pick up some 16mm ones. Dont forget...if your gunna change these out to also get some lock washers and flat washers.

[seis gunnar]

Originally Posted by NJD022588

Since a 4mm screw fits, the diameter is 4mm, right? I'm not sure what the depth is, but most likely around 16mm.

I've made the same assumption in the past too, my concern lies in that, with a partial thread bolt, the unthreaded shank is some times larger that the thread diameter, by just a tiny bit. You really need to mic it to know for sure. Since the hole isn't threaded you would assume the design engineer knows you normally have a minimum clearance for any bolt that passes through. Sorry I'm nuking this out a bit. Everybody

Nicks correct...diameter is 4mm and the stock screws are 16mm long. I personally wouldnt use those Jon and I'd go out to the local hardware store and spend (literally) a couple cents and pick up some 16mm ones. Dont forget...if your gunna change these out to also get some lock washers and flat washers.

Yep, I'll admit I'm being cheap. I was thinking about putting a die on them and add a few more threads to make sure I had enough to grip the carb body. Thanks for the reminder, about the washers, its those little things that get you every time.

[M-Oorb]

Trust me I know I'm very forgetful about those things...end up taking 10 trips to the hardware store for a job that shoulda taken 30 min haha
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