[stpltn250r]

The reason I ask is I will be running a 52mm crankshop and want the right size filter. Its going on a 685cc 2 stroke single. I looked at K&N RU3840. Its 10'' long but the ID of the flange is 57mm. On crank shop website they use the filter RU3130. It has an ID of the flange at 89mm, but is only 7'' long. They run those carbs on gas, but would it work for alky??

[acecarlos]

Will it work, yes, however; IMO you should run the biggest air filter you can fit if you are running a 685CC Single 2 Stroke. One of the limiting factors on top end performance from a BB Single is intake and filter capacity. Unrestricted airflow should be a top priority for any high performance 2 Stroke.

Carlos.

[Tate]

i run on gas for my rappy but it was on alky just added a pwj and big billet duel feed bowl. i would think you might need the 56mil carb

[stpltn250r]

Its a Liger cylinder. So its using the cr500 intake. And I found another filter on there site(k&n). RU1785. Its got a mounting flange id of 3.5. The outside id of 5" and a length of 8.5". I think that's gonna be the one. It seems to have the most filter surface area.

[stpltn250r]

I haven't ordered one yet. Talked to the mechanic and might go with a bigger Carb. 54 or 56. I ordered both 3130 & 1785 filters. We will see.

[dirtracer]

Did you ever try the crankshop carbs. Has anybody try the crankshop carbs.

[Moser Racing]

Crankshop carbs work well, jmo try the 65x52 oval carb on that 685 single, we use them on our 800 twins (snowmobile race engines) with good results, 2-3 more hp than 56mm crankshop carb, or try the new 52mm lectron carbs, dyno'd 2 full mod 800 rotax engines last week with these new carbs and better than expected results, jmo any of these carbs will work well.

[dirtracer]

i'm currently running pwk bored out to 41mm. i what something with more midrange-topend power. what do you think about the CS 48/52 carb. i'm running it on a cr 500 motor.

[rsss396]

cpc use to make 48 round flat side carb that have allot of adjustment and use mikuni parts they are nice carbs

lectron has the field covered real good up to 48 and even 50 but the 52's are over priced

but then lectrons are known for it wide open tunability not its mid and low range

[dirtracer]

rsss396
I would like to see what would happen at 6K rpm with your motor if you had a 48mm lecrtron on your motor and what your motor would do with a bigger then 52mm carb on it.

[rsss396]

I will be testing the Lectron 52 I used last year on the dyno against a 56 crankshop sometime this spring

[stpltn250r]

I bought the 54mm T style CrankShop carb. Dual powerjets. Dual inlet bowl. Still got some bugs to work out. But its worked really well so far. Oh yeah. Its huge!!!!