998/813 probs?

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It is a great carb. Many swear by them. The only issue that I have read is shaft wear. So it might not go as long between rebuilds. NBD Just kinda depends how much you play. The throttle response is supposed to be better with the excelerator pump.
 
i use these carbs and others. i favor the 813. it allows you to run the lsn slightly leaner and not have the wo-wompp -- as i hammer the throttle open.- the 813 likes the short velocity stack- the hole on this stack is larger then on the 1" velocity stack. the 1" stack works well on a light car with a hi-rpm engine.- if you have room to really let it rev out.- i never use the stock intake manifold- ever. use ada manafold- there is a hole on the back of the 813 that must be sealed off after its installed on an engine- this is why some complain about short throttle shaft life. dirt-trail trash gets in the hole and wears out the throttle shaft- pump seal- bump bore hole- . its a ez fix with shoe-goo.- yea, the 990 is a good carb also.-
 
could you show me a pic of what i need to shoe goo alfred? i will be putting the 998 on my xt & putting my 990 on my son's xt. i don't have the carb in front of me to look for what you are talking about. as for the stack i have a 1" i think so it'll have to do for now. i'll look up the ada manifold. keep the info coming if anyone has any. thank you.
 
bit off topic here- i am good @ this!! ported engines are louder than most stockers. i carefully assembled a f-270- open crank- gitzmotor lightened fly wheel- ported piston- this engine absolutely rocks- its about 1/4 louder at least- than a gitzmotor 30.5 full mod. no bs. the 30.5 is no slouch- it has huge midrange- you would have to hear this little f-270 to see- hear what i am saying----- this engine on a xb platform with grp bulldog narrows- it will actually get up on top of grass thats about 3" tall- tall fescue grass- then it really starts reving out like a crazed indian-- no bs.
 
yea, i read a thread about the hole on these stacks a week or two ago.- fact is- the hole on the carb side of the .75 stack is larger than the hole on the 1" stack. just saying---.
 
Dreggsta said:
this the manifold you were talking bout alfred? http://www.davesmotors.com/av547_2what's wrong w/the stock manifold?
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There is nothing wrong with the plastic manifold, it wont warp and should not crack for quite a while. Tightening evenly is important to maintaining the same sealing pressure from side to side, failing to do this can cause an air leak as it is not as rigid or forgiving as a billet intake. The plastic one can also be ported very easily to give you the same performance of a billet spacer in terms of flow rate. I did it to mine with a fine sanding wheel and dremel, took a minute to do, but gained alot lol.
 
alfred e numan said:
the hole on the carb side -- the hole is larger on the 3/4" than the 1".
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I am full of it-- wrong agan!!! the hole on the 1" stack is larger than the hole on the 3/4" stack--- its monday- thats a good excuse aint it???? LOL!
 
Dreggsta said:
what are they or it? i did a search but the search engine doesn't pull up anything for 813 or 998. only for walbro & that's a lot of threads lol.
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The 998 is a revised 813. Im running the 998, notice a much quicker rev with the motor bolted down to a test bench, no stumble and no bog. Real life experience was noticed also when you stab the throttle and that extra fuel charge is sprayed in. The issues with worn throttle shafts may be a thing of the past with the 998 carb. With most revised parts, they will often fix bugs and improve the design, like throttle shafts and fuel metering in this particular carb for instance.

I would highly recommend a 998, especially in big bore/ported applications.
 
so alfred, i'm trying to understand, which stack is it you like w/the 813?

meathooks, is the brass thing in the top middle of the inlet the injector for the pump?
 
yea, sorry bout the mix-up. for me, the 3/4" velocity stack seems to give the xb a little better bottom -mid power. the 1" stack seems to give more high rpm. this has been the case with either smaller displacement or larger displacement engines. the torquer velocity stack does not have a tapered inlet. looks sorta like a can cut in half with a hole on one end. cannot really call it a velocity stack. this seems to give a engine a big gulp of air @ lower speeds- yea, this other carb with a pump sounds interesting. i know that on the 813, the added fuel from the pump comes out of the high speed nozzle- check valve in the bore of the carb- its not a spray like on a full sized carb- holly- barry grant- ect- it just comes out in drops. this comes from me loading up the 813 with gas, holding it in my hand and moving the throttle back and forth. it would be great if the 998 would squirt fuel instead of having it just come out in drops--.
 
yeh i noticed that about the torqer. i thot if i wanted to go that route i might as well use the stock air filter housing lol. it's not tapered either. great info alfred. as always lol. ;)
 
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