OzVMX Forum

Clubroom => Tech Talk => Topic started by: NRD on April 24, 2009, 07:14:00 pm

Title: Carb size
Post by: NRD on April 24, 2009, 07:14:00 pm

Hi guys
Would a 38mm carb fitted to a KLX instead of the original 32mm be too big?  Thanks.

Title: Re: Carb size
Post by: JC on April 25, 2009, 09:15:17 am

I would have tho't so since they're only a 2valve engine so have limited breathing capacity. Perhaps ream the 32 a little??? Or maybe try 34mm

Derail would have a better idea but he doesn't seem to have been on the forum for ages. I'm fairly sure he uses stock 32mm carb, even on his bored & stroked KLX (to about 300) & I've seen his racing against open class 2strokes very competitively. ie at the pointy end. You could do a search for Derail & PM him.

Title: Re: Carb size
Post by: NRD on April 25, 2009, 11:44:57 am

Thanks JC
I'll see if I can contact derail and see what he says.
Cheers.

Title: Re: Carb size
Post by: LWC82PE on April 25, 2009, 01:39:33 pm

and they had already increased the size on the KLX from 28? on the STD KL250.

Title: Re: Carb size
Post by: NRD on April 26, 2009, 09:44:32 am

I don't really WANT to put a 38mm carb on but I can get a lectron  cheap and was wondering if it will work. I have discovered that the filter side is too big anyway and won't fit the boot onto the airbox. Thanks for your input.

Title: Re: Carb size
Post by: derail on April 26, 2009, 07:08:13 pm

Hi NRD, I have a couple of KLX250, one is 260cc and the other is around 300cc, I use 36mm carbs on both of them without any problem, I think 38mm might be a bit big and agree with JC, the biggest problem is getting the KLX breathing better. Be sure to put an 1-1/2" exhaust on it and open up the air box. The best gain is spending some time and getting the jetting correct, that way it punches right across the rev range. Others would know more about carbs than me but my memories of early Lectron carbs is that they were good at high revs (i.e road racing) but not so responsive down low.
I think a standard carb off a DR400 is 36mm and has an adjustable fuel jet in the pilot circuit-  easy starting both hot and cold.
 hope this helps

Cheers, Derail

Title: Re: Carb size
Post by: JC on April 27, 2009, 08:42:17 am

Derail,

Have you got the 260 up & running now? If so, how does it go?

Title: Re: Carb size
Post by: derail on April 27, 2009, 07:45:23 pm

JC, I only recently got the 260 finished. Had it running and rode it up and down the road to get the jetting close. I'll take it to cd6 and get it on a track before I make final judgement but it seems to go ok
If i can, I'll attach an image

Title: Re: Carb size
Post by: NRD on April 28, 2009, 10:26:09 pm

Thanks derail. I hope to make it to cd6 so I'll try and track you down for a chat.
Cheers.