anyone running the high cr rb head?

Questions and Answers about the best carb and Head mods available for the KDX.
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BobbyZ
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anyone running the high cr rb head?

Post by BobbyZ »

well like it says in the title I am planning on doing the head mod,carb bore set up for race gas on my 93 motor thats going into a 03-05 125 mx frame.I like to run race gas for 2 reasons,peace of mind from the ethanol gas and I feel that the lead may help with lubrication........oh and more power Partyman

current mods are PC pipe shorty silencer no arrestor,2mm over bore with a old frp port job and plans to switch to the v force reeds and block over my current boysens with rad valve and the bike is just going to be a play pit rider seeing the occasional trail ride from pit to pit and or day at the track............I'll have another e series for the trail days ;)

anybody running it? impressions etc?

Thanks Rob
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fuzzy
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Post by fuzzy »

It won't hurt your motors trail performance. Compression helps everywhere. Just ensures that you have to have your own fuel, or race gas available at fill-up.

No ethanol is nice...ethanol attracts water, which is bad. No need for lead, can run unleaded race gas. Lead Lubricates/cushions valves, not rings. Nice thing about it is it's very consistent batch to batch, and you can jet to the gnat's ass.
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
IdahoCharley
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Post by IdahoCharley »

" ...Compression helps everywhere..."

Without any other changes it can actually hurt over rev and high rpms.

Higher compression certainly has its own advantages but for every significant change there can be a performance cost somewhere else. Higher compression in general on a typical stock KDX motor will likely benefit the lower and mid-power areas. You may lose some of the limited over rev on the 200 motor - don't know squat about how it may affect the 220 engine. Changes in ignition advance may be able to get back some of the lost in the 200 but again it will give up some of the lower end just gained in the bottom end of the rpm range. Trade-offs.
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riggy
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Post by riggy »

I had my head and carb done by ron at the same time . so I can only comment on both together . I noticed faster throttle response more power through all the gears , seems the bottom to mid was the big gain with the carb and head work . I would recommend it worth every penny imo . :supz:
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