990 carb

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R

rampage idiot

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I keep hearing everybody rave about the 990, just a thought I live in Pa. and in the colder months what is the trick to starting it, I am running a 668 and don't know if I am headed for grief going to a 990. as always Thanks
 
You may want to try a nkg cr8hsa plug this is a hot plug. The nkg cmr7 is a cold plug,in the summer use the 7 and winter use the8. Hope this helps.
 
The 990 is a great carb. If it's tuned right, it'll fire without much hassle. If you have trouble starting it, you can put a few drops of fuel down the spark plug hole, that'll get it running.
 
Yes the 6 would be hotter. I've got the 990 and love it, I had the velocity stack with choke but they do leak air I fixed the air leak but to me it wasn't worth wondering if somehow some little dust or something was getting past or would. now i use a shredder. It's really not that much of a difference to start maybe 3 or 4 more pulls. I'm not sure what people think about this but I've never had trouble. Just pick up a can of starting fluid good for weedeaters, chainsaws etc. and just spray a DOT, I mean just a tiny little Squirt and it fires on first pull even if cold. When I first installed it it was giving me trouble one little squirt to the filter on the edge. Never had a problem since, or had to use it again. Hope this helps
 
lower the # on the plug the hotter!! Now if u mean weather condition cordy u would be correct Hotter weather use a cooler plug to help keep from over heating Vice-vresa
 
Why is outside temp a determining factor on which plug to use? I know that the design of the engine determines which plug to use. Higher compression engines need colder plugs to prevent pre-ignition, etc. I'd say outside temps effect your tune, more than anything.
 
never really understood why the plug people have there numbers mixed up- champions-autolites-ect- higher the number-the hotter the plug- its easy to get these heat ranges mixed up thats for shure. I do not have a means of measuring coil out put- some claim that a tighter air gap - flywheel to coil will produce a hotter spark. Instead of the factory setting of .30 mm, some set this gap to .20mm. Seems to me this would effect the timing some. -- Yea, chokeless carbs require a few more cranks to light off the engine- I just prime up the engine either tru the plug hole- or intake- did this on a 990 equipped f 270 yesterday morning-@45 degrees- brand new engine started with about 6 inchest of pull on the rip cord.
 
Deluge said:
Why is outside temp a determining factor on which plug to use? I know that the design of the engine determines which plug to use. Higher compression engines need colder plugs to prevent pre-ignition, etc. I'd say outside temps effect your tune, more than anything.
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These lil engines may not matter a bit ! But on a Cr250, Kx250 and KX500 MX Race bikes I have seen holes melted in the top of a pistons from running a BR5es on 100+ degree days To hot of a plug on a in 100 + weather is a Factor
 
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